National Library of Energy BETA

Sample records for turbulent jet ignition

  1. Plasma jet ignition device

    DOE Patents [OSTI]

    McIlwain, Michael E.; Grant, Jonathan F.; Golenko, Zsolt; Wittstein, Alan D.

    1985-01-15

    An ignition device of the plasma jet type is disclosed. The device has a cylindrical cavity formed in insulating material with an electrode at one end. The other end of the cylindrical cavity is closed by a metal plate with a small orifice in the center which plate serves as a second electrode. An arc jumping between the first electrode and the orifice plate causes the formation of a highly-ionized plasma in the cavity which is ejected through the orifice into the engine cylinder area to ignite the main fuel mixture. Two improvements are disclosed to enhance the operation of the device and the length of the plasma plume. One improvement is a metal hydride ring which is inserted in the cavity next to the first electrode. During operation, the high temperature in the cavity and the highly excited nature of the plasma breaks down the metal hydride, liberating hydrogen which acts as an additional fuel to help plasma formation. A second improvement consists of a cavity insert containing a plurality of spaced, metal rings. The rings act as secondary spark gap electrodes reducing the voltage needed to maintain the initial arc in the cavity.

  2. Impulsively started incompressible turbulent jet

    SciTech Connect (OSTI)

    Witze, P O

    1980-10-01

    Hot-film anemometer measurements are presented for the centerline velocity of a suddenly started jet of air. The tip penetration of the jet is shown to be proportional to the square-root of time. A theoretical model is developed that assumes the transient jet can be characterized as a spherical vortex interacting with a steady-state jet. The model demonstrates that the ratio of nozzle radius to jet velocity defines a time constant that uniquely characterizes the behavior and similarity of impulsively started incompressible turbulent jets.

  3. PDF Study of Round Turbulent Condensing Jet using GPU Hardware...

    Office of Scientific and Technical Information (OSTI)

    Conference: PDF Study of Round Turbulent Condensing Jet using GPU Hardware. Citation Details In-Document Search Title: PDF Study of Round Turbulent Condensing Jet using GPU ...

  4. DNS of a turbulent lifted DME jet flame

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Minamoto, Yuki; Chen, Jacqueline H.

    2016-05-07

    A three-dimensional direct numerical simulation (DNS) of a turbulent lifted dimethyl ether (DME) slot jet flame was performed at elevated pressure to study interactions between chemical reactions with low-temperature heat release (LTHR), negative temperature coefficient (NTC) reactions and shear generated turbulence in a jet in a heated coflow. By conditioning on mixture fraction, local reaction zones and local heat release rate, the turbulent flame is revealed to exhibit a “pentabrachial” structure that was observed for a laminar DME lifted flame [Krisman et al., (2015)]. The propagation characteristics of the stabilization and triple points are also investigated. Potential stabilization points, spatialmore » locations characterized by preferred temperature and mixture fraction conditions, exhibit autoignition characteristics with large reaction rate and negligible molecular diffusion. The actual stabilization point which coincides with the most upstream samples from the pool of potential stabilization points fovr each spanwise location shows passive flame structure with large diffusion. The propagation speed along the stoichiometric surface near the triple point is compared with the asymptotic value obtained from theory [Ruetsch et al., (1995)]. At stoichiometric conditions, the asymptotic and averaged DNS values of flame displacement speed deviate by a factor of 1.7. However, accounting for the effect of low-temperature species on the local flame speed increase, these two values become comparable. In conclusion, this suggests that the two-stage ignition influences the triple point propagation speed through enhancement of the laminar flame speed in a configuration where abundant low-temperature products from the first stage, low-temperature ignition are transported to the lifted flame by the high-velocity jet.« less

  5. The deterministic chaos and random noise in turbulent jet

    SciTech Connect (OSTI)

    Yao, Tian-Liang; Liu, Hai-Feng Xu, Jian-Liang; Li, Wei-Feng

    2014-06-01

    A turbulent flow is usually treated as a superposition of coherent structure and incoherent turbulence. In this paper, the largest Lyapunov exponent and the random noise in the near field of round jet and plane jet are estimated with our previously proposed method of chaotic time series analysis [T. L. Yao, et al., Chaos 22, 033102 (2012)]. The results show that the largest Lyapunov exponents of the round jet and plane jet are in direct proportion to the reciprocal of the integral time scale of turbulence, which is in accordance with the results of the dimensional analysis, and the proportionality coefficients are equal. In addition, the random noise of the round jet and plane jet has the same linear relation with the Kolmogorov velocity scale of turbulence. As a result, the random noise may well be from the incoherent disturbance in turbulence, and the coherent structure in turbulence may well follow the rule of chaotic motion.

  6. Structure of hydrogen-rich transverse jets in a vitiated turbulent flow

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lyra, Sgouria; Wilde, Benjamin; Kolla, Hemanth; Seitzman, Jerry M.; Lieuwen, Timothy C.; Chen, Jacqueline H.

    2014-11-24

    Our paper reports the results of a joint experimental and numerical study of the flow characteristics and flame structure of a hydrogen rich jet injected normal to a turbulent, vitiated crossflow of lean methane combustion products. Simultaneous high-speed stereoscopic PIV and OH PLIF measurements were obtained and analyzed alongside three-dimensional direct numerical simulations of inert and reacting JICF with detailed H2/COH2/CO chemistry. Both the experiment and the simulation reveal that, contrary to most previous studies of reacting JICF stabilized in low-to-moderate temperature air crossflow, the present conditions lead to a burner-attached flame that initiates uniformly around the burner edge. Significantmore » asymmetry is observed, however, between the reaction zones located on the windward and leeward sides of the jet, due to the substantially different scalar dissipation rates. The windward reaction zone is much thinner in the near field, while also exhibiting significantly higher local and global heat release than the much broader reaction zone found on the leeward side of the jet. The unsteady dynamics of the windward shear layer, which largely control the important jet/crossflow mixing processes in that region, are explored in order to elucidate the important flow stability implications arising in the inert and reacting JICF. The paper concludes with an analysis of the ignition, flame characteristics, and global structure of the burner-attached flame. FurthermoreChemical explosive mode analysis (CEMA) shows that the entire windward shear layer, and a large region on the leeward side of the jet, are highly explosive prior to ignition and are dominated by non-premixed flame structures after ignition. The predominantly mixing limited nature of the flow after ignition is examined by computing the Takeno flame index, which shows that ~70% of the heat release occurs in non-premixed regions.« less

  7. Structure of hydrogen-rich transverse jets in a vitiated turbulent flow

    SciTech Connect (OSTI)

    Lyra, Sgouria; Wilde, Benjamin; Kolla, Hemanth; Seitzman, Jerry M.; Lieuwen, Timothy C.; Chen, Jacqueline H.

    2014-11-24

    Our paper reports the results of a joint experimental and numerical study of the flow characteristics and flame structure of a hydrogen rich jet injected normal to a turbulent, vitiated crossflow of lean methane combustion products. Simultaneous high-speed stereoscopic PIV and OH PLIF measurements were obtained and analyzed alongside three-dimensional direct numerical simulations of inert and reacting JICF with detailed H2/COH2/CO chemistry. Both the experiment and the simulation reveal that, contrary to most previous studies of reacting JICF stabilized in low-to-moderate temperature air crossflow, the present conditions lead to a burner-attached flame that initiates uniformly around the burner edge. Significant asymmetry is observed, however, between the reaction zones located on the windward and leeward sides of the jet, due to the substantially different scalar dissipation rates. The windward reaction zone is much thinner in the near field, while also exhibiting significantly higher local and global heat release than the much broader reaction zone found on the leeward side of the jet. The unsteady dynamics of the windward shear layer, which largely control the important jet/crossflow mixing processes in that region, are explored in order to elucidate the important flow stability implications arising in the inert and reacting JICF. The paper concludes with an analysis of the ignition, flame characteristics, and global structure of the burner-attached flame. FurthermoreChemical explosive mode analysis (CEMA) shows that the entire windward shear layer, and a large region on the leeward side of the jet, are highly explosive prior to ignition and are dominated by non-premixed flame structures after ignition. The predominantly mixing limited nature of the flow after ignition is examined by computing the Takeno flame index, which shows that ~70% of the heat release occurs in non-premixed regions.

  8. Numerical calculation of two-phase turbulent jets

    SciTech Connect (OSTI)

    Saif, A.A.

    1995-05-01

    Two-phase turbulent round jets were numerically simulated using a multidimensional two-phase CFD code based on the two-fluid model. The turbulence phenomena were treated with the standard k-{epsilon} model. It was modified to take into account the additional dissipation of turbulent kinetic energy by the dispersed phase. Within the context of the two-fluid model it is more appropriate and physically justified to treat the diffusion by an interfacial force in the momentum equation. In this work, the diffusion force and the additional dissipation effect by the dispersed phase were modeled starting from the classical turbulent energy spectrum analysis. A cut-off frequency was proposed to decrease the dissipation effect by the dispersed phase when large size particles are introduced in the flow. The cut-off frequency combined with the bubble-induced turbulence effect allows for an increase in turbulence for large particles. Additional care was taken in choosing the right kind of experimental data from the literature so that a good separate effect test was possible for their models. The models predicted the experimental data very closely and they were general enough to predict extreme limit cases: water-bubble and air-droplet jets.

  9. Large-eddy simulation of turbulent circular jet flows

    SciTech Connect (OSTI)

    Jones, S. C.; Sotiropoulos, F.; Sale, M. J.

    2002-07-01

    This report presents a numerical method for carrying out large-eddy simulations (LES) of turbulent free shear flows and an application of a method to simulate the flow generated by a nozzle discharging into a stagnant reservoir. The objective of the study was to elucidate the complex features of the instantaneous flow field to help interpret the results of recent biological experiments in which live fish were exposed to the jet shear zone. The fish-jet experiments were conducted at the Pacific Northwest National Laboratory (PNNL) under the auspices of the U.S. Department of Energys Advanced Hydropower Turbine Systems program. The experiments were designed to establish critical thresholds of shear and turbulence-induced loads to guide the development of innovative, fish-friendly hydropower turbine designs.

  10. Auto-ignition during instationary jet evolution of dimethyl ether (DME) in a high-pressure atmosphere

    SciTech Connect (OSTI)

    Fast, G.; Kuhn, D.; Class, A.G.; Maas, U.

    2009-01-15

    The auto-ignition process during transient injection of gaseous dimethyl ether (DME) in a constant high-pressure atmosphere is studied experimentally by laser-optical methods and compared with numerical calculations. With different non-intrusive measurement techniques jet properties and auto-ignition are investigated at high temporal and spatial resolution. The open jet penetrates a constant pressure oxidative atmosphere of up to 4 MPa. During the transient evolution, the fuel jet entrains air at up to 720 K. The subsequent auto-ignition of the ignitable part of the jet occurs simultaneously over a wide spatial extension. The ignition delay times are not affected by variation of the nozzle exit velocity. Thus, the low-temperature oxidation is slow compared with the shorter time scales of mixing, so that chemical kinetics is dominating the process. The typical two-stage ignition is resolved optically with high-speed shadowgraphy at a sampling rate of 10 kHz. The 2D fields of jet velocity and transient mixture fraction are measured phase-coupled with Particle Image Velocimetry (PIV) and Tracer Laser Induced Fluorescence (LIF) during the time-frame of ignition. The instationary Probability Density Functions (PDF) of mixture fraction are described very well by Beta functions within the complete area of the open jet. Additional 1D flamelet simulations of the auto-ignition process are computed with a detailed reaction mechanism for DME [S. Fischer, F. Dryer, H. Curran, Int. J. Chem. Kinet. 32 (12) (2000) 713-740; H. Curran, S. Fischer, F. Dryer, Int. J. Chem. Kinet. 32 (12) (2000) 741-759]. Calculated ignition delay times are in very good agreement with the measured mean ignition delay times of 3 ms. Supplemental flamelet simulations address the influence of DME and air temperature, pressure and strain. Underneath a critical strain rate the air temperature is identified to be the most sensitive factor on ignition delay time. (author)

  11. Oscillations of a Turbulent Jet Incident Upon an Edge

    SciTech Connect (OSTI)

    J.C. Lin; D. Rockwell

    2000-09-19

    For the case of a jet originating from a fully turbulent channel flow and impinging upon a sharp edge, the possible onset and nature of coherent oscillations has remained unexplored. In this investigation, high-image-density particle image velocimetry and surface pressure measurements are employed to determine the instantaneous, whole-field characteristics of the turbulent jet-edge interaction in relation to the loading of the edge. It is demonstrated that even in absence of acoustic resonant or fluid-elastic effects, highly coherent, self-sustained oscillations rapidly emerge above the turbulent background. Two clearly identifiable modes of instability are evident. These modes involve large-scale vortices that are phase-locked to the gross undulations of the jet and its interaction with the edge, and small-scale vortices, which are not phase-locked. Time-resolved imaging of instantaneous vorticity and velocity reveals the form, orientation, and strength of the large-scale concentrations of vorticity approaching the edge in relation to rapid agglomeration of small-scale vorticity concentrations. Such vorticity field-edge interactions exhibit rich complexity, relative to the simplified pattern of vortex-edge interaction traditionally employed for the quasi-laminar edgetone. Furthermore, these interactions yield highly nonlinear surface pressure signatures. The origin of this nonlinearity, involving coexistence of multiple frequency components, is interpreted in terms of large- and small-scale vortices embedded in distributed vorticity layers at the edge. Eruption of the surface boundary layer on the edge due to passage of the large-scale vortex does not occur; rather apparent secondary vorticity concentrations are simply due to distension of the oppositely-signed vorticity layer at the tip of the edge. The ensemble-averaged turbulent statistics of the jet quickly take on an identity that is distinct from the statistics of the turbulent boundary layer in the channel

  12. Spark ignited turbulent flame kernel growth. Annual report, January--December, 1992

    SciTech Connect (OSTI)

    Santavicca, D.A.

    1994-06-01

    Cyclic combustion variations in spark-ignition engines limit the use of dilute charge strategies for achieving low NO{sub x} emissions and improved fuel economy. Results from an experimental study of the effect of incomplete fuel-air mixing (ifam) on spark-ignited flame kernel growth in turbulent propane-air mixtures are presented. The experiments were conducted in a turbulent flow system that allows for independent variation of flow parameters, ignition system parameters, and the degree of fuel-air mixing. Measurements were made at 1 atm and 300 K conditions. Five cases were studied; a premixed and four incompletely mixed cases with 6%, 13%, 24% and 33% RMS (root-mean-square) fluctuations in the fuel/air equivalence ratio. High speed laser shadowgraphy at 4,000 frames-per-second was used to record flame kernel growth following spark ignition, from which the equivalent flame kernel radius as a function of time was determined. The effect of ifam was evaluated in terms of the flame kernel growth rate, cyclic variations in the flame kernel growth, and the rate of misfire. The results show that fluctuations in local mixture strength due to ifam cause the flame kernel surface to become wrinkled and distorted; and that the amount of wrinkling increases as the degree of ifam. Ifam was also found to result in a significant increase in cyclic variations in the flame kernel growth. The average flame kernel growth rates for the premixed and the incompletely mixed cases were found to be within the experimental uncertainty except for the 33%-RMS-fluctuation case where the growth rate is significantly lower. The premixed and 6%-RMS-fluctuation cases had a 0% misfire rate. The misfire rates were 1% and 2% for the 13%-RMS-fluctuation and 24%-RMS-fluctuation cases, respectively; however, it drastically increased to 23% in the 33%-RMS-fluctuation case.

  13. ANALYSIS OF TURBULENT MIXING JETS IN LARGE SCALE TANK

    SciTech Connect (OSTI)

    Lee, S; Richard Dimenna, R; Robert Leishear, R; David Stefanko, D

    2007-03-28

    Flow evolution models were developed to evaluate the performance of the new advanced design mixer pump for sludge mixing and removal operations with high-velocity liquid jets in one of the large-scale Savannah River Site waste tanks, Tank 18. This paper describes the computational model, the flow measurements used to provide validation data in the region far from the jet nozzle, the extension of the computational results to real tank conditions through the use of existing sludge suspension data, and finally, the sludge removal results from actual Tank 18 operations. A computational fluid dynamics approach was used to simulate the sludge removal operations. The models employed a three-dimensional representation of the tank with a two-equation turbulence model. Both the computational approach and the models were validated with onsite test data reported here and literature data. The model was then extended to actual conditions in Tank 18 through a velocity criterion to predict the ability of the new pump design to suspend settled sludge. A qualitative comparison with sludge removal operations in Tank 18 showed a reasonably good comparison with final results subject to significant uncertainties in actual sludge properties.

  14. Laminar and turbulent nozzle-jet flows and their acoustic near-field

    SciTech Connect (OSTI)

    Bhler, Stefan; Obrist, Dominik; Kleiser, Leonhard

    2014-08-15

    We investigate numerically the effects of nozzle-exit flow conditions on the jet-flow development and the near-field sound at a diameter-based Reynolds number of Re{sub D} = 18?100 and Mach number Ma = 0.9. Our computational setup features the inclusion of a cylindrical nozzle which allows to establish a physical nozzle-exit flow and therefore well-defined initial jet-flow conditions. Within the nozzle, the flow is modeled by a potential flow core and a laminar, transitional, or developing turbulent boundary layer. The goal is to document and to compare the effects of the different jet inflows on the jet flow development and the sound radiation. For laminar and transitional boundary layers, transition to turbulence in the jet shear layer is governed by the development of Kelvin-Helmholtz instabilities. With the turbulent nozzle boundary layer, the jet flow development is characterized by a rapid changeover to a turbulent free shear layer within about one nozzle diameter. Sound pressure levels are strongly enhanced for laminar and transitional exit conditions compared to the turbulent case. However, a frequency and frequency-wavenumber analysis of the near-field pressure indicates that the dominant sound radiation characteristics remain largely unaffected. By applying a recently developed scaling procedure, we obtain a close match of the scaled near-field sound spectra for all nozzle-exit turbulence levels and also a reasonable agreement with experimental far-field data.

  15. Ignition of ethane, propane, and butane in counterflow jets of cold fuel versus hot air under variable pressures

    SciTech Connect (OSTI)

    Fotache, C.G.; Wang, H.; Law, C.K.

    1999-06-01

    This study investigates experimentally the nonpremixed ignition of ethane, propane, n-butane, and isobutane in a configuration of opposed fuel versus heated air jets. For each of these fuels the authors explore the effects of inert dilution, system pressure, and flow strain rate, for fuel concentrations ranging between 3--100% by volume, pressures between 0.2 and 8 atm, and strain rates of 100--600 s{sup {minus}1}. Qualitatively, these fuels share a number of characteristics. First, flame ignition typically occurs after an interval of mild oxidation, characterized by minimal heat release, fuel conversion, and weak light emission. The temperature extent of this regime decreases with increasing the fuel concentration, the ambient pressure, or the flow residence time. Second, the response to strain rate, pressure, and fuel concentration is similar for all investigated fuels, in that the ignition temperatures monotonically decrease with increasing fuel content, decreasing flow strain, and increasing ambient pressure. The C{sub 4} alkanes, however, exhibit three distinct p-T ignition regimes, similar to the homogeneous explosion limits. Finally, at 1 atm, 100% fuel, and a fixed flow strain rate the ignition temperature increases in the order of ethane < propane < n-butane < i-butane. Numerical simulation was conducted for ethane ignition using detailed reaction kinetics and transport descriptions. The modeling results suggest that ignition for all fuels studied at pressures below 5 atm is initiated by fuel oxidation following the high-temperature mechanism of radical chain branching and with little contribution by low-to-intermediate temperature chemistry.

  16. Flow topologies and turbulence scales in a jet-in-cross-flow

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Oefelein, Joseph C.; Ruiz, Anthony M.; Lacaze, Guilhem

    2015-04-03

    This study presents a detailed analysis of the flow topologies and turbulence scales in the jet-in-cross-flow experiment of [Su and Mungal JFM 2004]. The analysis is performed using the Large Eddy Simulation (LES) technique with a highly resolved grid and time-step and well controlled boundary conditions. This enables quantitative agreement with the first and second moments of turbulence statistics measured in the experiment. LES is used to perform the analysis since experimental measurements of time-resolved 3D fields are still in their infancy and because sampling periods are generally limited with direct numerical simulation. A major focal point is the comprehensivemore » characterization of the turbulence scales and their evolution. Time-resolved probes are used with long sampling periods to obtain maps of the integral scales, Taylor microscales, and turbulent kinetic energy spectra. Scalar-fluctuation scales are also quantified. In the near-field, coherent structures are clearly identified, both in physical and spectral space. Along the jet centerline, turbulence scales grow according to a classical one-third power law. However, the derived maps of turbulence scales reveal strong inhomogeneities in the flow. From the modeling perspective, these insights are useful to design optimized grids and improve numerical predictions in similar configurations.« less

  17. Flow topologies and turbulence scales in a jet-in-cross-flow

    SciTech Connect (OSTI)

    Oefelein, Joseph C.; Ruiz, Anthony M.; Lacaze, Guilhem

    2015-04-03

    This study presents a detailed analysis of the flow topologies and turbulence scales in the jet-in-cross-flow experiment of [Su and Mungal JFM 2004]. The analysis is performed using the Large Eddy Simulation (LES) technique with a highly resolved grid and time-step and well controlled boundary conditions. This enables quantitative agreement with the first and second moments of turbulence statistics measured in the experiment. LES is used to perform the analysis since experimental measurements of time-resolved 3D fields are still in their infancy and because sampling periods are generally limited with direct numerical simulation. A major focal point is the comprehensive characterization of the turbulence scales and their evolution. Time-resolved probes are used with long sampling periods to obtain maps of the integral scales, Taylor microscales, and turbulent kinetic energy spectra. Scalar-fluctuation scales are also quantified. In the near-field, coherent structures are clearly identified, both in physical and spectral space. Along the jet centerline, turbulence scales grow according to a classical one-third power law. However, the derived maps of turbulence scales reveal strong inhomogeneities in the flow. From the modeling perspective, these insights are useful to design optimized grids and improve numerical predictions in similar configurations.

  18. Structure of turbulent hydrogen jet diffusion flames with or without swirl

    SciTech Connect (OSTI)

    Takahashi, Fumiaki; Vangsness, M.D.; Durbin, M.D.; Schmoll, W.J.

    1995-12-31

    The aerodynamic and thermal structure of double-concentric turbulent hydrogen jet diffusion flames with or without swirl has been investigated using three-component laser-Doppler velocimetry (LDV) and coherent anti-Stokes Raman spectroscopy. The LDV data were conditionally sampled upon the origin of the fluid (jet, annulus, or external) to avoid the velocity-bias problem and to gain more detailed information on the turbulent structure. As the mean jet velocity was increased, the turbulent flame zone shifted inward and the thermal layer became thinner, whereas swirl created a radial velocity even at the annulus air exit, thereby shifting the flame zone outward and broadening the thermal layer. The probability-density functions (pdf) of velocity components,m their 21 moments (up to fourth order), temperature pdf, mean, and root-mean-square fluctuation temperature were determined at numerous radial locations at seven axial heights in the near field (<26.5 jet diameters). The data can be used to validate computational models.

  19. TiO{sub 2} Film Deposition by Atmospheric Thermal Plasma CVD Using Laminar and Turbulence Plasma Jets

    SciTech Connect (OSTI)

    Ando, Yasutaka; Tobe, Shogo [Ashikaga Institute of Technology, 268-1 Omae, Ashikaga, Tochigi 326-8558 (Japan); Tahara, Hirokazu [Osaka Institute of Technology, 5-16-1 Omiya, Asahi-Ku, Osaka 535-8585 (Japan)

    2008-02-21

    In this study, to provide continuous plasma atmosphere on the substrate surface in the case of atmospheric thermal plasma CVD, TiO{sub 2} film deposition by thermal plasma CVD using laminar plasma jet was carried out. For comparison, the film deposition using turbulence plasma jet was conducted as well. Consequently, transition of the plasma jet from laminar to turbulent occurred on the condition of over 3.5 1/min in Ar working gas flow rate and the plasma jet became turbulent on the condition of over 10 1/min. In the case of the turbulent plasma jet use, anatase rich titanium oxide film could be obtained though plasma jet could not contact with the surface of the substrate continuously even on the condition that feedstock material was injected into the plasma jet. On the other hand,, in the case of laminar gas flow rate, the plasma jet could contact with the substrate continuously without melt down of the substrate during film deposition. Besides, titanium oxide film could be obtained even in the case of the laminar plasma jet use. From these results, this technique was thought to have high potential for atmospheric thermal plasma CVD.

  20. Flow, Mixing and Combustion of Transient Turbulent Gaseous Jets in Confined

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Cylindrical Geometries | Argonne Leadership Computing Facility Flow, Mixing and Combustion of Transient Turbulent Gaseous Jets in Confined Cylindrical Geometries PI Name: Christos Frouzakis PI Email: frouzakis@lav.mavt.ethz.ch Institution: Swiss Federal Institute of Technology Zurich (ETHZ) Allocation Program: ESP Year: 2015 Research Domain: Engineering Tier 2 Code Development Project Numerical Methods/Algorithms Direct numerical simulations for this project will be based on the open source

  1. Understanding and predicting soot generation in turbulent non-premixed jet flames.

    SciTech Connect (OSTI)

    Wang, Hai; Kook, Sanghoon; Doom, Jeffrey; Oefelein, Joseph Charles; Zhang, Jiayao; Shaddix, Christopher R.; Schefer, Robert W.; Pickett, Lyle M.

    2010-10-01

    This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogate fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame measurements revealed that flame temperature has a strong impact on the rate of soot nucleation and particle coagulation, but little sensitivity in the overall trends was found with different fuels. An extensive array of non-intrusive optical and laser-based measurements was performed in turbulent non-premixed jet flames established on specially designed piloted burners. Soot concentration data was collected throughout the flames, together with instantaneous images showing the relationship between soot and the OH radical and soot and PAH. A detailed chemical kinetic mechanism for ethylene combustion, including fuel-rich chemistry and benzene formation steps, was compiled, validated, and reduced. The reduced ethylene mechanism was incorporated into a high-fidelity LES code, together with a moment-based soot model and models for thermal radiation, to evaluate the ability of the chemistry and soot models to predict soot formation in the jet diffusion flame. The LES results highlight the importance of including an optically-thick radiation model

  2. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore » the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.« less

  3. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane air jet flames

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methaneair chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methaneair mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmorethe boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.less

  4. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames

    SciTech Connect (OSTI)

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall on the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.

  5. Global NOx Measurements in Turbulent Nitrogen-Diluted Hydrogen Jet Flames

    SciTech Connect (OSTI)

    Weiland, N.T.; Strakey, P.A.

    2007-03-01

    Turbulent hydrogen diffusion flames diluted with nitrogen are currently being studied to assess their ability to achieve the DOE Turbine Programs aggressive emissions goal of 2 ppm NOx in a hydrogen-fueled IGCC gas turbine combustor. Since the unstrained adiabatic flame temperatures of these diluted flames are not low enough to eliminate thermal NOx formation the focus of the current work is to study how the effects of flame residence time and global flame strain can be used to help achieve the stated NOx emissions goal. Dry NOx measurements are presented as a function of jet diameter nitrogen dilution and jet velocity for a turbulent hydrogen/nitrogen jet issuing from a thin-lipped tube in an atmospheric pressure combustor. The NOx emission indices from these experiments are normalized by the flame residence time to ascertain the effects of global flame strain and fuel Lewis Number on the NOx emissions. In addition dilute hydrogen diffusion flame experiments were performed in a high-pressure combustor at 2 4 and 8 atm. The NOx emission data from these experiments are discussed as well as the results from a Computational Fluid Dynamics modeling effort currently underway to help explain the experimental data.

  6. The application of complex network time series analysis in turbulent heated jets

    SciTech Connect (OSTI)

    Charakopoulos, A. K.; Karakasidis, T. E. Liakopoulos, A.; Papanicolaou, P. N.

    2014-06-15

    In the present study, we applied the methodology of the complex network-based time series analysis to experimental temperature time series from a vertical turbulent heated jet. More specifically, we approach the hydrodynamic problem of discriminating time series corresponding to various regions relative to the jet axis, i.e., time series corresponding to regions that are close to the jet axis from time series originating at regions with a different dynamical regime based on the constructed network properties. Applying the transformation phase space method (k nearest neighbors) and also the visibility algorithm, we transformed time series into networks and evaluated the topological properties of the networks such as degree distribution, average path length, diameter, modularity, and clustering coefficient. The results show that the complex network approach allows distinguishing, identifying, and exploring in detail various dynamical regions of the jet flow, and associate it to the corresponding physical behavior. In addition, in order to reject the hypothesis that the studied networks originate from a stochastic process, we generated random network and we compared their statistical properties with that originating from the experimental data. As far as the efficiency of the two methods for network construction is concerned, we conclude that both methodologies lead to network properties that present almost the same qualitative behavior and allow us to reveal the underlying system dynamics.

  7. Probability density function treatment of turbulence/chemistry interactions during the ignition of a temperature-stratified mixture for application to HCCI engine modeling

    SciTech Connect (OSTI)

    Bisetti, Fabrizio; Chen, J.-Y.; Hawkes, Evatt R.; Chen, Jacqueline H.

    2008-12-15

    Homogeneous charge compression ignition (HCCI) engine technology promises to reduce NO{sub x} and soot emissions while achieving high thermal efficiency. Temperature and mixture stratification are regarded as effective means of controlling the start of combustion and reducing the abrupt pressure rise at high loads. Probability density function methods are currently being pursued as a viable approach to modeling the effects of turbulent mixing and mixture stratification on HCCI ignition. In this paper we present an assessment of the merits of three widely used mixing models in reproducing the moments of reactive scalars during the ignition of a lean hydrogen/air mixture ({phi}=0.1, p=41atm, and T=1070 K) under increasing temperature stratification and subject to decaying turbulence. The results from the solution of the evolution equation for a spatially homogeneous joint PDF of the reactive scalars are compared with available direct numerical simulation (DNS) data [E.R. Hawkes, R. Sankaran, P.P. Pebay, J.H. Chen, Combust. Flame 145 (1-2) (2006) 145-159]. The mixing models are found able to quantitatively reproduce the time history of the heat release rate, first and second moments of temperature, and hydroxyl radical mass fraction from the DNS results. Most importantly, the dependence of the heat release rate on the extent of the initial temperature stratification in the charge is also well captured. (author)

  8. Experimental study of vorticity-strain rate interaction in turbulent partially-premixed jet flames using tomographic particle image velocimetry

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Coriton, Bruno; Frank, Jonathan H.

    2016-02-16

    In turbulent flows, the interaction between vorticity, ω, and strain rate, s, is considered a primary mechanism for the transfer of energy from large to small scales through vortex stretching. The ω-s coupling in turbulent jet flames is investigated using tomographic particle image velocimetry (TPIV). TPIV provides a direct measurement of the three-dimensional velocity field from which ω and s are determined. The effects of combustion and mean shear on the ω-s interaction are investigated in turbulent partially premixed methane/air jet flames with high and low probabilities of localized extinction as well as in a non-reacting isothermal air jet withmore » Reynolds number of approximately 13,000. Results show that combustion causes structures of high vorticity and strain rate to agglomerate in highly correlated, elongated layers that span the height of the probe volume. In the non-reacting jet, these structures have a more varied morphology, greater fragmentation, and are not as well correlated. The enhanced spatiotemporal correlation of vorticity and strain rate in the stable flame results in stronger ω-s interaction characterized by increased enstrophy and strain-rate production rates via vortex stretching and straining, respectively. The probability of preferential local alignment between ω and the eigenvector of the intermediate principal strain rate, s2, which is intrinsic to the ω-s coupling in turbulent flows, is larger in the flames and increases with the flame stability. The larger mean shear in the flame imposes a preferential orientation of ω and s2 tangential to the shear layer. The extensive and compressive principal strain rates, s1 and s3, respectively, are preferentially oriented at approximately 45° with respect to the jet axis. As a result, the production rates of strain and vorticity tend to be dominated by instances in which ω is parallel to the s1¯-s2¯ plane and orthogonal to s3¯.« less

  9. The effect of turbulence on the stability of liquid jets and the resulting droplet size distributions. Third quarterly technical report, July 1, 1993--September 30, 1993

    SciTech Connect (OSTI)

    Mansour, A.; Chigier, N.

    1993-12-01

    Laminar and turbulent columns of liquids issuing from capillary tubes were studied in order to determine the effects of turbulence on the stability of liquid jets and to establish the influence of liquid turbulence on droplet size distributions after breakup. Two capillary tubes were chosen with diameters D{sub 1}=3.0mm and D{sub 2}=1.2mm; jet Reynolds numbers were 1000--30000, and 400--7200. For water injection into stagnant air, stability curve is bounded by a laminar portion, where a jet radius and {delta}{sub o} initial disturbance amplitude, and a fully developed turbulent portion characterized by high initial disturbance amplitude (ln(a/{delta}{sub o,T}) {approximately} 4.85). In the transition region, ln(a/{delta}{sub o}) is not single valued; it decreases with increasing Reynolds number. In absence of aerodynamic effects, turbulent jets are as stable as laminar jets. For this breakup mode turbulence propagates initial disturbances with amplitudes orders of magnitude larger than laminar jets ({delta}{sub o,T}=28{times}10{sup 6} {delta}{sub o,L}). Growth rates of initial disturbances are same for both laminar and turbulent columns with theoretical Weber values. Droplet size distribution is bi-modal; the number ratio of large (> D/2), to small (< D/2) droplets is 3 and independent of Reynolds number. For laminar flow optimum wavelength ({lambda}{sub opt}) corresponding to fastest growing disturbance is equal to 4.45D, exactly the theoretical Weber value. For turbulent flow conditions, the turbulent column segments. Typically, segments with lengths of one to several wavelengths, detach from the liquid jet. The long ligaments contract under the action of surface tension, resulting in droplet sizes larger than predicted by Rayleigh and Weber. For turbulent flow conditions, {lambda}{sub opt} = 9.2D, about 2 times the optimum Weber wavelength.

  10. Mechanisms of flame stabilisation at low lifted height in a turbulent lifted slot-jet flame

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Karami, Shahram; Hawkes, Evatt R.; Talei, Mohsen; Chen, Jacqueline H.

    2015-07-23

    A turbulent lifted slot-jet flame is studied using direct numerical simulation (DNS). A one-step chemistry model is employed with a mixture-fraction-dependent activation energy which can reproduce qualitatively the dependence of the laminar burning rate on the equivalence ratio that is typical of hydrocarbon fuels. The basic structure of the flame base is first examined and discussed in the context of earlier experimental studies of lifted flames. Several features previously observed in experiments are noted and clarified. Some other unobserved features are also noted. Comparison with previous DNS modelling of hydrogen flames reveals significant structural differences. The statistics of flow andmore » relative edge-flame propagation velocity components conditioned on the leading edge locations are then examined. The results show that, on average, the streamwise flame propagation and streamwise flow balance, thus demonstrating that edge-flame propagation is the basic stabilisation mechanism. Fluctuations of the edge locations and net edge velocities are, however, significant. It is demonstrated that the edges tend to move in an essentially two-dimensional (2D) elliptical pattern (laterally outwards towards the oxidiser, then upstream, then inwards towards the fuel, then downstream again). It is proposed that this is due to the passage of large eddies, as outlined in Suet al.(Combust. Flame, vol. 144 (3), 2006, pp. 494–512). However, the mechanism is not entirely 2D, and out-of-plane motion is needed to explain how flames escape the high-velocity inner region of the jet. Finally, the time-averaged structure is examined. A budget of terms in the transport equation for the product mass fraction is used to understand the stabilisation from a time-averaged perspective. The result of this analysis is found to be consistent with the instantaneous perspective. The budget reveals a fundamentally 2D structure, involving transport in both the streamwise and transverse

  11. Mechanisms of flame stabilisation at low lifted height in a turbulent lifted slot-jet flame

    SciTech Connect (OSTI)

    Karami, Shahram; Hawkes, Evatt R.; Talei, Mohsen; Chen, Jacqueline H.

    2015-07-23

    A turbulent lifted slot-jet flame is studied using direct numerical simulation (DNS). A one-step chemistry model is employed with a mixture-fraction-dependent activation energy which can reproduce qualitatively the dependence of the laminar burning rate on the equivalence ratio that is typical of hydrocarbon fuels. The basic structure of the flame base is first examined and discussed in the context of earlier experimental studies of lifted flames. Several features previously observed in experiments are noted and clarified. Some other unobserved features are also noted. Comparison with previous DNS modelling of hydrogen flames reveals significant structural differences. The statistics of flow and relative edge-flame propagation velocity components conditioned on the leading edge locations are then examined. The results show that, on average, the streamwise flame propagation and streamwise flow balance, thus demonstrating that edge-flame propagation is the basic stabilisation mechanism. Fluctuations of the edge locations and net edge velocities are, however, significant. It is demonstrated that the edges tend to move in an essentially two-dimensional (2D) elliptical pattern (laterally outwards towards the oxidiser, then upstream, then inwards towards the fuel, then downstream again). It is proposed that this is due to the passage of large eddies, as outlined in Suetal.(Combust. Flame, vol.144 (3), 2006, pp.494512). However, the mechanism is not entirely 2D, and out-of-plane motion is needed to explain how flames escape the high-velocity inner region of the jet. Finally, the time-averaged structure is examined. A budget of terms in the transport equation for the product mass fraction is used to understand the stabilisation from a time-averaged perspective. The result of this analysis is found to be consistent with the instantaneous perspective. The budget reveals a fundamentally 2D structure, involving transport in both the

  12. Mechanisms of flame stabilisation at low lifted height in a turbulent lifted slot-jet flame

    SciTech Connect (OSTI)

    Karami, Shahram; Hawkes, Evatt R.; Talei, Mohsen; Chen, Jacqueline H.

    2015-07-23

    A turbulent lifted slot-jet flame is studied using direct numerical simulation (DNS). A one-step chemistry model is employed with a mixture-fraction-dependent activation energy which can reproduce qualitatively the dependence of the laminar burning rate on the equivalence ratio that is typical of hydrocarbon fuels. The basic structure of the flame base is first examined and discussed in the context of earlier experimental studies of lifted flames. Several features previously observed in experiments are noted and clarified. Some other unobserved features are also noted. Comparison with previous DNS modelling of hydrogen flames reveals significant structural differences. The statistics of flow and relative edge-flame propagation velocity components conditioned on the leading edge locations are then examined. The results show that, on average, the streamwise flame propagation and streamwise flow balance, thus demonstrating that edge-flame propagation is the basic stabilisation mechanism. Fluctuations of the edge locations and net edge velocities are, however, significant. It is demonstrated that the edges tend to move in an essentially two-dimensional (2D) elliptical pattern (laterally outwards towards the oxidiser, then upstream, then inwards towards the fuel, then downstream again). It is proposed that this is due to the passage of large eddies, as outlined in Suet al.(Combust. Flame, vol. 144 (3), 2006, pp. 494–512). However, the mechanism is not entirely 2D, and out-of-plane motion is needed to explain how flames escape the high-velocity inner region of the jet. Finally, the time-averaged structure is examined. A budget of terms in the transport equation for the product mass fraction is used to understand the stabilisation from a time-averaged perspective. The result of this analysis is found to be consistent with the instantaneous perspective. The budget reveals a fundamentally 2D structure, involving transport in both

  13. Jet plume injection and combustion system for internal combustion engines

    DOE Patents [OSTI]

    Oppenheim, A.K.; Maxson, J.A.; Hensinger, D.M.

    1993-12-21

    An improved combustion system for an internal combustion engine is disclosed wherein a rich air/fuel mixture is furnished at high pressure to one or more jet plume generator cavities adjacent to a cylinder and then injected through one or more orifices from the cavities into the head space of the cylinder to form one or more turbulent jet plumes in the head space of the cylinder prior to ignition of the rich air/fuel mixture in the cavity of the jet plume generator. The portion of the rich air/fuel mixture remaining in the cavity of the generator is then ignited to provide a secondary jet, comprising incomplete combustion products which are injected into the cylinder to initiate combustion in the already formed turbulent jet plume. Formation of the turbulent jet plume in the head space of the cylinder prior to ignition has been found to yield a higher maximum combustion pressure in the cylinder, as well as shortening the time period to attain such a maximum pressure. 24 figures.

  14. Jet plume injection and combustion system for internal combustion engines

    DOE Patents [OSTI]

    Oppenheim, Antoni K.; Maxson, James A.; Hensinger, David M.

    1993-01-01

    An improved combustion system for an internal combustion engine is disclosed wherein a rich air/fuel mixture is furnished at high pressure to one or more jet plume generator cavities adjacent to a cylinder and then injected through one or more orifices from the cavities into the head space of the cylinder to form one or more turbulent jet plumes in the head space of the cylinder prior to ignition of the rich air/fuel mixture in the cavity of the jet plume generator. The portion of the rich air/fuel mixture remaining in the cavity of the generator is then ignited to provide a secondary jet, comprising incomplete combustion products which are injected into the cylinder to initiate combustion in the already formed turbulent jet plume. Formation of the turbulent jet plume in the head space of the cylinder prior to ignition has been found to yield a higher maximum combustion pressure in the cylinder, as well as shortening the time period to attain such a maximum pressure.

  15. Fast Ignition

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    fast ignition Fast Ignition Researchers Study Fast Ignition University of California at San Diego researchers participate in experiments on the Titan laser at LLNL's Jupiter Laser Facility to study fast ignition. The approach being taken by the National Ignition Facility to achieve thermonuclear ignition and burn is called the "central hot spot" scenario. This technique relies on simultaneous compression and ignition of a spherical fuel capsule in an implosion, roughly like in a diesel

  16. Effect of fuel composition and differential diffusion on flame stabilization in reacting syngas jets in turbulent cross-flow

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Minamoto, Yuki; Kolla, Hemanth; Grout, Ray W.; Gruber, Andrea; Chen, Jacqueline H.

    2015-07-24

    Here, three-dimensional direct numerical simulation results of a transverse syngas fuel jet in turbulent cross-flow of air are analyzed to study the influence of varying volume fractions of CO relative to H2 in the fuel composition on the near field flame stabilization. The mean flame stabilizes at a similar location for CO-lean and CO-rich cases despite the trend suggested by their laminar flame speed, which is higher for the CO-lean condition. To identify local mixtures having favorable mixture conditions for flame stabilization, explosive zones are defined using a chemical explosive mode timescale. The explosive zones related to flame stabilization aremore » located in relatively low velocity regions. The explosive zones are characterized by excess hydrogen transported solely by differential diffusion, in the absence of intense turbulent mixing or scalar dissipation rate. The conditional averages show that differential diffusion is negatively correlated with turbulent mixing. Moreover, the local turbulent Reynolds number is insufficient to estimate the magnitude of the differential diffusion effect. Alternatively, the Karlovitz number provides a better indicator of the importance of differential diffusion. A comparison of the variations of differential diffusion, turbulent mixing, heat release rate and probability of encountering explosive zones demonstrates that differential diffusion predominantly plays an important role for mixture preparation and initiation of chemical reactions, closely followed by intense chemical reactions sustained by sufficient downstream turbulent mixing. The mechanism by which differential diffusion contributes to mixture preparation is investigated using the Takeno Flame Index. The mean Flame Index, based on the combined fuel species, shows that the overall extent of premixing is not intense in the upstream regions. However, the Flame Index computed based on individual contribution of H2 or CO species reveals that hydrogen

  17. Effect of fuel composition and differential diffusion on flame stabilization in reacting syngas jets in turbulent cross-flow

    SciTech Connect (OSTI)

    Minamoto, Yuki; Kolla, Hemanth; Grout, Ray W.; Gruber, Andrea; Chen, Jacqueline H.

    2015-07-24

    Here, three-dimensional direct numerical simulation results of a transverse syngas fuel jet in turbulent cross-flow of air are analyzed to study the influence of varying volume fractions of CO relative to H2 in the fuel composition on the near field flame stabilization. The mean flame stabilizes at a similar location for CO-lean and CO-rich cases despite the trend suggested by their laminar flame speed, which is higher for the CO-lean condition. To identify local mixtures having favorable mixture conditions for flame stabilization, explosive zones are defined using a chemical explosive mode timescale. The explosive zones related to flame stabilization are located in relatively low velocity regions. The explosive zones are characterized by excess hydrogen transported solely by differential diffusion, in the absence of intense turbulent mixing or scalar dissipation rate. The conditional averages show that differential diffusion is negatively correlated with turbulent mixing. Moreover, the local turbulent Reynolds number is insufficient to estimate the magnitude of the differential diffusion effect. Alternatively, the Karlovitz number provides a better indicator of the importance of differential diffusion. A comparison of the variations of differential diffusion, turbulent mixing, heat release rate and probability of encountering explosive zones demonstrates that differential diffusion predominantly plays an important role for mixture preparation and initiation of chemical reactions, closely followed by intense chemical reactions sustained by sufficient downstream turbulent mixing. The mechanism by which differential diffusion contributes to mixture preparation is investigated using the Takeno Flame Index. The mean Flame Index, based on the combined fuel species, shows that the overall extent of premixing is not intense in the upstream regions. However, the Flame Index computed based on individual contribution of H2 or CO species reveals that

  18. Transported PDF Modeling of Nonpremixed Turbulent CO/H-2/N-2 Jet Flames

    SciTech Connect (OSTI)

    Zhao, xinyu; Haworth, D. C.; Huckaby, E. David

    2012-01-01

    Turbulent CO/H{sub 2}/N{sub 2} (syngas) flames are simulated using a transported composition probability density function (PDF) method. A consistent hybrid Lagrangian particle/Eulerian mesh algorithm is used to solve the modeled PDF transport equation. The model includes standard k? turbulence, gradient transport for scalars, and Euclidean minimum spanning tree (EMST) mixing. Sensitivities of model results to variations in the turbulence model, the treatment of radiation heat transfer, the choice of chemical mechanism, and the PDF mixing model are explored. A baseline model reproduces the measured mean and rms temperature, major species, and minor species profiles reasonably well, and captures the scaling that is observed in the experiments. Both our results and the literature suggest that further improvements can be realized with adjustments in the turbulence model, the radiation heat transfer model, and the chemical mechanism. Although radiation effects are relatively small in these flames, consideration of radiation is important for accurate NO prediction. Chemical mechanisms that have been developed specifically for fuels with high concentrations of CO and H{sub 2} perform better than a methane mechanism that was not designed for this purpose. It is important to account explicitly for turbulencechemistry interactions, although the details of the mixing model do not make a large difference in the results, within reasonable limits.

  19. Turbulent eddies in a compressible jet in crossflow measured using pulse-burst particle image velocimetry

    SciTech Connect (OSTI)

    Beresh, Steven J.; Wagner, Justin L.; Henfling, John F.; Spillers, Russell Wayne; Pruett, Brian Owen Matthew

    2016-01-01

    Pulse-burst Particle Image Velocimetry(PIV) has been employed to acquire time-resolved data at 25 kHz of a supersonic jet exhausting into a subsonic compressible crossflow. Data were acquired along the windward boundary of the jet shear layer and used to identify turbulenteddies as they convect downstream in the far-field of the interaction. Eddies were found to have a tendency to occur in closely spaced counter-rotating pairs and are routinely observed in the PIV movies, but the variable orientation of these pairs makes them difficult to detect statistically. Correlated counter-rotating vortices are more strongly observed to pass by at a larger spacing, both leading and trailing the reference eddy. This indicates the paired nature of the turbulenteddies and the tendency for these pairs to recur at repeatable spacing. Velocity spectra reveal a peak at a frequency consistent with this larger spacing between shear-layer vortices rotating with identical sign. The spatial scale of these vortices appears similar to previous observations of compressible jets in crossflow. Furthermore,super-sampled velocity spectra to 150 kHz reveal a power-law dependency of –5/3 in the inertial subrange as well as a –1 dependency at lower frequencies attributed to the scales of the dominant shear-layer eddies.

  20. Turbulent eddies in a compressible jet in crossflow measured using pulse-burst particle image velocimetry

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Beresh, Steven J.; Wagner, Justin L.; Henfling, John F.; Spillers, Russell Wayne; Pruett, Brian Owen Matthew

    2016-01-01

    Pulse-burst Particle Image Velocimetry(PIV) has been employed to acquire time-resolved data at 25 kHz of a supersonic jet exhausting into a subsonic compressible crossflow. Data were acquired along the windward boundary of the jet shear layer and used to identify turbulenteddies as they convect downstream in the far-field of the interaction. Eddies were found to have a tendency to occur in closely spaced counter-rotating pairs and are routinely observed in the PIV movies, but the variable orientation of these pairs makes them difficult to detect statistically. Correlated counter-rotating vortices are more strongly observed to pass by at a larger spacing,more » both leading and trailing the reference eddy. This indicates the paired nature of the turbulenteddies and the tendency for these pairs to recur at repeatable spacing. Velocity spectra reveal a peak at a frequency consistent with this larger spacing between shear-layer vortices rotating with identical sign. The spatial scale of these vortices appears similar to previous observations of compressible jets in crossflow. Furthermore,super-sampled velocity spectra to 150 kHz reveal a power-law dependency of –5/3 in the inertial subrange as well as a –1 dependency at lower frequencies attributed to the scales of the dominant shear-layer eddies.« less

  1. Three dimensional analysis of turbulent steam jets in enclosed structures : a CFD approach.

    SciTech Connect (OSTI)

    Ishii, M.; NguyenLe, Q.

    1999-04-20

    This paper compares the three-dimensional numerical simulation with the experimental data of a steam blowdown event in a light water reactor containment building. The temperature and pressure data of a steam blowdown event was measured at the Purdue University Multi-Dimensional Integrated Test Assembly (PUMA), a scaled model of the General Electric simplified Boiling Water Reactor. A three step approach was used to analyze the steam jet behavior. First, a 1-Dimensional, system level RELAP5/Mod3.2 model of the steam blowdown event was created and the results used to set the initial conditions for the PUMA blowdown experiments. Second, 2-Dimensional CFD models of the discharged steam jets were computed using PHOENICS, a commercially available CFD package. Finally, 3-Dimensional model of the PUMA drywell was created with the boundary conditions based on experimental measurements. The results of the 1-D and 2-D models were reported in the previous meeting. This paper discusses in detail the formulation and the results of the 3-Dimensional PHOENICS model of the PUMA drywell. It is found that the 3-D CFD solutions compared extremely well with the measured data.

  2. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry: Spray Simulations

    SciTech Connect (OSTI)

    Rutland, Christopher J.

    2009-04-26

    The Terascale High-Fidelity Simulations of Turbulent Combustion (TSTC) project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of the approach is direct numerical simulation (DNS) featuring the highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. Under this component of the TSTC program the simulation code named S3D, developed and shared with coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for turbulent liquid fuel spray dynamics. Major accomplishments include improved fundamental understanding of mixing and auto-ignition in multi-phase turbulent reactant mixtures and turbulent fuel injection spray jets.

  3. Temperature, Oxygen, and Soot-Volume-Fraction Measurements in a Turbulent C2H4-Fueled Jet Flame

    SciTech Connect (OSTI)

    Kearney, Sean P.; Guildenbecher, Daniel Robert; Winters, Caroline; Farias, Paul Abraham; Grasser, Thomas W.; Hewson, John C.

    2015-09-01

    We present a detailed set of measurements from a piloted, sooting, turbulent C 2 H 4 - fueled diffusion flame. Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (CARS) is used to monitor temperature and oxygen, while laser-induced incandescence (LII) is applied for imaging of the soot volume fraction in the challenging jet-flame environment at Reynolds number, Re = 20,000. Single-laser shot results are used to map the mean and rms statistics, as well as probability densities. LII data from the soot-growth region of the flame are used to benchmark the soot source term for one-dimensional turbulence (ODT) modeling of this turbulent flame. The ODT code is then used to predict temperature and oxygen fluctuations higher in the soot oxidation region higher in the flame.

  4. Advanced CFD Models for High Efficiency Compression Ignition Engines

    Broader source: Energy.gov [DOE]

    Advanced CFD models for high efficiency compression-ignition engines can be used to show how turbulence-chemistry interactions influence autoignition and combustion.

  5. Ignition Experiments

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ignition experiments Ignition Experiments The goal of many NIF experiments is to create a self-sustaining "burn" of fusion fuel (the hydrogen isotopes deuterium and tritium) that produces as much or more energy than the energy required to initiate the fusion reaction-an event called ignition. In moving closer to achieving ignition, NIF researchers are fulfilling the vision of early laser pioneers who conceived of using the x rays generated by a powerful, brief laser pulse to fuse

  6. Numerical Simulations of Boiling Jet Impingement Cooling in Power Electronics

    SciTech Connect (OSTI)

    Narumanchi, S.; Troshko, A.; Hassani, V.; Bharathan, D.

    2006-12-01

    This paper explores turbulent boiling jet impingement for cooling power electronic components in hybrid electric vehicles.

  7. Structure of hydrogen-rich transverse jets in a vitiated

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lyra, Sgouria; Wilde, Benjamin; Kolla, Hemanth; Seitzman, Jerry M.; Lieuwen, Timothy C.; Chen, Jacqueline H.

    2014-11-24

    Our paper reports the results of a joint experimental and numerical study of the flow characteristics and flame structure of a hydrogen rich jet injected normal to a turbulent, vitiated crossflow of lean methane combustion products. Simultaneous high-speed stereoscopic PIV and OH PLIF measurements were obtained and analyzed alongside three-dimensional direct numerical simulations of inert and reacting JICF with detailed H2/COH2/CO chemistry. Both the experiment and the simulation reveal that, contrary to most previous studies of reacting JICF stabilized in low-to-moderate temperature air crossflow, the present conditions lead to a burner-attached flame that initiates uniformly around the burner edge. Significantmoreasymmetry is observed, however, between the reaction zones located on the windward and leeward sides of the jet, due to the substantially different scalar dissipation rates. The windward reaction zone is much thinner in the near field, while also exhibiting significantly higher local and global heat release than the much broader reaction zone found on the leeward side of the jet. The unsteady dynamics of the windward shear layer, which largely control the important jet/crossflow mixing processes in that region, are explored in order to elucidate the important flow stability implications arising in the inert and reacting JICF. The paper concludes with an analysis of the ignition, flame characteristics, and global structure of the burner-attached flame. FurthermoreChemical explosive mode analysis (CEMA) shows that the entire windward shear layer, and a large region on the leeward side of the jet, are highly explosive prior to ignition and are dominated by non-premixed flame structures after ignition. The predominantly mixing limited nature of the flow after ignition is examined by computing the Takeno flame index, which shows that ~70% of the heat release occurs in non-premixed regions.less

  8. Sudden Viscous Dissipation of Compressing Turbulence

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Davidovits, Seth; Fisch, Nathaniel J.

    2016-03-11

    Here we report compression of turbulent plasma can amplify the turbulent kinetic energy, if the compression is fast compared to the viscous dissipation time of the turbulent eddies. A sudden viscous dissipation mechanism is demonstrated, whereby this amplified turbulent kinetic energy is rapidly converted into thermal energy, suggesting a new paradigm for fast ignition inertial fusion.

  9. Terascale Direct Numerical Simulations of Turbulent Combustion: Capabilities and Limits (PReSS Talk)

    SciTech Connect (OSTI)

    Yoo, Chun Sang

    2009-03-26

    The rapid growth in computational capabilities has provided great opportunities for direct numerical simulations (DNS) of turbulent combustion, a type of simulations without any turbulence model. With the help of terascale high performance supercomputing (HPC) resources, we are now able to provide fundamental insight into turbulence-chemistry interaction in simple laboratory-scale turbulent flames with detailed chemistry using three-dimensional (3D) DNS. However, the actual domain size of 3D-DNS is still limited within {approx} O(10 cm{sup 3}) due to its tremendously high grid resolution required to resolve the smallest turbulent length scale as well as flame structures. Moreover, 3D-DNS will require more computing powers to investigate next-generation engines, of which operating conditions will be characterized by higher pressures, lower temperatures, and higher levels of dilution. In this talk, I will discuss the capabilities and limits of DNS of turbulent combustion and present some results of ignition/extinction characteristics of a highly diluted hydrogen flame counter-flowing against heated air. The results of our recent 3D-DNS of a spatially-developing turbulent lifted hydrogen jet flame in heated coflow will also be presented. The 3D-DNS was performed at a jet Reynolds number of 11,000 with {approx} 1 billion grid points, which required 3.5 million CPU hours on Cray XT3/XT4 at Oak Ridge National Laboratories.

  10. Laser ignition

    DOE Patents [OSTI]

    Early, James W. (Los Alamos, NM); Lester, Charles S. (San Juan Pueblo, NM)

    2002-01-01

    In the apparatus of the invention, a first excitation laser or other excitation light source is used in tandem with an ignitor laser to provide a compact, durable, engine deployable fuel ignition laser system. The beam from the excitation light source is split with a portion of it going to the ignitor laser and a second portion of it being recombined with the first portion after a delay before injection into the ignitor laser. Reliable fuel ignition is provided over a wide range of fuel conditions by using a single remote excitation light source for one or more small lasers located proximate to one or more fuel combustion zones.

  11. Laser ignition

    DOE Patents [OSTI]

    Early, James W. (Los Alamos, NM); Lester, Charles S. (San Juan Pueblo, NM)

    2002-01-01

    In the apparatus of the invention, a first excitation laser or other excitation light source capable of producing alternating beams of light having different wavelengths is used in tandem with one or more ignitor lasers to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using the single remote excitation light source for pumping one or more small lasers located proximate to one or more fuel combustion zones with alternating wavelengths of light.

  12. Confinement scaling and ignition in tokamaks

    SciTech Connect (OSTI)

    Perkins, F.W.; Sun, Y.C.

    1985-10-01

    A drift wave turbulence model is used to compute the scaling and magnitude of central electron temperature and confinement time of tokamak plasmas. The results are in accord with experiment. Application to ignition experiments shows that high density (1 to 2) . 10/sup 15/ cm/sup -3/, high field, B/sub T/ > 10 T, but low temperature T approx. 6 keV constitute the optimum path to ignition.

  13. A Multicomponent Blend as a Diesel Fuel Surrogate for Compression Ignition Engine Applications

    SciTech Connect (OSTI)

    Pei, Yuanjiang; Mehl, Marco; Liu, Wei; Lu, Tianfeng; Pitz, William J.; Som, Sibendu

    2015-05-12

    A mixture of n-dodecane and m-xylene is investigated as a diesel fuel surrogate for compression ignition engine applications. Compared to neat n-dodecane, this binary mixture is more representative of diesel fuel because it contains an alkyl-benzene which represents an important chemical class present in diesel fuels. A detailed multi-component mechanism for n-dodecane and m-xylene was developed by combining a previously developed n-dodecane mechanism with a recently developed mechanism for xylenes. The xylene mechanism is shown to reproduce experimental ignition data from a rapid compression machine and shock tube, speciation data from the jet stirred reactor and flame speed data. This combined mechanism was validated by comparing predictions from the model with experimental data for ignition in shock tubes and for reactivity in a flow reactor. The combined mechanism, consisting of 2885 species and 11754 reactions, was reduced to a skeletal mechanism consisting 163 species and 887 reactions for 3D diesel engine simulations. The mechanism reduction was performed using directed relation graph (DRG) with expert knowledge (DRG-X) and DRG-aided sensitivity analysis (DRGASA) at a fixed fuel composition of 77% of n-dodecane and 23% m-xylene by volume. The sample space for the reduction covered pressure of 1 – 80 bar, equivalence ratio of 0.5 – 2.0, and initial temperature of 700 – 1600 K for ignition. The skeletal mechanism was compared with the detailed mechanism for ignition and flow reactor predictions. Finally, the skeletal mechanism was validated against a spray flame dataset under diesel engine conditions documented on the Engine Combustion Network (ECN) website. These multi-dimensional simulations were performed using a Representative Interactive Flame (RIF) turbulent combustion model. Encouraging results were obtained compared to the experiments with regards to the predictions of ignition delay and lift-off length at different ambient temperatures.

  14. Laser ignition

    DOE Patents [OSTI]

    Early, James W. (Los Alamos, NM); Lester, Charles S. (San Juan Pueblo, NM)

    2002-01-01

    In the apparatus of the invention, a first excitation laser or other excitation light source is used in tandem with an ignitor laser to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using a single remote excitation light source for one or more small lasers located proximate to one or more fuel combustion zones. In the embodiment of the invention claimed herein, the beam from the excitation light source is split with a portion of it going to the ignitor laser and a second portion of it being combined with either the first portion after a delay before injection into the ignitor laser.

  15. Laser ignition

    DOE Patents [OSTI]

    Early, James W.; Lester, Charles S.

    2003-01-01

    In the apparatus of the invention, a first excitation laser or other excitation light source is used in tandem with an ignitor laser to provide a compact, durable, engine deployable fuel ignition laser system. Reliable fuel ignition is provided over a wide range of fuel conditions by using a single remote excitation light source for one or more small lasers located proximate to one or more fuel combustion zones. In a third embodiment, alternating short and long pulses of light from the excitation light source are directed into the ignitor laser. Each of the embodiments of the invention can be multiplexed so as to provide laser light energy sequentially to more than one ignitor laser.

  16. Advanced CFD Models for High Efficiency Compression Ignition...

    Broader source: Energy.gov (indexed) [DOE]

    Advanced CFD models for high efficiency compression-ignition engines can be used to show how turbulence-chemistry interactions influence autoignition and combustion. p-19raja.pdf ...

  17. Turbulence and combustion interaction: High resolution local flame front structure visualization using simultaneous single-shot PLIF imaging of CH, OH, and CH{sub 2}O in a piloted premixed jet flame

    SciTech Connect (OSTI)

    Li, Z.S.; Li, B.; Sun, Z.W.; Alden, M. [Division of Combustion Physics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden); Bai, X.S. [Division of Fluid Mechanics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden)

    2010-06-15

    High resolution planar laser-induced fluorescence (PLIF) was applied to investigate the local flame front structures of turbulent premixed methane/air jet flames in order to reveal details about turbulence and flame interaction. The targeted turbulent flames were generated on a specially designed coaxial jet burner, in which low speed stoichiometric gas mixture was fed through the outer large tube to provide a laminar pilot flame for stabilization of the high speed jet flame issued through the small inner tube. By varying the inner tube flow speed and keeping the mixture composition as that of the outer tube, different flames were obtained covering both the laminar and turbulent flame regimes with different turbulent intensities. Simultaneous CH/CH{sub 2}O, and also OH PLIF images were recorded to characterize the influence of turbulence eddies on the reaction zone structure, with a spatial resolution of about 40 {mu}m and temporal resolution of around 10 ns. Under all experimental conditions, the CH radicals were found to exist only in a thin layer; the CH{sub 2}O were found in the inner flame whereas the OH radicals were seen in the outer flame with the thin CH layer separating the OH and CH{sub 2}O layers. The outer OH layer is thick and it corresponds to the oxidation zone and post-flame zone; the CH{sub 2}O layer is thin in laminar flows; it becomes broad at high speed turbulent flow conditions. This phenomenon was analyzed using chemical kinetic calculations and eddy/flame interaction theory. It appears that under high turbulence intensity conditions, the small eddies in the preheat zone can transport species such as CH{sub 2}O from the reaction zones to the preheat zone. The CH{sub 2}O species are not consumed in the preheat zone due to the absence of H, O, and OH radicals by which CH{sub 2}O is to be oxidized. The CH radicals cannot exist in the preheat zone due to the rapid reactions of this species with O{sub 2} and CO{sub 2} in the inner-layer of the

  18. Sandia Energy - The CRF's Turbulent Combustion Lab (TCL) Captures...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    CRF's Turbulent Combustion Lab (TCL) Captures the Moment of Hydrogen Ignition Home Energy Transportation Energy CRF Facilities News News & Events Research & Capabilities The CRF's...

  19. Enhanced ignition for I. C. engines with premixed gases

    SciTech Connect (OSTI)

    Dale, J.D.; Oppenheim, A.K.

    1981-01-01

    The development of lean charge, fast burn engines depends crucially on enhanced ignition. Enhanced ignition involves not only high energies and long duration of ignition, but also a wide dispersion of its sources, so that combustion is carried out at as many sites throughout the charge as possible. Upon this premise, various ignition systems for I.C. engines, operating with premixed charge, are reviewed. The systems are grouped as follows: high energy spark plugs; plasma jet igniters; photochemical, laser, and microwave ignition concepts; torch cells; divided chamber stratified charge engines; flame jet igniters; combustion jet ignition concepts; EGR ignition system. The first three derive the power from electrical energy, the rest are powered by exothermic chemical reactions. The review emphasizes the concept of staging the processes of initiation and propagation of combustion. Relative positions of various ignition systems are expressed on the plane of relative energies (the ratio of energy consumed by the ignition system, or contained in a pre-chamber, to that of the compressed charge in the main chamber) and relative volumes (the ratio of the volume of the pre-chamber to that of the compressed charge). In principle, ignition systems for engines operating with premixed charge lie on the half-plane of relative energies below one, between 10/sup -5/ for standard spark plugs to 10/sup -1/ for divided chamber stratified charge engines, while their relative volumes extend from 0 for spark igniters to 0.2 for stratified charge engines. This suggests that proper compartmentization of the combustion process may lead to significant improvements in both pollution emissions from the cylinder and specific fuel consumption of I.C. engines.

  20. Advanced ignition and propulsion technology program

    SciTech Connect (OSTI)

    Oldenborg, R.; Early, J.; Lester, C.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Reliable engine re-ignition plays a crucial role in enabling commercial and military aircraft to fly safely at high altitudes. This project addressed research elements critical to the optimization of laser-based igniter. The effort initially involved a collaborative research and development agreement with B.F. Goodrich Aerospace and Laser Fare, Inc. The work involved integrated experiments with theoretical modeling to provide a basic understanding of the chemistry and physics controlling the laser-induced ignition of fuel aerosols produced by turbojet engine injectors. In addition, the authors defined advanced laser igniter configurations that minimize laser packaging size, weight, complexity and power consumption. These innovative ignition concepts were shown to reliably ignite jet fuel aerosols over a broad range of fuel/air mixture and a t fuel temperatures as low as -40 deg F. The demonstrated fuel ignition performance was highly superior to that obtained by the state-of-the-art, laser-spark ignition method utilizing comparable laser energy. The authors also developed a laser-based method that effectively removes optically opaque deposits of fuel hydrocarbon combustion residues from laser window surfaces. Seven patents have been either issued or are pending that resulted from the technology developments within this project.

  1. Turbulent combustion

    SciTech Connect (OSTI)

    Talbot, L.; Cheng, R.K.

    1993-12-01

    Turbulent combustion is the dominant process in heat and power generating systems. Its most significant aspect is to enhance the burning rate and volumetric power density. Turbulent mixing, however, also influences the chemical rates and has a direct effect on the formation of pollutants, flame ignition and extinction. Therefore, research and development of modern combustion systems for power generation, waste incineration and material synthesis must rely on a fundamental understanding of the physical effect of turbulence on combustion to develop theoretical models that can be used as design tools. The overall objective of this program is to investigate, primarily experimentally, the interaction and coupling between turbulence and combustion. These processes are complex and are characterized by scalar and velocity fluctuations with time and length scales spanning several orders of magnitude. They are also influenced by the so-called {open_quotes}field{close_quotes} effects associated with the characteristics of the flow and burner geometries. The authors` approach is to gain a fundamental understanding by investigating idealized laboratory flames. Laboratory flames are amenable to detailed interrogation by laser diagnostics and their flow geometries are chosen to simplify numerical modeling and simulations and to facilitate comparison between experiments and theory.

  2. Electron dynamics and plasma jet formation in a helium atmospheric pressure dielectric barrier discharge jet

    SciTech Connect (OSTI)

    Algwari, Q. Th.; O'Connell, D.

    2011-09-19

    The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of the dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.

  3. Enhanced ignition for I. C. engines with premixed charge

    SciTech Connect (OSTI)

    Dale, J.D.; Oppenheim, A.K.

    1980-10-01

    The development of lean charge, fast burn engines depends crucially on enhanced ignition, since one can obtain thereby proper means for increasing the rate of burn in mixtures characterized notoriously by low normal burning speeds. Enhanced ignition involves a wide dispersion of its sources so that combustion is carried out at as many sites throughout the charge as possible. Upon this premise, various ignition systems for I.C. engines, operating with premixed charge, are reviewed. The systems are grouped within the following categories: (1) high energy spark plugs; (2) plasma jet igniters; (3) photochemical, laser, and microwave ignition concepts; (4) torch cells; (5) divided chamber stratified charge engines; (6) flame jet igniters; (7) combustion jet ignition concepts; (8) EGR ignition system. The first three derive the power from electrical energy, the rest are powered by exothermic chemical reactions at a significantly lower, practically negligible, fuel consumption. The concept of staging the processes of initiation and propagation of combustion is emphasized. Relative positions of various ignition systems are expressed on the plane of relative energies and relative volumes. In principle, ignition systems for engines operating with premixed charge lie on the half-plane of relative energies below one, between 10/sup -5/ for standard spark plugs to 10/sup -1/ for divided chamber stratified charge engines, while their relative volumes extend from 0 for spark igniters to 0.2 for stratified charge engines. This suggests that proper compartmentization of the combustion process may lead to significant improvements in both pollution emissions from the cylinder and specific fuel consumption of I.C. engines.

  4. Laser ignition

    DOE Patents [OSTI]

    Early, James W.; Lester, Charles S.

    2004-01-13

    Sequenced pulses of light from an excitation laser with at least two resonator cavities with separate output couplers are directed through a light modulator and a first polarzing analyzer. A portion of the light not rejected by the first polarizing analyzer is transported through a first optical fiber into a first ignitor laser rod in an ignitor laser. Another portion of the light is rejected by the first polarizing analyzer and directed through a halfwave plate into a second polarization analyzer. A first portion of the output of the second polarization analyzer passes through the second polarization analyzer to a second, oscillator, laser rod in the ignitor laser. A second portion of the output of the second polarization analyzer is redirected by the second polarization analyzer to a second optical fiber which delays the beam before the beam is combined with output of the first ignitor laser rod. Output of the second laser rod in the ignitor laser is directed into the first ignitor laser rod which was energized by light passing through the first polarizing analyzer. Combined output of the first ignitor laser rod and output of the second optical fiber is focused into a combustible fuel where the first short duration, high peak power pulse from the ignitor laser ignites the fuel and the second long duration, low peak power pulse directly from the excitation laser sustains the combustion.

  5. Laser preheat enhanced ignition

    DOE Patents [OSTI]

    Early, J.W.

    1999-03-02

    A method for enhancing fuel ignition performance by preheating the fuel with laser light at a wavelength that is absorbable by the fuel prior to ignition with a second laser is provided. 11 figs.

  6. Thermal ignition combustion system

    DOE Patents [OSTI]

    Kamo, R.; Kakwani, R.M.; Valdmanis, E.; Woods, M.E.

    1988-04-19

    The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m C and a specific heat greater than 480 J/kg C with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber. 8 figs.

  7. Thermal ignition combustion system

    DOE Patents [OSTI]

    Kamo, Roy; Kakwani, Ramesh M.; Valdmanis, Edgars; Woods, Melvins E.

    1988-01-01

    The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m.degree. C. and a specific heat greater than 480 J/kg.degree. C. with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber.

  8. Low profile thermite igniter

    DOE Patents [OSTI]

    Halcomb, Danny L.; Mohler, Jonathan H.

    1991-03-05

    A thermite igniter/heat source comprising a housing, high-density thermite, and low-density thermite. The housing has a relatively low profile and can focus energy by means of a torch-like ejection of hot reaction products and is externally ignitable.

  9. Features of a point design for fast ignition

    SciTech Connect (OSTI)

    Tabak, M; Clark, D; Town, R J; Key, M H; Amendt, P; Ho, D; Meeker, D J; Shay, H D; Lasinski, B F; Kemp, A; Divol, L; Mackinnon, A J; Patel, P; Strozzi, D; Grote, D P

    2009-10-26

    Fast Ignition is an inertial fusion scheme in which fuel is first assembled and then heated to the ignition temperature with an external heating source. In this note we consider cone and shell implosions where the energy supplied by short pulse lasers is transported to the fuel by electrons. We describe possible failure modes for this scheme and how to overcome them. In particular, we describe two sources of cone tip failure, an axis jet driven from the compressed fuel mass and hard photon preheat leaking through the implosion shell, and laser prepulse that can change the position of laser absorption and the angular distribution of the emitted electrons.

  10. COLLOQUIUM: In Pursuit of Ignition on the National Ignition Facility |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Princeton Plasma Physics Lab March 26, 2014, 3:00pm to 4:30pm Colloquia MBG Auditorium COLLOQUIUM: In Pursuit of Ignition on the National Ignition Facility Dr. M. John Edwards Lawrence Livermore National Laboratory Presentation: PDF icon WC26MAR2014_JEdwards.pdf The Inertial Confinement Fusion (ICF) Program is conducting experiments at the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory with the goal of igniting a propagating thermonuclear burn wave in DT fuel

  11. Ignition system monitoring assembly

    DOE Patents [OSTI]

    Brushwood, John Samuel

    2003-11-04

    An ignition system monitoring assembly for use in a combustion engine is disclosed. The assembly includes an igniter having at least one positioning guide with at least one transmittal member being maintained in a preferred orientation by one of the positioning guides. The transmittal member is in optical communication with a corresponding target region, and optical information about the target region is conveyed to the reception member via the transmittal member. The device allows real-time observation of optical characteristics of the target region. The target region may be the spark gap between the igniter electrodes, or other predetermined locations in optical communication with the transmittal member. The reception member may send an output signal to a processing member which, in turn, may produce a response to the output signal.

  12. Heating National Ignition Facility, Realistic Financial Planning...

    Office of Environmental Management (EM)

    National Ignition Facility, Realistic Financial Planning & Rapid Modification Lessons Learned Report Apr 2010 Heating National Ignition Facility, Realistic Financial Planning &...

  13. Fusion and Ignition

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ignition Fusion and Ignition What is Fusion? Fusion is the process that powers the sun and the stars. Fusion describes what happens when the nuclei of light atoms overcome the electrical resistance that keeps them apart and get close enough to activate the strong nuclear force that holds them together, or "fuse." When fused, they form a bigger nucleus; two elements combine to create a different element at the level of the nucleus. Making elements fuse requires an enormous amount of

  14. Scientists ignite aluminum water mix

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Scientists ignite aluminum water mix Scientists ignite aluminum water mix Don't worry, that beer can you're holding is not going to spontaneously burst into flames. June 30, 2014 Los Alamos National Laboratory chemist Bryce Tappan ignites a small quantity of aluminum nanoparticle water mixture. In open air, the compound burns like a Fourth of July sparkler. Los Alamos National Laboratory chemist Bryce Tappan ignites a small quantity of aluminum nanoparticle water mixture. In open air, the

  15. Structure and Dynamics of Fuel Jets Injected into a High-Temperature Subsonic Crossflow: High-Data-Rate Laser Diagnostic Investigation under Steady and Oscillatory Conditions

    SciTech Connect (OSTI)

    Lucht, Robert; Anderson, William

    2015-01-23

    An investigation of subsonic transverse jet injection into a subsonic vitiated crossflow is discussed. The reacting jet in crossflow (RJIC) system investigated as a means of secondary injection of fuel in a staged combustion system. The measurements were performed in test rigs featuring (a) a steady, swirling crossflow and (b) a crossflow with low swirl but significant oscillation in the pressure field and in the axial velocity. The rigs are referred to as the steady state rig and the instability rig. Rapid mixing and chemical reaction in the near field of the jet injection is desirable in this application. Temporally resolved velocity measurements within the wake of the reactive jets using 2D-PIV and OH-PLIF at a repetition rate of 5 kHz were performed on the RJIC flow field in a steady state water-cooled test rig. The reactive jets were injected through an extended nozzle into the crossflow which is located in the downstream of a low swirl burner (LSB) that produced the swirled, vitiated crossflow. Both H2/N2 and natural gas (NG)/air jets were investigated. OH-PLIF measurements along the jet trajectory show that the auto-ignition starts on the leeward side within the wake region of the jet flame. The measurements show that jet flame is stabilized in the wake of the jet and wake vortices play a significant role in this process. PIV and OH–PLIF measurements were performed at five measurement planes along the cross- section of the jet. The time resolved measurements provided significant information on the evolution of complex flow structures and highly transient features like, local extinction, re-ignition, vortex-flame interaction prevalent in a turbulent reacting flow. Nanosecond-laser-based, single-laser-shot coherent anti-Stokes Raman scattering (CARS) measurements of temperature and H2 concentraiton were also performed. The structure and dynamics of a reacting transverse jet injected into a vitiated oscillatory crossflow presents a unique opportunity for

  16. DNS/LES of Complex Turbulent Flows | Argonne Leadership Computing Facility

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Autoignition of a turbulent hydrogen jet injected into hot oxygen Autoignition of a turbulent hydrogen jet injected into hot oxygen. The green isocontours illustrate the turbulent structures in the fuel, the blue isocontours show the HO2 radical (an important precursor to autoignition), and the orange isosurfaces illustrate temperature. Credit: Rajapadiyan Asaithambi and Krishnan Mahesh, University of Minnesota DNS/LES of Complex Turbulent Flows PI Name: Krishnan Mahesh PI Email: mahesh@umn.edu

  17. Turbulent burning rates of methane and methane-hydrogen mixtures

    SciTech Connect (OSTI)

    Fairweather, M. [School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Ormsby, M.P.; Sheppard, C.G.W. [School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Woolley, R. [Department of Mechanical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2009-04-15

    Methane and methane-hydrogen (10%, 20% and 50% hydrogen by volume) mixtures have been ignited in a fan stirred bomb in turbulence and filmed using high speed cine schlieren imaging. Measurements were performed at 0.1 MPa (absolute) and 360 K. A turbulent burning velocity was determined for a range of turbulence velocities and equivalence ratios. Experimental laminar burning velocities and Markstein numbers were also derived. For all fuels the turbulent burning velocity increased with turbulence velocity. The addition of hydrogen generally resulted in increased turbulent and laminar burning velocity and decreased Markstein number. Those flames that were less sensitive to stretch (lower Markstein number) burned faster under turbulent conditions, especially as the turbulence levels were increased, compared to stretch-sensitive (high Markstein number) flames. (author)

  18. National Ignition Facility | Princeton Plasma Physics Lab

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    National Ignition Facility Subscribe to RSS - National Ignition Facility National Ignition Facility Image: National Ignition Facility Summary of Assessment of Prospects for Inertial Fusion Energy Read more about Summary of Assessment of Prospects for Inertial Fusion Energy National Ignition Facility (NIF): Under Pressure: Ramp-Compression Smashes Record Read more about National Ignition Facility (NIF): Under Pressure: Ramp-Compression Smashes Record NATIONAL IGNITION FACILITY Read more about

  19. Burner ignition system

    DOE Patents [OSTI]

    Carignan, Forest J.

    1986-01-21

    An electronic ignition system for a gas burner is battery operated. The battery voltage is applied through a DC-DC chopper to a step-up transformer to charge a capacitor which provides the ignition spark. The step-up transformer has a significant leakage reactance in order to limit current flow from the battery during initial charging of the capacitor. A tank circuit at the input of the transformer returns magnetizing current resulting from the leakage reactance to the primary in succeeding cycles. An SCR in the output circuit is gated through a voltage divider which senses current flow through a flame. Once the flame is sensed, further sparks are precluded. The same flame sensor enables a thermopile driven main valve actuating circuit. A safety valve in series with the main gas valve responds to a control pressure thermostatically applied through a diaphragm. The valve closes after a predetermined delay determined by a time delay orifice if the pilot gas is not ignited.

  20. Fuzzy jets

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mackey, Lester; Nachman, Benjamin; Schwartzman, Ariel; Stansbury, Conrad

    2016-06-01

    Here, collimated streams of particles produced in high energy physics experiments are organized using clustering algorithms to form jets . To construct jets, the experimental collaborations based at the Large Hadron Collider (LHC) primarily use agglomerative hierarchical clustering schemes known as sequential recombination. We propose a new class of algorithms for clustering jets that use infrared and collinear safe mixture models. These new algorithms, known as fuzzy jets , are clustered using maximum likelihood techniques and can dynamically determine various properties of jets like their size. We show that the fuzzy jet size adds additional information to conventional jet taggingmore » variables in boosted topologies. Furthermore, we study the impact of pileup and show that with some slight modifications to the algorithm, fuzzy jets can be stable up to high pileup interaction multiplicities.« less

  1. Ignition dynamics of high explosives

    SciTech Connect (OSTI)

    Ali, A.N.; Son, S.F.; Sander, R.K.; Asay, B.W.; Brewster, M.Q.

    1999-04-01

    The laser ignition of the explosives HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, C{sub 4}H{sub 8}N{sub 8}O{sub 8}), {delta}-phase HMX, PBX 9501 (95% HMX, 2.5% Estane, 2.5% BDNPA/BDNPF), TATB (1,3,5-triamino-2,4,6-trinitrobenzene, C{sub 6}H{sub 6}N{sub 6}O{sub 6}), and PBX 9502 (95% TATB, 5% Kel-F) and aged PBX 9502 has been conducted with the intent to compare the relative sensitivities of those explosives and to investigate the effect of beam profile, binder addition, and porosity. It has been found that there was little difference between a gaussian beam and a top hat profile on the laser ignition of HMX. The authors observe that the addition of binder in the amounts present in PBX 9501 resulted in longer ignition delays than that of HMX. In contrast to HMX, the addition of binder to TATB in PBX 9502 shows no measurable effect. Porosity effects were considered by comparing the ignition of granular HMX and pressed HMX pellets. Porosity appears to increase ignition delay due to an increased effective absorption scale and increased convective heat loss. This porosity effect also resulted in longer ignition delays for {delta}-phase HMX than for {beta}-phase HMX. In order to simulate ignition in voids or cracks, the standard ignition experiment was modified to include a NaCl window placed at variable distances above the sample surface. When ignition experiments were performed at 29 W/cm{sup 2} and 38 W/cm{sup 2} a critical gap distance was observed of 6 {+-} 0.4 mm below which ignition was severely inhibited. This result underscores the importance of gas phase processes in ignition and illustrates that conditions can exist where simple ignition criteria such as surface temperature is inadequate.

  2. Particle Ignition and Char Combustion

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... reactivity of lignin residues that remain after biomass is processed and on quantifying the residue's ignition delay and char combustion rates during oxy-fuel combustion of coal. ...

  3. Increasing jet entrainment, mixing and spreading

    DOE Patents [OSTI]

    Farrington, Robert B.

    1994-01-01

    A free jet of air is disturbed at a frequency that substantially matches natural turbulences in the free jet to increase the entrainment, mixing, and spreading of air by the free jet, for example in a room or other enclosure. The disturbances are created by pulsing the flow of air that creates the free jet at the desired frequency. Such pulsing of the flow of air can be accomplished by sequentially occluding and opening a duct that confines and directs the flow of air, such as by rotating a disk on an axis transverse to the flow of air in the duct.

  4. Increasing jet entrainment, mixing and spreading

    DOE Patents [OSTI]

    Farrington, R.B.

    1994-08-16

    A free jet of air is disturbed at a frequency that substantially matches natural turbulences in the free jet to increase the entrainment, mixing, and spreading of air by the free jet, for example in a room or other enclosure. The disturbances are created by pulsing the flow of air that creates the free jet at the desired frequency. Such pulsing of the flow of air can be accomplished by sequentially occluding and opening a duct that confines and directs the flow of air, such as by rotating a disk on an axis transverse to the flow of air in the duct. 11 figs.

  5. Ignition and Inertial Confinement Fusion at The National Ignition Facility

    SciTech Connect (OSTI)

    Moses, E

    2009-10-01

    The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and for studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). The NIF is now conducting experiments to commission the laser drive, the hohlraum and the capsule and to develop the infrastructure needed to begin the first ignition experiments in FY 2010. Demonstration of ignition and thermonuclear burn in the laboratory is a major NIF goal. NIF will achieve this by concentrating the energy from the 192 beams into a mm{sup 3}-sized target and igniting a deuterium-tritium mix, liberating more energy than is required to initiate the fusion reaction. NIF's ignition program is a national effort managed via the National Ignition Campaign (NIC). The NIC has two major goals: execution of DT ignition experiments starting in FY2010 with the goal of demonstrating ignition and a reliable, repeatable ignition platform by the conclusion of the NIC at the end of FY2012. The NIC will also develop the infrastructure and the processes required to operate NIF as a national user facility. The achievement of ignition at NIF will demonstrate the scientific feasibility of ICF and focus worldwide attention on laser fusion as a viable energy option. A laser fusion-based energy concept that builds on NIF, known as LIFE (Laser Inertial Fusion Energy), is currently under development. LIFE is inherently safe and can provide a global carbon-free energy generation solution in the 21st century. This paper describes recent progress on NIF, NIC, and the LIFE concept.

  6. Ignite High Tech Startups | Open Energy Information

    Open Energy Info (EERE)

    Name: Ignite High Tech Startups Place: United States Sector: Services Product: General Financial & Legal Services ( Private family-controlled ) References: Ignite High Tech...

  7. Ignition of Aluminum Particles and Clouds

    SciTech Connect (OSTI)

    Kuhl, A L; Boiko, V M

    2010-04-07

    Here we review experimental data and models of the ignition of aluminum (Al) particles and clouds in explosion fields. The review considers: (i) ignition temperatures measured for single Al particles in torch experiments; (ii) thermal explosion models of the ignition of single Al particles; and (iii) the unsteady ignition Al particles clouds in reflected shock environments. These are used to develop an empirical ignition model appropriate for numerical simulations of Al particle combustion in shock dispersed fuel explosions.

  8. Approximate Model for Turbulent Stagnation Point Flow.

    SciTech Connect (OSTI)

    Dechant, Lawrence

    2016-01-01

    Here we derive an approximate turbulent self-similar model for a class of favorable pressure gradient wedge-like flows, focusing on the stagnation point limit. While the self-similar model provides a useful gross flow field estimate this approach must be combined with a near wall model is to determine skin friction and by Reynolds analogy the heat transfer coefficient. The combined approach is developed in detail for the stagnation point flow problem where turbulent skin friction and Nusselt number results are obtained. Comparison to the classical Van Driest (1958) result suggests overall reasonable agreement. Though the model is only valid near the stagnation region of cylinders and spheres it nonetheless provides a reasonable model for overall cylinder and sphere heat transfer. The enhancement effect of free stream turbulence upon the laminar flow is used to derive a similar expression which is valid for turbulent flow. Examination of free stream enhanced laminar flow suggests that the rather than enhancement of a laminar flow behavior free stream disturbance results in early transition to turbulent stagnation point behavior. Excellent agreement is shown between enhanced laminar flow and turbulent flow behavior for high levels, e.g. 5% of free stream turbulence. Finally the blunt body turbulent stagnation results are shown to provide realistic heat transfer results for turbulent jet impingement problems.

  9. Large eddy simulation of forced ignition of an annular bluff-body burner

    SciTech Connect (OSTI)

    Subramanian, V.; Domingo, P.; Vervisch, L.

    2010-03-15

    The optimization of the ignition process is a crucial issue in the design of many combustion systems. Large eddy simulation (LES) of a conical shaped bluff-body turbulent nonpremixed burner has been performed to study the impact of spark location on ignition success. This burner was experimentally investigated by Ahmed et al. [Combust. Flame 151 (2007) 366-385]. The present work focuses on the case without swirl, for which detailed measurements are available. First, cold-flow measurements of velocities and mixture fractions are compared with their LES counterparts, to assess the prediction capabilities of simulations in terms of flow and turbulent mixing. Time histories of velocities and mixture fractions are recorded at selected spots, to probe the resolved probability density function (pdf) of flow variables, in an attempt to reproduce, from the knowledge of LES-resolved instantaneous flow conditions, the experimentally observed reasons for success or failure of spark ignition. A flammability map is also constructed from the resolved mixture fraction pdf and compared with its experimental counterpart. LES of forced ignition is then performed using flamelet fully detailed tabulated chemistry combined with presumed pdfs. Various scenarios of flame kernel development are analyzed and correlated with typical flow conditions observed in this burner. The correlations between, velocities and mixture fraction values at the sparking time and the success or failure of ignition, are then further discussed and analyzed. (author)

  10. IGNITION AND FRONTIER SCIENCE ON THE NATIONAL IGNITION FACILITY

    SciTech Connect (OSTI)

    Moses, E

    2009-06-22

    The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and experiments studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). The NIF construction Project was certified by the Department of Energy as complete on March 30, 2009. NIF, a 192-beam Nd-glass laser facility, will produce 1.8 MJ, 500 TW of light at the third-harmonic, ultraviolet light of 351 nm. On March 10, 2009, a total 192-beam energy of 1.1 MJ was demonstrated; this is approximately 30 times more energy than ever produced in an ICF laser system. The principal goal of NIF is to achieve ignition of a deuterium-tritium (DT) fuel capsule and provide access to HED physics regimes needed for experiments related to national security, fusion energy and for broader frontier scientific exploration. NIF experiments in support of indirect drive ignition will begin in FY2009. These first experiments represent the next phase of the National Ignition Campaign (NIC). The NIC is a 1.7 billion dollar national effort to achieve fusion ignition and is coordinated through a detailed execution plan that includes the science, technology, and equipment. Equipment required for ignition experiments include diagnostics, cryogenic target manipulator, and user optics. Participants in this effort include LLNL, General Atomics (GA), Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), and the University of Rochester Laboratory for Energetics (LLE). The primary goal for NIC is to have all of the equipment operational and integrated into the facility and be ready to begin a credible ignition campaign in 2010. With NIF now operational, the long-sought goal of achieving self-sustained nuclear fusion and energy gain in the laboratory is much closer to realization. Successful demonstration of ignition and net energy gain on NIF will be a major step towards demonstrating the feasibility of

  11. Progress Toward Ignition on the National Ignition Facility

    SciTech Connect (OSTI)

    Kauffman, R L

    2011-10-17

    The principal approach to ignition on the National Ignition Facility (NIF) is indirect drive. A schematic of an ignition target is shown in Figure 1. The laser beams are focused through laser entrance holes at each end of a high-Z cylindrical case, or hohlraum. The lasers irradiate the hohlraum walls producing x-rays that ablate and compress the fuel capsule in the center of the hohlraum. The hohlraum is made of Au, U, or other high-Z material. For ignition targets, the hohlraum is {approx}0.5 cm diameter by {approx}1 cm in length. The hohlraum absorbs the incident laser energy producing x-rays for symmetrically imploding the capsule. The fuel capsule is a {approx}2-mm-diameter spherical shell of CH, Be, or C filled with DT fuel. The DT fuel is in the form of a cryogenic layer on the inside of the capsule. X-rays ablate the outside of the capsule, producing a spherical implosion. The imploding shell stagnates in the center, igniting the DT fuel. NIC has overseen installation of all of the hardware for performing ignition experiments, including commissioning of approximately 50 diagnostic systems in NIF. The diagnostics measure scattered optical light, x-rays from the hohlraum over the energy range from 100 eV to 500 keV, and x-rays, neutrons, and charged particles from the implosion. An example of a diagnostic is the Magnetic Recoil Spectrometer (MRS) built by a collaboration of scientists from MIT, UR-LLE, and LLNL shown in Figure 2. MRS measures the neutron spectrum from the implosion, providing information on the neutron yield and areal density that are metrics of the quality of the implosion. Experiments on NIF extend ICF research to unexplored regimes in target physics. NIF can produce more than 50 times the laser energy and more than 20 times the power of any previous ICF facility. Ignition scale hohlraum targets are three to four times larger than targets used at smaller facilities, and the ignition drive pulses are two to five times longer. The larger

  12. SCB thermite igniter studies

    SciTech Connect (OSTI)

    Bickes, R.W. Jr.; Wackerbarth, D.E.; Mohler, J.H.

    1996-12-31

    The authors report on recent studies comparing the ignition threshold of temperature cycled, SCB thermite devices with units that were not submitted to temperature cycling. Aluminum/copper-oxide thermite was pressed into units at two densities, 45% of theoretical maximum density (TMD) or 47% of TMD. Half of each of the density sets underwent three thermal cycles; each cycle consisted of 2 hours at 74 C and 2 hours at {minus}54 C, with a 5 minute maximum transfer time between temperatures. The temperature cycled units were brought to ambient temperature before the threshold testing. Both the density and the thermal cycling affected the all-fire voltage. Using a 5.34 {micro}F CDU (capacitor discharge unit) firing set, the all-fire voltage for the units that were not temperature cycled increased with density from 32.99 V (45% TMD) to 39.32 V (47% TMD). The all-fire voltages for the thermally cycled units were 34.42 V (45% TMD) and 58.1 V (47% TMD). They also report on no-fire levels at ambient temperature for two component designs; the 5 minute no-fire levels were greater than 1.2 A. Units were also subjected to tests in which 1 W of RF power was injected into the bridges at 10 MHz for 5 minutes. The units survived and fired normally afterwards. Finally, units were subjected to pin-to-pin electrostatic discharge (ESD) tests. None of the units fired upon application of the ESD pulse, and all of the tested units fired normally afterwards.

  13. Enhanced Model for Fast Ignition

    SciTech Connect (OSTI)

    Mason, Rodney J.

    2010-10-12

    Laser Fusion is a prime candidate for alternate energy production, capable of serving a major portion of the nation's energy needs, once fusion fuel can be readily ignited. Fast Ignition may well speed achievement of this goal, by reducing net demands on laser pulse energy and timing precision. However, Fast Ignition has presented a major challenge to modeling. This project has enhanced the computer code ePLAS for the simulation of the many specialized phenomena, which arise with Fast Ignition. The improved code has helped researchers to understand better the consequences of laser absorption, energy transport, and laser target hydrodynamics. ePLAS uses efficient implicit methods to acquire solutions for the electromagnetic fields that govern the accelerations of electrons and ions in targets. In many cases, the code implements fluid modeling for these components. These combined features, "implicitness and fluid modeling," can greatly facilitate calculations, permitting the rapid scoping and evaluation of experiments. ePLAS can be used on PCs, Macs and Linux machines, providing researchers and students with rapid results. This project has improved the treatment of electromagnetics, hydrodynamics, and atomic physics in the code. It has simplified output graphics, and provided new input that avoids the need for source code access by users. The improved code can now aid university, business and national laboratory users in pursuit of an early path to success with Fast Ignition.

  14. June 11, 1999: National Ignition Facility | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    1, 1999: National Ignition Facility June 11, 1999: National Ignition Facility June 11, 1999: National Ignition Facility June 11, 1999 Secretary Richardson dedicates the National Ignition Facility target chamber at DOE's Lawrence Livermore National Laboratory.

  15. National Ignition Facility | National Nuclear Security Administration

    National Nuclear Security Administration (NNSA)

    National Ignition Facility Glass amplifiers in Laser Bay 2 at the National Ignition Facility. The construction of the 192-beam 1.8 MJ UV NIF, the world's most energetic laser, was ...

  16. Laser ablation based fuel ignition

    DOE Patents [OSTI]

    Early, James W.; Lester, Charles S.

    1998-01-01

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition.

  17. Laser ablation based fuel ignition

    DOE Patents [OSTI]

    Early, J.W.; Lester, C.S.

    1998-06-23

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition. 3 figs.

  18. Confinement of ignition and yield on the National Ignition Facility

    SciTech Connect (OSTI)

    Tobin, M.; Karpenko, V.; Foley, D.; Anderson, A.; Burnham, A.; Reitz, T.; Latkowski, J.; Bernat, T.

    1996-06-14

    The National Ignition Facility Target Areas and Experimental Systems has reached mid-Title I design. Performance requirements for the Target Area are reviewed and design changes since the Conceptual Design Report are discussed. Development activities confirm a 5-m radius chamber and the viability of a boron carbide first wall. A scheme for cryogenic target integration with the NIF Target Area is presented.

  19. Surface breakdown igniter for mercury arc devices

    DOE Patents [OSTI]

    Bayless, John R.

    1977-01-01

    Surface breakdown igniter comprises a semiconductor of medium resistivity which has the arc device cathode as one electrode and has an igniter anode electrode so that when voltage is applied between the electrodes a spark is generated when electrical breakdown occurs over the surface of the semiconductor. The geometry of the igniter anode and cathode electrodes causes the igniter discharge to be forced away from the semiconductor surface.

  20. Hot surface ignition system control module with accelerated igniter warm-up test program

    SciTech Connect (OSTI)

    Brown, B.T.

    1986-10-07

    This patent describes a gas burner control system which consists of: a burner; an electrical resistance igniter for igniting the burner; valve means for controlling flow of gas to the burner; and a control module, including a microcomputer, for controlling operation of the igniter and the valve means, the microcomputer being programmed to provide a preselected igniter warm-up time period for enabling the igniter to attain a temperature sufficient to ignite gas, the microcomputer being further programmed to provide a test routine including a program for providing an accelerated igniter warm-up time period which is shorter than the preselected igniter warm-up time period but sufficiently long for enabling the igniter to attain at least the minimum temperature required to ignite gas, the program in the test routine being executed in response to a unique signal effected by the control module and a test device which is external from and detachably connected to the control module.

  1. Integral low-energy thermite igniter

    DOE Patents [OSTI]

    Gibson, A.; Haws, L.D.; Mohler, J.H.

    1983-05-13

    In a thermite igniter/heat source comprising a container holding an internal igniter load, there is provided the improvement wherein the container consists essentially of consumable consolidated thermite having a low gas output upon combustion, whereby upon ignition, substantially all of the container and said load is consumed with low gas production.

  2. Integral low-energy thermite igniter

    DOE Patents [OSTI]

    Gibson, Albert; Haws, Lowell D.; Mohler, Jonathan H.

    1984-08-14

    In a thermite igniter/heat source comprising a container holding an internal igniter load, there is provided the improvement wherein the container consists essentially of consumable consolidated thermite having a low gas output upon combustion, whereby upon ignition, substantially all of the container and said load is consumed with low gas production.

  3. Simultaneous dual mode combustion engine operating on spark ignition and homogenous charge compression ignition

    DOE Patents [OSTI]

    Fiveland, Scott B.; Wiggers, Timothy E.

    2004-06-22

    An engine particularly suited to single speed operation environments, such as stationary power generators. The engine includes a plurality of combustion cylinders operable under homogenous charge compression ignition, and at least one combustion cylinder operable on spark ignition concepts. The cylinder operable on spark ignition concepts can be convertible to operate under homogenous charge compression ignition. The engine is started using the cylinders operable under spark ignition concepts.

  4. Igniter and actuator output testing

    SciTech Connect (OSTI)

    Evans, N.A.

    1988-01-01

    Closed system mechanical work output measurements were made for five types of thermal battery igniters and one type of valve actuator. Each unit was fired into a high-precision fit piston/cylinder arrangement, and the work output was determined from measuring the rise of a known weight. The results showed that work output for an individual igniter type varied over a considerable range while the mean work output values of the various igniter types appeared to depend principally on the type of closure disc and the details of the charge mix. The large variability in igniter output was the principal inducement to build a second apparatus, with approximately 10 times the capacity of the first, to investigate the output actuators. Compared with igniters, the actuator work output was appropriately in scale, but the variability was considerably reduced (R=1.5), and was attributed to increase in scale. Motion picture photography at 8000 to 9000 frames per second was used to determine the motion of the rising weight and the associated output pressure, which exhibited three distinct phases. Initially, the average acceleration of the weight was of the order of 100 g during the first half-millisecond of weight rise and corresponded to average pressures of 15,000 to 37,000 psi, depending principally on the mass of the weight. This was followed by a significant weight rise at a constant pressure of approximately 150 to 450 psi. Finally, the weight decelerated to rest under gravity to reach the maximum recorded height. 2 refs., 9 figs., 2 tabs.

  5. Desensitizing nano powders to electrostatic discharge ignition

    SciTech Connect (OSTI)

    Steelman, Ryan; Clark, Billy; Pantoya, Michelle L.; Heaps, Ronald J.; Daniels, Michael A.

    2015-08-01

    Electrostatic discharge (ESD) is a main cause for ignition in powder media ranging from grain silos to fireworks. Nanoscale particles are orders of magnitude more ESD ignition sensitive than their micron scale counterparts. This study shows that at least 13 vol. % carbon nanotubes (CNT) added to nano-aluminum and nano-copper oxide particles (nAl + CuO) eliminates ESD ignition sensitivity. The CNT act as a conduit for electric energy and directs electric charge through the powder to desensitize the reactive mixture to ignition. For nanoparticles, the required CNT concentration for desensitizing ESD ignition acts as a diluent to quench energy propagation.

  6. Turbulence-chemistry interactions in reacting flows

    SciTech Connect (OSTI)

    Barlow, R.S.; Carter, C.D.

    1993-12-01

    Interactions between turbulence and chemistry in nonpremixed flames are investigated through multiscalar measurements. Simultaneous point measurements of major species, NO, OH, temperature, and mixture fraction are obtained by combining spontaneous Raman scattering, Rayleigh scattering, and laser-induced fluorescence (LIF). NO and OH fluorescence signals are converted to quantitative concentrations by applying shot-to-shot corrections for local variations of the Boltzmann fraction and collisional quenching rate. These measurements of instantaneous thermochemical states in turbulent flames provide insights into the fundamental nature of turbulence-chemistry interactions. The measurements also constitute a unique data base for evaluation and refinement of turbulent combustion models. Experimental work during the past year has focused on three areas: (1) investigation of the effects of differential molecular diffusion in turbulent combustion: (2) experiments on the effects of Halon CF{sub 3}Br, a fire retardant, on the structure of turbulent flames of CH{sub 4} and CO/H{sub 2}/N{sub 2}; and (3) experiments on NO formation in turbulent hydrogen jet flames.

  7. High-voltage miniature igniter development

    SciTech Connect (OSTI)

    Willkens, C.A.; Axelson, S.R.; Bateman, L.S.; Croucher, D.D.

    1996-09-01

    In 1988, Norton introduced its line of low-voltage 12- and 24-V miniature igniters made from a patented ceramic/intermetallic material. These igniters demonstrated superior strength and speed in a compact low-wattage assembly for gas-fired ignition. High-voltage igniters are being developed to complete the family of igniters for gas-fired ignition. These igniters have extremely low power requirements in the range of 50--100 W, are designed to operate at line voltages of 120 V, and are leading to designs for operation up to 230 V. These were developed using compositional and dimensional changes to the low voltage igniters. The 120 V igniter has exceeded 200,000 cycles in life testing and has been submitted for agency approval. These igniters are also undergoing field testing in various demanding gas-fired appliances. The evolution of the low-voltage igniter into the high-voltage model, as well as performance and material development issues are discussed.

  8. Confinement of ignition and yield on the National Ignition Facility

    SciTech Connect (OSTI)

    Tobin, M.; Karpenko, V.; Foley, D.; Anderson, A.; Burnham, A.; Reitz, T.; Latkowski, J.; Bernat, T.

    1996-12-31

    The National Ignition Facility Target Area and Experimental Systems has reached mid-Title I design. Performance requirements for the Target Area are reviewed and design changes since the Conceptual Design Report are discussed. Development activities confirm a 5-m radius chamber and the viability of a boron carbide first wall. A scheme for cryogenic target integration with the NIF Target Area is presented. 16 refs., 3 figs.

  9. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry

    SciTech Connect (OSTI)

    Im, Hong G [University of Michigan] [University of Michigan; Trouve, Arnaud [University of Maryland] [University of Maryland; Rutland, Christopher J [University of Wisconsin] [University of Wisconsin; Chen, Jacqueline H [Sandia National Laboratories] [Sandia National Laboratories

    2012-08-13

    The TSTC project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of our approach is direct numerical simulation (DNS) featuring highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. The code named S3D, developed and shared with Chen and coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for spray dynamics, combustion, and pollutant formation processes in turbulent combustion. Major accomplishments include improved characteristic boundary conditions, fundamental studies of auto-ignition in turbulent stratified reactant mixtures, flame-wall interaction, and turbulent flame extinction by water spray. The overarching scientific issue in our recent investigations is to characterize criticality phenomena (ignition/extinction) in turbulent combustion, thereby developing unified criteria to identify ignition and extinction conditions. The computational development under TSTC has enabled the recent large-scale 3D turbulent combustion simulations conducted at Sandia National Laboratories.

  10. Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry

    SciTech Connect (OSTI)

    Hong G. Im; Arnaud Trouve; Christopher J. Rutland; Jacqueline H. Chen

    2009-02-02

    The TSTC project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of our approach is direct numerical simulation (DNS) featuring highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. The code named S3D, developed and shared with Chen and coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for spray dynamics, combustion, and pollutant formation processes in turbulent combustion. Major accomplishments include improved characteristic boundary conditions, fundamental studies of auto-ignition in turbulent stratified reactant mixtures, flame-wall interaction, and turbulent flame extinction by water spray. The overarching scientific issue in our recent investigations is to characterize criticality phenomena (ignition/extinction) in turbulent combustion, thereby developing unified criteria to identify ignition and extinction conditions. The computational development under TSTC has enabled the recent large-scale 3D turbulent combustion simulations conducted at Sandia National Laboratories.

  11. Particle Ignition and Char Combustion

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ignition and Char Combustion - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Energy Defense Waste Management Programs Advanced

  12. Diagnostics for Fast Ignition Science

    SciTech Connect (OSTI)

    MacPhee, A; Akli, K; Beg, F; Chen, C; Chen, H; Clarke, R; Hey, D; Freeman, R; Kemp, A; Key, M; King, J; LePape, S; Link, A; Ma, T; Nakamura, N; Offermann, D; Ovchinnikov, V; Patel, P; Phillips, T; Stephens, R; Town, R; Wei, M; VanWoerkom, L; Mackinnon, A

    2008-05-06

    The concept for Electron Fast Ignition Inertial Confinement Fusion demands sufficient laser energy be transferred from the ignitor pulse to the assembled fuel core via {approx}MeV electrons. We have assembled a suite of diagnostics to characterize such transfer. Recent experiments have simultaneously fielded absolutely calibrated extreme ultraviolet multilayer imagers at 68 and 256eV; spherically bent crystal imagers at 4 and 8keV; multi-keV crystal spectrometers; MeV x-ray bremmstrahlung and electron and proton spectrometers (along the same line of sight); nuclear activation samples and a picosecond optical probe based interferometer. These diagnostics allow careful measurement of energy transport and deposition during and following laser-plasma interactions at extremely high intensities in both planar and conical targets. Augmented with accurate on-shot laser focal spot and pre-pulse characterization, these measurements are yielding new insight into energy coupling and are providing critical data for validating numerical PIC and hybrid PIC simulation codes in an area that is crucial for many applications, particularly fast ignition. Novel aspects of these diagnostics and how they are combined to extract quantitative data on ultra high intensity laser plasma interactions are discussed, together with implications for full-scale fast ignition experiments.

  13. DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS

    SciTech Connect (OSTI)

    Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.; Falconer, David A.

    2010-09-01

    By examining many X-ray jets in Hinode/X-Ray Telescope coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H{alpha} macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major coronal mass ejections. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 A snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T {approx} 10{sup 4} - 10{sup 5} K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

  14. New perspectives on superparameterization for geophysical turbulence

    SciTech Connect (OSTI)

    Majda, Andrew J.; Grooms, Ian

    2014-08-15

    This is a research expository paper regarding superparameterization, a class of multi-scale numerical methods designed to cope with the intermittent multi-scale effects of inhomogeneous geophysical turbulence where energy often inverse-cascades from the unresolved scales to the large scales through the effects of waves, jets, vortices, and latent heat release from moist processes. Original as well as sparse spacetime superparameterization algorithms are discussed for the important case of moist atmospheric convection including the role of multi-scale asymptotic methods in providing self-consistent constraints on superparameterization algorithms and related deterministic and stochastic multi-cloud parameterizations. Test models for the statistical numerical analysis of superparameterization algorithms are discussed both to elucidate the performance of the basic algorithms and to test their potential role in efficient multi-scale data assimilation. The very recent development of grid-free seamless stochastic superparameterization methods for geophysical turbulence appropriate for eddy-permitting mesoscale ocean turbulence is presented here including a general formulation and illustrative applications to two-layer quasigeostrophic turbulence, and another difficult test case involving one-dimensional models of dispersive wave turbulence. This last test case has randomly generated solitons as coherent structures which collapse and radiate wave energy back to the larger scales, resulting in strong direct and inverse turbulent energy cascades.

  15. Fast ignition of inertial confinement fusion targets

    SciTech Connect (OSTI)

    Gus'kov, S. Yu.

    2013-01-15

    Results of studies on fast ignition of inertial confinement fusion (ICF) targets are reviewed. The aspects of the fast ignition concept, which consists in the separation of the processes of target ignition and compression due to the synchronized action of different energy drivers, are considered. Criteria for the compression ratio and heating rate of a fast ignition target, the energy balance, and the thermonuclear gain are discussed. The results of experimental and theoretical studies of the heating of a compressed target by various types of igniting drivers, namely, beams of fast electrons and light ions produced under the action of a petawatt laser pulse on the target, a heavy-ion beam generated in the accelerator, an X-ray pulse, and a hydrodynamic flow of laser-accelerated matter, are analyzed. Requirements to the igniting-driver parameters that depend on the fast ignition criteria under the conditions of specific target heating mechanisms, as well as possibilities of practical implementation of these requirements, are discussed. The experimental programs of various laboratories and the prospects of practical implementation of fast ignition of ICF targets are reviewed. To date, fast ignition is the most promising method for decreasing the ignition energy and increasing the thermonuclear gain of an ICF plasma. A large number of publications have been devoted to investigations of this method and adjacent problems of the physics of igniting drivers and their interaction with plasma. This review presents results of only some of these studies that, in the author's opinion, allow one to discuss in detail the main physical aspects of the fast ignition concept and understand the current state and prospects of studies in this direction.

  16. National Ignition Facility & Photon Science

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    33 National Ignition Facility & Photon Science Frequently asked Questions Q. What is NIF? A. The National Ignition Facility (NIF) is the world's largest and highest-energy laser. NIF's 192 intense laser beams are capable of delivering to their target more than 100 times the energy of any previous laser system. experiments on the path to ignition began in 2010. during full-scale ignition experiments, NIF will direct up to 1.8 million joules of ultraviolet laser energy in billionth-of-a-second

  17. Igniter containing titanium hydride and potassium perchlorate

    DOE Patents [OSTI]

    Dietzel, Russel W.; Leslie, William B.

    1976-01-01

    An explosive device is described which employs a particular titanium hydride-potassium perchlorate composition directly ignitible by an electrical bridgewire.

  18. Temperature and species-concentration measurements in turbulent flames by the CARS technique

    SciTech Connect (OSTI)

    Goss, L.P.; Schreiber, P.W.; Switzer, G.L.; Trump, D.D.

    1983-09-01

    Simultaneous temperature and N/sub 2/-concentration data have been obtained employing a 10-Hz coherent anti-stokes Raman spectroscopy system on two propane-air turbulent-jet diffusion flames with Reynolds numbers of 2000 and 6000. Average values, probability density functions, and correlation plots show reasonable trends for both centerline and radial profiles of the turbulent flames.

  19. National Ignition Facility (NIF): Under Pressure: Ramp-Compression Smashes

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Record | Princeton Plasma Physics Lab National Ignition Facility (NIF): Under Pressure: Ramp-Compression Smashes Record American Fusion News Category: National Ignition Facility Link: National Ignition Facility (NIF): Under Pressure: Ramp-Compression Smashes Record

  20. Mutual colliding impact fast ignition

    SciTech Connect (OSTI)

    Winterberg, Friedwardt

    2014-09-15

    It is proposed to apply the well established colliding beam technology of high energy physics to the fast hot spot ignition of a highly compressed DT (deuterium-tritium) target igniting a larger D (deuterium) burn, by accelerating a small amount of solid deuterium, and likewise a small amount of tritium, making a head-on collision in the center of the target, projecting them through conical ducts situated at the opposite side of the target and converging in its center. In their head-on collision, the relative collision velocity is 5/3 times larger compared to the collision velocity of a stationary target. The two pieces have for this reason to be accelerated to a smaller velocity than would otherwise be needed to reach upon impact the same temperature. Since the velocity distribution of the two head-on colliding projectiles is with its two velocity peaks non-Maxwellian, the maximum cross section velocity product turns out to be substantially larger than the maximum if averaged over a Maxwellian. The D and T projectiles would have to be accelerated with two sabots driven by powerful particle or laser beams, permitting a rather large acceleration length. With the substantially larger cross section-velocity product by virtue of the non-Maxwellian velocity distribution, a further advantage is that the head-on collision produces a large magnetic field by the thermomagnetic Nernst effect, enhancing propagating burn. With this concept, the ignition of the neutron-less hydrogen-boron (HB{sup 11}) reaction might even be possible in a heterogeneous assembly of the hydrogen and the boron to reduce the bremsstrahlung-losses, resembling the heterogeneous assembly in a graphite-natural uranium reactor, there to reduce the neutron losses.

  1. Direct numerical simulation of turbulent reacting flows

    SciTech Connect (OSTI)

    Chen, J.H.

    1993-12-01

    The development of turbulent combustion models that reflect some of the most important characteristics of turbulent reacting flows requires knowledge about the behavior of key quantities in well defined combustion regimes. In turbulent flames, the coupling between the turbulence and the chemistry is so strong in certain regimes that is is very difficult to isolate the role played by one individual phenomenon. Direct numerical simulation (DNS) is an extremely useful tool to study in detail the turbulence-chemistry interactions in certain well defined regimes. Globally, non-premixed flames are controlled by two limiting cases: the fast chemistry limit, where the turbulent fluctuations. In between these two limits, finite-rate chemical effects are important and the turbulence interacts strongly with the chemical processes. This regime is important because industrial burners operate in regimes in which, locally the flame undergoes extinction, or is at least in some nonequilibrium condition. Furthermore, these nonequilibrium conditions strongly influence the production of pollutants. To quantify the finite-rate chemistry effect, direct numerical simulations are performed to study the interaction between an initially laminar non-premixed flame and a three-dimensional field of homogeneous isotropic decaying turbulence. Emphasis is placed on the dynamics of extinction and on transient effects on the fine scale mixing process. Differential molecular diffusion among species is also examined with this approach, both for nonreacting and reacting situations. To address the problem of large-scale mixing and to examine the effects of mean shear, efforts are underway to perform large eddy simulations of round three-dimensional jets.

  2. Turbocharged Spark Ignited Direct Injection - A Fuel Economy...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Turbocharged Spark Ignited Direct Injection - A Fuel Economy Solution for The US Turbocharged Spark Ignited Direct Injection - A Fuel Economy Solution for The US Turbocharged SIDI ...

  3. Light-Duty Reactivity Controlled Compression Ignition Drive Cycle...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Ignition Drive Cycle Fuel Economy and Emissions Estimates Light-Duty Reactivity Controlled Compression Ignition Drive Cycle Fuel Economy and Emissions Estimates Vehicle ...

  4. High Fidelity Modeling of Premixed Charge Compression Ignition...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Fidelity Modeling of Premixed Charge Compression Ignition Engines High Fidelity Modeling of Premixed Charge Compression Ignition Engines Most accurate and detailed chemical kinetic ...

  5. Effects of Ignition Quality and Fuel Composition on Critical...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Effects of Ignition Quality and Fuel Composition on Critical Equivalence Ratio Effects of Ignition Quality and Fuel Composition on Critical Equivalence Ratio Our research shows ...

  6. Physics of compact ignition tokamak designs

    SciTech Connect (OSTI)

    Singer, C.E.; Ku, L.P.; Bateman, G.; Seidl, F.; Sugihara, M.

    1986-03-01

    Models for predicting plasma performance in compact ignition experiments are constructed on the basis of theoretical and empirical constraints and data from tokamak experiments. Emphasis is placed on finding transport and confinement models which reproduce results of both ohmically and auxiliary heated tokamak data. Illustrations of the application of the models to compact ignition designs are given.

  7. Heat transfer characteristics of igniter output plumes

    SciTech Connect (OSTI)

    Evans, N.A.; Durand, N.A.

    1989-01-01

    Seven types of pyrotechnic igniters were each mounted at one end of a closed cylindrical bore hole representative of the center hole in a thermal battery. Measurements of local bore wall temperature, T/sub w/, using commercially available, fast response (10 /mu/sec) sheathed chromel-constantan thermocouples allowed calculation of local heat transfer rates, q, and wall heat flows, Q. The principal charge constituents of all these igniters were titanium and potassium perchlorate, while three types also contained barium styphnate as an ignition sensitizer. Igniter closure disc materials included glass-ceramic, glass, metal (plain, scored, with and without capture cone), and kapton/RTV. All igniters produced the lowest values of T/sub w/ and q at the beginning of the bore, and, except for the igniter with the kapton/RTV closure disc, these quantities increased with distance along the bore. For igniters containing only titanium/potassium perchlorate, the rates of increase of Q along the bore length, compared with those for T/sub w/ and q, were generally lower and more variable. The inclusion of barium styphnate produced rates of change in Q that were essentially constant to the end of the bore. The highest overall average wall temperatures were achieved by two igniter types with metal closure discs and no capture cone. No clear correlation was established between peak bore pressure and maximum wall temperature. 3 refs., 8 figs., 1 tab.

  8. Pyrotechnic ignition studies using a gun tunnel

    SciTech Connect (OSTI)

    Evans, N.A.

    1989-01-01

    A gun tunnel is being used to investigate the ignition characteristics of center-hole iron/potassium perchlorate thermal battery discs. Details are given of the construction, operation, and data reduction method for the gun tunnel. To simulate an igniter, this system can readily produce a pulse of hot argon at maximum pressures and temperatures up to P/sub max/ = 8 MPa and T/sub max/ = 4000K, respectively, with flow times of the order of 3 msec. For a single battery disc, a segment of the ignition boundary was found to lie in the region of T/sub max/ = 1200 to 1300K and 0.7 MPa < P/sub max/ < 2.0 MPa. The results also showed two types of ignition: prompt ignition, requiring an average delivered enthalpy /ovr /Delta/H//sub ig/ = 6 cal during an average flow time /ovr /Delta/t//sub ig/ = 0.7 msec, and delayed ignition, with /ovr /Delta/H//sub ig/ = 16 cal and /ovr /Delta/t//sub ig/ = 2.4 msec. In addition, near an ignition boundary, high speed motion photography showed the ignition delay increased to 6 msec with significant spatial non-uniformity. 1 ref., 6 figs.

  9. Pulsed jet combustion generator for premixed charge engines

    DOE Patents [OSTI]

    Oppenheim, A. K.; Stewart, H. E.; Hom, K.

    1990-01-01

    A method and device for generating pulsed jets which will form plumes comprising eddie structures, which will entrain a fuel/air mixture from the head space of an internal combustion engine, and mixing this fuel/air mixture with a pre-ignited fuel/air mixture of the plumes thereby causing combustion of the reactants to occur within the interior of the eddie structures.

  10. NO concentration imaging in turbulent nonpremixed flames

    SciTech Connect (OSTI)

    Schefer, R.W.

    1993-12-01

    The importance of NO as a pollutant species is well known. An understanding of the formation characteristics of NO in turbulent hydrocarbon flames is important to both the desired reduction of pollutant emissions and the validation of proposed models for turbulent reacting flows. Of particular interest is the relationship between NO formation and the local flame zone, in which the fuel is oxidized and primary heat release occurs. Planar imaging of NO provides the multipoint statistics needed to relate NO formation to the both the flame zone and the local turbulence characteristics. Planar imaging of NO has been demonstrated in turbulent flames where NO was seeded into the flow at high concentrations (2000 ppm) to determine the gas temperature distribution. The NO concentrations in these experiments were significantly higher than those expected in typical hydrocarbon-air flames, which require a much lower detectability limit for NO measurements. An imaging technique based on laser-induced fluorescence with sufficient sensitivity to study the NO formation mechanism in the stabilization region of turbulent lifted-jet methane flames.

  11. Turbulent Nonpremixed Flames (TNF): Experimental Data Archives and Computational Submodels

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    In the 1990s an international collaboration formed around a series of workshops that became known collectively as the International Workshop on Measurement and Computation of Turbulent Non-Premixed Flames (TNF). An online library, hosted by Sandia National Laboratory (California) was established that provides data sets and submodels or "mechanisms" for the study of turbulence-chemistry interactions in turbulent nonpremixed and partially premixed combustion. Data are organized by flame types: simple jet flames, piloted jet flames, bluff body flames, and swirl flames. These data sets provide a means for collaborative comparisons of both measured and simulated/modeled research results and also assist scientists in determining priorities for further research. More than 20 data sets or databases are available from this website, along with various downloadable files of chemical mechanisms. The website also provides an extensive bibliography and the proceedings of the workshops themselves from 1996 through 2012. Information continues to be added to this collection.

  12. PLIF measurement of fuel concentration distribution in transient hydrogen jet flame

    SciTech Connect (OSTI)

    Tomita, Eiji; Hamamoto, Yoshisuke; Yoshiyama, Sadami; Toda, Hitoshi

    1999-07-01

    To know the concentration field of fuel spray or jet is very important because the following combustion process strongly depends on it. Recently, planar laser induced fluorescence (PLIF) measurement is often used to clarify two-dimensional concentration field of fuel and other species. In this study, PLIF measurement was applied to investigate the concentration distribution of a transient hydrogen jet with combustion. The jet penetrates with entraining ambient air and hydrogen is mixed with the air. Each experimental run of the jet shows different configuration and concentration distribution although averaged jet shows axisymmetric ones. Normalized concentration in radial direction presents Gaussian distribution and normalized concentration in axial direction is expressed by the relation inverse to the axial direction. The mixture was ignited near the nozzle exit after some delay time (t = 3.6ms) during injection ({approximately}11ms). For example, the fuel concentration in the transient jet at t = 1.0 and 1.4ms after the spark ignition (t = 4.6 and 5.0 ms respectively) was obtained as shown in a figure. The behavior of the flame development was measured in the transient flame jet by analyzing these images. The velocities of the jet and flame tips were also determined.

  13. National Ignition Facility | National Nuclear Security Administration |

    National Nuclear Security Administration (NNSA)

    (NNSA) National Ignition Facility Glass amplifiers in Laser Bay 2 at the National Ignition Facility. The construction of the 192-beam 1.8 MJ UV NIF, the world's most energetic laser, was completed in March 2009. Current experiments are focusing on using the NIF laser and other ICF high energy density facilities leading to demonstrate fusion ignition and thermonuclear burn in the laboratory. The NIF is also being used to support basic science and SSP experiments. By the end of FY 2012, the

  14. Gas-flow measurements in a jet flame using cross-correlation of high speed particle-images

    SciTech Connect (OSTI)

    Shioji, Masahiro; Kawasaki, Kiyoshi; Kawanabe, Hiroshi; Ikegami, Makoto

    1999-07-01

    Time changes of a two-dimensional distribution of velocities in a methane jet flame and a nitrogen jet are measured by cross-correlation particle image velocimetry (PIV). The mean velocity and the intensity of turbulence are obtained and compared with those measured by HWA in order to ascertain the accuracy of PIV. Furthermore, the effect of combustion on turbulence characteristics is discussed based on the deformation of eddies with time change and distribution of time and spatial scales.

  15. Princeton Plasma Physics Lab - National Ignition Facility

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Feb 2013 14:30:50 +0000 jgreenwa 1361 at http:www.pppl.gov National Ignition Facility (NIF): Under Pressure: Ramp-Compression Smashes Record http:www.pppl.govnode248

  16. lasers. National Ignition Facility | National Nuclear Security...

    National Nuclear Security Administration (NNSA)

    target shot of fiscal year 2015 WASHINGTON - Last week, the National Ignition Facility (NIF) fired its 300th laser target shot in fiscal year (FY) 2015, meeting the year's goal...

  17. Premix charge, compression ignition combustion system optimization |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Premix charge, compression ignition combustion system optimization Premix charge, compression ignition combustion system optimization Presentation given at DEER 2006, August 20-24, 2006, Detroit, Michigan. Sponsored by the U.S. DOE's EERE FreedomCar and Fuel Partnership and 21st Century Truck Programs. 2006_deer_gustafson.pdf (1.47 MB) More Documents & Publications Advanced Combustion Technology to Enable High Efficiency Clean Combustion Heavy-Duty HCCI Development

  18. Loss/gain on ignition test report

    SciTech Connect (OSTI)

    Winstead, M.L.

    1996-01-10

    Document provides the results of tests done on Product Cans from the HC-21C sludge stabilization process. Tests included running a simulated Thermogravimetric Analysis, TGA, on the processed material that have received Loss On Ignition (LOI) sample results that show a gain on ignition or a high LOI and reprocessing product cans with high LOIs. Also, boat material temperatures in the furnace were tracked during the testing.

  19. Ignition methods and apparatus using microwave energy

    DOE Patents [OSTI]

    DeFreitas, Dennis M.; Darling, Timothy W.; Migliori, Albert; Rees, Daniel E.

    1997-01-01

    An ignition apparatus for a combustor includes a microwave energy source that emits microwave energy into the combustor at a frequency within a resonant response of the combustor, the combustor functioning as a resonant cavity for the microwave energy so that a plasma is produced that ignites a combustible mixture therein. The plasma preferably is a non-contact plasma produced in free space within the resonant cavity spaced away from with the cavity wall structure and spaced from the microwave emitter.

  20. Infrared Thermographic Study of Laser Ignition

    SciTech Connect (OSTI)

    Mohler, Jonathan H.; Chow, Charles T. S.

    1986-07-01

    Pyrotechnic ignition has been studied in the past by making a limited number of discrete temperature-time observations during ignition. Present-day infrared scanning techniques make it possible to record thermal profiles, during ignition, with high spacial and temporal resolution. Data thus obtained can be used with existing theory to characterize pyrotechnic materials and to develop more precise kinetic models of the ignition process. Ignition has been studied theoretically and experimentally using various thermal methods. It has been shown that the whole process can, ideally, be divided into two stages. In the first stage, the sample pellet behaves like an inert body heated by an external heat source. The second stage is governed by the chemical reaction in the heated volume produced during the first stage. High speed thermographic recording of the temperature distribution in the test sample during laser ignition makes it possible to calculate the heat content at any instant. Thus, one can actually observe laser heating and the onset of self-sustained combustion in the pellet. The experimental apparatus used to make these observations is described. The temperature distributions recorded are shown to be in good agreement with those predicted by heat transfer theory. Heat content values calculated from the observed temperature distributions are used to calculate thermal and kinetic parameters for several samples. These values are found to be in reasonable agreement with theory.

  1. Infrared thermographic study of laser ignition

    SciTech Connect (OSTI)

    Mohler, J.H.; Chow, C.T.S.

    1986-07-21

    Pyrotechnic ignition has been studied in the past by making a limited number of discrete temperature-time observations during ignition. Present-day infrared scanning techniques make it possible to record thermal profiles, during ignition, with high spacial and temporal resolution. Data thus obtained can be used with existing theory to characterize pyrotechnic materials and to develop more precise kinetic models of the ignition process. Ignition has been studied theoretically and experimentally using various thermal methods. It has been shown that the whole process can, ideally, be divided into two stages. In the first stage, the sample pellet behaves like an inert body heated by an external heat source. The second stage is governed by the chemical reaction in the heated volume produced during the first stage. High speed thermographic recording of the temperature distribution in the test sample during laser ignition makes it possible to calculate the heat content at any instant. Thus, one can actually observe laser heating and the onset of self-sustained combustion in the pellet.

  2. Role of metastable atoms in the propagation of atmospheric pressure dielectric barrier discharge jets

    SciTech Connect (OSTI)

    Li Qing; Zhu Ximing; Li Jiangtao; Pu Yikang [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2010-02-15

    In the experiment of plasma jets generated in a tube dielectric barrier discharge configuration, three distinguishable modes, namely, laminar, transition, and turbulent jet modes, have been identified. Flows of helium, neon, and argon gases shared the hydrodynamic law when their plasma jets spraying into ambient air of atmospheric pressure and room temperature. Aiming to reveal the basic processes, we propose that plasma jet length is mainly determined by reactions involving metastable atoms. These processes are responsible for the variation in plasma jet length versus gas flow rate and working gas species. To investigate this proposal in detail, we have obtained three significant experimental results, i.e., (1) the plasma jet lengths of helium, neon, and argon are different; (2) the plasma jet length of krypton slightly changes with gas flow rate, with three modes indistinguishable; and (3) there are large differences between optical emission spectra of helium, neon, argon, and krypton flow gases. These observations are in good agreement with our proposal.

  3. Jet-wall interaction effects on diesel combustion and soot formation.

    SciTech Connect (OSTI)

    Pickett, Lyle M.; Lopez, J. Javier

    2004-09-01

    The effects of wall interaction on combustion and soot formation processes of a diesel fuel jet were investigated in an optically-accessible constant-volume combustion vessel at experimental conditions typical of a diesel engine. At identical ambient and injector conditions, soot processes were studied in free jets, plane wall jets, and 'confined' wall jets (a box-shaped geometry simulating secondary interaction with adjacent walls and jets in an engine). The investigation showed that soot levels are significantly lower in a plane wall jet compared to a free jet. At some operating conditions, sooting free jets become soot-free as plane wall jets. Possible mechanisms to explain the reduced or delayed soot formation upon wall interaction include an increased fuel-air mixing rate and a wall-jet-cooling effect. However, in a confined-jet configuration, there is an opposite trend in soot formation. Jet confinement causes combustion gases to be redirected towards the incoming jet, causing the lift-off length to shorten and soot to increase. This effect can be avoided by ending fuel injection prior to the time of significant interaction with redirected combustion gases. For a fixed confined-wall geometry, an increase in ambient gas density delays jet interaction, allowing longer injection durations with no increase in soot. Jet interaction with redirected combustion products may also be avoided using reduced ambient oxygen concentration because of an increased ignition delay. Although simplified geometries were employed, the identification of important mechanisms affecting soot formation after the time of wall interaction is expected to be useful for understanding these processes in more complex and realistic diesel engine geometries.

  4. Implications of Upwells as Hydrodynamic Jets in a Pulse Jet Mixed System

    SciTech Connect (OSTI)

    Pease, Leonard F.; Bamberger, Judith A.; Minette, Michael J.

    2015-08-01

    satisfies these criteria when vigorous breakthrough is achieved, not all available data follow the free jet profile for the central upwell, particularly at lower nozzle velocities. Alternative flow regimes are considered and new models for cloud height, “cavern height,” and the rate of jet penetration (jet celerity) are benchmarked against data to anchor scaling analyses. This analytical modeling effort to provide a technical basis for scaling PJM mixed vessels has significant implications for vessel mixing, because jet physics underlies “cavern” height, cloud height, and the volume of mixing considerations. A new four-parameter cloud height model compares favorably to experimental results. This model is predictive of breakthrough in 8 ft vessel tests with the two-part simulant. Analysis of the upwell in the presence of yield stresses finds evidence of expanding turbulent jets, confined turbulent jets, and confined laminar flows. For each, the critical elevation at which jet momentum depletes is predicted, which compare favorably to experimental cavern height data. Partially coupled momentum and energy balances suggest that these are limiting cases of a gradual transition from a turbulent expanding flow to a confined laminar flow. This analysis of the central upwell alone lays essential groundwork for complete analysis of mode three mixing (i.e., breakthrough with slow peripheral mixing). Consideration of jet celerity shows that the rate of jet penetration is a governing consideration in breakthrough to the surface. Estimates of the volume of mixing are presented. This analysis shows that flow along the vessel wall is sluggish such that the central upwell governs the volume of mixing. This analysis of the central upwell alone lays essential groundwork for complete analysis of mode three mixing and estimates of hydrogen release rates from first principles.

  5. Plasmoid Instabilities Mediated Three-Dimensional Magnetohydrodynamic Turbulent Reconnection

    SciTech Connect (OSTI)

    Huang, Yi-min; Guo, Fan

    2015-07-21

    After some introductory remarks on fast reconnection in resistive MHD due to plasmoid instability, oblique tearing modes in 3D, and previous studies on 3D turbulent reconnection, the subject is presented under the following topics: 3D simulation setup, time evolution of the 3D simulation, comparison with Sweet-Parker and 2D plasmoid reconnection, and diagnostics of the turbulent state (decomposition of mean fields and fluctuations, power spectra of energy fluctuations, structure function and eddy anisotropy with respect to local magnetic field). Three primary conclusions were reached: (1) The results suggest that 3D plasmoid instabilities can lead to self-generated turbulent reconnection (evidence of energy cascade and development of inertial range, energy fluctuations preferentially align with the local magnetic field, which is one of the characteristics of MHD turbulence); (2) The turbulence is highly inhomogeneous, due to the presence of magnetic shear and outflow jets (conventional MHD turbulence theories or phenomenologies may not be applicable – e.g. scale-dependent anisotropy as predicted by Goldreich & Sridhar is not found); (3) 3D turbulent reconnection is different from 2D plasmoid-dominated reconnection in many aspects. However, in fully developed state, reconnection rates in 2D and 3D are comparable — this result needs to be further checked in higher S.

  6. Radiosonde measurements of turbulence

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Turbulence detection on aerial platforms using orientation sensors R. Giles Harrison, Robin J. Hogan, George W. Rogers, Alyssa M. Heath and Keri A. Nicoll Department of Meteorology University of Reading, UK r.g.harrison@reading.ac.uk 2 "Bumpiness" (or turbulence), still remains an aircraft hazard, even at cruising altitudes How can in-situ direct position and orientation sensing can be used to detect turbulence affecting aerial platforms? * Investigated using balloon platforms,

  7. Direct Numerical Simulations of Autoignition in Stratified Dimethyl-ether (DME)/Air Turbulent Mixtures

    SciTech Connect (OSTI)

    Bansal, Gaurav; Mascarenhas, Ajith; Chen, Jacqueline H.

    2014-10-01

    In our paper, two- and three-dimensional direct numerical simulations (DNS) of autoignition phenomena in stratified dimethyl-ether (DME)/air turbulent mixtures are performed. A reduced DME oxidation mechanism, which was obtained using rigorous mathematical reduction and stiffness removal procedure from a detailed DME mechanism with 55 species, is used in the present DNS. The reduced DME mechanism consists of 30 chemical species. This study investigates the fundamental aspects of turbulence-mixing-autoignition interaction occurring in homogeneous charge compression ignition (HCCI) engine environments. A homogeneous isotropic turbulence spectrum is used to initialize the velocity field in the domain. Moreover, the computational configuration corresponds to a constant volume combustion vessel with inert mass source terms added to the governing equations to mimic the pressure rise due to piston motion, as present in practical engines. DME autoignition is found to be a complex three-staged process; each stage corresponds to a distinct chemical kinetic pathway. The distinct role of turbulence and reaction in generating scalar gradients and hence promoting molecular transport processes are investigated. Then, by applying numerical diagnostic techniques, the different heat release modes present in the igniting mixture are identified. In particular, the contribution of homogeneous autoignition, spontaneous ignition front propagation, and premixed deflagration towards the total heat release are quantified.

  8. Direct Numerical Simulations of Autoignition in Stratified Dimethyl-ether (DME)/Air Turbulent Mixtures

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bansal, Gaurav; Mascarenhas, Ajith; Chen, Jacqueline H.

    2014-10-01

    In our paper, two- and three-dimensional direct numerical simulations (DNS) of autoignition phenomena in stratified dimethyl-ether (DME)/air turbulent mixtures are performed. A reduced DME oxidation mechanism, which was obtained using rigorous mathematical reduction and stiffness removal procedure from a detailed DME mechanism with 55 species, is used in the present DNS. The reduced DME mechanism consists of 30 chemical species. This study investigates the fundamental aspects of turbulence-mixing-autoignition interaction occurring in homogeneous charge compression ignition (HCCI) engine environments. A homogeneous isotropic turbulence spectrum is used to initialize the velocity field in the domain. Moreover, the computational configuration corresponds to amore » constant volume combustion vessel with inert mass source terms added to the governing equations to mimic the pressure rise due to piston motion, as present in practical engines. DME autoignition is found to be a complex three-staged process; each stage corresponds to a distinct chemical kinetic pathway. The distinct role of turbulence and reaction in generating scalar gradients and hence promoting molecular transport processes are investigated. Then, by applying numerical diagnostic techniques, the different heat release modes present in the igniting mixture are identified. In particular, the contribution of homogeneous autoignition, spontaneous ignition front propagation, and premixed deflagration towards the total heat release are quantified.« less

  9. Applied Turbulent Combustion

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ... Furthermore, combined spontaneous Raman spectroscopy, Rayleigh scatter, and OHCO-laser-induced fluorescence measurements have been used to quantify in situ turbulent flame mixture ...

  10. Analytical model for fast-shock ignition

    SciTech Connect (OSTI)

    Ghasemi, S. A. Farahbod, A. H.; Sobhanian, S.

    2014-07-15

    A model and its improvements are introduced for a recently proposed approach to inertial confinement fusion, called fast-shock ignition (FSI). The analysis is based upon the gain models of fast ignition, shock ignition and considerations for the fast electrons penetration into the pre-compressed fuel to examine the formation of an effective central hot spot. Calculations of fast electrons penetration into the dense fuel show that if the initial electron kinetic energy is of the order ∼4.5 MeV, the electrons effectively reach the central part of the fuel. To evaluate more realistically the performance of FSI approach, we have used a quasi-two temperature electron energy distribution function of Strozzi (2012) and fast ignitor energy formula of Bellei (2013) that are consistent with 3D PIC simulations for different values of fast ignitor laser wavelength and coupling efficiency. The general advantages of fast-shock ignition in comparison with the shock ignition can be estimated to be better than 1.3 and it is seen that the best results can be obtained for the fuel mass around 1.5 mg, fast ignitor laser wavelength ∼0.3  micron and the shock ignitor energy weight factor about 0.25.

  11. Autoignited laminar lifted flames of propane in coflow jets with tribrachial edge and mild combustion

    SciTech Connect (OSTI)

    Choi, B.C.; Kim, K.N.; Chung, S.H.

    2009-02-15

    Characteristics of laminar lifted flames have been investigated experimentally by varying the initial temperature of coflow air over 800 K in the non-premixed jets of propane diluted with nitrogen. The result showed that the lifted flame with the initial temperature below 860 K maintained the typical tribrachial structure at the leading edge, which was stabilized by the balance mechanism between the propagation speed of tribrachial flame and the local flow velocity. For the temperature above 860 K, the flame was autoignited without having any external ignition source. The autoignited lifted flames were categorized in two regimes. In the case with tribrachial edge structure, the liftoff height increased nonlinearly with jet velocity. Especially, for the critical condition near blowout, the lifted flame showed a repetitive behavior of extinction and reignition. In such a case, the autoignition was controlled by the non-adiabatic ignition delay time considering heat loss such that the autoignition height was correlated with the square of the adiabatic ignition delay time. In the case with mild combustion regime at excessively diluted conditions, the liftoff height increased linearly with jet velocity and was correlated well with the square of the adiabatic ignition delay time. (author)

  12. ATMOSPHERIC CIRCULATION OF BROWN DWARFS: JETS, VORTICES, AND TIME VARIABILITY

    SciTech Connect (OSTI)

    Zhang, Xi; Showman, Adam P.

    2014-06-10

    A variety of observational evidence demonstrates that brown dwarfs exhibit active atmospheric circulations. In this study we use a shallow-water model to investigate the global atmospheric dynamics in the stratified layer overlying the convective zone on these rapidly rotating objects. We show that the existence and properties of the atmospheric circulation crucially depend on key parameters including the energy injection rate and radiative timescale. Under conditions of strong internal heat flux and weak radiative dissipation, a banded flow pattern comprised of east-west jet streams spontaneously emerges from the interaction of atmospheric turbulence with the planetary rotation. In contrast, when the internal heat flux is weak and/or radiative dissipation is strong, turbulence injected into the atmosphere damps before it can self-organize into jets, leading to a flow dominated by transient eddies and isotropic turbulence instead. The simulation results are not very sensitive to the form of the forcing. Based on the location of the transition between jet-dominated and eddy-dominated regimes, we suggest that many brown dwarfs may exhibit atmospheric circulations dominated by eddies and turbulence (rather than jets) due to the strong radiative damping on these worlds, but a jet structure is also possible under some realistic conditions. Our simulated light curves capture important features from observed infrared light curves of brown dwarfs, including amplitude variations of a few percent and shapes that fluctuate between single-peak and multi-peak structures. More broadly, our work shows that the shallow-water system provides a useful tool to illuminate fundamental aspects of the dynamics on these worlds.

  13. Ignition of THKP and TKP pyrotechnic powders :

    SciTech Connect (OSTI)

    Maharrey, Sean P.; Erikson, William W; Highley, Aaron M.; Wiese-Smith, Deneille; Kay, Jeffrey J

    2014-03-01

    We have conducted Simultaneous Thermogravimetric Modulated Beam Mass Spectrometry (STMBMS) experiments on igniter/actuator pyrotechnic powders to characterize the reactive processes controlling the ignition and combustion behavior of these materials. The experiments showed a complex, interactive reaction manifold involving over ten reaction pathways. A reduced dimensionality reaction manifold was developed from the detailed 10-step manifold and is being incorporated into existing predictive modeling codes to simulate the performance of pyrotechnic powders for NW component development. The results from development of the detailed reaction manifold and reduced manifold are presented. The reduced reaction manifold has been successfully used by SNL/NM modelers to predict thermal ignition events in small-scale testing, validating our approach and improving the capability of predictive models.

  14. Ignition of deuterium-trtium fuel targets

    DOE Patents [OSTI]

    Musinski, Donald L.; Mruzek, Michael T.

    1991-01-01

    A method of igniting a deuterium-tritium ICF fuel target to obtain fuel burn in which the fuel target initially includes a hollow spherical shell having a frozen layer of DT material at substantially uniform thickness and cryogenic temperature around the interior surface of the shell. The target is permitted to free-fall through a target chamber having walls heated by successive target ignitions, so that the target is uniformly heated during free-fall to at least partially melt the frozen fuel layer and form a liquid single-phase layer or a mixed liquid/solid bi-phase layer of substantially uniform thickness around the interior shell surface. The falling target is then illuminated from exteriorly of the chamber while the fuel layer is at substantially uniformly single or bi-phase so as to ignite the fuel layer and release energy therefrom.

  15. Ignition of deuterium-tritium fuel targets

    DOE Patents [OSTI]

    Musinski, D.L.; Mruzek, M.T.

    1991-08-27

    Disclosed is a method of igniting a deuterium-tritium ICF fuel target to obtain fuel burn in which the fuel target initially includes a hollow spherical shell having a frozen layer of DT material at substantially uniform thickness and cryogenic temperature around the interior surface of the shell. The target is permitted to free-fall through a target chamber having walls heated by successive target ignitions, so that the target is uniformly heated during free-fall to at least partially melt the frozen fuel layer and form a liquid single-phase layer or a mixed liquid/solid bi-phase layer of substantially uniform thickness around the interior shell surface. The falling target is then illuminated from exteriorly of the chamber while the fuel layer is at substantially uniformly single or bi-phase so as to ignite the fuel layer and release energy therefrom. 5 figures.

  16. Low current extended duration spark ignition system

    DOE Patents [OSTI]

    Waters, Stephen Howard; Chan, Anthony Kok-Fai

    2005-08-30

    A system for firing a spark plug is disclosed. The system includes a timing controller configured to send a first timing signal and a second timing signal. The system also includes an ignition transformer having a primary winding and a secondary winding and a spark-plug that is operably associated with the secondary winding. A first switching element is disposed between the timing controller and the primary winding of the ignition transformer. The first switching element controls a supply of power to the primary winding based on the first timing signal. Also, a second switching element is disposed between the timing controller and the primary winding of the ignition transformer. The second switching element controls the supply of power to the primary winding based on the second timing signal. A method for firing a spark plug is also disclosed.

  17. Gas turbine igniter with ball-joint support

    SciTech Connect (OSTI)

    Steber, C.E.; Travis, R.J.; Rizzo, J.A.

    1990-02-27

    This patent describes a support for an igniter for a combustor of a gas turbine, the combustor being of a type including a casing and a liner within the casing. It comprises: a ball joint; means for supporting the ball joint disposed a substantial distance outward from the casing; a body section of the igniter affixed in the ball joint; means for permitting the ball joint, and the body section to rotate through a substantial range; an igniter tip on the body section; and a hole in the liner. The igniter tip entering through the hole and into an interior of the liner. The hole being a tight fit to the igniter tip, whereby leakage past the igniter tip through the hole is limited. The substantial range being sufficient to permit fitting the igniter tip in the hole in the presence of manufacturing tolerances, and to permit the igniter tip to track the hole in the presence of differential thermal expansion during operation.

  18. Spherical strong-shock generation for shock-ignition inertial...

    Office of Scientific and Technical Information (OSTI)

    a shock-ignition target design for the National Ignition Facility. The timing of the x-ray flash from shock convergence in the center of the solid plastic target is used to infer ...

  19. Spherical strong-shock generation for shock-ignition inertial...

    Office of Scientific and Technical Information (OSTI)

    Spherical strong-shock generation for shock-ignition inertial fusion Citation Details In-Document Search Title: Spherical strong-shock generation for shock-ignition inertial fusion ...

  20. National Ignition Facility project acquisition plan revision 1

    SciTech Connect (OSTI)

    Clobes, A.R.

    1996-10-01

    The purpose of this National Ignition Facility Acquisition Plan is to describe the overall procurement strategy planned for the National Ignition Facility M Project. It was prepared for the NIP Prood Office by the NIF Procurement Manager.

  1. Semiconductor bridge, SCB, ignition of energetic materials

    SciTech Connect (OSTI)

    Bickes, R.W.; Grubelich, M.D.; Harris, S.M.; Merson, J.A.; Tarbell, W.W.

    1997-04-01

    Sandia National Laboratories` semiconductor bridge, SCB, is now being used for the ignition or initiation of a wide variety of exeoergic materials. Applications of this new technology arose because of a need at the system level to provide light weight, small volume and low energy explosive assemblies. Conventional bridgewire devices could not meet the stringent size, weight and energy requirements of our customers. We present an overview of SCB technology and the ignition characteristics for a number of energetic materials including primary and secondary explosives, pyrotechnics, thermites and intermetallics. We provide examples of systems designed to meet the modern requirements that sophisticated systems must satisfy in today`s market environments.

  2. Need for the National Ignition Facility

    SciTech Connect (OSTI)

    Crandall, D.H.

    1996-12-31

    This paper has an attitude - that the National Ignition Facility (NIF) is needed. The NIF will be unique in its ability to address high energy density physics and to test fusion ignition in the laboratory. This is a major scientific step and has high appeal to scientists and engineers. The reason for taking this step now is the importance of high energy density physics for US policy on nuclear weapons. The fact that the same capability and experiments give the most fundamental information on the potential of inertial fusion for commercial energy, and have value for applications in astrophysics, further supports the case for proceeding with this facility. 21 refs., 6 figs.

  3. Development and Benchmarking of a Hybrid PIC Code For Dense Plasmas and Fast Ignition

    SciTech Connect (OSTI)

    Witherspoon, F. Douglas; Welch, Dale R.; Thompson, John R.; MacFarlane, Joeseph J.; Phillips, Michael W.; Bruner, Nicki; Mostrom, Chris; Thoma, Carsten; Clark, R. E.; Bogatu, Nick; Kim, Jin-Soo; Galkin, Sergei; Golovkin, Igor E.; Woodruff, P. R.; Wu, Linchun; Messer, Sarah J.

    2014-05-20

    Radiation processes play an important role in the study of both fast ignition and other inertial confinement schemes, such as plasma jet driven magneto-inertial fusion, both in their effect on energy balance, and in generating diagnostic signals. In the latter case, warm and hot dense matter may be produced by the convergence of a plasma shell formed by the merging of an assembly of high Mach number plasma jets. This innovative approach has the potential advantage of creating matter of high energy densities in voluminous amount compared with high power lasers or particle beams. An important application of this technology is as a plasma liner for the flux compression of magnetized plasma to create ultra-high magnetic fields and burning plasmas. HyperV Technologies Corp. has been developing plasma jet accelerator technology in both coaxial and linear railgun geometries to produce plasma jets of sufficient mass, density, and velocity to create such imploding plasma liners. An enabling tool for the development of this technology is the ability to model the plasma dynamics, not only in the accelerators themselves, but also in the resulting magnetized target plasma and within the merging/interacting plasma jets during transport to the target. Welch pioneered numerical modeling of such plasmas (including for fast ignition) using the LSP simulation code. Lsp is an electromagnetic, parallelized, plasma simulation code under development since 1995. It has a number of innovative features making it uniquely suitable for modeling high energy density plasmas including a hybrid fluid model for electrons that allows electrons in dense plasmas to be modeled with a kinetic or fluid treatment as appropriate. In addition to in-house use at Voss Scientific, several groups carrying out research in Fast Ignition (LLNL, SNL, UCSD, AWE (UK), and Imperial College (UK)) also use LSP. A collaborative team consisting of HyperV Technologies Corp., Voss Scientific LLC, FAR-TECH, Inc., Prism

  4. Experimental study on confined two-phase jets

    SciTech Connect (OSTI)

    Levy, Y.; Albagli, D. )

    1991-09-01

    The basic mixing phenomena in confined, coaxial, particle-laden turbulent flows are studied within the scope of ram combustor research activities. Cold-flow experiments in a relatively simple configuration of confined, coaxial two-phase jets provided both qualitative and quantitative insight on the multiphase mixing process. Pressure, tracer gas concentration, and two-phase velocity measurements revealed that unacceptably long ram combustors are needed for complete confined jet mixing. Comparison of the experimental results with a previous numerical simulation displayed a very good agreement, indicating the potential of the experimental facility for validation of computational parametric studies. 38 refs.

  5. Groundbreaking at National Ignition Facility | National Nuclear Security

    National Nuclear Security Administration (NNSA)

    Administration | (NNSA) Groundbreaking at National Ignition Facility Groundbreaking at National Ignition Facility Livermore, CA Secretary Pena participates in the ground breaking ceremony for the National Ignition Facility, a centerpiece of the stockpile stewardship program, at the Lawrence Livermore National Laboratory

  6. Fully Developed Turbulent Mixing in an Annular Sector

    SciTech Connect (OSTI)

    Lim, Hyun-Kyung; Zhou, Yijie; de Almeida, Valmor F; Glimm, James G

    2014-01-01

    We review recent progress on the characterization of turbulent mixing fluid flow and relate these ideas to high-speed, two-phase Couette flow with application to mixing in a centrifugal contactor. The general ideas are more broadly applicable and have been applied to the study of Rayleigh-Taylor and Richtmyer-Meshkov fluid mixing, combustion in the engine of a scram jet and the analysis of inertial confinement pellet simulations.

  7. Methanol with dimethyl ether ignition promotor as fuel for compression ignition engines

    SciTech Connect (OSTI)

    Brook, D.L.; Cipolat, D.; Rallis, C.J.

    1984-08-01

    Reduction of the world dependence upon crude oil necessitates the use of long term alternative fuels for internal combustion engines. Alcohols appear to offer a solution as in the short term they can be manufactured from natural gas and coal, while ultimately they may be produced from agricultural products. A fair measure of success has been achieved in using alcohols in spark ignition engines. However the more widely used compression ignition engines cannot utilize unmodified pure alcohols. The current techniques for using alcohol fuels in compression ignition engines all have a number of shortcomings. This paper describes a novel technique where an ignition promotor, dimethyl ether (DME), is used to increase the cetane rating of methanol. The systems particular advantage is that the DME can be catalyzed from the methanol base fuel, in situ. This fuel system matches the performance characteristics of diesel oil fuel.

  8. Interpretation of extragalactic jets

    SciTech Connect (OSTI)

    Norman, M.L.

    1985-01-01

    The nature of extragalatic radio jets is modeled. The basic hypothesis of these models is that extragalatic jets are outflows of matter which can be described within the framework of fluid dynamics and that the outflows are essentially continuous. The discussion is limited to the interpretation of large-scale (i.e., kiloparsec-scale) jets. The central problem is to infer the physical parameters of the jets from observed distributions of total and polarized intensity and angle of polarization as a function of frequency. 60 refs., 6 figs.

  9. Jets in QCD

    SciTech Connect (OSTI)

    Seymour, M.H.

    1996-02-01

    Many analyses at the collider utilize the hadronic jets that are the footprints of QCD partons. These are used both to study the QCD processes themselves and increasingly as tools to study other physics, for example top mass reconstruction. However, jets are not fundamental degrees of freedom in the theory, so we need an {ital operational} {ital jet} {ital definition} and {ital reliable} {ital methods} {ital to} {ital calculate} {ital their} {ital properties}. This talk covers both of these important areas of jet physics. {copyright} {ital 1996 American Institute of Physics.}

  10. Deep Dive Topic: Approach to ignition

    SciTech Connect (OSTI)

    Hurricane, O. A.; Kline, J. L.; Meezan, N.; Mackinnon, A.

    2015-07-14

    The current high-foot and related implosions have adequate CR and implosion velocity to ignite, but require improved finesse particularly in, but not limited to, implosion symmetry. This is being pursued. The challenge of controlling drive symmetry is also motivating lower convergence ratio designs. These require higher velocity implosions and are also being pursued.

  11. National Ignition Facility Title II Design Plan

    SciTech Connect (OSTI)

    Kumpan, S

    1997-03-01

    This National Ignition Facility (NIF) Title II Design Plan defines the work to be performed by the NIF Project Team between November 1996, when the U.S. Department of Energy (DOE) reviewed Title I design and authorized the initiation of Title H design and specific long-lead procurements, and September 1998, when Title 11 design will be completed.

  12. Injury and mortality of juvenile salmon entrained in a submerged jet entering still water

    SciTech Connect (OSTI)

    Deng, Zhiqun; Mueller, Robert P.; Richmond, Marshall C.; Johnson, Gary E.

    2010-05-21

    Juvenile salmon can be injured and killed when they pass through hydroelectric turbines and other downstream passage alternatives. The hydraulic conditions in these complex environments that pose a risk to the health of fish include turbulent shear flows, collisions with hydraulic structures, cavitation, and rapid change of pressure. Improvements in the understating of the biological responses of juvenile salmon in turbulent shear flows can reduce salmon injury and mortality. In a series of studies, juvenile fall Chinook salmon (Oncorhynchus tshawythscha) were exposed to turbulent shear flows in two mechanisms: 1) the slow-fish-to-fast-water mechanism, where test fish were introduced into a turbulent jet from slow-moving water through an introduction tube placed just outside the edge of the jet; 2) the fast-fish-to-slow-water mechanism, where test fish were carried by the fast-moving water of a submerged turbulent jet into the slow-moving water of a flume. All fish exposures to the water jet were recorded by two high-speed, high-resolution cameras. Motion-tracking analysis was then performed on the digital videos to quantify associated kinematic and dynamic parameters. The main results for the slow-fish-to-fast-water mechanism were described in Deng et al (2005). This chapter will discuss the test results of the fast-fish-to-slow-water mechanism and compare the results of the two mechanisms.

  13. Fundamental Studies of Ignition Process in Large Natural Gas Engines Using Laser Spark Ignition

    SciTech Connect (OSTI)

    Azer Yalin; Bryan Willson

    2008-06-30

    Past research has shown that laser ignition provides a potential means to reduce emissions and improve engine efficiency of gas-fired engines to meet longer-term DOE ARES (Advanced Reciprocating Engine Systems) targets. Despite the potential advantages of laser ignition, the technology is not seeing practical or commercial use. A major impediment in this regard has been the 'open-path' beam delivery used in much of the past research. This mode of delivery is not considered industrially practical owing to safety factors, as well as susceptibility to vibrations, thermal effects etc. The overall goal of our project has been to develop technologies and approaches for practical laser ignition systems. To this end, we are pursuing fiber optically coupled laser ignition system and multiplexing methods for multiple cylinder engine operation. This report summarizes our progress in this regard. A partial summary of our progress includes: development of a figure of merit to guide fiber selection, identification of hollow-core fibers as a potential means of fiber delivery, demonstration of bench-top sparking through hollow-core fibers, single-cylinder engine operation with fiber delivered laser ignition, demonstration of bench-top multiplexing, dual-cylinder engine operation via multiplexed fiber delivered laser ignition, and sparking with fiber lasers. To the best of our knowledge, each of these accomplishments was a first.

  14. BOUndary Plasma Turbulence

    Energy Science and Technology Software Center (OSTI)

    2008-01-25

    BOUT is a parallelized 3D nonlocal electromagnetic turbulence code. The principal calculations are the boundary plasma turbulence in a realistic magnetic geometry. BOUT uses fluid Braginskii equations for plasma vorticity, density, electron and ion temperature and Parallel mementum. With sources added in the core-edge region and sinks in the scrape-off-layer (SOL), BOUT follows the self-consistent profile evolution together with turbulence. BOUT also includes coupling to a magnetohyfrodynamic equlibrium (EFIT package) and a two-dimensional hydrodynamic edgemore » transport model (UEDGE package).« less

  15. Observations of Edge Turbulence

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Edge Turbulence near the X-point of Alcator C-Mod APS-2007 (1) J.L. Terry, S.J. Zweben*, B. LaBombard, I. Cziegler, O. Grulke + , D.P. Stotler* MIT - Plasma Science and Fusion...

  16. The National Ignition Facility (NIF) and the National Ignition Campaign (NIC)

    SciTech Connect (OSTI)

    Moses, E

    2009-09-17

    The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and experiments studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). NIF construction was certified by the Department of Energy as complete on March 27, 2009. NIF, a 192-beam Nd:glass laser facility, will ultimately produce 1.8-MJ, 500-TW of 351-nm third-harmonic, ultraviolet light. On March 10, 2009, total 192-beam energy of 1.1 MJ was demonstrated; this is approximately 30 times more energy than ever produced in an ICF laser system. The principal goal of NIF is to achieve ignition of a deuterium-tritium (DT) fuel capsule and provide access to HED physics regimes needed for experiments related to national security, fusion energy and broader frontier scientific exploration. NIF experiments in support of indirect-drive ignition began in August 2009. These first experiments represent the next phase of the National Ignition Campaign (NIC). The NIC is a national effort to achieve fusion ignition and is coordinated through a detailed execution plan that includes the science, technology, and equipment. Equipment required for ignition experiments includes diagnostics, a cryogenic target manipulator, and user optics. Participants in this effort include LLNL, General Atomics (GA), Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), and the University of Rochester Laboratory for Energetics (LLE). The primary goal for NIC is to have all of the equipment operational, integrated into the facility, and ready to begin a credible ignition campaign in 2010. With NIF now operational, the long-sought goal of achieving self-sustained nuclear fusion and energy gain in the laboratory is much closer to realization. Successful demonstration of ignition and net energy gain on NIF will be a major step towards demonstrating the feasibility of Inertial Fusion Energy (IFE) and will likely

  17. Studies of the effects of curvature on dilution jet mixing

    SciTech Connect (OSTI)

    Holdeman, J.D.; Srinivasan, Ram: Reynolds, R.S.; White, C.D. Allied-Signal Aerospace Co., Phoenix, AZ )

    1992-02-01

    An analytical program was conducted using both three-dimensional numerical and empirical models to investigate the effects of transition liner curvature on the mixing of jets injected into a confined crossflow. The numerical code is of the TEACH type with hybrid numerics; it uses the power-law and SIMPLER algorithms, an orthogonal curvilinear coordinate system, and an algebraic Reynolds stress turbulence model. From the results of the numerical calculations, an existing empirical model for the temperature field downstream of single and multiple rows of jets injected into a straight rectangular duct was extended to model the effects of curvature. Temperature distributions, calculated with both the numerical and empirical models, are presented to show the effects of radius of curvature and inner and outer wall injection for single and opposed rows of cool dilution jets injected into a hot mainstream flow. 27 refs.

  18. Conceptual Design - Polar Drive Ignition Campaign

    SciTech Connect (OSTI)

    Hansen, R

    2012-04-05

    The Laboratory for Laser Energetics (LLE) at the University of Rochester is proposing a collaborative effort with Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratories (LANL), the Naval Research Laboratory (NRL), and General Atomics (GA) with the goal of developing a cryogenic polar drive (PD) ignition platform on the National Ignition Facility (NIF). The scope of this proposed project requires close discourse among theorists, experimentalists, and laser and system engineers. This document describes how this proposed project can be broken into a series of parallel independent activities that, if implemented, could deliver this goal in the 2017 timeframe. This Conceptual Design document is arranged into two sections: mission need and design requirements. Design requirements are divided into four subsystems: (1) A point design that details the necessary target specifications and laser pulse requirements; (2) The beam smoothing subsystem that describes the MultiFM 1D smoothing by spectral dispersion (SSD); (3) New optical elements that include continuous phase plates (CPP's) and distributed polarization rotators (DPR's); and (4) The cryogenic target handling and insertion subsystem, which includes the design, fabrication, testing, and deployment of a dedicated PD ignition target insertion cryostat (PD-ITIC). This document includes appendices covering: the primary criteria and functional requirements, the system design requirements, the work breakdown structure, the target point design, the experimental implementation plan, the theoretical unknowns and technical implementation risks, the estimated cost and schedule, the development plan for the DPR's, the development plan for MultiFM 1D SSD, and a list of acronym definitions. While work on the facility modifications required for PD ignition has been in progress for some time, some of the technical details required to define the specific modifications for a Conceptual Design Review (CDR) remain

  19. Rapid ignition of fluidized bed boiler

    DOE Patents [OSTI]

    Osborn, Liman D.

    1976-12-14

    A fluidized bed boiler is started up by directing into the static bed of inert and carbonaceous granules a downwardly angled burner so that the hot gases cause spouting. Air is introduced into the bed at a rate insufficient to fluidize the entire bed. Three regions are now formed in the bed, a region of lowest gas resistance, a fluidized region and a static region with a mobile region at the interface of the fluidized and static regions. Particles are transferred by the spouting action to form a conical heap with the carbonaceous granules concentrated at the top. The hot burner gases ignite the carbonaceous matter on the top of the bed which becomes distributed in the bed by the spouting action and bed movement. Thereafter the rate of air introduction is increased to fluidize the entire bed, the spouter/burner is shut off, and the entire fluidized bed is ignited.

  20. Radiological assessments for the National Ignition Facility

    SciTech Connect (OSTI)

    Hong, Kou-John; Lazaro, M.A.

    1996-08-01

    The potential radiological impacts of the National Ignition Facility (NIF), a proposed facility for fusion ignition and high energy density experiments, were assessed for five candidate sites to assist in site selection. The GENII computer program was used to model releases of radionuclides during normal NIF operations and a postulated accident and to calculate radiation doses to the public. Health risks were estimated by converting the estimated doses into health effects using a standard cancer fatality risk factor. The greatest calculated radiation dose was less than one thousandth of a percent of the dose received from natural background radiation; no cancer fatalities would be expected to occur in the public as the result of normal operations. The highest dose conservatively estimated to result from a postulated accident could lead to one in one million risk of cancer.

  1. Test report for core drilling ignitability testing

    SciTech Connect (OSTI)

    Witwer, K.S.

    1996-08-08

    Testing was carried out with the cooperation of Westinghouse Hanford Company and the United States Bureau of Mines at the Pittsburgh Research Center in Pennsylvania under the Memorandum of Agreement 14- 09-0050-3666. Several core drilling equipment items, specifically those which can come in contact with flammable gasses while drilling into some waste tanks, were tested under conditions similar to actual field sampling conditions. Rotary drilling against steel and rock as well as drop testing of several different pieces of equipment in a flammable gas environment were the specific items addressed. The test items completed either caused no ignition of the gas mixture, or, after having hardware changes or drilling parameters modified, produced no ignition in repeat testing.

  2. National Ignition Facility & Photon Science

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    security maintaining the nuclear weapons stockpile As the largest, highest-energy laser ever built, the National Ignition Facility (NIF) can create conditions in the laboratory-temperatures of 100 million degrees and pressures 100 billion times that of the earth's atmosphere-similar to those in stars and nuclear weapons. NIF is the only facility that can perform controlled, experimental studies of thermonuclear burn, the phenomenon that gives rise to the immense energy of modern nuclear weapons.

  3. National Ignition Facility | National Nuclear Security Administration

    National Nuclear Security Administration (NNSA)

    Ignition Facility Former Army Ranger wins Sandia-sponsored student of the year award Former Army Ranger Damon Alcorn recently received the Sandia National Laboratories-Livermore Chamber of Commerce Student of the Year Award. Presented at the Chamber's State of the City Luncheon last month, the annual award highlights a Las Positas College student with exemplary academic... NNSA makers and hackers engage innovation and partnerships NNSA's labs change the world everyday through cutting-edge

  4. Multiple laser pulse ignition method and apparatus

    DOE Patents [OSTI]

    Early, James W. (Los Alamos, NM)

    1998-01-01

    Two or more laser light pulses with certain differing temporal lengths and peak pulse powers can be employed sequentially to regulate the rate and duration of laser energy delivery to fuel mixtures, thereby improving fuel ignition performance over a wide range of fuel parameters such as fuel/oxidizer ratios, fuel droplet size, number density and velocity within a fuel aerosol, and initial fuel temperatures.

  5. Multiple laser pulse ignition method and apparatus

    DOE Patents [OSTI]

    Early, J.W.

    1998-05-26

    Two or more laser light pulses with certain differing temporal lengths and peak pulse powers can be employed sequentially to regulate the rate and duration of laser energy delivery to fuel mixtures, thereby improving fuel ignition performance over a wide range of fuel parameters such as fuel/oxidizer ratios, fuel droplet size, number density and velocity within a fuel aerosol, and initial fuel temperatures. 18 figs.

  6. IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES

    SciTech Connect (OSTI)

    Jason M. Keith

    2005-02-01

    This report describes work performed during a thirty month project which involves the production of dimethyl ether (DME) on-site for use as an ignition-improving additive in a compression-ignition natural gas engine. A single cylinder spark ignition engine was converted to compression ignition operation. The engine was then fully instrumented with a cylinder pressure transducer, crank shaft position sensor, airflow meter, natural gas mass flow sensor, and an exhaust temperature sensor. Finally, the engine was interfaced with a control system for pilot injection of DME. The engine testing is currently in progress. In addition, a one-pass process to form DME from natural gas was simulated with chemical processing software. Natural gas is reformed to synthesis gas (a mixture of hydrogen and carbon monoxide), converted into methanol, and finally to DME in three steps. Of additional benefit to the internal combustion engine, the offgas from the pilot process can be mixed with the main natural gas charge and is expected to improve engine performance. Furthermore, a one-pass pilot facility was constructed to produce 3.7 liters/hour (0.98 gallons/hour) DME from methanol in order to characterize the effluent DME solution and determine suitability for engine use. Successful production of DME led to an economic estimate of completing a full natural gas-to-DME pilot process. Additional experimental work in constructing a synthesis gas to methanol reactor is in progress. The overall recommendation from this work is that natural gas to DME is not a suitable pathway to improved natural gas engine performance. The major reasons are difficulties in handling DME for pilot injection and the large capital costs associated with DME production from natural gas.

  7. System studies of compact ignition tokamaks

    SciTech Connect (OSTI)

    Galambos, J.D.; Blackfield, D.T.; Peng, Y.K.M.; Reid, R.L.; Strickler, D.J.; Selcow, E.

    1987-08-01

    The new Tokamak Systems Code, used to investigate Compact Ignition Tokamaks (CITs), can simultaneously vary many parameters, satisfy many constraints, and minimize or maximize a figure of merit. It is useful in comparing different CIT design configurations over wide regions of parameter space and determining a desired design point for more detailed physics and engineering analysis, as well as for performing sensitivity studies for physics or engineering issues. Operational windows in major radius (R) and toroidal field (B) space for fixed ignition margin are calculated for the Ignifed and Inconel candidate CITs. The minimum R bounds are predominantly physics limited, and the maximum R portions of the windows are engineering limited. For a modified Kaye-Goldston plasma-energy-confinement scaling, the minimum size is 1.15 m for the Ignifed device and 1.25 m for the Inconel device. With the Ignition Technical Oversight Committee (ITOC) physics guidance of B/sup 2/a/q and I/sub p/ >10 MA, the Ignifed and Base-line Inconel devices have a minimum size of 1.2 and 1.25 m and a toroidal field of 11 and 10.4 T, respectively. Sensitivity studies show Ignifed to be more sensitive to coil temperature changes than the Inconel device, whereas the Inconel device is more sensitive to stress perturbations.

  8. The national ignition facility and atomic data

    SciTech Connect (OSTI)

    Crandall, David H.

    1998-07-08

    The National Ignition Facility (NIF) is under construction, capping over 25 years of development of the inertial confinement fusion concept by providing the facility to obtain fusion ignition in the laboratory for the first time. The NIF is a 192 beam glass laser to provide energy controlled in space and time so that a millimeter-scale capsule containing deuterium and tritium can be compressed to fusion conditions. Light transport, conversion of light in frequency, interaction of light with matter in solid and plasma forms, and diagnostics of extreme material conditions on small scale all use atomic data in preparing for use of the NIF. The NIF will provide opportunity to make measurements of atomic data in extreme physical environments related to fusion energy, nuclear weapon detonation, and astrophysics. The first laser beams of NIF should be operational in 2001 and the full facility completed at the end of 2003. NIF is to provide 1.8 megajoule of blue light on fusion targets and is intended to achieve fusion ignition by about the end of 2007. Today's inertial fusion development activities use atomic data to design and predict fusion capsule performance and in non-fusion applications to analyze radiation transport and radiation effects on matter. Conditions investigated involve radiation temperature of hundreds of eV, pressures up to gigabars and time scales of femptoseconds.

  9. The national ignition facility and atomic data

    SciTech Connect (OSTI)

    Crandall, D.H.

    1998-07-01

    The National Ignition Facility (NIF) is under construction, capping over 25 years of development of the inertial confinement fusion concept by providing the facility to obtain fusion ignition in the laboratory for the first time. The NIF is a 192 beam glass laser to provide energy controlled in space and time so that a millimeter-scale capsule containing deuterium and tritium can be compressed to fusion conditions. Light transport, conversion of light in frequency, interaction of light with matter in solid and plasma forms, and diagnostics of extreme material conditions on small scale all use atomic data in preparing for use of the NIF. The NIF will provide opportunity to make measurements of atomic data in extreme physical environments related to fusion energy, nuclear weapon detonation, and astrophysics. The first laser beams of NIF should be operational in 2001 and the full facility completed at the end of 2003. NIF is to provide 1.8 megajoule of blue light on fusion targets and is intended to achieve fusion ignition by about the end of 2007. Today{close_quote}s inertial fusion development activities use atomic data to design and predict fusion capsule performance and in non-fusion applications to analyze radiation transport and radiation effects on matter. Conditions investigated involve radiation temperature of hundreds of eV, pressures up to gigabars and time scales of femptoseconds. {copyright} {ital 1998 American Institute of Physics.}

  10. Ignition threshold for non-Maxwellian plasmas

    SciTech Connect (OSTI)

    Hay, Michael J.; Fisch, Nathaniel J.

    2015-11-15

    An optically thin p-{sup 11}B plasma loses more energy to bremsstrahlung than it gains from fusion reactions, unless the ion temperature can be elevated above the electron temperature. In thermal plasmas, the temperature differences required are possible in small Coulomb logarithm regimes, characterized by high density and low temperature. Ignition could be reached more easily if the fusion reactivity can be improved with nonthermal ion distributions. To establish an upper bound for the potential utility of a nonthermal distribution, we consider a monoenergetic beam with particle energy selected to maximize the beam-thermal reactivity. Comparing deuterium-tritium (DT) and p-{sup 11}B, the minimum Lawson criteria and minimum ρR required for inertial confinement fusion (ICF) volume ignition are calculated with and without the nonthermal feature. It turns out that channeling fusion alpha energy to maintain such a beam facilitates ignition at lower densities and ρR, improves reactivity at constant pressure, and could be used to remove helium ash. On the other hand, the reactivity gains that could be realized in DT plasmas are significant, the excess electron density in p-{sup 11}B plasmas increases the recirculated power cost to maintain a nonthermal feature and thereby constrains its utility to ash removal.

  11. Magnetic booster fast ignition macron accelerator

    SciTech Connect (OSTI)

    Winterberg, F.

    2006-11-15

    A new fast ignition scheme was recently proposed where the ignition is done by the impact of a small solid projectile accelerated to velocities in excess of 10{sup 8} cm/s, with the acceleration done in two steps: first, by laser ablation of a flyer plate, and second by injecting the flyer plate into a conical duct. The two principal difficulties of this scheme are as follows: first, the required large mass ratio for the laser ablation rocket propelled flyer plate, and second, the Rayleigh-Taylor instability of the flyer plate during its implosive compression in the conical duct. To overcome these difficulties, it is suggested to accelerate a projectile by a magnetic fusion booster stage, made up of a dense, wall-confined magnetized plasma brought to thermonuclear temperatures. After ignition, this plasma undergoes a thermonuclear excursion greatly increasing its pressure, resulting in the explosion of a weakened segment of the wall, with the segment becoming a fast moving projectile. The maximum velocity this projectile can reach is the velocity of sound of the booster stage plasma, which at a temperature of 10{sup 8} K is of the order 10{sup 8} cm/s.

  12. Laser–plasma interactions for fast ignition

    SciTech Connect (OSTI)

    Kemp, A. J.; Fiuza, F.; Debayle, A.; Johzaki, T.; Mori, W. B.; Patel, P. K.; Sentoku, Y.; Silva, L. O.

    2014-04-17

    In the electron-driven fast-ignition approach to inertial confinement fusion, petawatt laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense laser- plasma interactions (LPI) relevant to fast ignition. Increases in computational and modeling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multidimensional particle-in-cell (PIC) simulations of LPI at relevant scales. We discuss the physics of the interaction in terms of laser absorption fraction, the laser-generated electron spectra, divergence, and their temporal evolution. Scaling with irradiation conditions such as laser intensity, f-number and wavelength are considered, as well as the dependence on plasma parameters. Different numerical modeling approaches and configurations are addressed, providing an overview of the modeling capabilities and limitations. In addition, we discuss the comparison of simulation results with experimental observables. In particular, we address the question of surrogacy of today's experiments for the full-scale fast ignition problem.

  13. Laser spark distribution and ignition system

    DOE Patents [OSTI]

    Woodruff, Steven; McIntyre, Dustin L.

    2008-09-02

    A laser spark distribution and ignition system that reduces the high power optical requirements for use in a laser ignition and distribution system allowing for the use of optical fibers for delivering the low peak energy pumping pulses to a laser amplifier or laser oscillator. An optical distributor distributes and delivers optical pumping energy from an optical pumping source to multiple combustion chambers incorporating laser oscillators or laser amplifiers for inducing a laser spark within a combustion chamber. The optical distributor preferably includes a single rotating mirror or lens which deflects the optical pumping energy from the axis of rotation and into a plurality of distinct optical fibers each connected to a respective laser media or amplifier coupled to an associated combustion chamber. The laser spark generators preferably produce a high peak power laser spark, from a single low power pulse. The laser spark distribution and ignition system has application in natural gas fueled reciprocating engines, turbine combustors, explosives and laser induced breakdown spectroscopy diagnostic sensors.

  14. Laser–plasma interactions for fast ignition

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kemp, A. J.; Fiuza, F.; Debayle, A.; Johzaki, T.; Mori, W. B.; Patel, P. K.; Sentoku, Y.; Silva, L. O.

    2014-04-17

    In the electron-driven fast-ignition approach to inertial confinement fusion, petawatt laser pulses are required to generate MeV electrons that deposit several tens of kilojoules in the compressed core of an imploded DT shell. We review recent progress in the understanding of intense laser- plasma interactions (LPI) relevant to fast ignition. Increases in computational and modeling capabilities, as well as algorithmic developments have led to enhancement in our ability to perform multidimensional particle-in-cell (PIC) simulations of LPI at relevant scales. We discuss the physics of the interaction in terms of laser absorption fraction, the laser-generated electron spectra, divergence, and their temporalmore » evolution. Scaling with irradiation conditions such as laser intensity, f-number and wavelength are considered, as well as the dependence on plasma parameters. Different numerical modeling approaches and configurations are addressed, providing an overview of the modeling capabilities and limitations. In addition, we discuss the comparison of simulation results with experimental observables. In particular, we address the question of surrogacy of today's experiments for the full-scale fast ignition problem.« less

  15. Exploring the effect of fluid dynamics and kinetic mechanisms on n-heptane autoignition in transient jets

    SciTech Connect (OSTI)

    Viggiano, Annarita [Department of Environmental Engineering and Physics, University of Basilicata, viale dell'Ateneo Lucano 10, 85100 Potenza (Italy)

    2010-02-15

    The influence of physical parameters and of flow patterns on the prediction of n-heptane ignition dynamic in transient reacting n-heptane jets, in high pressure environment under laminar conditions, has been explored by using different kinetic mechanisms. Some preliminary transient laminar flamelet computations have been performed, thus showing that the sensitivity of the ignition time to strain rate depends on the kinetic mechanism used. Therefore, the structure of the reacting jet, in particular the localization of ignition spots, is investigated. The results show that, if the initial temperature of the reacting mixture is out of the intermediate range (800-1000 K) towards lower values, the fluid dynamics has an essential role. In this case, the ignition delay time is almost insensitive to the specific kinetic mechanism adopted, conversely it is severely shortened by increasing the streamwise velocity. The burning spot is located in the core of fuel roll-up, where low values of scalar dissipation rate occur. Nevertheless, the most reactive mixture fraction conditions are well predicted by chemical kinetics, as they are in good agreement with those computed for the one-dimensional diffusion layer. When the initial temperature of fuel and air is increased in the intermediate range, ignition is strongly dependent on the kinetic mechanism used. In these cases, the choice of an accurate chemical scheme is fundamental in order to obtain reliable results. (author)

  16. Angular Scaling In Jets

    SciTech Connect (OSTI)

    Jankowiak, Martin; Larkoski, Andrew J.; /SLAC

    2012-02-17

    We introduce a jet shape observable defined for an ensemble of jets in terms of two-particle angular correlations and a resolution parameter R. This quantity is infrared and collinear safe and can be interpreted as a scaling exponent for the angular distribution of mass inside the jet. For small R it is close to the value 2 as a consequence of the approximately scale invariant QCD dynamics. For large R it is sensitive to non-perturbative effects. We describe the use of this correlation function for tests of QCD, for studying underlying event and pile-up effects, and for tuning Monte Carlo event generators.

  17. Turbulent Flame Propagation Characteristics of High Hydrogen Content Fuels

    SciTech Connect (OSTI)

    Seitzman, Jerry; Lieuwen, Timothy

    2014-09-30

    This final report describes the results of an effort to better understand turbulent flame propagation, especially at conditions relevant to gas turbines employing fuels with syngas or hydrogen mixtures. Turbulent flame speeds were measured for a variety of hydrogen/carbon monoxide (H2/CO) and hydrogen/methane (H2/CH4) fuel mixtures with air as the oxidizer. The measurements include global consumption speeds (ST,GC) acquired in a turbulent jet flame at pressures of 1-10 atm and local displacement speeds (ST,LD) acquired in a low-swirl burner at atmospheric pressure. The results verify the importance of fuel composition in determining turbulent flame speeds. For example, different fuel-air mixtures having the same unstretched laminar flame speed (SL,0) but different fuel compositions resulted in significantly different ST,GC for the same turbulence levels (u'). This demonstrates the weakness of turbulent flame speed correlations based simply on u'/SL,0. The results were analyzed using a steady-steady leading points concept to explain the sensitivity of turbulent burning rates to fuel (and oxidizer) composition. Leading point theories suggest that the premixed turbulent flame speed is controlled by the flame front characteristics at the flame brush leading edge, or, in other words, by the flamelets that advance farthest into the unburned mixture (the so-called leading points). For negative Markstein length mixtures, this is assumed to be close to the maximum stretched laminar flame speed (SL,max) for the given fuel-oxidizer mixture. For the ST,GC measurements, the data at a given pressure were well-correlated with an SL,max scaling. However the variation with pressure was not captured, which may be due to non-quasi-steady effects that are not included in the current model. For the ST,LD data, the leading points model again faithfully captured the variation of turbulent flame speed over a wide range of fuel-compositions and turbulence intensities. These results provide

  18. A spray-suppression model for turbulent combustion

    SciTech Connect (OSTI)

    DESJARDIN,PAUL E.; TIESZEN,SHELDON R.; GRITZO,LOUIS A.

    2000-02-14

    A spray-suppression model that captures the effects of liquid suppressant on a turbulent combusting flow is developed and applied to a turbulent diffusion flame with water spray suppression. The spray submodel is based on a stochastic separated flow approach that accounts for the transport and evaporation of liquid droplets. Flame extinguishment is accounted for by using a perfectly stirred reactor (PSR) submodel of turbulent combustion. PSR pre-calculations of flame extinction times are determined using CHEMKIN and are compared to local turbulent time scales of the flow to determine if local flame extinguishment has occurred. The PSR flame extinguishment and spray submodels are incorporated into Sandia's flow fire simulation code, VULCAN, and cases are run for the water spray suppression studies of McCaffrey for turbulent hydrogen-air jet diffusion flames. Predictions of flame temperature decrease and suppression efficiency are compared to experimental data as a function of water mass loading using three assumed values of drop sizes. The results show that the suppression efficiency is highly dependent on the initial droplet size for a given mass loading. A predicted optimal suppression efficiency was observed for the smallest class of droplets while the larger drops show increasing suppression efficiency with increasing mass loading for the range of mass loadings considered. Qualitative agreement to the experiment of suppression efficiency is encouraging, however quantitative agreement is limited due to the uncertainties in the boundary conditions of the experimental data for the water spray.

  19. Modeling jet and outflow feedback during star cluster formation

    SciTech Connect (OSTI)

    Federrath, Christoph; Schrn, Martin; Banerjee, Robi; Klessen, Ralf S.

    2014-08-01

    Powerful jets and outflows are launched from the protostellar disks around newborn stars. These outflows carry enough mass and momentum to transform the structure of their parent molecular cloud and to potentially control star formation itself. Despite their importance, we have not been able to fully quantify the impact of jets and outflows during the formation of a star cluster. The main problem lies in limited computing power. We would have to resolve the magnetic jet-launching mechanism close to the protostar and at the same time follow the evolution of a parsec-size cloud for a million years. Current computer power and codes fall orders of magnitude short of achieving this. In order to overcome this problem, we implement a subgrid-scale (SGS) model for launching jets and outflows, which demonstrably converges and reproduces the mass, linear and angular momentum transfer, and the speed of real jets, with ?1000 times lower resolution than would be required without the SGS model. We apply the new SGS model to turbulent, magnetized star cluster formation and show that jets and outflows (1) eject about one-fourth of their parent molecular clump in high-speed jets, quickly reaching distances of more than a parsec, (2) reduce the star formation rate by about a factor of two, and (3) lead to the formation of ?1.5 times as many stars compared to the no-outflow case. Most importantly, we find that jets and outflows reduce the average star mass by a factor of ? three and may thus be essential for understanding the characteristic mass of the stellar initial mass function.

  20. Ignitor with stable low-energy thermite igniting system

    DOE Patents [OSTI]

    Kelly, Michael D.; Munger, Alan C.

    1991-02-05

    A stable compact low-energy igniting system in an ignitor utilizes two components, an initiating charge and an output charge. The initiating charge is a thermite in ultra-fine powder form compacted to 50-70% of theoretical maximum density and disposed in a cavity of a header of the ignitor adjacent to an electrical ignition device, or bridgewire, mounted in the header cavity. The initiating charge is ignitable by operation of the ignition device in a hot-wire mode. The output charge is a thermite in high-density consoladated form compacted to 90-99% of theoretical maximum density and disposed adjacent to the initiating charge on an opposite end thereof from the electrical ignition device and ignitable by the initiating charge. A sleeve is provided for mounting the output charge to the ignitor header with the initiating charge confined therebetween in the cavity.

  1. Stoichiometric Compression Ignition (SCI) Engine Concept | Department of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Energy Stoichiometric Compression Ignition (SCI) Engine Concept Stoichiometric Compression Ignition (SCI) Engine Concept Presentation given at DEER 2006, August 20-24, 2006, Detroit, Michigan. Sponsored by the U.S. DOE's EERE FreedomCar and Fuel Partnership and 21st Century Truck Programs. 2006_deer_winsor.pdf (369.5 KB) More Documents & Publications An Experimental Investigation of the Origin of Increased NOx Emissions When Fueling a Heavy-Duty Compression-Ignition Engine with Soy

  2. High Efficiency Fuel Reactivity Controlled Compression Ignition Combustion

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    | Department of Energy Fuel Reactivity Controlled Compression Ignition Combustion High Efficiency Fuel Reactivity Controlled Compression Ignition Combustion An optimized dual-fuel PCCI concept, RCCI, is proposed. deer10_reitz.pdf (960.46 KB) More Documents & Publications Effect of Compression Ratio and Piston Geometry on RCCI load limit Optimization of Advanced Diesel Engine Combustion Strategies Comparison of Conventional Diesel and Reactivity Controlled Compression Ignition (RCCI)

  3. National Ignition Facility & Photon Science NIF AT A GLANCe

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    5 National Ignition Facility & Photon Science NIF AT A GLANCe the national ignition Facility at a glance The National Ignition Facility (NIF) is the world's largest laser system, housed in a 10-story building the size of three football fields at lawrence livermore National laboratory, east of san Francisco. NIF's 192 laser beams are capable of delivering at least 100 times more energy than any previous laser system. during full-scale ignition experiments, NIF will focus up to 1.8 million

  4. Cosmos Ignite Innovations Pvt Ltd | Open Energy Information

    Open Energy Info (EERE)

    Innovations Pvt Ltd Jump to: navigation, search Name: Cosmos Ignite Innovations Pvt Ltd Place: Delhi (NCT), India Zip: 110017 Product: Company started by two Stanford and New Delhi...

  5. Modeling the Number of Ignitions Following an Earthquake: Developing...

    Office of Environmental Management (EM)

    Developing Prediction Limits for Overdispersed Count Data Authors: Elizabeth J. Kelly and Raymond N. Tell PDF icon Modeling the Number of Ignitions Following an Earthquake:...

  6. Zone heated inlet ignited diesel particulate filter regeneration...

    Office of Scientific and Technical Information (OSTI)

    Data Explorer Search Results Zone heated inlet ignited diesel particulate filter ... An exhaust system that processes exhaust generated by an engine is provided. The system ...

  7. Radiochemical tracers as a mix diagnostic for the ignition double...

    Office of Scientific and Technical Information (OSTI)

    for the ignition double-shell capsule One of the most important challenges confronting laser-driven capsule implosion experiments will be a quantitative evaluation of the...

  8. A Simulation Study of Fast Ignition with Ultrahigh Intensity Lasers |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Argonne Leadership Computing Facility Simulation Study of Fast Ignition with Ultrahigh Intensity Lasers Authors: Tonge, J., May, J., Mori, B., Fiuza, F., Martins, S.F., Fonseca, R.A., Silva, L.O., Ren, C. The coupling efficiency between the ignition laser and the target core for the fast ignition concept is studied using two-dimensional particle-in-cell simulations. The details of the energy transport within the weakly collisional overdense plasma of a fast ignition target are examined by

  9. Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms...

    Office of Scientific and Technical Information (OSTI)

    for Physics-Based Model Development. Citation Details In-Document Search Title: Ultrafast Laser Diagnostics for Energetic-Material Ignition Mechanisms: Tools for Physics-Based ...

  10. Heavy Alcohols as a Fuel Blending Agent for Compression Ignition...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Avoidance Characterization of Dual-Fuel Reactivity Controlled Compression Ignition (RCCI) Using Hydrated Ethanol and Diesel Fuel BiodieselFuelManagementBestPracticesReport.pdf

  11. Laser Spark Distribution and Ignition System - Energy Innovation...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Find More Like This Return to Search Laser Spark Distribution and Ignition System A method ... Contact NETL About This Technology Publications: PDF Document Publication Laser Spark ...

  12. Occupational dose estimates for the National Ignition Facility...

    Office of Scientific and Technical Information (OSTI)

    The National Ignition Facility (NIF) is currently being constructed at Lawrence Livermore National Laboratory (LLNL). During peak operation, the NIF will attain D-T fusion yields ...

  13. Effect of Premixed Charge Compression Ignition on Vehicle Fuel...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Effect of Premixed Charge Compression Ignition on Vehicle Fuel Economy and Emissions Reduction over Transient Driving Cycles In conventional vehicles, most engine operating points ...

  14. "New Results from the National Ignition Facility", Dr. John Lindl...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    MBG Auditorium "New Results from the National Ignition Facility", Dr. John Lindl, Lawrence Livermore National Laboratory Since completion of the NIF construction project in March ...

  15. Identifying Turbulent Structures through Topological Segmentation

    SciTech Connect (OSTI)

    Bremer, Peer-Timo; Gruber, Andrea; Bennett, Janine C.; Gyulassy, Attila; Kolla, Hemanth; Chen, Jacqueline H.; Grout, Ray W.

    2016-01-01

    A new method of extracting vortical structures from a turbulent flow is proposed whereby topological segmentation of an indicator function scalar field is used to identify the regions of influence of the individual vortices. This addresses a long-standing challenge in vector field topological analysis: indicator functions commonly used produce a scalar field based on the local velocity vector field; reconstructing regions of influence for a particular structure requires selecting a threshold to define vortex extent. In practice, the same threshold is rarely meaningful throughout a given flow. By also considering the topology of the indicator field function, the characteristics of vortex strength and extent can be separated and the ambiguity in the choice of the threshold reduced. The proposed approach is able to identify several types of vortices observed in a jet in cross-flow configuration simultaneously where no single threshold value for a selection of common indicator functions appears able to identify all of these vortex types.

  16. Ion Fast Ignition-Establishing a Scientific Basis for Inertial Fusion Energy --- Final Report

    SciTech Connect (OSTI)

    Stephens, Richard Burnite; Foord, Mark N.; Wei, Mingsheng; Beg, Farhat N.; Schumacher, Douglass W.

    2013-10-31

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy reactors. FI differs from conventional ?central hot spot? (CHS) target ignition by decoupling compression from heating: using a laser (or heavy ion beam or Z pinch) drive pulse (10?s of nanoseconds) to create a dense fuel and a second, much shorter (~10 picoseconds) high intensity pulse to ignite a small volume within the dense fuel. The compressed fuel is opaque to laser light. The ignition laser energy must be converted to a jet of energetic charged particles to deposit energy in the dense fuel. The original concept called for a spray of laser-generated hot electrons to deliver the energy; lack of ability to focus the electrons put great weight on minimizing the electron path. An alternative concept, proton-ignited FI, used those electrons as intermediaries to create a jet of protons that could be focused to the ignition spot from a more convenient distance. Our program focused on the generation and directing of the proton jet, and its transport toward the fuel, none of which were well understood at the onset of our program. We have developed new experimental platforms, diagnostic packages, computer modeling analyses, and taken advantage of the increasing energy available at laser facilities to create a self-consistent understanding of the fundamental physics underlying these issues. Our strategy was to examine the new physics emerging as we added the complexity necessary to use proton beams in an inertial fusion energy (IFE) application. From the starting point of a proton beam accelerated from a flat, isolated foil, we 1) curved it to focus the beam, 2) attached the foil to a superstructure, 3) added a side sheath to protect it from the surrounding plasma, and finally 4) studied the proton beam behavior as it passed through a protective end cap into plasma. We built up, as we proceeded

  17. EPISODIC JETS AS THE CENTRAL ENGINE OF GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Yuan Feng; Zhang Bing E-mail: zhang@physics.unlv.edu

    2012-09-20

    Most gamma-ray bursts (GRBs) have erratic light curves, which demand that the GRB central engine launches an episodic outflow. Recent Fermi observations of some GRBs indicate a lack of the thermal photosphere component as predicted by the baryonic fireball model, which suggests a magnetic origin of GRBs. Given that powerful episodic jets have been observed along with continuous jets in other astrophysical black hole systems, here we propose an intrinsically episodic, magnetically dominated jet model for the GRB central engine. Accumulation and eruption of free magnetic energy in the corona of a differentially rotating, turbulent accretion flow around a hyperaccreting black hole lead to ejections of episodic, magnetically dominated plasma blobs. These blobs are accelerated magnetically, collide with each other at large radii, trigger rapid magnetic reconnection and turbulence, efficient particle acceleration, and radiation, and power the observed episodic prompt gamma-ray emission from GRBs.

  18. Modeling the Fuel Spray and Combustion Process of the Ignition Quality Tester with KIVA-3V

    SciTech Connect (OSTI)

    Bogin, G. E. Jr.; DeFilippo, A.; Chen, J. Y.; Chin, G.; Luecke, J.; Ratcliff, M. A.; Zigler, B. T.; Dean, A. M.

    2010-05-01

    Discusses the use of KIVA-3V to develop a model that reproduces ignition behavior inside the Ignition Quality Tester, which measures the ignition delay of low-volatility fuels.

  19. National Ignition Facility & Photon Science

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    1 National Ignition Facility & Photon Science limitless energy the Promise of Limitless energy harnessing the energy of the sun and stars to meet the earth's energy needs has been a decades-long scientific and engineering quest. While a self-sustaining fusion burn has been achieved for brief periods under experimental conditions, the amount of energy that went into creating it was greater than the amount of energy it generated. There was no energy gain, which is essential if fusion energy is

  20. National Ignition Facility & Photon Science

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    making a star 17 How to make a miniature star The idea for the National Ignition Facility (NIF) grew out of a decades-long effort to generate fusion burn and energy gain in the laboratory. Current nuclear power plants, which use the splitting of atoms (fission) to produce energy, have been pumping out electric power for more than 50 years. But achieving nuclear fusion burn and gain has not yet been demonstrated as viable for energy production. For fusion burn and gain to occur, a special fuel

  1. Low emissions compression ignited engine technology

    DOE Patents [OSTI]

    Coleman, Gerald N.; Kilkenny, Jonathan P.; Fluga, Eric C.; Duffy, Kevin P.

    2007-04-03

    A method and apparatus for operating a compression ignition engine having a cylinder wall, a piston, and a head defining a combustion chamber. The method and apparatus includes delivering fuel substantially uniformly into the combustion chamber, the fuel being dispersed throughout the combustion chamber and spaced from the cylinder wall, delivering an oxidant into the combustion chamber sufficient to support combustion at a first predetermined combustion duration, and delivering a diluent into the combustion chamber sufficient to change the first predetermined combustion duration to a second predetermined combustion duration different from the first predetermined combustion duration.

  2. SHOCK CORRUGATION BY RAYLEIGH-TAYLOR INSTABILITY IN GAMMA-RAY BURST AFTERGLOW JETS

    SciTech Connect (OSTI)

    Duffell, Paul C.; MacFadyen, Andrew I. E-mail: macfadyen@nyu.edu

    2014-08-10

    Afterglow jets are Rayleigh-Taylor unstable and therefore turbulent during the early part of their deceleration. There are also several processes which actively cool the jet. In this Letter, we demonstrate that if cooling significantly increases the compressibility of the flow, the turbulence collides with the forward shock, destabilizing and corrugating it. In this case, the forward shock is turbulent enough to produce the magnetic fields responsible for synchrotron emission via small-scale turbulent dynamo. We calculate light curves assuming the magnetic field is in energy equipartition with the turbulent kinetic energy and discover that dynamic magnetic fields are well approximated by a constant magnetic-to-thermal energy ratio of 1%, though there is a sizeable delay in the time of peak flux as the magnetic field turns on only after the turbulence has activated. The reverse shock is found to be significantly more magnetized than the forward shock, with a magnetic-to-thermal energy ratio of the order of 10%. This work motivates future Rayleigh-Taylor calculations using more physical cooling models.

  3. Multi-zone modelling of partially premixed low-temperature combustion in pilot-ignited natural-gas engines

    SciTech Connect (OSTI)

    Krishnan, S. R.; inivasan, K. K.

    2010-09-14

    Detailed results from a multi-zone phenomenological simulation of partially premixed advanced-injection low-pilot-ignited natural-gas low-temperature combustion are presented with a focus on early injection timings (the beginning of (pilot) injection (BOI)) and very small diesel quantities (2-3 per cent of total fuel energy). Combining several aspects of diesel and spark ignition engine combustion models, the closed-cycle simulation accounted for diesel autoignition, diesel spray combustion, and natural-gas combustion by premixed turbulent flame propagation. The cylinder contents were divided into an unburned zone, several pilot fuel zones (or 'packets') that modelled diesel evaporation and ignition, a flame zone for natural-gas combustion, and a burned zone. The simulation predicted the onset of ignition, cylinder pressures, and heat release rate profiles satisfactorily over a wide range of BOIs (20-60° before top dead centre (before TDC)) but especially well at early BOIs. Strong coupling was observed between pilot spray combustion in the packets and premixed turbulent combustion in the flame zone and, therefore, the number of ignition centres (packets) profoundly affected flame combustion. The highest local peak temperatures (greater than 2000 K) were observed in the packets, while the flame zone was much cooler (about 1650 K), indicating that pilot diesel spray combustion is probably the dominant source of engine-out emissions of nitrogen oxide (NOx). Further, the 60° before TDC BOI yielded the lowest average peak packet temperatures (about 1720 K) compared with the 20° before TDC BOI (about 2480 K) and 40° before TDC BOI (about 2700 K). These trends support experimental NOx trends, which showed the lowest NOx emissions for the 60°, 20°, and 40° before TDC BOIs in that order. Parametric studies showed that increasing the intake charge temperature, pilot quantity, and natural-gas equivalence ratio all led to higher peak

  4. B-jets and z + b-jets at CDF

    SciTech Connect (OSTI)

    Jeans, Daniel; /Rome U.

    2006-06-01

    The authors present CDF cross-section measurements for the inclusive production of b jets and the production of b jets in association with a Z{sup 0} boson. Both measurements are in reasonable agreement with NLO QCD predictions.

  5. Recent progress on the Compact Ignition Tokamak (CIT)

    SciTech Connect (OSTI)

    Ignat, D.W.

    1987-01-01

    This report describes work done on the Compact Ignition Tokamak (CIT), both at the Princeton Plasma Physics Laboratory (PPPL) and at other fusion laboratories in the United States. The goal of CIT is to reach ignition in a tokamak fusion device in the mid-1990's. Scientific and engineering features of the design are described, as well as projected cost and schedule.

  6. Turbulent flame speeds and NOx kinetics of HHC fuels with contaminants and high dilution levels

    SciTech Connect (OSTI)

    Petersen, Eric; Krejci, Michael; Mathieu, Olivier; Vissotski, Andrew; Ravi, Sankar; Plichta, Drew; Sikes, Travis; Levacque, Anthony; Aul, Christopher; Petersen, Eric

    2012-09-30

    This progress report documents the second year of the project, from October 1, 2011 through September 30, 2012. Characterization of the new turbulent flame speed vessel design was completed. Turbulence statistics of three impellers with different geometric features were measured using particle image velocimetry inside a Plexiglas model (~1:1 scale) of a cylindrical flame speed vessel (30.5 cm ID 35.6 cm L). With four impellers arranged in a central-symmetric configuration, turbulence intensities between 1.2 and 1.7 m/s with negligible mean flow (0.1u) were attained at the lowest fan speeds. Acceptable ranges for homogeneity and isotropy ratios of the velocity fields were set within a narrow bandwidth near unity (0.9-1.1). Homogeneity ratios were unaffected by changes to the impeller geometry, and the prototype with the higher number of blades caused the flow to become anisotropic. The integral length scale of the flow fields varied between 27 and 20 mm, which correlates well with those typically observed inside a gas turbine combustor. The mechanism to independently vary the intensity level and the integral length scale was established, where turbulence intensity level was dependent on the rotational speed of the fan, and the integral length scale decreased with increasing blade pitch angle. Ignition delay times of H?/O? mixtures highly diluted with Ar and doped with various amounts of N?O (100, 400, 1600, 3200 ppm) were measured in a shock tube behind reflected shock waves over a wide range of temperatures (940-1675 K). The pressure range investigated during this work (around 1.6, 13, and 30 atm) allows studying the effect of N?O on hydrogen ignition at pressure conditions that have never been heretofore investigated. Ignition delay times were decreased when N?O was added to the mixture only for the higher nitrous oxide concentrations, and some changes in the activation energy were also observed at 1.5 and 30 atm. When it occurred, the decrease in the ignition

  7. PBXN-9 Ignition Kinetics and Deflagration Rates

    SciTech Connect (OSTI)

    Glascoe, E; Maienschein, J; Burnham, A; Koerner, J; Hsu, P; Wemhoff, A

    2008-04-24

    The ignition kinetics and deflagration rates of PBXN-9 were measured using specially designed instruments at LLNL and compared with previous work on similar HMX based materials. Ignition kinetics were measured based on the One Dimensional Time-to-Explosion combined with ALE3D modeling. Results of these experiments indicate that PBXN-9 behaves much like other HMX based materials (i.e. LX-04, LX-07, LX-10 and PBX-9501) and the dominant factor in these experiments is the type of explosive, not the type of binder/plasticizer. In contrast, the deflagration behavior of PBXN-9 is quite different from similar high weight percent HMX based materials (i.e LX-10, LX-07 and PBX-9501). PBXN-9 burns in a laminar manner over the full pressure range studied (0-310 MPa) unlike LX-10, LX-07, and PBX-9501. The difference in deflagration behavior is attributed to the nature of the binder/plasticizer alone or in conjunction with the volume of binder present in PBXN-9.

  8. SCB ignition of pyrotechnics, thermites and intermetallics

    SciTech Connect (OSTI)

    Bickes, R.W. Jr.; Grubelich, M.C.

    1996-09-01

    We investigated ignition of pyrotechnics, metal-fuel/metal-oxide compositions (thermites), and exothermic alloy compositions (intermetallics) using a semiconductor bridge (SCB). It was shown that these materials could be ignited at low energy levels with an appropriately designed SCB, proper loading density, and good thermal isolation. Materials tested included Al/CuO, B/BaCrO{sub 4}, TiH{sub 1.65}/KClO{sub 4}, Ti/KClO{sub 4}, Zr/BaCrO{sub 4}, Zr/CuO, Zr/Fe{sub 2}O{sub 3}, Zr/KClO{sub 4}, and 100-mesh Al/Pd. Firing set was a capacitor discharge unit with charge capacitors ranging from 3 to 20,000 {mu}F at charge voltages 5-50 V. Devices functioned a few miliseconds after onset of current pulse at input energies as low as 3 mJ. We also report on a thermite torch design.

  9. Safety overview of the National Ignition Facility

    SciTech Connect (OSTI)

    Brereton, S.J.; McLouth, L.; Odell, B.; Singh, M.; Tobin, M.; Trent, M.

    1996-05-23

    The National Ignition Facility (NIF) is a proposed US Department of Energy inertial confinement laser fusion facility. The candidate sites for locating the NIF are: Los Alamos National Laboratory, Sandia National Laboratory, the Nevada Test Site, and Lawrence Livermore National Laboratory (LLNL), the preferred site. The NIF will operate by focusing 192 laser beams onto a tiny deuterium- tritium target located at the center of a spherical target chamber. The NIF mission is to achieve inertial confinement fusion (ICF) ignition, access physical conditions in matter of interest to nuclear weapons physics, provide an above ground simulation capability for nuclear weapons effects testing, and contribute to the development of inertial fusion for electrical power production. The NIF has been classified as a radiological, low hazard facility on the basis of a preliminary hazards analysis and according to the DOE methodology for facility classification. This requires that a safety analysis be prepared under DOE Order 5481.1B, Safety Analysis and Review System. A draft Preliminary Safety Analysis Report (PSAR) has been written, and this will be finalized later in 1996. This paper summarizes the safety issues associated with the operation of the NIF. It provides an overview of the hazards, estimates maximum routine and accidental exposures for the preferred site of LLNL, and concludes that the risks from NIF operations are low.

  10. National Ignition Facility project acquisition plan

    SciTech Connect (OSTI)

    Callaghan, R.W.

    1996-04-01

    The purpose of this National Ignition Facility Acquisition Plan is to describe the overall procurement strategy planned for the National Ignition Facility (NIF) Project. The scope of the plan describes the procurement activities and acquisition strategy for the following phases of the NIF Project, each of which receives either plant and capital equipment (PACE) or other project cost (OPC) funds: Title 1 and 2 design and Title 3 engineering (PACE); Optics manufacturing facilitization and pilot production (OPC); Convention facility construction (PACE); Procurement, installation, and acceptance testing of equipment (PACE); and Start-up (OPC). Activities that are part of the base Inertial Confinement Fusion (ICF) Program are not included in this plan. The University of California (UC), operating Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory, and Lockheed-Martin, which operates Sandia National Laboratory (SNL) and the University of Rochester Laboratory for Laser Energetics (UR-LLE), will conduct the acquisition of needed products and services in support of their assigned responsibilities within the NIF Project structure in accordance with their prime contracts with the Department of Energy (DOE). LLNL, designated as the lead Laboratory, will have responsibility for all procurements required for construction, installation, activation, and startup of the NIF.

  11. Stockpile Stewardship and the National Ignition Facility

    SciTech Connect (OSTI)

    Moses, E

    2012-01-04

    The National Ignition Facility (NIF), the world's most energetic laser system, is operational at Lawrence Livermore National Laboratory (LLNL). Since the completion of the construction project in March 2009, NIF has completed nearly 150 target experiments for the National Ignition Campaign (NIC), High Energy Density Stewardship Science (HEDSS) in the areas of radiation transport, material dynamics at high pressure in the solid state, as well as fundamental science and other national security missions. NIF capabilities and infrastructure are in place to support all of its missions with over 50 X-ray, optical and nuclear diagnostic systems and the ability to shoot cryogenic targets and DT layered capsules. NIF is now qualified for use of tritium and other special materials as well as to perform high yield experiments and classified experiments. DT implosions with record indirect-drive neutron yield of 4.5 x 10{sup 14} neutrons have been achieved. A series of 43 experiments were successfully executed over a 27-day period, demonstrating the ability to perform precise experiments in new regimes of interest to HEDSS. This talk will provide an update of the progress on the NIF capabilities, NIC accomplishments, as well as HEDSS and fundamental science experimental results and an update of the experimental plans for the coming year.

  12. Radial flow pulse jet mixer (Patent) | DOEPatents

    Office of Scientific and Technical Information (OSTI)

    Radial flow pulse jet mixer Title: Radial flow pulse jet mixer The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing ...

  13. Igniter for gas discharge pipe with a flame detection system

    SciTech Connect (OSTI)

    Guerra, R.E.

    1990-03-06

    This patent describes a method of burning waste gas, using an igniter of the type having a nozzle, a main gas conduit extending to the nozzle, and an electrical spark means for creating a spark in the nozzle. It comprises: mounting the igniter to a waste gas discharge pipe with the nozzle directed across the opening of the gas discharge pipe; supplying a gaseous fuel to the main gas conduit; igniting the gaseous fuel with the electrical spark means, creating a flame for igniting the waste gas being discharged from the gas discharge pipe; providing the igniter with an auxiliary gas line extending to the vicinity of the nozzle; and supplying a second and lower volume source of waste gas to the auxiliary gas line for burning at the nozzle.

  14. Variable valve timing in a homogenous charge compression ignition engine

    DOE Patents [OSTI]

    Lawrence, Keith E.; Faletti, James J.; Funke, Steven J.; Maloney, Ronald P.

    2004-08-03

    The present invention relates generally to the field of homogenous charge compression ignition engines, in which fuel is injected when the cylinder piston is relatively close to the bottom dead center position for its compression stroke. The fuel mixes with air in the cylinder during the compression stroke to create a relatively lean homogeneous mixture that preferably ignites when the piston is relatively close to the top dead center position. However, if the ignition event occurs either earlier or later than desired, lowered performance, engine misfire, or even engine damage, can result. The present invention utilizes internal exhaust gas recirculation and/or compression ratio control to control the timing of ignition events and combustion duration in homogeneous charge compression ignition engines. Thus, at least one electro-hydraulic assist actuator is provided that is capable of mechanically engaging at least one cam actuated intake and/or exhaust valve.

  15. Organic vapor jet printing system

    DOE Patents [OSTI]

    Forrest, Stephen R

    2012-10-23

    An organic vapor jet printing system includes a pump for increasing the pressure of an organic flux.

  16. Jet Fuel from Microalgal Lipids

    SciTech Connect (OSTI)

    Not Available

    2006-07-01

    A fact sheet on production of jet fuel or multi-purpose military fuel from lipids produced by microalgae.

  17. Organic vapor jet printing system

    DOE Patents [OSTI]

    Forrest, Stephen R.

    2016-05-03

    An organic vapor jet printing system includes a pump for increasing the pressure of an organic flux.

  18. Applied Turbulent Combustion

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Turbulent Combustion - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Energy Defense Waste Management Programs Advanced Nuclear

  19. Realistic Probability Estimates For Destructive Overpressure Events In Heated Center Wing Tanks Of Commercial Jet Aircraft

    SciTech Connect (OSTI)

    Alvares, N; Lambert, H

    2007-02-07

    The Federal Aviation Administration (FAA) identified 17 accidents that may have resulted from fuel tank explosions on commercial aircraft from 1959 to 2001. Seven events involved JP 4 or JP 4/Jet A mixtures that are no longer used for commercial aircraft fuel. The remaining 10 events involved Jet A or Jet A1 fuels that are in current use by the commercial aircraft industry. Four fuel tank explosions occurred in center wing tanks (CWTs) where on-board appliances can potentially transfer heat to the tank. These tanks are designated as ''Heated Center Wing Tanks'' (HCWT). Since 1996, the FAA has significantly increased the rate at which it has mandated airworthiness directives (ADs) directed at elimination of ignition sources. This effort includes the adoption, in 2001, of Special Federal Aviation Regulation 88 of 14 CFR part 21 (SFAR 88 ''Fuel Tank System Fault Tolerance Evaluation Requirements''). This paper addresses SFAR 88 effectiveness in reducing HCWT ignition source probability. Our statistical analysis, relating the occurrence of both on-ground and in-flight HCWT explosions to the cumulative flight hours of commercial passenger aircraft containing HCWT's reveals that the best estimate of HCWT explosion rate is 1 explosion in 1.4 x 10{sup 8} flight hours. Based on an analysis of SFAR 88 by Sandia National Laboratories and our independent analysis, SFAR 88 reduces current risk of historical HCWT explosion by at least a factor of 10, thus meeting an FAA risk criteria of 1 accident in billion flight hours. This paper also surveys and analyzes parameters for Jet A fuel ignition in HCWT's. Because of the paucity of in-flight HCWT explosions, we conclude that the intersection of the parameters necessary and sufficient to result in an HCWT explosion with sufficient overpressure to rupture the HCWT is extremely rare.

  20. Catalytic igniters and their use to ignite lean hydrogen-air mixtures

    DOE Patents [OSTI]

    McLean, William J.; Thorne, Lawrence R.; Volponi, Joanne V.

    1988-01-01

    A catalytic igniter which can ignite a hydrogen-air mixture as lean as 5.5% hydrogen with induction times ranging from 20 s to 400 s, under conditions which may be present during a loss-of-liquid-coolant accident at a light water nuclear reactor comprises (a) a perforate catalytically active substrate, such as a platinum coated ceramic honeycomb or wire mesh screen, through which heated gases produced by oxidation of the mixture can freely flow and (b) a plurality of thin platinum wires mounted in a thermally conductive manner on the substrate and positioned thereon so as to be able to receive heat from the substrate and the heated gases while also in contact with unoxidized gases.

  1. Vortex diode jet

    DOE Patents [OSTI]

    Houck, Edward D.

    1994-01-01

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  2. Status Of The National Ignition Campaign And National Ignition Facility Integrated Computer Control System

    SciTech Connect (OSTI)

    Lagin, L; Brunton, G; Carey, R; Demaret, R; Fisher, J; Fishler, B; Ludwigsen, P; Marshall, C; Reed, R; Shelton, R; Townsend, S

    2011-03-18

    The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility that will contains a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for multiple experimental diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's laser beams are designed to compress fusion targets to conditions required for thermonuclear burn. NIF is operated by the Integrated Computer Control System (ICCS) in an object-oriented, CORBA-based system distributed among over 1800 frontend processors, embedded controllers and supervisory servers. In the fall of 2010, a set of experiments began with deuterium and tritium filled targets as part of the National Ignition Campaign (NIC). At present, all 192 laser beams routinely fire to target chamber center to conduct fusion and high energy density experiments. During the past year, the control system was expanded to include automation of cryogenic target system and over 20 diagnostic systems to support fusion experiments were deployed and utilized in experiments in the past year. This talk discusses the current status of the NIC and the plan for controls and information systems to support these experiments on the path to ignition.

  3. National Ignition Facility wet weather construction plan

    SciTech Connect (OSTI)

    Kugler, A N

    1998-01-01

    This report presents a wet weather construction plan for the National Ignition Facility (NIF) construction project. Construction of the NIF commenced in mid- 1997, and excavation of the site was completed in the fall. Preparations for placing concrete foundations began in the fall, and above normal rainfall is expected over the tinter. Heavy rainfall in late November impacted foundation construction, and a wet weather construction plan was determined to be needed. This wet weather constiction plan recommends a strategy, techniques and management practices to prepare and protect the site corn wet weather effects and allow construction work to proceed. It is intended that information in this plan be incorporated in the Stormwater Pollution Prevention Plan (SWPPP) as warranted.

  4. National Ignition Facility environmental protection systems

    SciTech Connect (OSTI)

    Mintz, J.M.; Reitz, T.C.; Tobin, M.T.

    1994-06-01

    The conceptual design of Environmental Protection Systems (EPS) for the National Ignition Facility (NIF) is described. These systems encompass tritium and activated debris handling, chamber, debris shield and general decontamination, neutron and gamma monitoring, and radioactive, hazardous and mixed waste handling. Key performance specifications met by EPS designs include limiting the tritium inventory to 300 Ci and total tritium release from NIF facilities to less than 10 Ci/yr. Total radiation doses attributable to NIF shall remain below 10 mrem/yr for any member of the general public and 500 mrem/yr for NIF staff. ALARA-based design features and operational procedures will, in most cases, result in much lower measured exposures. Waste minimization, improved cycle time and reduced exposures all result from the proposed CO2 robotic arm cleaning and decontamination system, while effective tritium control is achieved through a modern system design based on double containment and the proven detritiation technology.

  5. Fast Camera Imaging of Hall Thruster Ignition

    SciTech Connect (OSTI)

    C.L. Ellison, Y. Raitses and N.J. Fisch

    2011-02-24

    Hall thrusters provide efficient space propulsion by electrostatic acceleration of ions. Rotating electron clouds in the thruster overcome the space charge limitations of other methods. Images of the thruster startup, taken with a fast camera, reveal a bright ionization period which settles into steady state operation over 50 μs. The cathode introduces azimuthal asymmetry, which persists for about 30 μs into the ignition. Plasma thrusters are used on satellites for repositioning, orbit correction and drag compensation. The advantage of plasma thrusters over conventional chemical thrusters is that the exhaust energies are not limited by chemical energy to about an electron volt. For xenon Hall thrusters, the ion exhaust velocity can be 15-20 km/s, compared to 5 km/s for a typical chemical thruster

  6. Fuel quantity modulation in pilot ignited engines

    DOE Patents [OSTI]

    May, Andrew

    2006-05-16

    An engine system includes a first fuel regulator adapted to control an amount of a first fuel supplied to the engine, a second fuel regulator adapted to control an amount of a second fuel supplied to the engine concurrently with the first fuel being supplied to the engine, and a controller coupled to at least the second fuel regulator. The controller is adapted to determine the amount of the second fuel supplied to the engine in a relationship to the amount of the first fuel supplied to the engine to operate in igniting the first fuel at a specified time in steady state engine operation and adapted to determine the amount of the second fuel supplied to the engine in a manner different from the relationship at steady state engine operation in transient engine operation.

  7. Pre-ignition laser ablation of nanocomposite energetic materials

    SciTech Connect (OSTI)

    Stacy, S. C.; Massad, R. A.; Pantoya, M. L.

    2013-06-07

    Laser ignition of energetic material composites was studied for initiation with heating rates from 9.5 Multiplication-Sign 10{sup 4} to 1.7 Multiplication-Sign 10{sup 7} K/s. This is a unique heating rate regime for laser ignition studies because most studies employ either continuous wave CO{sub 2} lasers to provide thermal ignition or pulsed Nd:YAG lasers to provide shock ignition. In this study, aluminum (Al) and molybdenum trioxide (MoO{sub 3}) nanoparticle powders were pressed into consolidated pellets and ignited using a Nd:YAG laser (1064 nm wavelength) with varied pulse energy. Results show reduced ignition delay times corresponding to laser powers at the ablation threshold for the sample. Heating rate and absorption coefficient were determined from an axisymmetric heat transfer model. The model estimates absorption coefficients from 0.1 to 0.15 for consolidated pellets of Al + MoO{sub 3} at 1064 nm wavelength. Ablation resulted from fracturing caused by a rapid increase in thermal stress and slowed ignition of the pellet.

  8. GROWTH OF A LOCALIZED SEED MAGNETIC FIELD IN A TURBULENT MEDIUM

    SciTech Connect (OSTI)

    Cho, Jungyeon; Yoo, Hyunju

    2012-11-10

    Turbulence dynamo deals with the amplification of a seed magnetic field in a turbulent medium and has been studied mostly for uniform or spatially homogeneous seed magnetic fields. However, some astrophysical processes (e.g., jets from active galaxies, galactic winds, or ram-pressure stripping in galaxy clusters) can provide localized seed magnetic fields. In this paper, we numerically study amplification of localized seed magnetic fields in a turbulent medium. Throughout the paper, we assume that the driving scale of turbulence is comparable to the size of the system. Our findings are as follows. First, turbulence can amplify a localized seed magnetic field very efficiently. The growth rate of magnetic energy density is as high as that for a uniform seed magnetic field. This result implies that magnetic field ejected from an astrophysical object can be a viable source of a magnetic field in a cluster. Second, the localized seed magnetic field disperses and fills the whole system very fast. If turbulence in a system (e.g., a galaxy cluster or a filament) is driven at large scales, we expect that it takes a few large-eddy turnover times for the magnetic field to fill the whole system. Third, growth and turbulence diffusion of a localized seed magnetic field are also fast in high magnetic Prandtl number turbulence. Fourth, even in decaying turbulence, a localized seed magnetic field can ultimately fill the whole system. Although the dispersal rate of the magnetic field is not fast in purely decaying turbulence, it can be enhanced by an additional forcing.

  9. Flow cytometer jet monitor system

    DOE Patents [OSTI]

    Van den Engh, Ger

    1997-01-01

    A direct jet monitor illuminates the jet of a flow cytometer in a monitor wavelength band which is substantially separate from the substance wavelength band. When a laser is used to cause fluorescence of the substance, it may be appropriate to use an infrared source to illuminate the jet and thus optically monitor the conditions within the jet through a CCD camera or the like. This optical monitoring may be provided to some type of controller or feedback system which automatically changes either the horizontal location of the jet, the point at which droplet separation occurs, or some other condition within the jet in order to maintain optimum conditions. The direct jet monitor may be operated simultaneously with the substance property sensing and analysis system so that continuous monitoring may be achieved without interfering with the substance data gathering and may be configured so as to allow the front of the analysis or free fall area to be unobstructed during processing.

  10. Fuel reactivity effects on the efficiency and operational window of dual-fuel compression ignition engines

    SciTech Connect (OSTI)

    Splitter, Derek A; Reitz, Rolf

    2014-01-01

    Fuel reactivity effects on the efficiency and operational window of dual-fuel compression ignition engines

  11. Distributed ignition method and apparatus for a combustion engine

    DOE Patents [OSTI]

    Willi, Martin L.; Bailey, Brett M.; Fiveland, Scott B.; Gong, Weidong

    2006-03-07

    A method and apparatus for operating an internal combustion engine is provided. The method comprises the steps of introducing a primary fuel into a main combustion chamber of the engine, introducing a pilot fuel into the main combustion chamber of the engine, determining an operating load of the engine, determining a desired spark plug ignition timing based on the engine operating load, and igniting the primary fuel and pilot fuel with a spark plug at the desired spark plug ignition timing. The method is characterized in that the octane number of the pilot fuel is lower than the octane number of the primary fuel.

  12. Ignitability testing for core drilling system. Final report

    SciTech Connect (OSTI)

    Cashdollar, K.L.; Furno, A.; Green, G.M.; Thomas, R.A.; Witwer, K.S.

    1995-06-15

    As part of a study of the hazards of the inspection of nuclear waste material stored at the Hanford, WA site, the Department of Energy (DOE) and Westinghouse Hanford Company (WHC) have developed a core drilling system to sample the material in large waste storage tanks. In support of this work, the US Bureau of Mines has studied the probability of ignition while core drilling into simulated salt cake that was permeated with a flammable gas mixture. No ignitions were observed while core drilling into the saltcake with or without a purge gas and no ignitions were observed while drilling into a steel plate.

  13. Hydrogen-assisted catalytic ignition characteristics of different fuels

    SciTech Connect (OSTI)

    Zhong, Bei-Jing; Yang, Fan; Yang, Qing-Tao

    2010-10-15

    Hydrogen-assisted catalytic ignition characteristics of methane (CH{sub 4}), n-butane (n-C{sub 4}H{sub 10}) and dimethyl ether (DME) were studied experimentally in a Pt-coated monolith catalytic reactor. It is concluded that DME has the lowest catalytic ignition temperature and the least required H{sub 2} flow, while CH{sub 4} has the highest catalytic ignition temperature and the highest required H{sub 2} flow among the three fuels. (author)

  14. The National Ignition Facility: The Path to Ignition, High Energy Density Science and Inertial Fusion Energy

    SciTech Connect (OSTI)

    Moses, E

    2011-03-25

    The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in Livermore, CA, is a Nd:Glass laser facility capable of producing 1.8 MJ and 500 TW of ultraviolet light. This world's most energetic laser system is now operational with the goals of achieving thermonuclear burn in the laboratory and exploring the behavior of matter at extreme temperatures and energy densities. By concentrating the energy from its 192 extremely energetic laser beams into a mm{sup 3}-sized target, NIF can produce temperatures above 100 million K, densities of 1,000 g/cm{sup 3}, and pressures 100 billion times atmospheric pressure - conditions that have never been created in a laboratory and emulate those in the interiors of planetary and stellar environments. On September 29, 2010, NIF performed the first integrated ignition experiment which demonstrated the successful coordination of the laser, the cryogenic target system, the array of diagnostics and the infrastructure required for ignition. Many more experiments have been completed since. In light of this strong progress, the U.S. and the international communities are examining the implication of achieving ignition on NIF for inertial fusion energy (IFE). A laser-based IFE power plant will require a repetition rate of 10-20 Hz and a 10% electrical-optical efficiency laser, as well as further advances in large-scale target fabrication, target injection and tracking, and other supporting technologies. These capabilities could lead to a prototype IFE demonstration plant in 10- to 15-years. LLNL, in partnership with other institutions, is developing a Laser Inertial Fusion Energy (LIFE) baseline design and examining various technology choices for LIFE power plant This paper will describe the unprecedented experimental capabilities of the NIF, the results achieved so far on the path toward ignition, the start of fundamental science experiments and plans to transition NIF to an international user facility

  15. The Composition of GRB Jets and the ICMART Model

    SciTech Connect (OSTI)

    Zhang, Bing; Guo, Fan

    2015-07-16

    Models of gamma ray bursts (GRBs) are drawn from observations of light curves, spectra, and spectral evolution. The ICMART (Internal Collision-induced MAgnetic Reconnection & Turbulence) model and some of its features are presented. Increasing evidence points towards Poynting-flux-dominated jets in at least some (even a good fraction of) GRBs. The main emission component (Band) is of a synchrotron emission origin, produced by electrons accelerated in the emission region. The data seem to require that magnetic reconnection in the moderately-high sigma regime is the mechanism to accelerate particles. Extensive numerical simulations are needed to verify physical details of such a model, and some encouraging results have been obtained.

  16. Turbulent Flame Speeds and NOx Kinetics of HHC Fuels with Contaminants and High Dilution Levels

    SciTech Connect (OSTI)

    Peterson, Eric; Krejci, Michael; Mathieu, Olivier; Vissotski, Andrew; Ravi, Sankat; Plichta, Drew; Sikes, Travis; Levacque, Anthony; Camou, Alejandro; Aul, Christopher

    2014-01-24

    This final report documents the technical results of the 3-year project entitled, “Turbulent Flame Speeds and NOx Kinetics of HHC Fuels with Contaminants and High Dilution Levels,” funded under the NETL of DOE. The research was conducted under six main tasks: 1) program management and planning; 2) turbulent flame speed measurements of syngas mixtures; 3) laminar flame speed measurements with diluents; 4) NOx mechanism validation experiments; 5) fundamental NOx kinetics; and 6) the effect of impurities on NOx kinetics. Experiments were performed using primary constant-volume vessels for laminar and turbulent flame speeds and shock tubes for ignition delay times and species concentrations. In addition to the existing shock- tube and flame speed facilities, a new capability in measuring turbulent flame speeds was developed under this grant. Other highlights include an improved NOx kinetics mechanism; a database on syngas blends for real fuel mixtures with and without impurities; an improved hydrogen sulfide mechanism; an improved ammonia kintics mechanism; laminar flame speed data at high pressures with water addition; and the development of an inexpensive absorption spectroscopy diagnostic for shock-tube measurements of OH time histories. The Project Results for this work can be divided into 13 major sections, which form the basis of this report. These 13 topics are divided into the five areas: 1) laminar flame speeds; 2) Nitrogen Oxide and Ammonia chemical kinetics; 3) syngas impurities chemical kinetics; 4) turbulent flame speeds; and 5) OH absorption measurements for chemical kinetics.

  17. BARYON LOADING OF ACTIVE GALACTIC NUCLEUS JETS MEDIATED BY NEUTRONS

    SciTech Connect (OSTI)

    Toma, K.; Takahara, F.

    2012-08-01

    Plasmas of geometrically thick, black hole (BH) accretion flows in active galactic nuclei (AGNs) are generally collisionless for protons, and involve magnetic field turbulence. Under such conditions a fraction of protons can be accelerated stochastically and create relativistic neutrons via nuclear collisions. These neutrons can freely escape from the accretion flow and decay into protons in the dilute polar region above the rotating BH to form relativistic jets. We calculate geometric efficiencies of the neutron energy and mass injections into the polar region, and show that this process can deposit luminosity as high as L{sub j}{approx}2 Multiplication-Sign 10{sup -3} M-dot c{sup 2} and mass loading M-dot{sub j}{approx}6 Multiplication-Sign 10{sup -4} M-dot for the case of the BH mass M {approx} 10{sup 8} M{sub Sun }, where M-dot is the mass accretion rate. The terminal Lorentz factors of the jets are {Gamma} {approx} 3, and they may explain the AGN jets having low luminosities. For higher luminosity jets, which can be produced by additional energy inputs such as Poynting flux, the neutron decay still can be a dominant mass loading process, leading to, e.g., {Gamma} {approx} 50 for L{sub j,tot}{approx}3 Multiplication-Sign 10{sup -2} M-dot c{sup 2}.

  18. BIPOLAR JETS LAUNCHED FROM ACCRETION DISKS. II. THE FORMATION OF ASYMMETRIC JETS AND COUNTER JETS

    SciTech Connect (OSTI)

    Fendt, Christian; Sheikhnezami, Somayeh E-mail: nezami@mpia.de

    2013-09-01

    We investigate the jet launching from accretion disks, in particular the formation of intrinsically asymmetric jet/counter jet systems. We perform axisymmetric MHD simulations of the disk-jet structure on a bipolar computational domain covering both hemispheres. We apply various models such as asymmetric disks with (initially) different scale heights in each hemisphere, symmetric disks into which a local disturbance is injected, and jets launched into an asymmetric disk corona. We consider both a standard global magnetic diffusivity distribution and a novel local diffusivity model. Typical disk evolution first shows substantial disk warping and then results in asymmetric outflows with a 10%-30% mass flux difference. We find that the magnetic diffusivity profile is essential for establishing a long-term outflow asymmetry. We conclude that bipolar asymmetry in protostellar and extragalactic jets can indeed be generated intrinsically and maintained over a long time by disk asymmetries and the standard jet launching mechanism.

  19. Compact Ignition Tokamak Program: status of FEDC studies

    SciTech Connect (OSTI)

    Flanagan, C.A.

    1985-01-01

    Viewgraphs on the Compact Ignition Tokamak Program comprise the report. The technical areas discussed are the mechanical configuration status, magnet analysis, stress analysis, cooling between burns, TF coil joint, and facility/device layout options. (WRF)

  20. High Fidelity Modeling of Premixed Charge Compression Ignition Engines

    Broader source: Energy.gov [DOE]

    Most accurate and detailed chemical kinetic models for fuels of practical interest to engine manufacturers and fuels developers are applied for high fidelity engine analysis of premixed charge compression ignition engines.

  1. Gasoline Compression Ignition - Start of Injection Timing Sweep...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Contact Us For more information, contact Greg Cunningham at (630) 252-8232 or media@anl.gov. Gasoline Compression Ignition - Start of Injection Timing Sweep (VERIFI) Share Topic...

  2. The National Ignition Facility (NIF) - September 23, 2010 | Department...

    Broader source: Energy.gov (indexed) [DOE]

    NIF03.23.10(1).pdf More Documents & Publications The National Ignition Facility (NIF) - September 23, 2010 EIS-0236-S1: Supplemental Environmental Impact Statement EIS-0236-S1:...

  3. The National Ignition Facility (NIF) - September 23, 2010 | Department...

    Broader source: Energy.gov (indexed) [DOE]

    NIF03.23.10.pdf More Documents & Publications The National Ignition Facility (NIF) - September 23, 2010 EIS-0236-S1: Supplemental Environmental Impact Statement EIS-0236-S1:...

  4. Laser Ignition and Diagnostic Systems Delivered by Flexible Optical...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Vehicles and Fuels Vehicles and Fuels Find More Like This Return to Search Laser Ignition ... PDF Document Publication 09-068.pdf (441 KB) Technology Marketing Summary Laser-based ...

  5. Ram jet engine

    SciTech Connect (OSTI)

    Crispin, B.; Pohl, W.D.; Thomaier, D.; Voss, N.

    1983-11-29

    In a ram jet engine, a tubular combustion chamber is divided into a flame chamber followed by a mixing chamber. The ram air is supplied through intake diffusers located on the exterior of the combustion chamber. The intake diffusers supply combustion air directly into the flame chamber and secondary air is conveyed along the exterior of the combustion chambers and then supplied directly into the mixing chamber.

  6. Numerical simulation of alumina spraying in argon-helium plasma jet

    SciTech Connect (OSTI)

    Chang, C.H.

    1992-01-01

    A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)

  7. Numerical simulation of alumina spraying in argon-helium plasma jet

    SciTech Connect (OSTI)

    Chang, C.H.

    1992-08-01

    A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions. (15 refs.)

  8. Director of the National Ignition Facility, Lawrence Livermore National

    National Nuclear Security Administration (NNSA)

    Laboratory | National Nuclear Security Administration | (NNSA) Director of the National Ignition Facility, Lawrence Livermore National Laboratory Edward Moses Edward Moses September 2009 Edward Teller Medal Edward Moses of the Lawrence Livermore National Laboratory is a recipient of the 2009 Edward Teller Medal. Moses was cited for his "leadership in the development and completion of the National Ignition Facility" (NIF). As principal associate director for NIF and Photon Science

  9. New Methodologies for Analysis of Premixed Charge Compression Ignition

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Engines | Department of Energy New Methodologies for Analysis of Premixed Charge Compression Ignition Engines New Methodologies for Analysis of Premixed Charge Compression Ignition Engines Presentation given at the 2007 Diesel Engine-Efficiency & Emissions Research Conference (DEER 2007). 13-16 August, 2007, Detroit, Michigan. Sponsored by the U.S. Department of Energy's (DOE) Office of FreedomCAR and Vehicle Technologies (OFCVT). deer07_aceves.pdf (1012.81 KB) More Documents &

  10. Ignition technique for an in situ oil shale retort

    DOE Patents [OSTI]

    Cha, Chang Y.

    1983-01-01

    A generally flat combustion zone is formed across the entire horizontal cross-section of a fragmented permeable mass of formation particles formed in an in situ oil shale retort. The flat combustion zone is formed by either sequentially igniting regions of the surface of the fragmented permeable mass at successively lower elevations or by igniting the entire surface of the fragmented permeable mass and controlling the rate of advance of various portions of the combustion zone.

  11. Efficiency Considerations of Diesel Premixed Charge Compression Ignition

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Combustion | Department of Energy Considerations of Diesel Premixed Charge Compression Ignition Combustion Efficiency Considerations of Diesel Premixed Charge Compression Ignition Combustion Poster presented at the 16th Directions in Engine-Efficiency and Emissions Research (DEER) Conference in Detroit, MI, September 27-30, 2010. p-06_jacobs.pdf (226.27 KB) More Documents & Publications Biodiesel's Enabling Characteristics in Attaining Low Temperature Diesel Combustion System-Response

  12. Ignition and burn of a small magnetized fuel target

    SciTech Connect (OSTI)

    Kirkpatrick, Ronald C.

    2012-06-01

    The crucial step for inertial confinement fusion (ICF) is ignition, which leads to sufficiently high gain to enable design of a power producing system. Thus far, this step has not been demonstrated. Magnetized targets may provide an alternative path to ignition. In addition, the 1-D calculations presented here suggest that this approach may provide the gain and other characteristics needed for a practical fusion reactor.

  13. Delivering Innovations That Create Jobs: National Lab Ignites Business for

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Entrepreneurs | Department of Energy Delivering Innovations That Create Jobs: National Lab Ignites Business for Entrepreneurs Delivering Innovations That Create Jobs: National Lab Ignites Business for Entrepreneurs November 17, 2011 - 1:59pm Addthis DEP Shape Memory Therapeutics, Inc. is working to treat aneurysms with exclusively licensed LLNL-developed polymer materials that "remember" their shape. LLNL is a leader in the development of shape memory polymers, for use in medical

  14. Special Feature: Energy - The Spark that Ignited DOE Supercomputing

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Energy - The Spark that Ignited DOE Supercomputing Special Feature: Energy - The Spark that Ignited DOE Supercomputing Scientific Computing for Energy Independence and a Clean Energy Future September 16, 2013 Contact: Linda Vu, lvu@lbl.gov, +1 510 495 2402 1280px-OREGONSODD-EVENPLANREDUCEDTHELINESATGASSTATIONSDURINGTHEFUELCRISISINTHEFALLANDWINTEROF1973-74....-NARA-555498.jpg Oregon's odd-even plan reduced the lines at gas stations during the fuel crisis in the fall and winter of 1973-74. This

  15. Turbocharged Spark Ignited Direct Injection - A Fuel Economy Solution for

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    The US | Department of Energy Turbocharged Spark Ignited Direct Injection - A Fuel Economy Solution for The US Turbocharged Spark Ignited Direct Injection - A Fuel Economy Solution for The US Turbocharged SIDI is the most promising advanced gasoline technology; combines existing & proven technologies in a synergistic manner, offers double digit fuel economy benefits, much lower cost than diesel or hybrid. deer09_whitaker.pdf (488.25 KB) More Documents & Publications E85 Optimized

  16. Hydrocarbon fouling of SCR during Premixed Charge Compression Ignition

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    (PCCI) combustion | Department of Energy fouling of SCR during Premixed Charge Compression Ignition (PCCI) combustion Hydrocarbon fouling of SCR during Premixed Charge Compression Ignition (PCCI) combustion Analyzed the effects of higher hydrocarbon emissions from PCCI combustion on SCR catalysts in operating a light-duty 1.9-liter GM diesel engine in both PCCI and conventional combustion modes deer11_parks.pdf (1.16 MB) More Documents & Publications Efficient Emissions Control for

  17. Improving the Efficiency of Spark Ignited, Stoichiometric Natural Gas

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Engines | Department of Energy Spark Ignited, Stoichiometric Natural Gas Engines Improving the Efficiency of Spark Ignited, Stoichiometric Natural Gas Engines This work focused on using camless engine technology to improve the efficiency of a natural gas engine. Late intake close timing and cylinder deactivation were utilized to meet a peak BTE > 40%. p-09_giordano.pdf (459.54 KB) More Documents & Publications Vehicle Technologies Office Merit Review 2016: Utilizing Alternative Fuel

  18. Magnetized Turbulent Dynamo in Protogalaxies

    SciTech Connect (OSTI)

    Leonid Malyshkin; Russell M. Kulsrud

    2002-01-28

    The prevailing theory for the origin of cosmic magnetic fields is that they have been amplified to their present values by the turbulent dynamo inductive action in the protogalactic and galactic medium. Up to now, in calculation of the turbulent dynamo, it has been customary to assume that there is no back reaction of the magnetic field on the turbulence, as long as the magnetic energy is less than the turbulent kinetic energy. This assumption leads to the kinematic dynamo theory. However, the applicability of this theory to protogalaxies is rather limited. The reason is that in protogalaxies the temperature is very high, and the viscosity is dominated by magnetized ions. As the magnetic field strength grows in time, the ion cyclotron time becomes shorter than the ion collision time, and the plasma becomes strongly magnetized. As a result, the ion viscosity becomes the Braginskii viscosity. Thus, in protogalaxies the back reaction sets in much earlier, at field strengths much lower than those which correspond to field-turbulence energy equipartition, and the turbulent dynamo becomes what we call the magnetized turbulent dynamo. In this paper we lay the theoretical groundwork for the magnetized turbulent dynamo. In particular, we predict that the magnetic energy growth rate in the magnetized dynamo theory is up to ten times larger than that in the kinematic dynamo theory. We also briefly discuss how the Braginskii viscosity can aid the development of the inverse cascade of magnetic energy after the energy equipartition is reached.

  19. Advances in compressible turbulent mixing

    SciTech Connect (OSTI)

    Dannevik, W.P.; Buckingham, A.C.; Leith, C.E.

    1992-01-01

    This volume includes some recent additions to original material prepared for the Princeton International Workshop on the Physics of Compressible Turbulent Mixing, held in 1988. Workshop participants were asked to emphasize the physics of the compressible mixing process rather than measurement techniques or computational methods. Actual experimental results and their meaning were given precedence over discussions of new diagnostic developments. Theoretical interpretations and understanding were stressed rather than the exposition of new analytical model developments or advances in numerical procedures. By design, compressibility influences on turbulent mixing were discussed--almost exclusively--from the perspective of supersonic flow field studies. The papers are arranged in three topical categories: Foundations, Vortical Domination, and Strongly Coupled Compressibility. The Foundations category is a collection of seminal studies that connect current study in compressible turbulent mixing with compressible, high-speed turbulent flow research that almost vanished about two decades ago. A number of contributions are included on flow instability initiation, evolution, and transition between the states of unstable flow onset through those descriptive of fully developed turbulence. The Vortical Domination category includes theoretical and experimental studies of coherent structures, vortex pairing, vortex-dynamics-influenced pressure focusing. In the Strongly Coupled Compressibility category the organizers included the high-speed turbulent flow investigations in which the interaction of shock waves could be considered an important source for production of new turbulence or for the enhancement of pre-existing turbulence. Individual papers are processed separately.

  20. Numerical simulation of jet mixing concepts in Tank 241-SY-101

    SciTech Connect (OSTI)

    Trent, D.S.; Michener, T.E.

    1993-03-01

    The episodic gas release events (GRES) that have characterized the behavior of Tank 241-SY-101 for the past several years are thought to result from gases generated by the waste material in it that become trapped in the layer of settled solids at the bottom of the tank. Several concepts for mitigating the GREs have been proposed. One concept involves mobilizing the solid particles with mixing jets. The rationale behind this idea is to prevent formation of a consolidated layer of settled solids at the bottom of the tank, thus inhibiting the accumulation of gas bubbles in this layer. Numerical simulations were conducted using the TEMPEST computer code to assess the viability and effectiveness of the proposed jet discharge concepts and operating parameters. Before these parametric studies were commenced, a series of turbulent jet studies were conducted that established the adequacy of the TEMPEST code for this application. Configurations studied for Tank 241-SY-101 include centrally located downward discharging jets, draft tubes, and horizontal jets that are either stationary or rotating. Parameter studies included varying the jet discharge velocity, jet diameter, discharge elevation, and material properties. A total of 18 simulations were conducted and are reported in this document. The effect of gas bubbles on the mixing dynamics was not included within the scope of this study.

  1. Large optics for the National Ignition Facility

    SciTech Connect (OSTI)

    Baisden, P.

    2015-01-12

    The National Ignition Facility (NIF) laser with its 192 independent laser beams is not only the world’s largest laser, it is also the largest optical system ever built. With its 192 independent laser beams, the NIF requires a total of 7648 large-aperture (meter-sized) optics. One of the many challenges in designing and building NIF has been to carry out the research and development on optical materials, optics design, and optics manufacturing and metrology technologies needed to achieve NIF’s high output energies and precision beam quality. This paper describes the multiyear, multi-supplier, development effort that was undertaken to develop the advanced optical materials, coatings, fabrication technologies, and associated process improvements necessary to manufacture the wide range of NIF optics. The optics include neodymium-doped phosphate glass laser amplifiers; fused silica lenses, windows, and phase plates; mirrors and polarizers with multi-layer, high-reflectivity dielectric coatings deposited on BK7 substrates; and potassium di-hydrogen phosphate crystal optics for fast optical switches, frequency conversion, and polarization rotation. Also included is a discussion of optical specifications and custom metrology and quality-assurance tools designed, built, and fielded at supplier sites to verify compliance with the stringent NIF specifications. In addition, a brief description of the ongoing program to improve the operational lifetime (i.e., damage resistance) of optics exposed to high fluence in the 351-nm (3ω) is provided.

  2. Safety overview of the National Ignition Facility

    SciTech Connect (OSTI)

    Brereton, S.; McLouth, L.; Odell, B.; Singh, M.; Tobin, M.; Trent, M.; Yatabe, J.

    1996-12-31

    The National Ignition Facility (NIF) is a proposed U.S. Department of Energy inertial confinement laser fusion facility. The candidate sites for locating the NIF are: Los Alamos National Laboratory, Sandia National Laboratory - New Mexico, the Nevada Test Site, and Lawrence Livermore National Laboratory (LLNL), the preferred site. The NIF will operate by focusing 192 laser beams onto a tiny deuterium-tritium target located at the center of a spherical target chamber. The NIF has been classified as a radiological, low hazard facility on the basis of a preliminary hazards analysis and according to the DOE methodology for facility classification. This requires that a safety analysis be prepared under DOE Order 5481.1B, Safety Analysis and Review System. A draft Preliminary Safety Analysis Report (PSAR) has been written, and this will be finalized later in 1996, after independent review. This paper summarizes the safety issues associated with the construction and operation of the NIF. It provides an overview of the hazards, estimates maximum routine and accidental exposures for the preferred site of LLNL, and concludes that the risks from NIF operations are low. 9 refs., 2 figs., 2 tabs.

  3. National Ignition Facility Comes to Life

    SciTech Connect (OSTI)

    Moses, E

    2003-09-01

    First conceived of nearly 15 years ago, the National Ignition Facility (NIF) is up and running and successful beyond almost everyone's expectations. During commissioning of the first four laser beams, the laser system met design specifications for everything from beam quality to energy output. NIF will eventually have 192 laser beams. Yet with just 2% of its final beam configuration complete, NIF has already produced the highest energy laser shots in the world. In July, laser shots in the infrared wavelength using four beams produced a total of 26.5 kilojoules of energy per beam, not only meeting NIF's design energy requirement of 20 kilojoules per beam but also exceeding the energy of any other infrared laser beamline. In another campaign, NIF produced over 11.4 kilojoules of energy when the infrared light was converted to green light. An earlier performance campaign of laser light that had been frequency converted from infrared to ultraviolet really proved NIF's mettle. Over 10.4 kilojoules of ultraviolet energy were produced in about 4 billionths of a second. If all 192 beamlines were to operate at these levels, over 2 megajoules of energy would result. That much energy for the pulse duration of several nanoseconds is about 500 trillion watts of power, more than 500 times the US peak generating power.

  4. Jet initiation of PBX 9502

    SciTech Connect (OSTI)

    McAfee, J.M.

    1987-07-01

    This report details the progress of an effort to determine the quantitative aspects of the initiation of PBX 9502 (95% TATB, 5% Kel-F 800) by copper jets. The particular jet used was that produced by the LAW warhead (66-mm diameter, 42/sup 0/ angle cone, copper-lined, conical shaped charge). Fifteen experiments, in various configurations, have been fired to define the essential parameters for quantitatively measuring the jet performance and initiation of bare PBX 9502. 7 refs., 8 figs.

  5. Response Relationship Between Juvenile Salmon and an Autonomous Sensor in Turbulent Flows

    SciTech Connect (OSTI)

    Richmond, Marshall C.; Deng, Zhiqun; McKinstry, Craig A.; Mueller, Robert P.; Carlson, Thomas J.; Dauble, Dennis D.

    2009-01-27

    Juvenile fall chinook salmon (Oncorhynchus tshawythscha) and an autonomous sensor device (Sensor Fish) were exposed to turbulent shear flows in order to determine how hydraulic conditions effected fish injury response. Studies were designed to establish correlation metrics between Sensor Fish device measurements and live fish injuries by conducting concurrent releases in a range of turbulent shear flows. Comparisons were made for two exposure scenarios. In the fast-fish-to-slow-water scenario, test fish were carried by the fast-moving water of a submerged turbulent jet and exposed into the standing water of a flume. In the slow-fish-to-fast-water scenario, test fish were introduced into a turbulent jet from standing water through an introduction tube placed just outside the edge of the jet. Motion-tracking analysis was performed on high-speed, high-resolution digital videos of all the releases at water jet velocities ranging from 3 to 22.9 m · s-1. Velocities of the Sensor Fish were very similar to those of live fish, but maximum accelerations of live fish were larger than those by Sensor Fish for all the nozzle velocities of both cenarios. A 10% probability of major injury threshold was found to occur at sensor fish accelerations of 513 and 260 (m · s-2) for the fast-fish-to-slow-water and slow-fish-to-fast-water scenarios, respectively. The findings provide a linkage between laboratory experiments of fish injury, field survival studies, and numerical modeling.

  6. Theory of hydro-equivalent ignition for inertial fusion and its applications to OMEGA and the National Ignition Facility

    SciTech Connect (OSTI)

    Nora, R.; Betti, R.; Bose, A.; Woo, K. M.; Christopherson, A. R.; Meyerhofer, D. D.; McCrory, R. L.

    2014-05-15

    The theory of ignition for inertial confinement fusion capsules [R. Betti et al., Phys. Plasmas 17, 058102 (2010)] is used to assess the performance requirements for cryogenic implosion experiments on the Omega Laser Facility. The theory of hydrodynamic similarity is developed in both one and two dimensions and tested using multimode hydrodynamic simulations with the hydrocode DRACO [P. B. Radha et al., Phys. Plasmas 12, 032702 (2005)] of hydro-equivalent implosions (implosions with the same implosion velocity, adiabat, and laser intensity). The theory is used to scale the performance of direct-drive OMEGA implosions to the National Ignition Facility (NIF) energy scales and determine the requirements for demonstrating hydro-equivalent ignition on OMEGA. Hydro-equivalent ignition on OMEGA is represented by a cryogenic implosion that would scale to ignition on the NIF at 1.8?MJ of laser energy symmetrically illuminating the target. It is found that a reasonable combination of neutron yield and areal density for OMEGA hydro-equivalent ignition is 3 to 6??10{sup 13} and ?0.3?g/cm{sup 2}, respectively, depending on the level of laser imprinting. This performance has not yet been achieved on OMEGA.

  7. Nocturnal Low-Level-Jet-Dominated Atmospheric Boundary Layer Observed by a Doppler Lidar Over Oklahoma City during JU2003

    SciTech Connect (OSTI)

    Wang, Yansen; Klipp, Cheryl L.; Garvey, Dennis M.; Ligon, David; Williamson, Chatt C.; Chang, Sam S.; Newsom, Rob K.; Calhoun, Ron

    2007-12-01

    Boundary layer wind data observed by a Doppler lidar and sonic anemometers during the mornings of three intensive observational periods (IOP2, IOP3, and IOP7) of the Joint Urban 2003 (JU2003) field experiment are analyzed to extract the mean and turbulent characteristics of airflow over Oklahoma City, Oklahoma. A strong nocturnal low-level jet (LLJ) dominated the flow in the boundary layer over the measurement domain from midnight to the morning hours. Lidar scans through the LLJ taken after sunrise indicate that the LLJ elevation shows a gradual increase of 25-100 m over the urban area relative to that over the upstream suburban area. The mean wind speed beneath the jet over the urban area is about 10%-15% slower than that over the suburban area. Sonic anemometer observations combined with Doppler lidar observations in the urban and suburban areas are also analyzed to investigate the boundary layer turbulence production in the LLJ-dominated atmospheric boundary layer. The turbulence kinetic energy was higher over the urban domain mainly because of the shear production of building surfaces and building wakes. Direct transport of turbulent momentum flux from the LLJ to the urban street level was very small because of the relatively high elevation of the jet. However, since the LLJ dominated the mean wind in the boundary layer, the turbulence kinetic energy in the urban domain is correlated directly with the LLJ maximum speed and inversely with its height. The results indicate that the jet Richardson number is a reasonably good indicator for turbulent kinetic energy over the urban domain in the LLJ-dominated atmospheric boundary layer.

  8. Fuel burner having a intermittent pilot with pre-ignition testing

    SciTech Connect (OSTI)

    Peterson, S.M.

    1991-07-30

    This patent describes improvement in a fuel burner having a main burner and a pilot burner for lighting the main burner, an electrically-powered igniter for lighting the pilot burner, a source of electric energy, an igniter power supply receiving a demand signal and supplying power to the igniter responsive to the demand signal, a pilot sensor adjacent to the pilot burner and supplying a pilot signal responsive to presence of a pilot flame, and a main burner valve controlling flow of fuel to the main burner and opening responsive to the pilot signal. The improvement comprises: a pilot burner valve controlling flow of fuel to the pilot burner and opening responsive to a pilot valve control signal; igniter sensing means in sensing relation to the igniter for providing an igniter signal responsive to operation of the igniter; and pilot valve control means receiving the igniter signal, for providing the pilot valve control signal responsive to the igniter signal.

  9. The National Ignition Facility Diagnostic Set at the Completion of the National Ignition Campaign, September 2012

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kilkenny, J. D.; Bell, P. M.; Bradley, D. K.; Bleuel, D. L.; Caggiano, J. A.; Dewald, E. L.; Hsing, W. W.; Kalantar, D. H.; Kauffman, R. L.; Larson, D. J.; et al

    2016-01-06

    At the completion of the National Ignition Campaign (NIC), the National Ignition Facility (NIF) had about 36 different types of diagnostics. These were based on several decades of development on Nova and OMEGA and involved the whole U.S. inertial confinement fusion community. In 1994, the Joint Central Diagnostic Team documented a plan for a limited set of NIF diagnostics in the NIF Conceptual Design Report. Two decades later, these diagnostics, and many others, were installed workhorse tools for all users of NIF. We give a short description of each of the 36 different types of NIC diagnostics grouped by themore » function of the diagnostics, namely, target drive, target response and target assembly, stagnation, and burn. A comparison of NIF diagnostics with the Nova diagnostics shows that the NIF diagnostic capability is broadly equivalent to that of Nova in 1999. Although NIF diagnostics have a much greater degree of automation and rigor than Nova’s, new diagnostics are limited such as the higher-speed X-ray imager. Lastly, recommendations for future diagnostics on the NIF are discussed.« less

  10. The National Ignition Facility and the Path to Fusion Energy

    SciTech Connect (OSTI)

    Moses, E

    2011-07-26

    The National Ignition Facility (NIF) is operational and conducting experiments at the Lawrence Livermore National Laboratory (LLNL). The NIF is the world's largest and most energetic laser experimental facility with 192 beams capable of delivering 1.8 megajoules of 500-terawatt ultraviolet laser energy, over 60 times more energy than any previous laser system. The NIF can create temperatures of more than 100 million degrees and pressures more than 100 billion times Earth's atmospheric pressure. These conditions, similar to those at the center of the sun, have never been created in the laboratory and will allow scientists to probe the physics of planetary interiors, supernovae, black holes, and other phenomena. The NIF's laser beams are designed to compress fusion targets to the conditions required for thermonuclear burn, liberating more energy than is required to initiate the fusion reactions. Experiments on the NIF are focusing on demonstrating fusion ignition and burn via inertial confinement fusion (ICF). The ignition program is conducted via the National Ignition Campaign (NIC) - a partnership among LLNL, Los Alamos National Laboratory, Sandia National Laboratories, University of Rochester Laboratory for Laser Energetics, and General Atomics. The NIC program has also established collaborations with the Atomic Weapons Establishment in the United Kingdom, Commissariat a Energie Atomique in France, Massachusetts Institute of Technology, Lawrence Berkeley National Laboratory, and many others. Ignition experiments have begun that form the basis of the overall NIF strategy for achieving ignition. Accomplishing this goal will demonstrate the feasibility of fusion as a source of limitless, clean energy for the future. This paper discusses the current status of the NIC, the experimental steps needed toward achieving ignition and the steps required to demonstrate and enable the delivery of fusion energy as a viable carbon-free energy source.

  11. THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS

    SciTech Connect (OSTI)

    Federrath, Christoph; Schober, Jennifer; Bovino, Stefano; Schleicher, Dominik R. G.

    2014-12-20

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024{sup 3} cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ?/? = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ? 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm{sub crit}=129{sub ?31}{sup +43}, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars.

  12. CX-010179: Categorical Exclusion Determination

    Broader source: Energy.gov [DOE]

    Modeling and Experimental Studies of Controllable Cavity Turbulent Jet Ignition CX(s) Applied: B3.6 Date: 04/25/2013 Location(s): Michigan Offices(s): National Energy Technology Laboratory

  13. Direct Numerical Simulation of Autoiginition of a Hydrogen Jet in a

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Preheated Cross Flow | Argonne Leadership Computing Facility Numerical Simulation of Autoiginition of a Hydrogen Jet in a Preheated Cross Flow Authors: Abdilghanie, A., Frouzakis, C.E., Fischer, P Autoignition of a nitrogen-diluted hydrogen mixture issuing from a round nozzle into a cross-flowing turbulent stream of preheated air flowing in a channel at a friction Reynolds number Re = 180 is inves- tigated via 3-D direct numerical simulations (DNS) at two crossflow stream temperatures (930

  14. Simulating flame lift-off characteristics of diesel and biodiesel fuels using detailed chemical-kinetic mechanisms and LES turbulence model.

    SciTech Connect (OSTI)

    Som, S; Longman, D. E.; Luo, Z; Plomer, M; Lu, T; Senecal, P.K.; Pomraning, E

    2012-01-01

    Combustion in direct-injection diesel engines occurs in a lifted, turbulent diffusion flame mode. Numerous studies indicate that the combustion and emissions in such engines are strongly influenced by the lifted flame characteristics, which are in turn determined by fuel and air mixing in the upstream region of the lifted flame, and consequently by the liquid breakup and spray development processes. From a numerical standpoint, these spray combustion processes depend heavily on the choice of underlying spray, combustion, and turbulence models. The present numerical study investigates the influence of different chemical kinetic mechanisms for diesel and biodiesel fuels, as well as Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) turbulence models on predicting flame lift-off lengths (LOLs) and ignition delays. Specifically, two chemical kinetic mechanisms for n-heptane (NHPT) and three for biodiesel surrogates are investigated. In addition, the RNG k-{epsilon} (RANS) model is compared to the Smagorinsky based LES turbulence model. Using adaptive grid resolution, minimum grid sizes of 250 {micro}m and 125 {micro}m were obtained for the RANS and LES cases respectively. Validations of these models were performed against experimental data from Sandia National Laboratories in a constant volume combustion chamber. Ignition delay and flame lift-off validations were performed at different ambient temperature conditions. The LES model predicts lower ignition delays and qualitatively better flame structures compared to the RNG k-{epsilon} model. The use of realistic chemistry and a ternary surrogate mixture, which consists of methyl decanoate, methyl 9-decenoate, and NHPT, results in better predicted LOLs and ignition delays. For diesel fuel though, only marginal improvements are observed by using larger size mechanisms. However, these improved predictions come at a significant increase in computational cost.

  15. National Ignition Facility Configuration Management Plan

    SciTech Connect (OSTI)

    Cabral, S G; Moore, T L

    2002-10-01

    This Configuration Management Plan (CMP) describes the technical and administrative management process for controlling the National Ignition Facility (NIF) Project configuration. The complexity of the NIF Project (i.e., participation by multiple national laboratories and subcontractors involved in the development, fabrication, installation, and testing of NIF hardware and software, as well as construction and testing of Project facilities) requires implementation of the comprehensive configuration management program defined in this plan. A logical schematic illustrating how the plan functions is provided in Figure 1. A summary of the process is provided in Section 4.0, Configuration Change Control. Detailed procedures that make up the overall process are referenced. This CMP is consistent with guidance for managing a project's configuration provided in Department of Energy (DOE) Order 430.1, Guide PMG 10, ''Project Execution and Engineering Management Planning''. Configuration management is a formal discipline comprised of the following four elements: (1) Identification--defines the functional and physical characteristics of a Project and uniquely identifies the defining requirements. This includes selection of components of the end product(s) subject to control and selection of the documents that define the project and components. (2) Change management--provides a systematic method for managing changes to the project and its physical and functional configuration to ensure that all changes are properly identified, assessed, reviewed, approved, implemented, tested, and documented. (3) Data management--ensures that necessary information on the project and its end product(s) is systematically recorded and disseminated for decision-making and other uses. Identifies, stores and controls, tracks status, retrieves, and distributes documents. (4) Assessments and validation--ensures that the planned configuration requirements match actual physical configurations and

  16. Controlling the Electrostatic Discharge Ignition Sensitivity of Composite Energetic Materials Using Carbon Nanotube Additives

    SciTech Connect (OSTI)

    Kade H. Poper; Eric S. Collins; Michelle L. Pantoya; Michael Daniels

    2014-10-01

    Powder energetic materials are highly sensitive to electrostatic discharge (ESD) ignition. This study shows that small concentrations of carbon nanotubes (CNT) added to the highly reactive mixture of aluminum and copper oxide (Al + CuO) significantly reduces ESD ignition sensitivity. CNT act as a conduit for electric energy, bypassing energy buildup and desensitizing the mixture to ESD ignition. The lowest CNT concentration needed to desensitize ignition is 3.8 vol.% corresponding to percolation corresponding to an electrical conductivity of 0.04 S/cm. Conversely, added CNT increased Al + CuO thermal ignition sensitivity to a hot wire igniter.

  17. Using indium tin oxide material to implement the imaging of microwave plasma ignition process

    SciTech Connect (OSTI)

    Wang, Qiang; Hou, Lingyun; Zhang, Guixin Zhang, Boya; Liu, Cheng; Wang, Zhi; Huang, Jian

    2014-02-17

    In this paper, a method is introduced to get global observation of microwave plasma ignition process at high pressure. A microwave resonator was designed with an indium tin oxide coated glass at bottom. Microwave plasma ignition was implemented in methane and air mixture at 10 bars by a 2?ms-3?kW-2.45?GHz microwave pulse, and the high speed images of the ignition process were obtained. The images visually proved that microwave plasma ignition could lead to a multi-point ignition. The system may also be applied to obtain Schlieren images, which is commonly used to observe the development of flame kernel in an ignition process.

  18. Compound cooling flow turbulator for turbine component

    DOE Patents [OSTI]

    Lee, Ching-Pang; Jiang, Nan; Marra, John J; Rudolph, Ronald J

    2014-11-25

    Multi-scale turbulation features, including first turbulators (46, 48) on a cooling surface (44), and smaller turbulators (52, 54, 58, 62) on the first turbulators. The first turbulators may be formed between larger turbulators (50). The first turbulators may be alternating ridges (46) and valleys (48). The smaller turbulators may be concave surface features such as dimples (62) and grooves (54), and/or convex surface features such as bumps (58) and smaller ridges (52). An embodiment with convex turbulators (52, 58) in the valleys (48) and concave turbulators (54, 62) on the ridges (46) increases the cooling surface area, reduces boundary layer separation, avoids coolant shadowing and stagnation, and reduces component mass.

  19. Shroud for a submerged jet cutting nozzle

    DOE Patents [OSTI]

    Schwab, Thomas L.

    1978-01-01

    A shroud for a submerged jet cutting nozzle is described which separates the jet from surrounding fluid environment and enhances the cutting effect.

  20. OPENING ANGLES OF COLLAPSAR JETS

    SciTech Connect (OSTI)

    Mizuta, Akira; Ioka, Kunihito

    2013-11-10

    We investigate the jet propagation and breakout from the stellar progenitor for gamma-ray burst (GRB) collapsars by performing two-dimensional relativistic hydrodynamic simulations and analytical modeling. We find that the jet opening angle is given by θ{sub j} ∼ 1/5Γ{sub 0} and infer the initial Lorentz factor of the jet at the central engine, Γ{sub 0}, is a few for existing observations of θ{sub j}. The jet keeps the Lorentz factor low inside the star by converging cylindrically via collimation shocks under the cocoon pressure and accelerates at jet breakout before the free expansion to a hollow-cone structure. In this new picture, the GRB duration is determined by the sound crossing time of the cocoon, after which the opening angle widens, reducing the apparent luminosity. Some bursts violating the maximum opening angle θ{sub j,{sub max}} ∼ 1/5 ∼ 12° imply the existence of a baryon-rich sheath or a long-acting jet. We can explain the slopes in both Amati and Yonetoku spectral relations using an off-centered photosphere model, if we make only one assumption that the total jet luminosity is proportional to the initial Lorentz factor of the jet. We also numerically calibrate the pre-breakout model (Bromberg et al.) for later use.

  1. Methane ignition catalyzed by in situ generated palladium nanoparticles

    SciTech Connect (OSTI)

    Shimizu, T.; Abid, A.D.; Poskrebyshev, G.; Wang, H. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089 (United States); Nabity, J.; Engel, J.; Yu, J. [TDA Research, Inc., 12345 W. 52nd Ave, Wheat Ridge, CO 80033 (United States); Wickham, D. [Reaction Systems, LLC, 19039 E. Plaza Drive, Suite 290, Parker, CO 80134 (United States); Van Devener, B.; Anderson, S.L. [Department of Chemistry, University of Utah, Salt Lake City, UT 84112 (United States); Williams, S. [Air Force Research Laboratory, Mail Stop RZA, 1950 Fifth Street, WPAFB, OH 45433 (United States)

    2010-03-15

    Catalytic ignition of methane over the surfaces of freely-suspended and in situ generated palladium nanoparticles was investigated experimentally and numerically. The experiments were conducted in a laminar flow reactor. The palladium precursor was a compound (Pd(THD){sub 2}, THD: 2,2,6,6-tetramethyl-3,5-heptanedione) dissolved in toluene and injected into the flow reactor as a fine aerosol, along with a methane-oxygen-nitrogen mixture. For experimental conditions chosen in this study, non-catalytic, homogeneous ignition was observed at a furnace temperature of {proportional_to}1123 K, whereas ignition of the same mixture with the precursor was found to be {proportional_to}973 K. In situ production of Pd/PdO nanoparticles was confirmed by scanning mobility, transmission electron microscopy and X-ray photoelectron spectroscopy analyses of particles collected at the reactor exit. The catalyst particle size distribution was log-normal. Depending on the precursor loading, the median diameter ranged from 10 to 30 nm. The mechanism behind catalytic ignition was examined using a combined gas-phase and gas-surface reaction model. Simulation results match the experiments closely and suggest that palladium nanocatalyst significantly shortens the ignition delay times of methane-air mixtures over a wide range of conditions. (author)

  2. Evaluating the ignition sensitivity of thermal battery heat pellets

    SciTech Connect (OSTI)

    Thomas, E.V.

    1993-09-01

    Thermal batteries are activated by the ignition of heat pellets. If the heat pellets are not sensitive enough to the ignition stimulus, the thermal battery will not activate, resulting in a dud. Thus, to assure reliable thermal batteries, it is important to demonstrate that the pellets have satisfactory ignition sensitivity by testing a number of specimens. There are a number of statistical methods for evaluating the sensitivity of a device to some stimulus. Generally, these methods are applicable to the situation in which a single test is destructive to the specimen being tested, independent of the outcome of the test. In the case of thermal battery heat pellets, however, tests that result in a nonresponse do not totally degrade the specimen. This peculiarity provides opportunities to efficiently evaluate the ignition sensitivity of heat pellets. In this paper, a simple strategy for evaluating heat pellet ignition sensitivity (including experimental design and data analysis) is described. The relatively good asymptotic and small-sample efficiencies of this strategy are demonstrated.

  3. Boundary Layer Cloud Turbulence Characteristics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Boundary Layer Cloud Turbulence Characteristics Virendra Ghate Bruce Albrecht Parameter Observational Readiness (/10) Modeling Need (/10) Cloud Boundaries 9 9 Cloud Fraction Variance Skewness Up/Downdraft coverage Dominant Freq. signal Dissipation rate ??? Observation-Modeling Interface

  4. High-Pressure Turbulent Flame Speeds and Chemical Kinetics of Syngas Blends with and without Impurities

    SciTech Connect (OSTI)

    Peterson, Eric; Mathieu, Olivier; Morones, Anibal; Ravi, Sankar; Keesee, Charles; Hargis, Joshua; Vivanco, Jose

    2014-12-01

    This Topical Report documents the first year of the project, from October 1, 2013 through September 30, 2014. Efforts for this project included experiments to characterize the atmospheric-pressure turbulent flame speed vessel over a range of operating conditions (fan speeds and turbulent length scales). To this end, a new LDV system was acquired and set up for the detailed characterization of the turbulence field. Much progress was made in the area of impurity kinetics, which included a numerical study of the effect of impurities such as NO2, NO, H2S, and NH3 on ignition delay times and laminar flame speeds of syngas blends at engine conditions. Experiments included a series of laminar flame speed measurements for syngas (CO/H2) blends with various levels of CH4 and C2H6 addition, and the results were compared to the chemical kinetics model of NUI Galway. Also, a final NOx kinetics mechanism including ammonia was assembled, and a journal paper was written and is now in press. Overall, three journal papers and six conference papers related to this project were published this year. Finally, much progress was made on the design of the new high-pressure turbulent flame speed facility. An overall design that includes a venting system was decided upon, and the detailed design is in progress.

  5. Control of a high Reynolds number Mach 0.9 heated jet using plasma actuators

    SciTech Connect (OSTI)

    Kearney-Fischer, M.; Kim, J.-H.; Samimy, M.

    2009-09-15

    The results of particle image velocimetry (PIV) measurements in a high subsonic, heated, jet forced using localized arc filament plasma actuators (LAFPAs) show that LAFPAs can consistently produce significant mixing enhancement over a wide range of temperatures. These actuators have been used successfully in high Reynolds number, high-speed unheated jets. The facility consists of an axisymmetric jet with different nozzle blocks of exit diameter of 2.54 cm and variable jet temperature in an anechoic chamber. The focus of this paper is on a high subsonic (M{sub j}=0.9) jet. Twelve experiments with various forcing azimuthal modes (m=0, 1, and {+-}1) and temperatures (T{sub o}/T{sub a}=1.0, 1.4, and 2.0) at a fixed forcing Strouhal number (St{sub DF}=0.3) have been conducted and PIV results compared with the baseline results to characterize the effectiveness of LAFPAs for mixing enhancement. Centerline velocity and turbulent kinetic energy as well as jet width are used for determining the LAFPAs' effectiveness. The characteristics of large-scale structures are analyzed through the use of Galilean streamlines and swirling strength. Across the range of temperatures collected, the effectiveness of LAFPAs improves as temperature increases. Possible reasons for the increase in effectiveness are discussed.

  6. Data Analysis, Pre-Ignition Assessment, and Post-Ignition Modeling of the Large-Scale Annular Cookoff Tests

    SciTech Connect (OSTI)

    G. Terrones; F.J. Souto; R.F. Shea; M.W.Burkett; E.S. Idar

    2005-09-30

    In order to understand the implications that cookoff of plastic-bonded explosive-9501 could have on safety assessments, we analyzed the available data from the large-scale annular cookoff (LSAC) assembly series of experiments. In addition, we examined recent data regarding hypotheses about pre-ignition that may be relevant to post-ignition behavior. Based on the post-ignition data from Shot 6, which had the most complete set of data, we developed an approximate equation of state (EOS) for the gaseous products of deflagration. Implementation of this EOS into the multimaterial hydrodynamics computer program PAGOSA yielded good agreement with the inner-liner collapse sequence for Shot 6 and with other data, such as velocity interferometer system for any reflector and resistance wires. A metric to establish the degree of symmetry based on the concept of time of arrival to pin locations was used to compare numerical simulations with experimental data. Several simulations were performed to elucidate the mode of ignition in the LSAC and to determine the possible compression levels that the metal assembly could have been subjected to during post-ignition.

  7. Photothermally activated motion and ignition using aluminum nanoparticles

    SciTech Connect (OSTI)

    Abboud, Jacques E.; Chong Xinyuan; Zhang Mingjun; Zhang Zhili; Jiang Naibo; Roy, Sukesh; Gord, James R.

    2013-01-14

    The aluminum nanoparticles (Al NPs) are demonstrated to serve as active photothermal media, to enhance and control local photothermal energy deposition via the photothermal effect activated by localized surface plasmon resonance (LSPR) and amplified by Al NPs oxidation. The activation source is a 2-AA-battery-powered xenon flash lamp. The extent of the photothermally activated movement of Al NPs can be {approx}6 mm. Ignition delay can be {approx}0.1 ms. Both scanning electron microscopy and energy-dispersive X-ray spectroscopy measurements of motion-only and after-ignition products confirm significant Al oxidation occurs through sintering and bursting after the flash exposure. Simulations suggest local heat generation is enhanced by LSPR. The positive-feedback effects from the local heat generation amplified by Al oxidation produce a large increase in local temperature and pressure, which enhances movement and accelerates ignition.

  8. Stratified-charge glow plug ignition engine experiments. Topical report

    SciTech Connect (OSTI)

    Thring, R.H.; Leet, J.A.

    1991-05-01

    An investigation was conducted to study the feasibility of operating a natural gas two-stroke engine using glow plug ignition with very lean mixtures. The term Stratified-Charge Glow Plus Ignition (SCGI) was coined to describe the engine. A JLO DL 365 single-cylinder, two-stroke, diesel engine was converted first to a natural gas fueled spark-ignited engine for the baseline tests, and then to the SCGI engine. The engine was successfully run, but was found to be sensitive to various conditions such as the glow plug temperature. The engine ran very lean, to an equivalence ratio of 0.33, offering the potential of good fuel economy and low NOx emissions. Numerous photographs, diagrams, and charts are included.

  9. Thermonuclear microexplosion ignition by imploding a disk of relativistic electrons

    SciTech Connect (OSTI)

    Winterberg, F.

    1995-03-01

    A new ignition concept for thermonuclear reactions is described, in which an electron cloud produced by inductive charge injection and reaching the Brillouin limit, is magnetically compressed inside a long cylindrical solenoid. For sufficiently fast compression, the front of the cloud becomes a relativistically contracted annular disk of high-energy density, which upon impact on a grounded target leads to a cylindrical implosion easily exceeding the power fluxes required for the ignition of thermonuclear microexplosions. Unlike concepts proposed in the past to ignite thermonuclear microexplosions by relativistic electron beams, the energy delivered to the target is not in the form of kinetic particle energy but in the form of an intense electromagnetic pulse. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  10. Development of nuclear diagnostics for the National Ignition Facility (invited)

    SciTech Connect (OSTI)

    Glebov, V. Yu.; Meyerhofer, D. D.; Sangster, T. C.; Stoeckl, C.; Roberts, S.; Barrera, C. A.; Celeste, J. R.; Cerjan, C. J.; Dauffy, L. S.; Eder, D. C.; Griffith, R. L.; Haan, S. W.; Hammel, B. A.; Hatchett, S. P.; Izumi, N.; Kimbrough, J. R.; Koch, J. A.; Landen, O. L.; Lerche, R. A.; MacGowan, B. J.

    2006-10-15

    The National Ignition Facility (NIF) will provide up to 1.8 MJ of laser energy for imploding inertial confinement fusion (ICF) targets. Ignited NIF targets are expected to produce up to 10{sup 19} DT neutrons. This will provide unprecedented opportunities and challenges for the use of nuclear diagnostics in ICF experiments. In 2005, the suite of nuclear-ignition diagnostics for the NIF was defined and they are under development through collaborative efforts at several institutions. This suite includes PROTEX and copper activation for primary yield measurements, a magnetic recoil spectrometer and carbon activation for fuel areal density, neutron time-of-flight detectors for yield and ion temperature, a gamma bang time detector, and neutron imaging systems for primary and downscattered neutrons. An overview of the conceptual design, the developmental status, and recent results of prototype tests on the OMEGA laser will be presented.

  11. Ion beam requirements for fast ignition of inertial fusion targets

    SciTech Connect (OSTI)

    Honrubia, J. J.; Murakami, M.

    2015-01-15

    Ion beam requirements for fast ignition are investigated by numerical simulation taking into account new effects, such as ion beam divergence, not included before. We assume that ions are generated by the TNSA scheme in a curved foil placed inside a re-entrant cone and focused on the cone apex or beyond. From the focusing point to the compressed core, ions propagate with a given divergence angle. Ignition energies are obtained for two compressed fuel configurations heated by proton and carbon ion beams. The dependence of the ignition energies on the beam divergence angle and on the position of the ion beam focusing point has been analyzed. Comparison between TNSA and quasi-monoenergetic ions is also shown.

  12. WILDFIRE IGNITION RESISTANCE ESTIMATOR WIZARD SOFTWARE DEVELOPMENT REPORT

    SciTech Connect (OSTI)

    Phillips, M.; Robinson, C.; Gupta, N.; Werth, D.

    2012-10-10

    This report describes the development of a software tool, entitled “WildFire Ignition Resistance Estimator Wizard” (WildFIRE Wizard, Version 2.10). This software was developed within the Wildfire Ignition Resistant Home Design (WIRHD) program, sponsored by the U. S. Department of Homeland Security, Science and Technology Directorate, Infrastructure Protection & Disaster Management Division. WildFIRE Wizard is a tool that enables homeowners to take preventive actions that will reduce their home’s vulnerability to wildfire ignition sources (i.e., embers, radiant heat, and direct flame impingement) well in advance of a wildfire event. This report describes the development of the software, its operation, its technical basis and calculations, and steps taken to verify its performance.

  13. The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Rosenberg, M. J.; Rinderknecht, H. G.; et al

    2014-11-03

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D3He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2x higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infermore » the areal density (pR) and the shell center-of-mass radius (Rcm) from the downshift of the shock-produced D3He protons. The observed pR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time ('short-coast'), while longer-coasting implosions have lower pR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (~800 ps) than in the short-coast (~400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time. This result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel pR.« less

  14. The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

    SciTech Connect (OSTI)

    Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Rosenberg, M. J.; Rinderknecht, H. G.; Friedrich, S.; Bionta, R.; Olson, R.; Atherton, J.; Barrios, M.; Bell, P.; Benedetti, R.; Hopkins, L. Berzak; Betti, R.; Bradley, D.; Callahan, D.; Casey, D.; Collins, G.; Dixit, S.; Döppner, T.; Edgell, D.; Edwards, M. J.; Johnson, M. Gatu; Glenn, S.; Glenzer, S.; Grim, G.; Hatchett, S.; Jones, O.; Khan, S.; Kilkenny, J.; Kline, J.; Knauer, J.; Kritcher, A.; Kyrala, G.; Landen, O.; LePape, S.; Li, C. K.; Lindl, J.; Ma, T.; Mackinnon, A.; Macphee, A.; Manuel, M. J.-E.; Meyerhofer, D.; Moody, J.; Moses, E.; Nagel, S. R.; Nikroo, A.; Pak, A.; Parham, T.; Petrasso, R. D.; Prasad, R.; Ralph, J.; Rosen, M.; Ross, J. S.; Sangster, T. C.; Sepke, S.; Sinenian, N.; Sio, H. W.; Spears, B.; Springer, P.; Tommasini, R.; Town, R.; Weber, S.; Wilson, D.; Zacharias, R.

    2014-11-03

    The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D3He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D3He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2x higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infer the areal density (pR) and the shell center-of-mass radius (Rcm) from the downshift of the shock-produced D3He protons. The observed pR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time ('short-coast'), while longer-coasting implosions have lower pR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (~800 ps) than in the short-coast (~400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time. This result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel pR.

  15. Alignment of an x-Ray Imager Line of Sight in the National Ignition...

    Office of Scientific and Technical Information (OSTI)

    Alignment of an x-Ray Imager Line of Sight in the National Ignition Facility (NIF) Target ... Title: Alignment of an x-Ray Imager Line of Sight in the National Ignition Facility (NIF) ...

  16. Micromachined chemical jet dispenser

    DOE Patents [OSTI]

    Swierkowski, S.P.

    1999-03-02

    A dispenser is disclosed for chemical fluid samples that need to be precisely ejected in size, location, and time. The dispenser is a micro-electro-mechanical systems (MEMS) device fabricated in a bonded silicon wafer and a substrate, such as glass or silicon, using integrated circuit-like fabrication technology which is amenable to mass production. The dispensing is actuated by ultrasonic transducers that efficiently produce a pressure wave in capillaries that contain the chemicals. The 10-200 {micro}m diameter capillaries can be arranged to focus in one spot or may be arranged in a larger dense linear array (ca. 200 capillaries). The dispenser is analogous to some ink jet print heads for computer printers but the fluid is not heated, thus not damaging certain samples. Major applications are in biological sample handling and in analytical chemical procedures such as environmental sample analysis, medical lab analysis, or molecular biology chemistry experiments. 4 figs.

  17. Micromachined chemical jet dispenser

    DOE Patents [OSTI]

    Swierkowski, Steve P.

    1999-03-02

    A dispenser for chemical fluid samples that need to be precisely ejected in size, location, and time. The dispenser is a micro-electro-mechanical systems (MEMS) device fabricated in a bonded silicon wafer and a substrate, such as glass or silicon, using integrated circuit-like fabrication technology which is amenable to mass production. The dispensing is actuated by ultrasonic transducers that efficiently produce a pressure wave in capillaries that contain the chemicals. The 10-200 .mu.m diameter capillaries can be arranged to focus in one spot or may be arranged in a larger dense linear array (.about.200 capillaries). The dispenser is analogous to some ink jet print heads for computer printers but the fluid is not heated, thus not damaging certain samples. Major applications are in biological sample handling and in analytical chemical procedures such as environmental sample analysis, medical lab analysis, or molecular biology chemistry experiments.

  18. Water cooled steam jet

    DOE Patents [OSTI]

    Wagner, E.P. Jr.

    1999-01-12

    A water cooled steam jet for transferring fluid and preventing vapor lock, or vaporization of the fluid being transferred, has a venturi nozzle and a cooling jacket. The venturi nozzle produces a high velocity flow which creates a vacuum to draw fluid from a source of fluid. The venturi nozzle has a converging section connected to a source of steam, a diffuser section attached to an outlet and a throat portion disposed there between. The cooling jacket surrounds the venturi nozzle and a suction tube through which the fluid is being drawn into the venturi nozzle. Coolant flows through the cooling jacket. The cooling jacket dissipates heat generated by the venturi nozzle to prevent vapor lock. 2 figs.

  19. Jet fuel from LPG

    SciTech Connect (OSTI)

    Maples, R.E.; Jones, J.R.

    1983-02-01

    Explains how jet fuel can be manufactured from propane and/or butane with attractive rates of return. This scheme is advantageous where large reserves of LPG-bearing gas is available or LPG is in excess. The following sequence of processes in involved: dehydrogenation of propane (and/or butane) to propylene (and/or butylene); polymerization of this monomer to a substantial yield of the desired polymer by recycling undesired polymer; and hydrotreating the polymer to saturate double bonds. An attribute of this process scheme is that each of the individual processes has been practiced commercially. The process should have appeal in those parts of the world which have large reserves of LPG-bearing natural gas but little or no crude oil, or where large excesses of LPG are available. Concludes that economic analysis shows attractive rates of return in a range of reasonable propane costs and product selling prices.

  20. Water cooled steam jet

    DOE Patents [OSTI]

    Wagner, Jr., Edward P.

    1999-01-01

    A water cooled steam jet for transferring fluid and preventing vapor lock, or vaporization of the fluid being transferred, has a venturi nozzle and a cooling jacket. The venturi nozzle produces a high velocity flow which creates a vacuum to draw fluid from a source of fluid. The venturi nozzle has a converging section connected to a source of steam, a diffuser section attached to an outlet and a throat portion disposed therebetween. The cooling jacket surrounds the venturi nozzle and a suction tube through which the fluid is being drawn into the venturi nozzle. Coolant flows through the cooling jacket. The cooling jacket dissipates heat generated by the venturi nozzle to prevent vapor lock.

  1. National Ignition Facility & Photon Science HOW NIF WORKS

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    9 National Ignition Facility & Photon Science HOW NIF WORKS beam me up: how niF works In the National Ignition Facility (NIF), 192 laser beams travel a long path, about 1,500 meters, from their birth at the master oscillator-a device that generates the single pulse that seeds the entire NIF laser system-to the center of the target chamber. As the beams move through NIF's amplifiers, their energy increases exponentially. From beginning to end, the beams' total energy grows from one- billionth

  2. Correlating cookoff violence with pre-ignition damage.

    SciTech Connect (OSTI)

    Wente, William Baker; Hobbs, Michael L.; Kaneshige, Michael Jiro

    2010-03-01

    Predicting the response of energetic materials during accidents, such as fire, is important for high consequence safety analysis. We hypothesize that responses of ener-getic materials before and after ignition depend on factors that cause thermal and chemi-cal damage. We have previously correlated violence from PETN to the extent of decom-position at ignition, determined as the time when the maximum Damkoehler number ex-ceeds a threshold value. We seek to understand if our method of violence correlation ap-plies universally to other explosive starting with RDX.

  3. Ignition feedback regenerative free electron laser (FEL) amplifier

    DOE Patents [OSTI]

    Kim, Kwang-Je; Zholents, Alexander; Zolotorev, Max

    2001-01-01

    An ignition feedback regenerative amplifier consists of an injector, a linear accelerator with energy recovery, and a high-gain free electron laser amplifier. A fraction of the free electron laser output is coupled to the input to operate the free electron laser in the regenerative mode. A mode filter in this loop prevents run away instability. Another fraction of the output, after suitable frequency up conversion, is used to drive the photocathode. An external laser is provided to start up both the amplifier and the injector, thus igniting the system.

  4. Exhaust gas recirculation in a homogeneous charge compression ignition engine

    SciTech Connect (OSTI)

    Duffy, Kevin P.; Kieser, Andrew J.; Rodman, Anthony; Liechty, Michael P.; Hergart, Carl-Anders; Hardy, William L.

    2008-05-27

    A homogeneous charge compression ignition engine operates by injecting liquid fuel directly in a combustion chamber, and mixing the fuel with recirculated exhaust and fresh air through an auto ignition condition of the fuel. The engine includes at least one turbocharger for extracting energy from the engine exhaust and using that energy to boost intake pressure of recirculated exhaust gas and fresh air. Elevated proportions of exhaust gas recirculated to the engine are attained by throttling the fresh air inlet supply. These elevated exhaust gas recirculation rates allow the HCCI engine to be operated at higher speeds and loads rendering the HCCI engine a more viable alternative to a conventional diesel engine.

  5. Mode 1 drive asymmetry in inertial confinement fusion implosions on the National Ignition Facility

    SciTech Connect (OSTI)

    Spears, Brian K. Edwards, M. J.; Hatchett, S.; Kritcher, A.; Lindl, J.; Munro, D.; Patel, P.; Robey, H. F.; Town, R. P. J.; Kilkenny, J.; Knauer, J.

    2014-04-15

    Mode 1 radiation drive asymmetry (pole-to-pole imbalance) at significant levels can have a large impact on inertial confinement fusion implosions at the National Ignition Facility (NIF). This asymmetry distorts the cold confining shell and drives a high-speed jet through the hot spot. The perturbed hot spot shows increased residual kinetic energy and reduced internal energy, and it achieves reduced pressure and neutron yield. The altered implosion physics manifests itself in observable diagnostic signatures, especially the neutron spectrum which can be used to measure the neutron-weighted flow velocity, apparent ion temperature, and neutron downscattering. Numerical simulations of implosions with mode 1 asymmetry show that the resultant simulated diagnostic signatures are moved toward the values observed in many NIF experiments. The diagnostic output can also be used to build a set of integrated implosion performance metrics. The metrics indicate that P{sub 1} has a significant impact on implosion performance and must be carefully controlled in NIF implosions.

  6. Autoignited laminar lifted flames of methane, ethylene, ethane, and n-butane jets in coflow air with elevated temperature

    SciTech Connect (OSTI)

    Choi, B.C.; Chung, S.H.

    2010-12-15

    The autoignition characteristics of laminar lifted flames of methane, ethylene, ethane, and n-butane fuels have been investigated experimentally in coflow air with elevated temperature over 800 K. The lifted flames were categorized into three regimes depending on the initial temperature and fuel mole fraction: (1) non-autoignited lifted flame, (2) autoignited lifted flame with tribrachial (or triple) edge, and (3) autoignited lifted flame with mild combustion. For the non-autoignited lifted flames at relatively low temperature, the existence of lifted flame depended on the Schmidt number of fuel, such that only the fuels with Sc > 1 exhibited stationary lifted flames. The balance mechanism between the propagation speed of tribrachial flame and local flow velocity stabilized the lifted flames. At relatively high initial temperatures, either autoignited lifted flames having tribrachial edge or autoignited lifted flames with mild combustion existed regardless of the Schmidt number of fuel. The adiabatic ignition delay time played a crucial role for the stabilization of autoignited flames. Especially, heat loss during the ignition process should be accounted for, such that the characteristic convection time, defined by the autoignition height divided by jet velocity was correlated well with the square of the adiabatic ignition delay time for the critical autoignition conditions. The liftoff height was also correlated well with the square of the adiabatic ignition delay time. (author)

  7. A Reconnection Switch to Trigger gamma-Ray Burst Jet Dissipation

    SciTech Connect (OSTI)

    McKinney, Jonathan C.; Uzdensky, Dmitri A.

    2012-03-14

    Prompt gamma-ray burst (GRB) emission requires some mechanism to dissipate an ultrarelativistic jet. Internal shocks or some form of electromagnetic dissipation are candidate mechanisms. Any mechanism needs to answer basic questions, such as what is the origin of variability, what radius does dissipation occur at, and how does efficient prompt emission occur. These mechanisms also need to be consistent with how ultrarelativistic jets form and stay baryon pure despite turbulence and electromagnetic reconnection near the compact object and despite stellar entrainment within the collapsar model. We use the latest magnetohydrodynamical models of ultrarelativistic jets to explore some of these questions in the context of electromagnetic dissipation due to the slow collisional and fast collisionless reconnection mechanisms, as often associated with Sweet-Parker and Petschek reconnection, respectively. For a highly magnetized ultrarelativistic jet and typical collapsar parameters, we find that significant electromagnetic dissipation may be avoided until it proceeds catastrophically near the jet photosphere at large radii (r {approx} 10{sup 13}-10{sup 14}cm), by which the jet obtains a high Lorentz factor ({gamma} {approx} 100-1000), has a luminosity of L{sub j} {approx} 10{sup 50}-10{sup 51} erg s{sup -1}, has observer variability timescales of order 1s (ranging from 0.001-10s), achieves {gamma}{theta}{sub j} {approx} 10-20 (for opening half-angle {theta}{sub j}) and so is able to produce jet breaks, and has comparable energy available for both prompt and afterglow emission. A range of model parameters are investigated and simplified scaling laws are derived. This reconnection switch mechanism allows for highly efficient conversion of electromagnetic energy into prompt emission and associates the observed prompt GRB pulse temporal structure with dissipation timescales of some number of reconnecting current sheets embedded in the jet. We hope this work helps motivate the

  8. Radial flow pulse jet mixer

    DOE Patents [OSTI]

    VanOsdol, John G.

    2013-06-25

    The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing vessel is comprised of a sludge basin, a flow surface surrounding the sludge basin, and a downcoming flow annulus between the flow surface and an inner shroud. The pulse jet mixing vessel is additionally comprised of an upper vessel pressurization volume in fluid communication with the downcoming flow annulus, and an inner shroud surge volume separated from the downcoming flow annulus by the inner shroud. When the solid particles are resting on the sludge basin and a fluid such as water is atop the particles and extending into the downcoming flow annulus and the inner shroud surge volume, mixing occurs by pressurization of the upper vessel pressurization volume, generating an inward radial flow over the flow surface and an upwash jet at the center of the sludge basin.

  9. Fragmentation inside an identified jet

    SciTech Connect (OSTI)

    Procura, Massimiliano; Stewart, Iain W.

    2011-05-23

    Using Soft-Collinear Effective Theory (SCET) we derive factorization formulae for semi-inclusive processes where a light hadron h fragments from a jet whose invariant mass is measured. Our analysis yields a novel 'fragmenting jet function' G{sub i}{sup h}(s,z) that depends on the jet invariant mass {radical}(s), and on the fraction z of the large light-cone momentum components of the hadron and the parent parton i. We show that G{sub i}{sup h}(s,z) can be computed in terms of perturbatively calculable coefficients, J{sub ij}(s,z/x), integrated against standard non-perturbative fragmentation functions, D{sub j}{sup h}(x). Our analysis yields a simple replacement rule that allows any factorization theorem depending on a jet function J{sub i} to be converted to a semi-inclusive process with a fragmenting hadron h.

  10. Fast ignition: Dependence of the ignition energy on source and target parameters for particle-in-cell-modelled energy and angular distributions of the fast electrons

    SciTech Connect (OSTI)

    Bellei, C.; Divol, L.; Kemp, A. J.; Key, M. H.; Larson, D. J.; Strozzi, D. J.; Marinak, M. M.; Tabak, M.; Patel, P. K.

    2013-05-15

    The energy and angular distributions of the fast electrons predicted by particle-in-cell (PIC) simulations differ from those historically assumed in ignition designs of the fast ignition scheme. Using a particular 3D PIC calculation, we show how the ignition energy varies as a function of source-fuel distance, source size, and density of the pre-compressed fuel. The large divergence of the electron beam implies that the ignition energy scales with density more weakly than the ρ{sup −2} scaling for an idealized beam [S. Atzeni, Phys. Plasmas 6, 3316 (1999)], for any realistic source that is at some distance from the dense deuterium-tritium fuel. Due to the strong dependence of ignition energy with source-fuel distance, the use of magnetic or electric fields seems essential for the purpose of decreasing the ignition energy.

  11. Optimization of the process of plasma ignition of coal

    SciTech Connect (OSTI)

    Peregudov, V.S.

    2009-04-15

    Results are given of experimental and theoretical investigations of plasma ignition of coal as a result of its thermochemical preparation in application to the processes of firing up a boiler and stabilizing the flame combustion. The experimental test bed with a commercial-scale burner is used for determining the conditions of plasma ignition of low-reactivity high-ash anthracite depending on the concentration of coal in the air mixture and velocity of the latter. The calculations produce an equation (important from the standpoint of practical applications) for determining the energy expenditure for plasma ignition of coal depending on the basic process parameters. The tests reveal the difficulties arising in firing up a boiler with direct delivery of pulverized coal from the mill to furnace. A scheme is suggested, which enables one to reduce the energy expenditure for ignition of coal and improve the reliability of the process of firing up such a boiler. Results are given of calculation of plasma thermochemical preparation of coal under conditions of lower concentration of oxygen in the air mixture.

  12. Direct-drive–ignition designs with mid-Z ablators

    SciTech Connect (OSTI)

    Lafon, M.; Betti, R.; Anderson, K. S.; Collins, T. J. B.; Epstein, R.; McKenty, P. W.; Myatt, J. F.; Shvydky, A.; Skupsky, S.

    2015-03-15

    Achieving thermonuclear ignition using direct laser illumination relies on the capability to accelerate spherical shells to high implosion velocities while maintaining shell integrity. Ablator materials of moderate atomic number Z reduce the detrimental effects of laser–plasma instabilities in direct-drive implosions. To validate the physics of moderate-Z ablator materials for ignition target designs on the National Ignition Facility (NIF), hydro-equivalent targets are designed using pure plastic (CH), high-density carbon, and glass (SiO{sub 2}) ablators. The hydrodynamic stability of these targets is investigated through two-dimensional (2D) single-mode and multimode simulations. The overall stability of these targets to laser-imprint perturbations and low-mode asymmetries makes it possible to design high-gain targets. Designs using polar-drive illumination are developed within the NIF laser system specifications. Mid-Z ablator targets are an attractive candidate for direct-drive ignition since they present better overall performance than plastic ablator targets through reduced laser–plasma instabilities and a similar hydrodynamic stability.

  13. Drying low rank coal and retarding spontaneous ignition

    SciTech Connect (OSTI)

    Bixel, J.C.; Bellow, E.J.; Heaney, W.F.; Facinelli, S.H.

    1989-05-09

    A method is described of producing a dried particulate coal fuel having a reduced tendency to ignite spontaneously comprising spraying and intimately mixing the dried coal with an aqueous emulsion of a material selected from the group consisting of foots oils, petrolatum filtrate, and hydrocracker recycle oil.

  14. Safety analysis of optically ignited explosive and pyrotechnic devices

    SciTech Connect (OSTI)

    Merson, J.A.; Salas, F.J.; Holswade, S.

    1994-05-01

    The future of optical ordnance depends on the acceptance, validation and verification of the stated safety enhancement claims of optical ordnance over existing electrical explosive devices (EED`s). Sandia has been pursuing the development of optical ordnance, with the primary motivation of this effort being the enhancement of explosive safety by specifically reducing the potential of premature detonation that can occur with low energy electrically ignited explosive devices. By using semiconductor laser diodes for igniting these devices, safety improvements can be made without being detrimental to current system concerns since the inputs required for these devices are similar to electrical systems. Laser Diode Ignition (LDI) of the energetic material provides the opportunity to remove the bridgewire and electrically conductive pins from the charge cavity, creating a Faraday cage and thus isolating the explosive or pyrotechnic materials from stray electrical ignition sources. Recent results from our continued study of safety enhancements are presented. The areas of investigation which are presented include: (1) unintended optical source analysis, specifically lightning insensitivity, (2) electromagnetic radiation (EMR) and electrostatic discharge (ESD) insensitivity analysis, and (3) powder safety.

  15. CO/sub 2/-laser ignition of DAPP targets

    SciTech Connect (OSTI)

    Brannon, P.J.

    1981-07-01

    A pulse derived by shuttering a CO/sub 2/ laser operating in the cw mode has been used to ignite a diallyl phthalate pyrotechnic (DAPP) material. Data from this work along with some data taken earlier, while operating the laser in the pulse mode, are presented. When operating in the cw mode, a pulse is mechanically chopped out of the beam and focussed onto the DAPP material. It was found that the shuttered cw mode of operation gives a more reproducible pulse and a more accurate determination of the incident energy than the pulse mode does. The pulse widths for threshold ignition (50% ignitions) at different power levels have been determined for 254 and 127 mm-focal-length lenses which were used to focus the beam on the target. It was also found that targets could be penetrated without ignition of the DAPP material. A 2.54 mm-thick DAPP target is penetrated by the laser beam if the energy per unit area exceeds 29 +1 J/mm/sup 2/. Based on this study, recommendations are given for improving the present test procedures used for DAPP material.

  16. Modification of vortex dynamics and transport properties of transitional axisymmetric jets using zero-net-mass-flux actuation

    SciTech Connect (OSTI)

    nder, Asim; Meyers, Johan

    2014-07-15

    We study the near field of a zero-net-mass-flux (ZNMF) actuated round jet using direct numerical simulations. The Reynolds number of the jet Re{sub D} = 2000 and three ZNMF actuators are used, evenly distributed over a circle, and directed towards the main jet. The actuators are triggered in phase, and have a relatively low momentum coefficient of C{sub ?} = 0.0049 each. We study four different control frequencies with Strouhal numbers ranging from St{sub D} = 0.165 to St{sub D} = 1.32; next to that, also two uncontrolled baseline cases are included in the study. We find that this type of ZNMF actuation leads to strong deformations of the near-field jet region that are very similar to those observed for non-circular jets. At the end of the jet's potential core (x/D = 5), the jet-column cross section is deformed into a hexagram-like geometry that results from strong modifications of the vortex structures. Two mechanisms lead to these modifications, i.e., (i) self-deformation of the jet's primary vortex rings started by distortions in their azimuthal curvature by the actuation, and (ii) production of side jets by the development and subsequent detachment of secondary streamwise vortex pairs. Further downstream (x/D = 10), the jet transforms into a triangular pattern, as the sharp corner regions of the hexagram entrain fluid and spread. We further investigate the global characteristics of the actuated jets. In particular when using the jet preferred frequency, i.e., St{sub D} = 0.33, parameters such as entrainment, centerline decay rate, and mean turbulent kinetic energy are significantly increased. Furthermore, high frequency actuation, i.e., St{sub D} = 1.32, is found to suppress the mechanisms leading to large scale structure growth and turbulent kinetic energy production. The simulations further include a passive scalar equation, and passive scalar mixing is also quantified and visualized.

  17. Magnetohydrodynamic turbulence: Observation and experiment

    SciTech Connect (OSTI)

    Brown, M. R.; Schaffner, D. A.; Weck, P. J.

    2015-05-15

    We provide a tutorial on the paradigms and tools of magnetohydrodynamic (MHD) turbulence. The principal paradigm is that of a turbulent cascade from large scales to small, resulting in power law behavior for the frequency power spectrum for magnetic fluctuations E{sub B}(f). We will describe five useful statistical tools for MHD turbulence in the time domain: the temporal autocorrelation function, the frequency power spectrum, the probability distribution function of temporal increments, the temporal structure function, and the permutation entropy. Each of these tools will be illustrated with an example taken from MHD fluctuations in the solar wind. A single dataset from the Wind satellite will be used to illustrate all five temporal statistical tools.

  18. Detailed Chemical Kinetic Reaction Mechanisms for Primary Reference Fuels for Diesel Cetane Number and Spark-Ignition Octane Number

    SciTech Connect (OSTI)

    Westbrook, C K; Pitz, W J; Mehl, M; Curran, H J

    2010-03-03

    For the first time, a detailed chemical kinetic reaction mechanism is developed for primary reference fuel mixtures of n-hexadecane and 2,2,4,4,6,8,8-heptamethyl nonane for diesel cetane ratings. The mechanisms are constructed using existing rules for reaction pathways and rate expressions developed previously for the primary reference fuels for gasoline octane ratings, n-heptane and iso-octane. These reaction mechanisms are validated by comparisons between computed and experimental results for shock tube ignition and for oxidation under jet-stirred reactor conditions. The combined kinetic reaction mechanism contains the submechanisms for the primary reference fuels for diesel cetane ratings and submechanisms for the primary reference fuels for gasoline octane ratings, all in one integrated large kinetic reaction mechanism. Representative applications of this mechanism to two test problems are presented, one describing fuel/air autoignition variations with changes in fuel cetane numbers, and the other describing fuel combustion in a jet-stirred reactor environment with the fuel varying from pure 2,2,4,4,6,8,8-heptamethyl nonane (Cetane number of 15) to pure n-hexadecane (Cetane number of 100). The final reaction mechanism for the primary reference fuels for diesel fuel and gasoline is available on the web.

  19. Supercomputers Capture Turbulence in the Solar Wind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Supercomputers Capture Turbulence in the Solar Wind Supercomputers Capture Turbulence in the Solar Wind Berkeley Lab visualizations could help scientists forecast destructive space weather December 16, 2013 Linda Vu, +1 510 495 2402, lvu@lbl.gov eddies1.jpg This visualization zooms in on current sheets revealing the "cascade of turbulence" in the solar wind occurring down to electron scales. This is a phenomenon common in fluid dynamics-turbulent energy injected at large eddies is

  20. PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS (Journal...

    Office of Scientific and Technical Information (OSTI)

    PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS Citation Details In-Document Search Title: PROTOSTELLAR JETS ENCLOSED BY LOW-VELOCITY OUTFLOWS A protostellar jet and outflow...

  1. Simulation of hydrogen and hydrogen-assisted propane ignition in Pt catalyzed microchannel

    SciTech Connect (OSTI)

    Seshadri, Vikram; Kaisare, Niket S.

    2010-11-15

    This paper deals with self-ignition of catalytic microburners from ambient cold-start conditions. First, reaction kinetics for hydrogen combustion is validated with experimental results from the literature, followed by validation of a simplified pseudo-2D microburner model. The model is then used to study the self-ignition behavior of lean hydrogen/air mixtures in a Platinum-catalyzed microburner. Hydrogen combustion on Pt is a very fast reaction. During cold start ignition, hydrogen conversion reaches 100% within the first few seconds and the reactor dynamics are governed by the ''thermal inertia'' of the microburner wall structure. The self-ignition property of hydrogen can be used to provide the energy required for propane ignition. Two different modes of hydrogen-assisted propane ignition are considered: co-feed mode, where the microburner inlet consists of premixed hydrogen/propane/air mixtures; and sequential feed mode, where the inlet feed is switched from hydrogen/air to propane/air mixtures after the microburner reaches propane ignition temperature. We show that hydrogen-assisted ignition is equivalent to selectively preheating the inlet section of the microburner. The time to reach steady state is lower at higher equivalence ratio, lower wall thermal conductivity, and higher inlet velocity for both the ignition modes. The ignition times and propane emissions are compared. Although the sequential feed mode requires slightly higher amount of hydrogen, the propane emissions are at least an order of magnitude lower than the other ignition modes. (author)

  2. Characterization of semiconductor bridges (SCB) igniters for use in thermal batteries

    SciTech Connect (OSTI)

    Bickes, R.W.; Guidotti, R.A.; McCampbell, C.B.

    1996-05-01

    Semiconductor bridges (SCB) igniters were evaluated as possible replacements for conventional hot-wire igniters for use in thermal batteries. The all-fire and no-fire characteristics were determined using an up-down scheme; the Neyer/SENSIT program was used to analyze the data. The SCB igniters functioned with a higher no-fire level, relative to a hot-wire igniter, for a given all-fire level. This makes the SCB igniter safer and more reliable than its hot-wire counterpart. The SCB is very resistant to electrostatic discharge and does not require a sensitization mixture for ignition of the primary pyrotechnic charge. These factors, along with its amenability to large-scale production, make the SCB igniter ideally suited for use in thermal batteries.

  3. Ion Acceleration by Laser Plasma Interaction from Cryogenic Micro Jets - Oral Presentation

    SciTech Connect (OSTI)

    Propp, Adrienne

    2015-08-25

    Processes that occur in extreme conditions, such as in the center of stars and large planets, can be simulated in the laboratory using facilities such as SLAC National Accelerator Laboratory and the Jupiter Laser Facility (JLF) at Lawrence Livermore National Laboratory (LLNL). These facilities allow scientists to investigate the properties of matter by observing their interactions with high power lasers. Ion acceleration from laser plasma interaction is gaining greater attention today due to its widespread potential applications, including proton beam cancer therapy and fast ignition for energy production. Typically, ion acceleration is achieved by focusing a high power laser on thin foil targets through a mechanism called Target Normal Sheath Acceleration. Based on research and recent experiments, we hypothesized that a pure liquid cryogenic jet would be an ideal target for this type of interaction, capable of producing the highest proton energies possible with today’s laser technologies. Furthermore, it would provide a continuous, pure target, unlike metal foils which are consumed in the interaction and easily contaminated. In an effort to test this hypothesis and investigate new, potentially more efficient mechanisms of ion acceleration, we used the 527 nm split beam, frequency-doubled TITAN laser at JLF. Data from the cryogenic jets was limited due to the flow of current up the jet into the nozzle during the interaction, heating the jet and damaging the orifice. However, we acheived a pure proton beam with an indiciation of a monoenergetic feature. Furthermore, data from gold and carbon wires showed surprising and interesting results. Preliminary analysis of data from two ion emission diagnostics, Thomson parabola spectrometers (TPs) and radio chromic films (RCFs), suggests that shockwave acceleration occurred rather than target normal sheath acceleration, the standard mechanism of ion acceleration. Upon completion of the experiment at TITAN, I researched the

  4. DECELERATING RELATIVISTIC TWO-COMPONENT JETS

    SciTech Connect (OSTI)

    Meliani, Z.; Keppens, R. E-mail: Rony.Keppens@wis.kuleuven.b

    2009-11-10

    Transverse stratification is a common intrinsic feature of astrophysical jets. There is growing evidence that jets in radio galaxies consist of a fast low-density outflow at the jet axis, surrounded by a slower, denser, extended jet. The inner and outer jet components then have a different origin and launching mechanism, making their effective inertia, magnetization, associated energy flux, and angular momentum content different as well. Their interface will develop differential rotation, where disruptions may occur. Here we investigate the stability of rotating, two-component relativistic outflows typical for jets in radio galaxies. For this purpose, we parametrically explore the long-term evolution of a transverse cross section of radially stratified jets numerically, extending our previous study where a single, purely hydrodynamic evolution was considered. We include cases with poloidally magnetized jet components, covering hydro and magnetohydrodynamic (MHD) models. With grid-adaptive relativistic MHD simulations, augmented with approximate linear stability analysis, we revisit the interaction between the two jet components. We study the influence of dynamically important poloidal magnetic fields, with varying contributions of the inner component jet to the total kinetic energy flux of the jet, on their non-linear azimuthal stability. We demonstrate that two-component jets with high kinetic energy flux and inner jet effective inertia which is higher than the outer jet effective inertia are subject to the development of a relativistically enhanced, rotation-induced Rayleigh-Taylor-type instability. This instability plays a major role in decelerating the inner jet and the overall jet decollimation. This novel deceleration scenario can partly explain the radio source dichotomy, relating it directly to the efficiency of the central engine in launching the inner jet component. The FRII/FRI transition could then occur when the relative kinetic energy flux of the

  5. A jet fuel surrogate formulated by real fuel properties

    SciTech Connect (OSTI)

    Dooley, Stephen; Won, Sang Hee; Chaos, Marcos; Heyne, Joshua; Ju, Yiguang; Dryer, Frederick L.; Kumar, Kamal; Sung, Chih-Jen; Wang, Haowei; Oehlschlaeger, Matthew A.; Santoro, Robert J.; Litzinger, Thomas A.

    2010-12-15

    An implicit methodology based on chemical group theory to formulate a jet aviation fuel surrogate by the measurements of several combustion related fuel properties is tested. The empirical formula and derived cetane number of an actual aviation fuel, POSF 4658, have been determined. A three component surrogate fuel for POSF 4658 has been formulated by constraining a mixture of n-decane, iso-octane and toluene to reproduce the hydrogen/carbon ratio and derived cetane number of the target fuel. The validity of the proposed surrogate is evaluated by experimental measurement of select combustion properties of POSF 4658, and the POSF 4658 surrogate. (1)A variable pressure flow reactor has been used to chart the chemical reactivity of stoichiometric mixtures of POSF 4658/O{sub 2}/N{sub 2} and POSF 4658 surrogate/O{sub 2}/N{sub 2} at 12.5 atm and 500-1000 K, fixing the carbon content at 0.3% for both mixtures. (2)The high temperature chemical reactivity and chemical kinetic-molecular diffusion coupling of POSF 4658 and POSF 4658 surrogate have been evaluated by measurement of the strained extinction limit of diffusion flames. (3)The autoignition behavior of POSF 4658 and POSF 4658 surrogate has been measured with a shock tube at 674-1222 K and with a rapid compression machine at 645-714 K for stoichiometric mixtures of fuel in air at pressures close to 20 atm. The flow reactor study shows that the character and extent of chemical reactivity of both fuels at low temperature (500-675 K) and high temperature (900 K+) are extremely similar. Slight differences in the transition from the end of the negative temperature coefficient regime to hot ignition are observed. The diffusion flame strained extinction limits of the fuels are observed to be indistinguishable when compared on a molar basis. Ignition delay measurements also show that POSF 4658 exhibits NTC behavior. Moreover, the ignition delays of both fuels are also extremely similar over the temperature range studied in

  6. 2015 UTSR Poster Presentations Prediction of Auto-Ignition Regimes...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Bond Coats for Thermal Barrier Coating Systems Based on High Entropy Alloys Derek Hass, DVTI Autoignition of a Jet-A Spray in a Hot, Vitiated Air Flow Aimee Williams, Georgia...

  7. Nuclear diagnostics for the National Ignition Facility (invited)

    SciTech Connect (OSTI)

    Murphy, Thomas J.; Barnes, Cris W.; Berggren, R. R.; Bradley, P.; Caldwell, S. E.; Chrien, R. E.; Faulkner, J. R.; Gobby, P. L.; Hoffman, N.; Jimerson, J. L.

    2001-01-01

    The National Ignition Facility (NIF), currently under construction at the Lawrence Livermore National Laboratory, will provide unprecedented opportunities for the use of nuclear diagnostics in inertial confinement fusion experiments. The completed facility will provide 2 MJ of laser energy for driving targets, compared to the approximately 40 kJ that was available on Nova and the approximately 30 kJ available on Omega. Ignited NIF targets are anticipated to produce up to 10{sup 19} DT neutrons. In addition to a basic set of nuclear diagnostics based on previous experience, these higher NIF yields are expected to allow innovative nuclear diagnostic techniques to be utilized, such as neutron imaging, recoil proton techniques, and gamma-ray-based reaction history measurements.

  8. Inertial Confinement Fusion and the National Ignition Facility (NIF)

    SciTech Connect (OSTI)

    Ross, P.

    2012-08-29

    Inertial confinement fusion (ICF) seeks to provide sustainable fusion energy by compressing frozen deuterium and tritium fuel to extremely high densities. The advantages of fusion vs. fission are discussed, including total energy per reaction and energy per nucleon. The Lawson Criterion, defining the requirements for ignition, is derived and explained. Different confinement methods and their implications are discussed. The feasibility of creating a power plant using ICF is analyzed using realistic and feasible numbers. The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is shown as a significant step forward toward making a fusion power plant based on ICF. NIF is the world’s largest laser, delivering 1.8 MJ of energy, with a peak power greater than 500 TW. NIF is actively striving toward the goal of fusion energy. Other uses for NIF are discussed.

  9. Laser design basis for the National Ignition Facility

    SciTech Connect (OSTI)

    Hunt, J.T.; Manes, K.R.; Murray, J.R.; Renard, P.A.; Sawicki, R.; Trenholme, J.B.; Williams, W.

    1994-06-01

    Controlled nuclear fusion initiated by highly intense laser beams has been the subject of experiment for many years. The National Ignition Facility (NIF) represents the culmination of design efforts to provide a laser facility that will successfully demonstrate fusion ignition in the laboratory. In this so-called inertial confinement approach, energetic driver beams (laser, X-ray, or charged particle) heat the outer surface of a spherical capsule containing deuterium and tritium (DT) fuel. As the capsule surface explosively evaporates, reaction pressure compresses the DT fuel causing the central core of the fuel to reach extreme density and temperature. When the central temperature is high enough, DT fusion reactions occur. The energy released from these reactions further heats the compressed fuel, and fusion burn propagates outward through the colder regions of the capsule much more rapidly than the inertially confined capsule can expand. The resulting fusion reactions yield many times more energy than was absorbed from the driver beams.

  10. Final report for miniature laser ignited bellows motor

    SciTech Connect (OSTI)

    Renfro, S.L.

    1994-02-18

    A miniature optically ignited actuation device has been demonstrated using a laser diode as an ignition source. This pyrotechnic driven motor provides between 4 and 6 lbs of linear force across a 0.090 inch diameter surface. The physical envelope of the device is 1/2 inch long and 1/8 inch diameter. This unique application of optical energy can be used as a mechanical link in optical arming systems or other applications where low shock actuation is desired and space is limited. An analysis was performed to determine pyrotechnic materials suitable to actuate a bellows device constructed of aluminum or stainless steel. The aluminum bellows was chosen for further development and several candidate pyrotechnics were evaluated. The velocity profile and delivered force were quantified using an non-intrusive optical motion sensor.

  11. The Application of High Energy Ignition and Boosting/Mixing Technology to Increase Fuel Economy in Spark Ignition Gasoline Engines by Increasing EGR Dilution Capability

    SciTech Connect (OSTI)

    Keating, Edward; Gough, Charles

    2015-07-07

    This report summarizes activities conducted in support of the project “The Application of High Energy Ignition and Boosting/Mixing Technology to Increase Fuel Economy in Spark Ignition Gasoline Engines by Increasing EGR Dilution Capability” under COOPERATIVE AGREEMENT NUMBER DE-EE0005654, as outlined in the STATEMENT OF PROJECT OBJECTIVES (SOPO) dated May 2012.

  12. Advanced thermally stable jet fuels

    SciTech Connect (OSTI)

    Schobert, H.H.

    1999-01-31

    The Pennsylvania State University program in advanced thermally stable coal-based jet fuels has five broad objectives: (1) Development of mechanisms of degradation and solids formation; (2) Quantitative measurement of growth of sub-micrometer and micrometer-sized particles suspended in fuels during thermal stressing; (3) Characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) Elucidation of the role of additives in retarding the formation of carbonaceous solids; (5) Assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal. Future high-Mach aircraft will place severe thermal demands on jet fuels, requiring the development of novel, hybrid fuel mixtures capable of withstanding temperatures in the range of 400--500 C. In the new aircraft, jet fuel will serve as both an energy source and a heat sink for cooling the airframe, engine, and system components. The ultimate development of such advanced fuels requires a thorough understanding of the thermal decomposition behavior of jet fuels under supercritical conditions. Considering that jet fuels consist of hundreds of compounds, this task must begin with a study of the thermal degradation behavior of select model compounds under supercritical conditions. The research performed by The Pennsylvania State University was focused on five major tasks that reflect the objectives stated above: Task 1: Investigation of the Quantitative Degradation of Fuels; Task 2: Investigation of Incipient Deposition; Task 3: Characterization of Solid Gums, Sediments, and Carbonaceous Deposits; Task 4: Coal-Based Fuel Stabilization Studies; and Task 5: Exploratory Studies on the Direct Conversion of Coal to High Quality Jet Fuels. The major findings of each of these tasks are presented in this executive summary. A description of the sub-tasks performed under each of these tasks and the findings of those studies are provided in the remainder of this volume

  13. NREL Ignites New Renewable Fuels Heating Plant - News Releases | NREL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ignites New Renewable Fuels Heating Plant Innovative DOE Contract Helps Lab Reduce Fuel Use, Carbon Emissions November 20, 2008 Golden, Colo. - With the spark from a high intensity road flare, engineers at the U.S. Department of Energy's National Renewable Energy Laboratory lit its new, smoke-free Renewable Fuels Heating Plant today. The $3.3 million project is the Laboratory's latest step toward operating as a net-zero energy facility. The RFHP will heat NREL's South Table Mountain Campus

  14. Lawrence Livermore National Laboratory is home to the National Ignition

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laboratory is home to the National Ignition Facility (NIF), which began full operations in March 2009. NIF's 192 powerful laser beams, housed in a 10-story building the size of 3 football fields, can deliver nearly 2 million joules of ultraviolet laser energy in billionth-of-a- second pulses to the target chamber center. When NIF's laser beams focus all of their energy on a target the size of a pencil eraser, they briefly produce extraordinary temperature and pressure conditions within the

  15. Simulation of Laser-Plasma Interaction in National Ignition Facility

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Experiments | Argonne Leadership Computing Facility A volume visualization of the laser light that has been backscattered by Stimulated Raman Scattering A volume visualization of the laser light that has been backscattered by Stimulated Raman Scattering in a simulation of a National Ignition Facility inertial fusion experiment. The band of scattered light near the bottom of the simulation extends across all three quads and is an example of "cooperative backscattering." Eric Brugger

  16. High load operation in a homogeneous charge compression ignition engine

    SciTech Connect (OSTI)

    Duffy, Kevin P.; Kieser, Andrew J.; Liechty, Michael P.; Hardy, William L.; Rodman, Anthony; Hergart, Carl-Anders

    2008-12-23

    A homogeneous charge compression ignition engine is set up by first identifying combinations of compression ratio and exhaust gas percentages for each speed and load across the engines operating range. These identified ratios and exhaust gas percentages can then be converted into geometric compression ratio controller settings and exhaust gas recirculation rate controller settings that are mapped against speed and load, and made available to the electronic

  17. Santa Fe Jets and Heavy Flavor Workshop

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Santa Fe Jets and Heavy Flavor Workshop Santa Fe Jets and Heavy Flavor Workshop WHEN: Jan 11, 2016 8:30 AM - Jan 13, 2016 5:30 PM WHERE: Inn and Spa at Loretto 211 Old Santa Fe...

  18. BioJet Corporation | Open Energy Information

    Open Energy Info (EERE)

    93940 Sector: Carbon Product: Monterey-based carbon credit developer and producer of bio-jet fuel derived from jatropha. References: BioJet Corporation1 This article is a...

  19. The National Ignition Facility: Studying the Stars in the Laboratory

    SciTech Connect (OSTI)

    Boyd, R

    2008-09-17

    The National Ignition Facility, to be completed in 2009, will be the highest energy laser ever built. The high temperatures and densities it will produce will enable a number of experiments in inertial confinement fusion and stockpile stewardship, as well as in nuclear astrophysics, X-ray astronomy, hydrodynamics, and planetary science. The National Ignition Facility, NIF (1), located at Lawrence Livermore National Lab, (LLNL) is expected to produce inertial confinement fusion (ICF) by delivering sufficient laser energy to compress and heat a millimeter-radius pellet of DT sufficiently to produce fusion to {sup 4}He+neutron and 17.6 MeV per reaction. NIF will be completed by March, 2009, at which time a National Ignition Campaign (2), NIC, a series of experiments to optimize the ICF parameters, will begin. Although NIF is a research facility, a successful NIC would have implications for future energy sources. In addition to the goal of ICF, NIF will support programs in stockpile stewardship. However, the conditions that NIF creates will simulate those inside stars and planets sufficiently closely to provide compelling motivation for experiments in basic high-energy-density (HED) science especially, for the first time, in nuclear astrophysics.

  20. National Ignition Facility Quality Assurance Program Plan. Revision 1

    SciTech Connect (OSTI)

    Wolfe, C.R.; Yatabe, J.

    1996-09-01

    The National Ignition Facility (NIF) is a key constituent of the Department of Energy`s Stockpile Stewardship Program. The NIF will use inertial confinement fusion (ICF) to produce ignition and energy gain in ICF targets, and will perform weapons physics and high-energy- density experiments in support of national security and civilian objectives. The NIF Project is a national facility involving the collaboration of several DOE laboratories and subcontractors, including Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), and the University of Rochester Laboratory for Laser Energetics (UR/LLE). The primary mission of the NIF Project is the construction and start-up operation of laser-based facilities that will demonstrate fusion ignition in the laboratory to provide nuclear-weapons-related physics data, and secondarily, to propagate fusion burn aimed at developing a potential source of civilian energy. To support the accomplishment of this very important mission, the LLNL Laser Directorate created the NIF Project Office to organize and bring about the Project. The NIF Project Office has established this Quality Assurance Program to ensure its success. This issue of the Quality Assurance Program Plan (QAPP) adds the requirements for the conduct of Title 11 design, construction, procurement, and Title III engineering. This QAPP defines and describes the program-the management system-for specifying, achieving, and assuring the quality of all NIF Project work consistent with the policies of the Laboratory and the Laser Directorate.

  1. Jets in relativistic heavy ion collisions

    SciTech Connect (OSTI)

    Wang, Xin-Nian; Gyulassy, M.

    1990-09-01

    Several aspects of hard and semihard QCD jets in relativistic heavy ion collisions are discussed, including multiproduction of minijets and the interaction of a jet with dense nuclear matter. The reduction of jet quenching effect in deconfined phase of nuclear matter is speculated to provide a signature of the formation of quark gluon plasma. HIJING Monte Carlo program which can simulate events of jets production and quenching in heavy ion collisions is briefly described. 35 refs., 13 figs.

  2. Inclusive jet production at the Tevatron

    SciTech Connect (OSTI)

    Norniella, Olga; /Barcelona, IFAE

    2006-08-01

    Preliminary results on inclusive jet production in proton-antiproton collisions at {radical}s = 1.96 TeV based on 1 fb{sup -1} of CDF Run II data are presented. Measurements are preformed using different jet algorithms in a wide range of jet transverse momentum and jet rapidity. The measured cross sections are compared to next-to-leading order perturbative QCD calculations

  3. Cours-VII/Clavin2015.key

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    propagation downstream propagation Turbulence facilitates ignition of hydrocarbon lean mixtures Turbulence may suppress ignition of hydrocarbon rich mixtures Some hydrocarbon...

  4. Turbulent equipartitions in two dimensional drift convection

    SciTech Connect (OSTI)

    Isichenko, M.B.; Yankov, V.V.

    1995-07-25

    Unlike the thermodynamic equipartition of energy in conservative systems, turbulent equipartitions (TEP) describe strongly non-equilibrium systems such as turbulent plasmas. In turbulent systems, energy is no longer a good invariant, but one can utilize the conservation of other quantities, such as adiabatic invariants, frozen-in magnetic flux, entropy, or combination thereof, in order to derive new, turbulent quasi-equilibria. These TEP equilibria assume various forms, but in general they sustain spatially inhomogeneous distributions of the usual thermodynamic quantities such as density or temperature. This mechanism explains the effects of particle and energy pinch in tokamaks. The analysis of the relaxed states caused by turbulent mixing is based on the existence of Lagrangian invariants (quantities constant along fluid-particle or other orbits). A turbulent equipartition corresponds to the spatially uniform distribution of relevant Lagrangian invariants. The existence of such turbulent equilibria is demonstrated in the simple model of two dimensional electrostatically turbulent plasma in an inhomogeneous magnetic field. The turbulence is prescribed, and the turbulent transport is assumed to be much stronger than the classical collisional transport. The simplicity of the model makes it possible to derive the equations describing the relaxation to the TEP state in several limits.

  5. Highly turbulent counterflow flames: A laboratory scale benchmark for practical systems

    SciTech Connect (OSTI)

    Coppola, Gianfilippo; Coriton, Bruno; Gomez, Alessandro

    2009-09-15

    We propose a highly turbulent counterflow flame as a very useful benchmark of complexity intermediate between laminar flames and practical systems. By operating in a turbulent Reynolds number regime of relevance to practical systems such as gas turbines and internal combustion engines, it retains the interaction of turbulence and chemistry of such environments, but offers several advantages including: (a) the achievement of high Reynolds numbers without pilot flames, which is particularly advantageous from a modeling standpoint; (b) control of the transition from stable flames to local extinction/reignition conditions; (c) compactness of the domain by comparison with jet flames, with obvious advantages from both a diagnostic and, especially, a computational viewpoint; and (d) the reduction or, altogether, elimination of soot formation, thanks to the high strain rates and low residence times of such a system, and the establishment of conditions of large stoichiometric mixture fraction, as required for robust flame stabilization. We demonstrate the phenomenology of such highly strained turbulent flames under conditions spanning unpremixed, partially premixed and premixed regimes. The system lends itself to the validation of DNS and other computational models. It is also well-suited for the examination of practical fuel blends - a need that is becoming more and more pressing in view of the anticipated diversification of the future fossil fuel supply. (author)

  6. Pilot fuel ignited stratified charge rotary combustion engine and fuel injector therefor

    SciTech Connect (OSTI)

    Loyd, R. W.

    1980-02-12

    For a pilot fuel ignited stratified charge rotary, internal combustion engine, the fuel injection system and a fuel injector therefor comprises a fuel injector having plural discharge ports with at least one of the discharge ports located to emit a ''pilot'' fuel charge (relatively rich fuel-air mixture) into a passage in the engine housing, which passage communicates with the engine combustion chambers. An ignition element is located in the passage to ignite the ''pilot'' fuel (a relatively rich fuel-air mixture) flowing through the passage. At least one other discharge port of the fuel injector is in substantially direct communication with the combustion chambers of the engine to emit a main fuel charge into the latter. The ignited ''pilot'' fuelair mixture, when ignited, flashes into the combustion chambers to ignite the main, relatively lean, fuel-air mixture which is in the combustion chambers.

  7. Evaluation of a hybrid kinetics/mixing-controlled combustion model for turbulent premixed and diffusion combustion using KIVA-2

    SciTech Connect (OSTI)

    Nguyen, H.L.; Wey, Mingjyh.

    1990-01-01

    Two dimensional calculations were made of spark ignited premixed-charge combustion and direct injection stratified-charge combustion in gasoline fueled piston engines. Results are obtained using kinetic-controlled combustion submodel governed by a four-step global chemical reaction or a hybrid laminar kinetics/mixing-controlled combustion submodel that accounts for laminar kinetics and turbulent mixing effects. The numerical solutions are obtained by using KIVA-2 computer code which uses a kinetic-controlled combustion submodel governed by a four-step global chemical reaction (i.e., it assumes that the mixing time is smaller than the chemistry). A hybrid laminar/mixing-controlled combustion submodel was implemented into KIVA-2. In this model, chemical species approach their thermodynamics equilibrium with a rate that is a combination of the turbulent-mixing time and the chemical-kinetics time. The combination is formed in such a way that the longer of the two times has more influence on the conversion rate and the energy release. An additional element of the model is that the laminar-flame kinetics strongly influence the early flame development following ignition.

  8. Modeling the Number of Ignitions Following an Earthquake: Developing Prediction Limits for Overdispersed Count Data

    Broader source: Energy.gov [DOE]

    Modeling the Number of Ignitions Following an Earthquake: Developing Prediction Limits for Overdispersed Count Data Elizabeth J. Kelly and Raymond N. Tell

  9. Turbulence and waves in the solar wind

    SciTech Connect (OSTI)

    Roberts, D.A.; Goldstein, M.L. )

    1991-01-01

    Studies of turbulence and waves in the solar wind is discussed. Consideration is given to the observations and theory concerning the origin and evolution of interplanetary MHD fluctuations and to the observations, theory, and simulations of compressive fluctuations. Particular attention is given to extrapolations to near-sun and polar fields regions. Results obtained on turbulence at comets and magnetic turbulence of low-frequency waves excited by unstable distributions of ions are discussed. 230 refs.

  10. Jet energy calibration at the LHC

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Schwartzman, Ariel

    2015-11-10

    In this study, jets are one of the most prominent physics signatures of high energy proton–proton (p–p) collisions at the Large Hadron Collider (LHC). They are key physics objects for precision measurements and searches for new phenomena. This review provides an overview of the reconstruction and calibration of jets at the LHC during its first Run. ATLAS and CMS developed different approaches for the reconstruction of jets, but use similar methods for the energy calibration. ATLAS reconstructs jets utilizing input signals from their calorimeters and use charged particle tracks to refine their energy measurement and suppress the effects of multiplemore » p–p interactions (pileup). CMS, instead, combines calorimeter and tracking information to build jets from particle flow objects. Jets are calibrated using Monte Carlo (MC) simulations and a residual in situ calibration derived from collision data is applied to correct for the differences in jet response between data and Monte Carlo.« less

  11. Stochastic (w*) Convergence for Turbulent Combustion | Argonne...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Stochastic (w*) Convergence for Turbulent Combustion PI Name: James Glimm PI Email: ... chemistry for LES, and (2) stochastic (w*) convergence based on probability ...

  12. Visible imaging of edge turbulence in NSTX

    SciTech Connect (OSTI)

    S. Zweben; R. Maqueda; K. Hill; D. Johnson; et al

    2000-06-13

    Edge plasma turbulence in tokamaks and stellarators is believed to cause the radical heat and particle flux across the separatrix and into the scrape-off-layers of these devices. This paper describes initial measurements of 2-D space-time structure of the edge density turbulence made using a visible imaging diagnostic in the National Spherical Torus Experiment (NSTX). The structure of the edge turbulence is most clearly visible using a method of gas puff imaging to locally illuminate the edge density turbulence.

  13. 3 - 4 Turbulent combustion Princeton.key

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    real question The flame surface density is created by flameturbulence interactions. Writing an equation for it requires to rederive equations for an interface in turbulence...

  14. Sandia National Laboratories participation in the National Ignition Facility project

    SciTech Connect (OSTI)

    Boyes, J.; Boyer, W.; Chael, J.; Cook, D.; Cook, W.; Downey, T.; Hands, J.; Harjes, C.; Leeper, R.; McKay, P.; Micano, P.; Olson, R.; Porter, J.; Quintenz, J.; Roberts, V.; Savage, M.; Simpson, W.; Seth, A.; Smith, R.; Wavrik, M.; Wilson, M.

    1996-08-01

    The National Ignition Facility is a $1.1B DOE Defense Programs Inertial Confinement Fusion facility supporting the Science Based Stockpile Stewardship Program. The goal of the facility is to achieve fusion ignition and modest gain in the laboratory. The NIF project is responsible for the design and construction of the 192 beam, 1.8 MJ laser necessary to meet that goal. - The project is a National project with participation by Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Sandia National Laboratory (SNL), the University of Rochester Laboratory for Laser Energetics (URLLE) and numerous industrial partners. The project is centered at LLNL which has extensive expertise in large solid state lasers. The other partners in the project have negotiated their participation based on the specific expertise they can bring to the project. In some cases, this negotiation resulted in the overall responsibility for a WBS element; in other cases, the participating laboratories have placed individuals in the project in areas that need their individual expertise. The main areas of Sandia`s participation are in the management of the conventional facility design and construction, the design of the power conditioning system, the target chamber system, target diagnostic instruments, data acquisition system and several smaller efforts in the areas of system integration and engineering analysis. Sandia is also contributing to the technology development necessary to support the project by developing the power conditioning system and several target diagnostics, exploring alternate target designs, and by conducting target experiments involving the ``foot`` region of the NIF power pulse. The project has just passed the mid-point of the Title I (preliminary) design phase. This paper will summarize Sandia`s role in supporting the National Ignition Facility and discuss the areas in which Sandia is contributing. 3 figs.

  15. The ePLAS Code for Ignition Studies

    SciTech Connect (OSTI)

    Mason, Rodney J

    2012-09-20

    Inertial Confinement Fusion (ICF) presents unique opportunities for the extraction of clean energy from Fusion. Intense lasers and particle beams can create and interact with such plasmas, potentially yielding sufficient energy to satisfy all our national needs. However, few models are available to help aid the scientific community in the study and optimization of such interactions. This project enhanced and disseminated the computer code ePLAS for the early understanding and control of Ignition in ICF. ePLAS is a unique simulation code that tracks the transport of laser light to a target, the absorption of that light resulting in the generation and transport of hot electrons, and the heating and flow dynamics of the background plasma. It uses an implicit electromagnetic field-solving method to greatly reduce computing demands, so that useful target interaction studies can often be completed in 15 minutes on a portable 2.1 GHz PC. The code permits the rapid scoping of calculations for the optimization of laser target interactions aimed at fusion. Recent efforts have initiated the use of analytic equations of state (EOS), K-alpha image rendering graphics, allocatable memory for source-free usage, and adaption to the latest Mac and Linux Operating Systems. The speed and utility of ePLAS are unequaled in the ICF simulation community. This project evaluated the effects of its new EOSs on target heating, compared fluid and particle models for the ions, initiated the simultaneous use of both ion models in the code, and studied long time scale 500 ps hot electron deposition for shock ignition. ePLAS has been granted EAR99 export control status, permitting export without a license to most foreign countries. Beta-test versions of ePLAS have been granted to several Universities and Commercial users. The net Project was aimed at achieving early success in the laboratory ignition of thermonuclear targets and the mastery of controlled fusion power for the nation.

  16. The First Experiments on the National Ignition Facility

    SciTech Connect (OSTI)

    Landen, O L; Glenzer, S; Froula, D; Dewald, E; Suter, L J; Schneider, M; Hinkel, D; Fernandez, J; Kline, J; Goldman, S; Braun, D; Celliers, P; Moon, S; Robey, H; Lanier, N; Glendinning, G; Blue, B; Wilde, B; Jones, O; Schein, J; Divol, L; Kalantar, D; Campbell, K; Holder, J; MacDonald, J; Niemann, C; Mackinnon, A; Collins, R; Bradley, D; Eggert, J; Hicks, D; Gregori, G; Kirkwood, R; Young, B; Foster, J; Hansen, F; Perry, T; Munro, D; Baldis, H; Grim, G; Heeter, R; Hegelich, B; Montgomery, D; Rochau, G; Olson, R; Turner, R; Workman, J; Berger, R; Cohen, B; Kruer, W; Langdon, B; Langer, S; Meezan, N; Rose, H; Still, B; Williams, E; Dodd, E; Edwards, J; Monteil, M; Stevenson, M; Thomas, B; Coker, R; Magelssen, G; Rosen, P; Stry, P; Woods, D; Weber, S; Alvarez, S; Armstrong, G; Bahr, R; Bourgade, J; Bower, D; Celeste, J; Chrisp, M; Compton, S; Cox, J; Constantin, C; Costa, R; Duncan, J; Ellis, A; Emig, J; Gautier, C; Greenwood, A; Griffith, R; Holdner, F; Holtmeier, G; Hargrove, D; James, T; Kamperschroer, J; Kimbrough, J; Landon, M; Lee, D; Malone, R; May, M; Montelongo, S; Moody, J; Ng, E; Nikitin, A; Pellinen, D; Piston, K; Poole, M; Rekow, V; Rhodes, M; Shepherd, R; Shiromizu, S; Voloshin, D; Warrick, A; Watts, P; Weber, F; Young, P; Arnold, P; Atherton, L J; Bardsley, G; Bonanno, R; Borger, T; Bowers, M; Bryant, R; Buckman, S; Burkhart, S; Cooper, F; Dixit, S; Erbert, G; Eder, D; Ehrlich, B; Felker, B; Fornes, J; Frieders, G; Gardner, S; Gates, C; Gonzalez, M; Grace, S; Hall, T; Haynam, C; Heestand, G; Henesian, M; Hermann, M; Hermes, G; Huber, S; Jancaitis, K; Johnson, S; Kauffman, B; Kelleher, T; Kohut, T; Koniges, A E; Labiak, T; Latray, D; Lee, A; Lund, D; Mahavandi, S; Manes, K R; Marshall, C; McBride, J; McCarville, T; McGrew, L; Menapace, J; Mertens, E; Munro, D; Murray, J; Neumann, J; Newton, M; Opsahl, P; Padilla, E; Parham, T; Parrish, G; Petty, C; Polk, M; Powell, C; Reinbachs, I; Rinnert, R; Riordan, B; Ross, G; Robert, V; Tobin, M; Sailors, S; Saunders, R; Schmitt, M; Shaw, M; Singh, M; Spaeth, M; Stephens, A; Tietbohl, G; Tuck, J; Van Wonterghem, B; Vidal, R; Wegner, P; Whitman, P; Williams, K; Winward, K; Work, K

    2005-11-11

    A first set of laser-plasma interaction, hohlraum energetics and hydrodynamic experiments have been performed using the first 4 beams of the National Ignition Facility (NIF), in support of indirect drive Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP). In parallel, a robust set of optical and x-ray spectrometers, interferometer, calorimeters and imagers have been activated. The experiments have been undertaken with laser powers and energies of up to 8 TW and 17 kJ in flattop and shaped 1-9 ns pulses focused with various beam smoothing options.

  17. Gas-filled hohlraum experiments at the national ignition facility.

    SciTech Connect (OSTI)

    Fernndez, J. C.; Gautier, D. C.; Goldman, S. R.; Grimm, B. M.; Hegelich, B. M.; Kline, J. L.; Montgomery, D. S.; Lanier, N. E.; Rose, H. A.; Schmidt, D. M.; Swift, D. C.; Workman, J. B.; Alvarez, Sharon; Bower, Dan.; Braun, Dave.; Campbell, K.; DeWald, E.; Glenzer, S.; Holder, J.; Kamperschroer, J. H.; Kimbrough, Joe; Kirkwood, Robert; Landen, O. L.; Mccarville, Tom; Macgowan, B.; Mackinnon, A.; Niemann, C.; Schein, J.; Schneider, M; Watts, Phil; Young, Ben-li 194154; Young B.

    2004-01-01

    The summary of this paper is: (1) We have fielded on NIF a gas-filled hohlraum designed for future ignition experiments; (2) Wall-motion measurements are consistent with LASNEX simulations; (3) LPI back-scattering results have confounded expectations - (a) Stimulated Brillouin (SBS) dominates Raman (SRS) for any gas-fill species, (b) Measured SBS time-averaged reflectivity values are high, peak values are even higher, (c) SRS and SBS peak while laser-pulse is rising; and (4) Plasma conditions at the onset of high back-scattering yield high SBS convective linear gain - Wavelengths of the back-scattered light is predicted by linear theory.

  18. The Neutron Imaging System Fielded at the National Ignition Facility

    SciTech Connect (OSTI)

    Fittinghoff, D N; Atkinson, D P; Bower, D E; Drury, O B; Dzenitis, J M; Felker, B; Frank, M; Liddick, S N; Moran, M J; Roberson, G P; Weiss, P B; Grim, G P; Aragonez, R J; Archuleta, T N; Batha, S H; Clark, D D; Clark, D J; Danly, C R; Day, R D; Fatherley, V E; Finch, J P; Garcia, F P; Gallegos, R A; Guler, N; Hsu, A H; Jaramillo, S A; Loomis, E N; Mares, D; Martinson, D D; Merrill, F E; Morgan, G L; Munson, C; Murphy, T J; Oertel, J A; Polk, P J; Schmidt, D W; Tregillis, I L; Valdez, A C; Volegov, P L; Wang, T F; Wilde, C H; Wilke, M D; Wilson, D C; Buckles, R A; Cradick, J R; Kaufman, M I; Lutz, S S; Malone, R M; Traille, A

    2011-10-24

    We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n') reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system will be presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system will be presented. We will also discuss future improvements to the system hardware.

  19. Numerical routines for predicting ignition in pyrotechnic devices

    SciTech Connect (OSTI)

    Pierce, K.G.

    1986-06-01

    Two numerical models of the thermal processes leading to ignition in a pyrotechnic device have been developed. These models are based on finite difference approximations to the heat diffusion equation, with temperature-dependent thermal properties, in a single spatial coordinate. The derivation of the finite difference equations is discussed and the methods employed at boundaries and interfaces are given. The sources of the thermal-properties data are identified and how these data are used is explained. The program structure is explained and example runs of the programs are given.

  20. Ethane ignition and oxidation behind reflected shock waves

    SciTech Connect (OSTI)

    de Vries, Jaap; Hall, Joel M.; Simmons, Stefanie L.; Kalitan, Danielle M.; Petersen, Eric L.; Rickard, Matthew J.A.

    2007-07-15

    Several diluted C{sub 2}H{sub 6}/O{sub 2}/Ar mixtures of varying concentrations and equivalence ratios (0.5<{phi}<2.0) were studied at temperatures between 1218 and 1860 K and at pressures between 0.57 and 3.0 atm using a shock tube. The argon dilution ranged from 91 to 98% by volume. Reaction progress was monitored using chemiluminescence emission from OH{sup *} and CH{sup *} at 307 and 431 nm, respectively. The dependence of ignition delay time on temperature, activation energy, and reactant concentrations is given in a master correlation of all the experimental data. The overall activation energy was found to be 39.6 kcal/mol over the range of conditions studied. For the first time in a shock-tube C{sub 2}H{sub 6} oxidation study, detailed species profile data and quantitative OH{sup *} time histories were documented, in addition to ignition delay times, and compared against modern detailed mechanisms. Because of the comprehensive scope of the present study and the high precision of the experimental data, several conclusions can be drawn that could not have been reached from earlier studies. Although there is some discrepancy among previous ethane oxidation data, the present work clearly shows the convergence of ignition delay time measurements to those herein and the remarkable accuracy of current kinetics models over most of the parameter space explored, despite the variation in the literature data. However, two areas shown to still need more measurements and better modeling are those of higher pressures and fuel-rich ethane-air mixtures. After appropriate OH{sup *} and CH{sup *} submechanisms are added, two modern chemical kinetics mechanisms containing high-temperature ethane chemistry are compared to the data to gauge the current state of C{sub 2}H{sub 6} oxidation modeling over the conditions of this study. The reproduction of the OH{sup *} and CH{sup *} profiles, together with {tau}{sub ign} predictions by these models, are compared against the profiles

  1. The Role of Viscosity in TATB Hot Spot Ignition

    SciTech Connect (OSTI)

    Fried, L E; Zepeda-Ruis, L; Howard, W M; Najjar, F; Reaugh, J E

    2011-08-02

    The role of dissipative effects, such as viscosity, in the ignition of high explosive pores is investigated using a coupled chemical, thermal, and hydrodynamic model. Chemical reactions are tracked with the Cheetah thermochemical code coupled to the ALE3D hydrodynamic code. We perform molecular dynamics simulations to determine the viscosity of liquid TATB. We also analyze shock wave experiments to obtain an estimate for the shock viscosity of TATB. Using the lower bound liquid-like viscosities, we find that the pore collapse is hydrodynamic in nature. Using the upper bound viscosity from shock wave experiments, we find that the pore collapse is closest to the viscous limit.

  2. Simulation of Laser-plasma Interaction in National Ignition Facility

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Experiments | Argonne Leadership Computing Facility Figure 1a is a volume visualization of the laser light that has been backscattered by Stimulated Raman Scattering in a simulation of a National Ignition Facility inertial fusion experiment. At this point in time, light is scattering independently from the three laser quads (a quad is a group of 2x2 beams propagating in the same direction). Figure 1b is a volume visualization from the same simulation, but at a different time. The band of

  3. Controlling And Operating Homogeneous Charge Compression Ignition (Hcci) Engines

    SciTech Connect (OSTI)

    Flowers, Daniel L.

    2005-08-02

    A Homogeneous Charge Compression Ignition (HCCI) engine system includes an engine that produces exhaust gas. A vaporization means vaporizes fuel for the engine an air induction means provides air for the engine. An exhaust gas recirculation means recirculates the exhaust gas. A blending means blends the vaporized fuel, the exhaust gas, and the air. An induction means inducts the blended vaporized fuel, exhaust gas, and air into the engine. A control means controls the blending of the vaporized fuel, the exhaust gas, and the air and for controls the inducting the blended vaporized fuel, exhaust gas, and air into the engine.

  4. Can we characterize turbulence in premixed flames?

    SciTech Connect (OSTI)

    Lipatnikov, A.N. [Department of Applied Mechanics, Chalmers University of Technology, Gothenburg, 412 96 (Sweden)

    2009-06-15

    Modeling of premixed turbulent combustion involves averaging reaction rates in turbulent flows. The focus of most approaches to resolving this problem has been placed on determining the dependence of the mean rate w of product creation on the laminar flame speed S{sub L}, the rms turbulence velocity u', etc. The goal of the present work is to draw attention to another issue: May the input quantity u{sup '} for a model of w= w(u'/S{sub L},..) be considered to be known? The point is that heat release substantially affects turbulence and, hence, turbulence characteristics in premixed flames should be modeled. However, standard moment methods for numerically simulating turbulent flows do not allow us to evaluate the true turbulence characteristics in a flame. For instance, the Reynolds stresses in premixed flames are affected not only by turbulence itself, but also by velocity jump across flamelets. A common way to resolving this problem consists of considering the Reynolds stresses conditioned on unburned (or burned) mixture to be the true turbulence characteristics. In the present paper, this widely accepted but never proved hypothesis is put into question, first, by considering simple model constant-density problems (flame motion in an oscillating one-dimensional laminar flow; flame stabilized in a periodic shear, one-dimensional, laminar flow; turbulent mixing). In all the cases, the magnitude of velocity fluctuations, calculated using the conditioned Reynolds stresses, is affected by the intermittency of reactants and products and, hence, is not the true rms velocity. Second, the above claim is further supported by comparing balance equations for the mean and conditioned Reynolds stresses. The conditioned Reynolds stresses do not characterize the true turbulence in flames, because conditional averaging cuts off flow regions characterized by either high or low velocities. (author)

  5. Quenching and anisotropy of hydromagnetic turbulent transport

    SciTech Connect (OSTI)

    Karak, Bidya Binay; Brandenburg, Axel; Rheinhardt, Matthias; Käpylä, Petri J.; Käpylä, Maarit J.

    2014-11-01

    Hydromagnetic turbulence affects the evolution of large-scale magnetic fields through mean-field effects like turbulent diffusion and the α effect. For stronger fields, these effects are usually suppressed or quenched, and additional anisotropies are introduced. Using different variants of the test-field method, we determine the quenching of the turbulent transport coefficients for the forced Roberts flow, isotropically forced non-helical turbulence, and rotating thermal convection. We see significant quenching only when the mean magnetic field is larger than the equipartition value of the turbulence. Expressing the magnetic field in terms of the equipartition value of the quenched flows, we obtain for the quenching exponents of the turbulent magnetic diffusivity about 1.3, 1.1, and 1.3 for Roberts flow, forced turbulence, and convection, respectively. However, when the magnetic field is expressed in terms of the equipartition value of the unquenched flows, these quenching exponents become about 4, 1.5, and 2.3, respectively. For the α effect, the exponent is about 1.3 for the Roberts flow and 2 for convection in the first case, but 4 and 3, respectively, in the second. In convection, the quenching of turbulent pumping follows the same power law as turbulent diffusion, while for the coefficient describing the Ω×J effect nearly the same quenching exponent is obtained as for α. For forced turbulence, turbulent diffusion proportional to the second derivative along the mean magnetic field is quenched much less, especially for larger values of the magnetic Reynolds number. However, we find that in corresponding axisymmetric mean-field dynamos with dominant toroidal field the quenched diffusion coefficients are the same for the poloidal and toroidal field constituents.

  6. Advanced Thermally Stable Jet Fuels

    SciTech Connect (OSTI)

    A. Boehman; C. Song; H. H. Schobert; M. M. Coleman; P. G. Hatcher; S. Eser

    1998-01-01

    The Penn State program in advanced thermally stable jet fuels has five components: 1) development of mechanisms of degradation and solids formation; 2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles during thermal stressing; 3) characterization of carbonaceous deposits by various instrumental and microscopic methods; 4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and 5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics from coal.

  7. Turbulent electron transport in edge pedestal by electron temperature gradient turbulence

    SciTech Connect (OSTI)

    Singh, R.; Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 ; Jhang, Hogun; Diamond, P. H.; CMTFO and CASS, University of California, San Diego 92093-0424, California

    2013-11-15

    We present a model for turbulent electron thermal transport at the edge pedestal in high (H)-mode plasmas based on electron temperature gradient (ETG) turbulence. A quasi-linear analysis of electrostatic toroidal ETG modes shows that both turbulent electron thermal diffusivity and hyper-resistivity exhibits the Ohkawa scaling in which the radial correlation length of turbulence becomes the order of electron skin depth. Combination of the Ohkawa scales and the plasma current dependence results in a novel confinement scaling inside the pedestal region. It is also shown that ETG turbulence induces a thermoelectric pinch, which may accelerate the density pedestal formation.

  8. Jet pump for oil wells

    SciTech Connect (OSTI)

    Binks, R. H.; Christ, F. C.

    1985-03-12

    A fluid operated pump system which includes power fluid supply means comprising either the annulus between well casing and production tubing, or a secondary tubing, and a production tubing, set in a well, the production tubing having a housing at the lower end with which the power fluid supply means communicates. A pump unit, including a fluid operated jet pump, is movable downwardly through the production tubing into the housing to a fixed location and maintained at the fixed location by the forces of gravity and friction. The pump is operable in the housing by operating fluid under pressure supplied through the power fluid supply means to pump fluid from the well into the production tubing. A cavity is provided at the lower end of the pump unit between two balanced seals. The cavity communicates with the power fluid supply means and with the fluid operated jet pump. Power fluid introduced into the cavity causes no net force to be exerted on the pump unit. When pumping action takes place, produced fluids are taken from a lower pressure area below the pump unit and boosted to a higher pressure area above the pump unit by the fluid operated jet pump, resulting in a net downward force on the pump unit to cause the pump unit to be restrained against its fixed location without the need of latch means.

  9. Fluid jet electric discharge source

    DOE Patents [OSTI]

    Bender, Howard A.

    2006-04-25

    A fluid jet or filament source and a pair of coaxial high voltage electrodes, in combination, comprise an electrical discharge system to produce radiation and, in particular, EUV radiation. The fluid jet source is composed of at least two serially connected reservoirs, a first reservoir into which a fluid, that can be either a liquid or a gas, can be fed at some pressure higher than atmospheric and a second reservoir maintained at a lower pressure than the first. The fluid is allowed to expand through an aperture into a high vacuum region between a pair of coaxial electrodes. This second expansion produces a narrow well-directed fluid jet whose size is dependent on the size and configuration of the apertures and the pressure used in the reservoir. At some time during the flow of the fluid filament, a high voltage pulse is applied to the electrodes to excite the fluid to form a plasma which provides the desired radiation; the wavelength of the radiation being determined by the composition of the fluid.

  10. Atomic Chemistry in Turbulent Media I: Effect of Atomic Cooling...

    Office of Scientific and Technical Information (OSTI)

    Atomic Chemistry in Turbulent Media I: Effect of Atomic Cooling Citation Details In-Document Search Title: Atomic Chemistry in Turbulent Media I: Effect of Atomic Cooling Authors: ...

  11. Turbulence may be key to "fast magnetic reconnection" mystery

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Turbulence may be key to "fast magnetic reconnection" mystery Turbulence may be key to "fast magnetic reconnection" mystery The new research could lead to better understanding of ...

  12. ASCR Workshop on Turbulent Flow Simulations at the Exascale:...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ASCR Workshop on Turbulent Flow Simulations at the Exascale: Opportunities and Challenges ASCR Workshop on Turbulent Flow Simulations at the Exascale: Opportunities and Challenges...

  13. Implementation and Validation of the BHR Turbulence Model in...

    Office of Scientific and Technical Information (OSTI)

    Turbulence is an often studied and ubiquitous phenomenon in nature, and modeling its effects is essential in many practical applications. Specifically the behavior of turbulence in ...

  14. A comparison of experimental and numerical results on convective thermal mixing of three vertical, quasi-planar jets

    SciTech Connect (OSTI)

    Tokuhiro, A.T.; Kimura, N.; Nishimura, M.; Kobayashi, J.; Miyakoshi, H.

    1999-07-01

    The thermal-hydraulic mixing of three quasi-planar vertical water jets was experimentally and numerically investigated. The central jet was initially 5 C lower in temperature than the other two. The hydraulic diameter and average exit velocity-based Reynolds and Richardson numbers were, Re{sub D} = 2 x 10{sup 4}, Ri{sub D} = 0.002. Besides temperature measurements from a traversing array of 37 thermocouples, velocity measurements were made using laser and ultrasound Doppler velocimetries (LDV and UDV). In parallel the in-house code, CASCADE, featuring a {kappa}-{epsilon} turbulence model was used to simulate the experimental flow configuration. A comparison of the experimental and numerical results showed that code validation by LDV/UDV was possible and in particular that time-averaged field and frequency characteristics of transversely swaying jets, even under Reynolds averaging of the conservation equations, could be simulated. A representative comparison of the amplitude of oscillation is shown in Figure A-1 with an inset of the visualized flow and sample time-series of the temperature fluctuations at the position indicated. The difference in the predominant frequency, the numerically predicted {approximately}1.6 Hz versus the experimental {approximately}2.25 Hz, is attributed to the turbulence model that overestimate thus effective fluid viscosity. Development of an accurate numerical simulation is of relevance to the design of the liquid metal fast breeder reactor (LMFBR), where the lack of mixing of the cold sodium may initiate thermal striping; that is, poorly mixed hot and cold streams may thermally stress the components onto which they impinge. Turbulent mixing of jets is equally of general interest to environmental and material processing flows.

  15. Status of the US inertial fusion program and the National Ignition Facility

    SciTech Connect (OSTI)

    Crandall, David H.

    1997-04-15

    Research programs supported by the United States Office of Inertial Fusion and the NIF are summarized. The US inertial fusion program has developed an approach to high energy density physics and fusion ignition in the laboratory relying on the current physics basis of capsule drive by lasers and on the National Ignition Facility which is under construction. (AIP)

  16. Wildfire ignition resistant home design(WIRHD) program: Full-scale testing and demonstration final report.

    SciTech Connect (OSTI)

    Quarles, Stephen, L.; Sindelar, Melissa

    2011-12-13

    The primary goal of the Wildfire ignition resistant home design(WIRHD) program was to develop a home evaluation tool that could assess the ignition potential of a structure subjected to wildfire exposures. This report describes the tests that were conducted, summarizes the results, and discusses the implications of these results with regard to the vulnerabilities to homes and buildings.

  17. Stochastic models for turbulent reacting flows

    SciTech Connect (OSTI)

    Kerstein, A.

    1993-12-01

    The goal of this program is to develop and apply stochastic models of various processes occurring within turbulent reacting flows in order to identify the fundamental mechanisms governing these flows, to support experimental studies of these flows, and to further the development of comprehensive turbulent reacting flow models.

  18. Cyclone separator having boundary layer turbulence control

    DOE Patents [OSTI]

    Krishna, Coimbatore R.; Milau, Julius S.

    1985-01-01

    A cyclone separator including boundary layer turbulence control that is operable to prevent undue build-up of particulate material at selected critical areas on the separator walls, by selectively varying the fluid pressure at those areas to maintain the momentum of the vortex, thereby preventing particulate material from inducing turbulence in the boundary layer of the vortical fluid flow through the separator.

  19. Progress in Fast Ignition Studies with Electrons and Protons

    SciTech Connect (OSTI)

    MacKinnon, A. J.; Chen, H.; Hey, D.; Key, M. H.; MacPhee, A. G.; Patel, P. K.; Ping, Y.; Akli, K. U.; Stephens, R. B.; Bartal, T.; Beg, F. N.; Chawla, S.; Chen, S.; Higginson, D.; King, J. A.; Ma, T.; Wei, M. S.; Chen, C. D.; Chowdhury, E.; Link, A.

    2009-09-10

    Isochoric heating of inertially confined fusion plasmas by laser driven MeV electrons or protons is an area of great topical interest in the inertial confinement fusion community, particularly with respect to the fast ignition (FI) concept for initiating burn in a fusion capsule. In order to investigate critical aspects needed for a FI point design, experiments were performed to study 1) laser-to-electrons or protons conversion issues and 2) laser-cone interactions including prepulse effects. A large suite of diagnostics was utilized to study these important parameters. Using cone--wire surrogate targets it is found that pre-pulse levels on medium scale lasers such as Titan at Lawrence Livermore National Laboratory produce long scale length plasmas that strongly effect coupling of the laser to FI relevant electrons inside cones. The cone wall thickness also affects coupling to the wire. Conversion efficiency to protons has also been measured and modeled as a function of target thickness, material. Conclusions from the proton and electron source experiments will be presented. Recent advances in modeling electron transport and innovative target designs for reducing igniter energy and increasing gain curves will also be discussed. In conclusion, a program of study will be presented based on understanding the fundamental physics of the electron or proton source relevant to FI.

  20. Characterization of in situ oil shale retorts prior to ignition

    DOE Patents [OSTI]

    Turner, Thomas F.; Moore, Dennis F.

    1984-01-01

    Method and system for characterizing a vertical modified in situ oil shale retort prior to ignition of the retort. The retort is formed by mining a void at the bottom of a proposed retort in an oil shale deposit. The deposit is then sequentially blasted into the void to form a plurality of layers of rubble. A plurality of units each including a tracer gas cannister are installed at the upper level of each rubble layer prior to blasting to form the next layer. Each of the units includes a receiver that is responsive to a coded electromagnetic (EM) signal to release gas from the associated cannister into the rubble. Coded EM signals are transmitted to the receivers to selectively release gas from the cannisters. The released gas flows through the retort to an outlet line connected to the floor of the retort. The time of arrival of the gas at a detector unit in the outlet line relative to the time of release of gas from the cannisters is monitored. This information enables the retort to be characterized prior to ignition.

  1. Ignition and extinction phenomena in helium micro hollow cathode discharges

    SciTech Connect (OSTI)

    Kulsreshath, M. K.; Schwaederle, L.; Dufour, T.; Lefaucheux, P.; Dussart, R.; Overzet, L. J.

    2013-12-28

    Micro hollow cathode discharges (MHCD) were produced using 250??m thick dielectric layer of alumina sandwiched between two nickel electrodes of 8??m thickness. A through cavity at the center of the chip was formed by laser drilling technique. MHCD with a diameter of few hundreds of micrometers allowed us to generate direct current discharges in helium at up to atmospheric pressure. A slowly varying ramped voltage generator was used to study the ignition and the extinction periods of the microdischarges. The analysis was performed by using electrical characterisation of the V-I behaviour and the measurement of He*({sup 3}S{sub 1}) metastable atoms density by tunable diode laser spectroscopy. At the ignition of the microdischarges, 2??s long current peak as high as 24?mA was observed, sometimes followed by low amplitude damped oscillations. At helium pressure above 400?Torr, an oscillatory behaviour of the discharge current was observed just before the extinction of the microdischarges. The same type of instability in the extinction period at high pressure also appeared on the density of He*({sup 3}S{sub 1}) metastable atoms, but delayed by a few ?s relative to the current oscillations. Metastable atoms thus cannot be at the origin of the generation of the observed instabilities.

  2. Control and Information Systems for the National Ignition Facility

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Brunton, Gordon; Casey, Allan; Christensen, Marvin; Demaret, Robert; Fedorov, Mike; Flegel, Michael; Folta, Peg; Fraizer, Timothy; Hutton, Matthew; Kegelmeyer, Laura; et al

    2015-11-03

    Orchestration of every National Ignition Facility (NIF) shot cycle is managed by the Integrated Computer Control System (ICCS), which uses a scalable software architecture running code on more than 1950 front-end processors, embedded controllers, and supervisory servers. The ICCS operates laser and industrial control hardware containing 66 000 control and monitor points to ensure that all of NIF’s laser beams arrive at the target within 30 ps of each other and are aligned to a pointing accuracy of less than 50 μm root-mean-square, while ensuring that a host of diagnostic instruments record data in a few billionths of a second.more » NIF’s automated control subsystems are built from a common object-oriented software framework that distributes the software across the computer network and achieves interoperation between different software languages and target architectures. A large suite of business and scientific software tools supports experimental planning, experimental setup, facility configuration, and post-shot analysis. Standard business services using open-source software, commercial workflow tools, and database and messaging technologies have been developed. An information technology infrastructure consisting of servers, network devices, and storage provides the foundation for these systems. This paper is an overview of the control and information systems used to support a wide variety of experiments during the National Ignition Campaign.« less

  3. Target diagnostic system for the national ignition facility (invited)

    SciTech Connect (OSTI)

    Leeper, R.J.; Chandler, G.A.; Cooper, G.W.; Derzon, M.S.; Fehl, D.L.; Hebron, D.E.; Moats, A.R.; Noack, D.D.; Porter, J.L.; Ruggles, L.E.; Ruiz, C.L.; Torres, J.A.; Cable, M.D.; Bell, P.M.; Clower, C.A.; Hammel, B.A.; Kalantar, D.H.; Karpenko, V.P.; Kauffman, R.L.; Kilkenny, J.D.; Lee, F.D.; Lerche, R.A.; MacGowan, B.J.; Moran, M.J.; Nelson, M.B.; Olson, W.; Orzechowski, T.J.; Phillips, T.W.; Ress, D.; Tietbohl, G.L.; Trebes, J.E.; Bartlett, R.J.; Berggren, R.; Caldwell, S.E.; Chrien, R.E.; Failor, B.H.; Fernandez, J.C.; Hauer, A.; Idzorek, G.; Hockaday, R.G.; Murphy, T.J.; Oertel, J.; Watt, R.; Wilke, M.; Bradley, D.K.; Knauer, J.; Petrasso, R.D.; Li, C.K.

    1997-01-01

    A review of recent progress on the design of a diagnostic system proposed for ignition target experiments on the National Ignition Facility (NIF) will be presented. This diagnostic package contains an extensive suite of optical, x ray, gamma ray, and neutron diagnostics that enable measurements of the performance of both direct and indirect driven NIF targets. The philosophy used in designing all of the diagnostics in the set has emphasized redundant and independent measurement of fundamental physical quantities relevant to the operation of the NIF target. A unique feature of these diagnostics is that they are being designed to be capable of operating in the high radiation, electromagnetic pulse, and debris backgrounds expected on the NIF facility. The diagnostic system proposed can be categorized into three broad areas: laser characterization, hohlraum characterization, and capsule performance diagnostics. The operating principles of a representative instrument from each class of diagnostic employed in this package will be summarized and illustrated with data obtained in recent prototype diagnostic tests. {copyright} {ital 1997 American Institute of Physics.}

  4. The Neutron Imaging System Fielded at the National Ignition Facility

    SciTech Connect (OSTI)

    Merrill, F E; Buckles, R; Clark, D D; Danly, C R; Drury, O B; Dzenitis, J M; Fatherley, V E; Fittinghoff, D N; Gallegos, R; Grim, G P; Guler, N; Loomis, E N; Lutz, S; Malone, R M; Martinson, D D; Mares, D; Morley, D J; Morgan, G L; Oertel, J A; Tregillis, I L; Volegov, P L; Weiss, P B; Wilde, C H

    2012-08-01

    A neutron imaging diagnostic has recently been commissioned at the National Ignition Facility (NIF). This new system is an important diagnostic tool for inertial fusion studies at the NIF for measuring the size and shape of the burning DT plasma during the ignition stage of Inertial Confinement Fusion (ICF) implosions. The imaging technique utilizes a pinhole neutron aperture, placed between the neutron source and a neutron detector. The detection system measures the two dimensional distribution of neutrons passing through the pinhole. This diagnostic has been designed to collect two images at two times. The long flight path for this diagnostic, 28 m, results in a chromatic separation of the neutrons, allowing the independently timed images to measure the source distribution for two neutron energies. Typically the first image measures the distribution of the 14 MeV neutrons and the second image of the 6-12 MeV neutrons. The combination of these two images has provided data on the size and shape of the burning plasma within the compressed capsule, as well as a measure of the quantity and spatial distribution of the cold fuel surrounding this core.

  5. FIREBALL: Fusion Ignition Rocket Engine with Ballistic Ablative Lithium Liner

    SciTech Connect (OSTI)

    Martin, Adam K.; Eskridge, Richard H.; Lee, Michael H.; Fimognari, Peter J.

    2006-01-20

    Thermo-nuclear fusion may be the key to a high Isp, high specific power propulsion system. In a fusion system energy is liberated within, and imparted directly to, the propellant. In principle, this can overcome the performance limitations inherent in systems that require thermal power transfer across a material boundary, and/or multiple power conversion stages (NTR, NEP). A thermo-nuclear propulsion system, which attempts to overcome some of the problems inherent in the Orion concept, is described. A dense FRC plasmoid is accelerated to high velocity (in excess of 500 km/s) and is compressed into a detached liner (pulse unit). The kinetic energy of the FRC is converted into thermal and magnetic-field energy, igniting a fusion burn in the magnetically confined plasma. The fusion reaction serves as an ignition source for the liner, which is made out of detonable materials. The energy liberated in this process is converted to thrust by a pusher-plate, as in the classic Orion concept. However with this concept, the vehicle does not carry a magazine of autonomous pulse-units. By accelerating a second, heavier FRC, which acts as a piston, right behind the first one, the velocity required to initiate the fusion burn is greatly reduced.

  6. Direct Injection Compression Ignition Diesel Automotive Technology Education GATE Program

    SciTech Connect (OSTI)

    Anderson, Carl L

    2006-09-25

    The underlying goal of this prqject was to provide multi-disciplinary engineering training for graduate students in the area of internal combustion engines, specifically in direct injection compression ignition engines. The program was designed to educate highly qualified engineers and scientists that will seek to overcome teclmological barriers preventing the development and production of cost-effective high-efficiency vehicles for the U.S. market. Fu1iher, these highly qualified engineers and scientists will foster an educational process to train a future workforce of automotive engineering professionals who are knowledgeable about and have experience in developing and commercializing critical advanced automotive teclmologies. Eight objectives were defmed to accomplish this goal: 1. Develop an interdisciplinary internal co1nbustion engine curriculum emphasizing direct injected combustion ignited diesel engines. 2. Encourage and promote interdisciplinary interaction of the faculty. 3. Offer a Ph.D. degree in internal combustion engines based upon an interdisciplinary cuniculum. 4. Promote strong interaction with indusuy, develop a sense of responsibility with industry and pursue a self sustaining program. 5. Establish collaborative arrangements and network universities active in internal combustion engine study. 6. Further Enhance a First Class educational facility. 7. Establish 'off-campus' M.S. and Ph.D. engine programs of study at various indusuial sites. 8. Extend and Enhance the Graduate Experience.

  7. Control and Information Systems for the National Ignition Facility

    SciTech Connect (OSTI)

    Brunton, Gordon; Casey, Allan; Christensen, Marvin; Demaret, Robert; Fedorov, Mike; Flegel, Michael; Folta, Peg; Fraizer, Timothy; Hutton, Matthew; Kegelmeyer, Laura; Lagin, Lawrence; Ludwigsen, Pete; Reed, Robert; Speck, Douglas; Wilhelmsen, Karl

    2015-11-03

    Orchestration of every National Ignition Facility (NIF) shot cycle is managed by the Integrated Computer Control System (ICCS), which uses a scalable software architecture running code on more than 1950 front-end processors, embedded controllers, and supervisory servers. The ICCS operates laser and industrial control hardware containing 66 000 control and monitor points to ensure that all of NIF’s laser beams arrive at the target within 30 ps of each other and are aligned to a pointing accuracy of less than 50 μm root-mean-square, while ensuring that a host of diagnostic instruments record data in a few billionths of a second. NIF’s automated control subsystems are built from a common object-oriented software framework that distributes the software across the computer network and achieves interoperation between different software languages and target architectures. A large suite of business and scientific software tools supports experimental planning, experimental setup, facility configuration, and post-shot analysis. Standard business services using open-source software, commercial workflow tools, and database and messaging technologies have been developed. An information technology infrastructure consisting of servers, network devices, and storage provides the foundation for these systems. This paper is an overview of the control and information systems used to support a wide variety of experiments during the National Ignition Campaign.

  8. Finite Mach number spherical shock wave, application to shock ignition

    SciTech Connect (OSTI)

    Vallet, A.; Ribeyre, X.; Tikhonchuk, V.

    2013-08-15

    A converging and diverging spherical shock wave with a finite initial Mach number M{sub s0} is described by using a perturbative approach over a small parameter M{sub s}{sup ?2}. The zeroth order solution is the Guderley's self-similar solution. The first order correction to this solution accounts for the effects of the shock strength. Whereas it was constant in the Guderley's asymptotic solution, the amplification factor of the finite amplitude shock ?(t)?dU{sub s}/dR{sub s} now varies in time. The coefficients present in its series form are iteratively calculated so that the solution does not undergo any singular behavior apart from the position of the shock. The analytical form of the corrected solution in the vicinity of singular points provides a better physical understanding of the finite shock Mach number effects. The correction affects mainly the flow density and the pressure after the shock rebound. In application to the shock ignition scheme, it is shown that the ignition criterion is modified by more than 20% if the fuel pressure prior to the final shock is taken into account. A good agreement is obtained with hydrodynamic simulations using a Lagrangian code.

  9. Scaling laws in magnetized plasma turbulence

    SciTech Connect (OSTI)

    Boldyrev, Stanislav

    2015-06-28

    Interactions of plasma motion with magnetic fields occur in nature and in the laboratory in an impressively broad range of scales, from megaparsecs in astrophysical systems to centimeters in fusion devices. The fact that such an enormous array of phenomena can be effectively studied lies in the existence of fundamental scaling laws in plasma turbulence, which allow one to scale the results of analytic and numerical modeling to the sized of galaxies, velocities of supernovae explosions, or magnetic fields in fusion devices. Magnetohydrodynamics (MHD) provides the simplest framework for describing magnetic plasma turbulence. Recently, a number of new features of MHD turbulence have been discovered and an impressive array of thought-provoking phenomenological theories have been put forward. However, these theories have conflicting predictions, and the currently available numerical simulations are not able to resolve the contradictions. MHD turbulence exhibits a variety of regimes unusual in regular hydrodynamic turbulence. Depending on the strength of the guide magnetic field it can be dominated by weakly interacting Alfv\\'en waves or strongly interacting wave packets. At small scales such turbulence is locally anisotropic and imbalanced (cross-helical). In a stark contrast with hydrodynamic turbulence, which tends to ``forget'' global constrains and become uniform and isotropic at small scales, MHD turbulence becomes progressively more anisotropic and unbalanced at small scales. Magnetic field plays a fundamental role in turbulent dynamics. Even when such a field is not imposed by external sources, it is self-consistently generated by the magnetic dynamo action. This project aims at a comprehensive study of universal regimes of magnetic plasma turbulence, combining the modern analytic approaches with the state of the art numerical simulations. The proposed study focuses on the three topics: weak MHD turbulence, which is relevant for laboratory devices, the solar

  10. Numerical simulations of strong incompressible magnetohydrodynamic turbulence

    SciTech Connect (OSTI)

    Mason, J.; Cattaneo, F.; Perez, J. C.; Boldyrev, S.

    2012-05-15

    Magnetised plasma turbulence pervades the universe and is likely to play an important role in a variety of astrophysical settings. Magnetohydrodynamics (MHD) provides the simplest theoretical framework in which phenomenological models for the turbulent dynamics can be built. Numerical simulations of MHD turbulence are widely used to guide and test the theoretical predictions; however, simulating MHD turbulence and accurately measuring its scaling properties is far from straightforward. Computational power limits the calculations to moderate Reynolds numbers and often simplifying assumptions are made in order that a wider range of scales can be accessed. After describing the theoretical predictions and the numerical approaches that are often employed in studying strong incompressible MHD turbulence, we present the findings of a series of high-resolution direct numerical simulations. We discuss the effects that insufficiencies in the computational approach can have on the solution and its physical interpretation.

  11. Jet measurements by ALICE at LHC

    SciTech Connect (OSTI)

    Sultanov, Rishat; Collaboration: ALICE Collaboration

    2015-12-15

    Jets are collimated sprays of particles originating from fragmentation of high energy partons produced in a hard collision. They are an important diagnostic tool in studies of the Quark Gluon Plasma (QGP). The modification of the jet fragmentation pattern and its structure is a signature for the influence of hot and dense matter on the parton fragmentation process. Jet measurements in proton-proton collisions provide a baseline for similar measurements in heavy-ion collisions, while studies in proton-nucleus system allow to estimate cold nuclear matter effects. Here we present jet studies in different colliding systems (p–p, p–Pb, Pb–Pb) performed by the ALICE collaboration at LHC energies. Results on jet spectra, cross sections, nuclear modification factors, jet structure and other kinematic observables will be presented.

  12. Ignition characteristics of laser-ablated aluminum at shock pressures up to 2 GPa

    SciTech Connect (OSTI)

    Lee, Kyung-Cheol; Young Lee, Jae; Yoh, Jack J.; Taira, Tsubasa; Mo Koo, Goon

    2014-01-07

    The ignition of aluminum particles under high pressure and temperature conditions is considered. The laser ablation method is used to generate oxide-free aluminum particles exposed to pressures ranging between 0.35 and 2.2 GPa. A continuous wave CO{sub 2} laser radiation heats the surface of the aluminum target until ignition is observed. We confirm ignition by a spectroscopic analysis of AlO vibronic band of 484 nm wavelength, and the radiant temperature is measured with respect to various pressures for estimating the heating energy for ignition. The ignition characteristics of the oxide-free aluminum particles exposed to extremely high pressures are reported.

  13. Nonlinear compressions in merging plasma jets

    SciTech Connect (OSTI)

    Messer, S.; Case, A.; Wu, L.; Brockington, S.; Witherspoon, F. D.

    2013-03-15

    We investigate the dynamics of merging supersonic plasma jets using an analytic model. The merging structures exhibit supersonic, nonlinear compressions which may steepen into full shocks. We estimate the distance necessary to form such shocks and the resulting jump conditions. These theoretical models are compared to experimental observations and simulated dynamics. We also use those models to extrapolate behavior of the jet-merging compressions in a Plasma Jet Magneto-Inertial Fusion reactor.

  14. PHYSICAL PARAMETERS OF STANDARD AND BLOWOUT JETS

    SciTech Connect (OSTI)

    Pucci, Stefano; Romoli, Marco; Poletto, Giannina; Sterling, Alphonse C.

    2013-10-10

    The X-ray Telescope on board the Hinode mission revealed the occurrence, in polar coronal holes, of much more numerous jets than previously indicated by the Yohkoh/Soft X-ray Telescope. These plasma ejections can be of two types, depending on whether they fit the standard reconnection scenario for coronal jets or if they include a blowout-like eruption. In this work, we analyze two jets, one standard and one blowout, that have been observed by the Hinode and STEREO experiments. We aim to infer differences in the physical parameters that correspond to the different morphologies of the events. To this end, we adopt spectroscopic techniques and determine the profiles of the plasma temperature, density, and outflow speed versus time and position along the jets. The blowout jet has a higher outflow speed, a marginally higher temperature, and is rooted in a stronger magnetic field region than the standard event. Our data provide evidence for recursively occurring reconnection episodes within both the standard and the blowout jet, pointing either to bursty reconnection or to reconnection occurring at different locations over the jet lifetimes. We make a crude estimate of the energy budget of the two jets and show how energy is partitioned among different forms. Also, we show that the magnetic energy that feeds the blowout jet is a factor of 10 higher than the magnetic energy that fuels the standard event.

  15. continuously jet-stirred tank reactor

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    continuously jet-stirred tank reactor - Sandia Energy Energy Search Icon Sandia Home ... Predictive Simulation of Engines Transportation Energy Consortiums Engine Combustion ...

  16. Bioenergy Impacts … Renewable Jet Fuel

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    able to produce renewable jet fuel for the commercial aviation industry and the military. ... Biofuel is becoming an option for commercial and military airplanes BIOENERGY To learn ...

  17. Turbulent Combustion in SDF Explosions

    SciTech Connect (OSTI)

    Kuhl, A L; Bell, J B; Beckner, V E

    2009-11-12

    A heterogeneous continuum model is proposed to describe the dispersion and combustion of an aluminum particle cloud in an explosion. It combines the gas-dynamic conservation laws for the gas phase with a continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models. It incorporates a combustion model based on the mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gasdynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takes into account both the afterburning of the detonation products of the C-4 booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Numerical simulations of the explosion fields from 1.5-g Shock-Dispersed-Fuel (SDF) charge in a 6.6 liter calorimeter were used to validate the combustion model. Then the model was applied to 10-kg Al-SDF explosions in a an unconfined height-of-burst explosion. Computed pressure histories are compared with measured waveforms. Differences are caused by physical-chemical kinetic effects of particle combustion which induce ignition delays in the initial reactive blast wave and quenching of reactions at late times. Current simulations give initial insights into such modeling issues.

  18. Analysis of noise radiation mechanisms in hot subsonic jet from a validated large eddy simulation solution

    SciTech Connect (OSTI)

    Lorteau, Mathieu Cléro, Franck Vuillot, François

    2015-07-15

    In the framework of jet noise computation, a numerical simulation of a subsonic turbulent hot jet is performed using large-eddy simulation. A geometrical tripping is used in order to trigger the turbulence at the nozzle exit. In a first part, the validity of the simulation is assessed by comparison with experimental measurements. The mean and rms velocity fields show good agreement, so do the azimuthal composition of the near pressure field and the far field spectra. Discrepancies remain close to the nozzle exit which lead to a limited overestimation of the pressure levels in both near and far fields, especially near the 90{sup ∘} angular sector. Two point correlation analyses are then applied to the data obtained from the simulation. These enable to link the downstream acoustic radiation, which is the main direction of radiation, to pressure waves developing in the shear layer and propagating toward the potential core end. The intermittency of the downstream acoustic radiation is evidenced and related to the coherent structures developing in the shear layer.

  19. The ignition design space of magnetized target fusion

    SciTech Connect (OSTI)

    Lindemuth, Irvin R.

    2015-12-15

    The simple magnetized target implosion model of Lindemuth and Kirkpatrick [Nucl. Fusion 23, 263 (1983)] has been extended to survey the potential parameter space in which three types of magnetized targets—cylindrical with axial magnetic field, cylindrical with azimuthal magnetic field, and spherical with azimuthal magnetic field—might achieve ignition and produce large gain at achievable radial convergence ratios. The model has been used to compute the dynamic, time-dependent behavior of many initial parameter sets that have been based upon projected ignition conditions using the quasi-adiabatic and quasi-flux-conserving properties of magnetized target implosions. The time-dependent calculations have shown that energy gains greater than 30 can potentially be achieved for each type of target. By example, it is shown that high gain may be obtained at extremely low convergence ratios, e.g., less than 15, for appropriate initial conditions. It is also shown that reaching the ignition condition, i.e., when fusion deposition rates equal total loss rates, does not necessarily lead to high gain and high fuel burn-up. At the lower densities whereby fusion temperatures can be reached in magnetized targets, the fusion burn rate may be only comparable with the hydrodynamic heating/cooling rates. On the other hand, when the fusion burn rates significantly exceed the hydrodynamic rates, the calculations show a characteristic rapid increase in temperature due to alpha particle deposition with a subsequent increased burn rate and high gain. A major result of this paper is that each type of target operates in a different initial density-energy-velocity range. The results of this paper provide initial target plasma parameters and driver parameters that can be used to guide plasma formation and driver development for magnetized targets. The results indicate that plasmas for spherical, cylindrical with azimuthal field, and cylindrical with axial field targets must have an initial

  20. Terascale direct numerical simulations of turbulent combustion using S3D

    SciTech Connect (OSTI)

    Chen, Jackie; Klasky, Scott A; Hawkes, Evatt R; Sankaran, Ramanan; Choudhary, Alok; Yoo, Chun S; Liao, Wei-keng; Podhorszki, Norbert

    2009-01-01

    Computational science is paramount to the understanding of underlying processes in internal combustion engines of the future that will utilize non-petroleum-based alternative fuels, including carbon-neutral biofuels, and burn in new combustion regimes that will attain high efficiency while minimizing emissions of particulates and nitrogen oxides. Next-generation engines will likely operate at higher pressures, with greater amounts of dilution and utilize alternative fuels that exhibit a wide range of chemical and physical properties. Therefore, there is a significant role for high-fidelity simulations, direct numerical simulations (DNS), specifically designed to capture key turbulence-chemistry interactions in these relatively uncharted combustion regimes, and in particular, that can discriminate the effects of differences in fuel properties. In DNS, all of the relevant turbulence and flame scales are resolved numerically using high-order accurate numerical algorithms. As a consequence terascale DNS are computationally intensive, require massive amounts of computing power and generate tens of terabytes of data. Recent results from terascale DNS of turbulent flames are presented here, illustrating its role in elucidating flame stabilization mechanisms in a lifted turbulent hydrogen/air jet flame in a hot air coflow, and the flame structure of a fuel-lean turbulent premixed jet flame. Computing at this scale requires close collaborations between computer and combustion scientists to provide optimized scaleable algorithms and software for terascale simulations, efficient collective parallel I/O, tools for volume visualization of multiscale, multivariate data and automating the combustion workflow. The enabling computer science, applied to combustion science, is also required in many other terascale physics and engineering simulations. In particular, performance monitoring is used to identify the performance of key kernels in the DNS code, S3D and especially memory

  1. Scaling and dimensional analysis of acoustic streaming jets

    SciTech Connect (OSTI)

    Moudjed, B.; Botton, V.; Henry, D.; Ben Hadid, H.

    2014-09-15

    This paper focuses on acoustic streaming free jets. This is to say that progressive acoustic waves are used to generate a steady flow far from any wall. The derivation of the governing equations under the form of a nonlinear hydrodynamics problem coupled with an acoustic propagation problem is made on the basis of a time scale discrimination approach. This approach is preferred to the usually invoked amplitude perturbations expansion since it is consistent with experimental observations of acoustic streaming flows featuring hydrodynamic nonlinearities and turbulence. Experimental results obtained with a plane transducer in water are also presented together with a review of the former experimental investigations using similar configurations. A comparison of the shape of the acoustic field with the shape of the velocity field shows that diffraction is a key ingredient in the problem though it is rarely accounted for in the literature. A scaling analysis is made and leads to two scaling laws for the typical velocity level in acoustic streaming free jets; these are both observed in our setup and in former studies by other teams. We also perform a dimensional analysis of this problem: a set of seven dimensionless groups is required to describe a typical acoustic experiment. We find that a full similarity is usually not possible between two acoustic streaming experiments featuring different fluids. We then choose to relax the similarity with respect to sound attenuation and to focus on the case of a scaled water experiment representing an acoustic streaming application in liquid metals, in particular, in liquid silicon and in liquid sodium. We show that small acoustic powers can yield relatively high Reynolds numbers and velocity levels; this could be a virtue for heat and mass transfer applications, but a drawback for ultrasonic velocimetry.

  2. Stellar explosions, instabilities, and turbulence

    SciTech Connect (OSTI)

    Drake, R. P.; Kuranz, C. C.; Miles, A. R.; Muthsam, H. J.; Plewa, T.

    2009-04-15

    It has become very clear that the evolution of structure during supernovae is centrally dependent on the pre-existing structure in the star. Modeling of the pre-existing structure has advanced significantly, leading to improved understanding and to a physically based assessment of the structure that will be present when a star explodes. It remains an open question whether low-mode asymmetries in the explosion process can produce the observed effects or whether the explosion mechanism somehow produces jets of material. In any event, the workhorse processes that produce structure in an exploding star are blast-wave driven instabilities. Laboratory experiments have explored these blast-wave-driven instabilities and specifically their dependence on initial conditions. Theoretical work has shown that the relative importance of Richtmyer-Meshkov and Rayleigh-Taylor instabilities varies with the initial conditions and does so in ways that can make sense of a range of astrophysical observations.

  3. Compression-ignition fuel properties of Fischer-Tropsch syncrude

    SciTech Connect (OSTI)

    Suppes, G.J.; Terry, J.G.; Burkhart, M.L.; Cupps, M.P.

    1998-05-01

    Fischer-Tropsch conversion of natural gas to liquid hydrocarbon fuel typically includes Fischer-Tropsch synthesis followed by refining (hydrocracking and distillation) of the syncrude into mostly diesel or kerosene with some naphtha (a feedstock for gasoline production). Refining is assumed necessary, possibly overlooking the exception fuel qualities of syncrude for more direct utilization as a compression-ignition (CI) fuel. This paper evaluates cetane number, viscosity, cloud-point, and pour-point properties of syncrude and blends of syncrude with blend stocks such as ethanol and diethyl ether. The results show that blends comprised primarily of syncrude are potentially good CI fuels, with pour-point temperature depression being the largest development obstacle. The resulting blends may provide a much-needed and affordable alternative CI fuel. Particularly good market opportunities exist with Environmental Policy Act (EPACT) applications.

  4. National ignition facility environment, safety, and health management plan

    SciTech Connect (OSTI)

    1995-11-01

    The ES&H Management Plan describes all of the environmental, safety, and health evaluations and reviews that must be carried out in support of the implementation of the National Ignition Facility (NIF) Project. It describes the policy, organizational responsibilities and interfaces, activities, and ES&H documents that will be prepared by the Laboratory Project Office for the DOE. The only activity not described is the preparation of the NIF Project Specific Assessment (PSA), which is to be incorporated into the Programmatic Environmental Impact Statement for Stockpile Stewardship and Management (PEIS). This PSA is being prepared by Argonne National Laboratory (ANL) with input from the Laboratory participants. As the independent NEPA document preparers ANL is directly contracted by the DOE, and its deliverables and schedule are agreed to separately with DOE/OAK.

  5. HYDROGEN IGNITION MECHANISM FOR EXPLOSIONS IN NUCLEAR FACILITY PIPE SYSTEMS

    SciTech Connect (OSTI)

    Leishear, R

    2010-05-02

    Hydrogen and oxygen generation due to the radiolysis of water is a recognized hazard in pipe systems used in the nuclear industry, where the accumulation of hydrogen and oxygen at high points in the pipe system is expected, and explosive conditions exist. Pipe ruptures at nuclear facilities were attributed to hydrogen explosions inside pipelines, in nuclear facilities, i.e., Hamaoka, Nuclear Power Station in Japan, and Brunsbuettel in Germany. Prior to these accidents an ignition source for hydrogen was questionable, but these accidents, demonstrated that a mechanism was, in fact, available to initiate combustion and explosion. Hydrogen explosions may occur simultaneously with water hammer accidents in nuclear facilities, and a theoretical mechanism to relate water hammer to hydrogen deflagrations and explosions is presented herein.

  6. Shock-ignition relevant experiments with planar targets on OMEGA

    SciTech Connect (OSTI)

    Hohenberger, M.; Hu, S. X.; Anderson, K. S.; Boehly, T. R.; Sangster, T. C.; Seka, W.; Stoeckl, C.; Yaakobi, B.; Theobald, W.; Lafon, M.; Nora, R.; Fusion Science Center, University of Rochester, Rochester, New York 14623 ; Betti, R.; Meyerhofer, D. D.; Fusion Science Center, University of Rochester, Rochester, New York 14623; Departments of Mechanical Engineering and Physics, University of Rochester, Rochester, New York 14627 ; Casner, A.; Fratanduono, D. E.; Ribeyre, X.; Schurtz, G.

    2014-02-15

    We report on laser-driven, strong-shock generation and hot-electron production in planar targets in the presence of a pre-plasma at shock-ignition (SI) relevant laser and pre-plasma conditions. 2-D simulations reproduce the shock dynamics well, indicating ablator shocks of up to 75 Mbar have been generated. We observe hot-electron temperatures of ?70?keV at intensities of 1.4??10{sup 15}?W/cm{sup 2} with multiple overlapping beams driving the two-plasmon decay instability. When extrapolated to SI-relevant intensities of ?10{sup 16}?W/cm{sup 2}, the hot electron temperature will likely exceed 100?keV, suggesting that tightly focused beams without overlap are better suited for launching the ignitor shock.

  7. Validating hydrodynamic growth in National Ignition Facility implosions

    SciTech Connect (OSTI)

    Peterson, J. L. Casey, D. T.; Hurricane, O. A.; Raman, K. S.; Robey, H. F.; Smalyuk, V. A.

    2015-05-15

    We present new hydrodynamic growth experiments at the National Ignition Facility, which extend previous measurements up to Legendre mode 160 and convergence ratio 4, continuing the growth factor dispersion curve comparison of the low foot and high foot pulses reported by Casey et al. [Phys. Rev. E 90, 011102(R) (2014)]. We show that the high foot pulse has lower growth factor and lower growth rate than the low foot pulse. Using novel on-capsule fiducial markers, we observe that mode 160 inverts sign (changes phase) for the high foot pulse, evidence of amplitude oscillations during the Richtmyer-Meshkov phase of a spherically convergent system. Post-shot simulations are consistent with the experimental measurements for all but the shortest wavelength perturbations, reinforcing the validity of radiation hydrodynamic simulations of ablation front growth in inertial confinement fusion capsules.

  8. Final Scientific and Technical Report - Practical Fiber Delivered Laser Ignition Systems for Vehicles

    SciTech Connect (OSTI)

    Yalin, Azer

    2014-03-30

    Research has characterized advanced kagome fiber optics for their use in laser ignition systems. In comparison to past fibers used in laser ignition, these fibers have the important advantage of being relatively bend-insensitivity, so that they can be bent and coiled without degradation of output energy or beam quality. The results are very promising for practical systems. For pulse durations of ~12 ns, the fibers could deliver >~10 mJ pulses before damage onset. A study of pulse duration showed that by using longer pulse duration (~20 – 30 ns), it is possible to carry even higher pulse energy (by factor of ~2-3) which also provides future opportunities to implement longer duration sources. Beam quality measurements showed nearly single-mode output from the kagome fibers (i.e. M2 close to 1) which is the optimum possible value and, combined with their high pulse energy, shows the suitability of the fibers for laser ignition. Research has also demonstrated laser ignition of an engine including reliable (100%) ignition of a single-cylinder gasoline engine using the laser ignition system with bent and coiled kagome fiber. The COV of IMEP was <2% which is favorable for stable engine operation. These research results, along with the continued reduction in cost of laser sources, support our commercial development of practical laser ignition systems.

  9. A simplified model of TiH1.65/KClO4 pyrotechnic ignition.

    SciTech Connect (OSTI)

    Chen, Ken Shuang

    2009-04-01

    A simplified model was developed and is presented in this report for simulating thermal transport coupled with chemical reactions that lead to the pyrotechnic ignition of TiH1.65/KClO4 powder. The model takes into account Joule heating via a bridgewire, thermal contact resistance at the wire/powder interface, convective heat loss to the surroundings, and heat released from the TiH1.65- and KClO4-decomposition and TiO2-oxidation reactions. Chemical kinetic sub-models were put forth to describe the chemical reaction rate(s) and quantify the resultant heat release. The simplified model predicts pyrotechnic ignition when heat from the pyrotechnic reactions is accounted for. Effects of six key parameters on ignition were examined. It was found that the two reaction-rate parameters and the thermal contact resistance significantly affect the dynamic ignition process whereas the convective heat transfer coefficient essentially has no effect on the ignition time. Effects of the initial/ambient temperature and electrical current load through the wire are as expected. Ignition time increases as the initial/ambient temperature is lowered or the wire current load is reduced. Lastly, critical needs such as experiments to determine reaction-rate and other model-input parameters and to measure temperature profiles, time to ignition and burn-rate data for model validation as well as efforts in incorporating reaction-rate dependency on pressure are pointed out.

  10. Polar-direct-drive experiments on the National Ignition Facility

    SciTech Connect (OSTI)

    Hohenberger, M.; Radha, P. B.; Myatt, J. F.; Marozas, J. A.; Marshall, F. J.; Michel, D. T.; Regan, S. P.; Seka, W.; Shvydky, A.; Sangster, T. C.; Betti, R.; Boehly, T. R.; Bonino, M. J.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Fiksel, G.; Froula, D. H.; and others

    2015-05-15

    To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drivespecific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beam geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D{sub 2} gas were imploded with total drive energies ranging from ?500 to 750?kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8??10{sup 14} to 1.2??10{sup 15?}W/cm{sup 2}. Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport and cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data.

  11. Polar-direct-drive experiments on the National Ignition Facility

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hohenberger, M.; Radha, P. B.; Myatt, J. F.; LePape, S.; Marozas, J. A.; Marshall, F. J.; Michel, D. T.; Regan, S. P.; Seka, W.; Shvydky, A.; et al

    2015-05-11

    To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drive–specific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beammore » geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D₂ gas were imploded with total drive energies ranging from ~500 to 750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 10¹⁴ to 1.2 10¹⁵W/cm². Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport and cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data.« less

  12. Polar-direct-drive experiments on the National Ignition Facility

    SciTech Connect (OSTI)

    Hohenberger, M.; Radha, P. B.; Myatt, J. F.; LePape, S.; Marozas, J. A.; Marshall, F. J.; Michel, D. T.; Regan, S. P.; Seka, W.; Shvydky, A.; Sangster, T. C.; Bates, J. W.; Betti, R.; Boehly, T. R.; Bonino, M. J.; Casey, D. T.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Fiksel, G.; Fitzsimmons, P.; Frenje, J. A.; Froula, D. H.; Goncharov, V. N.; Harding, D. R.; Kalantar, D. H.; Karasik, M.; Kessler, T. J.; Kilkenny, J. D.; Knauer, J. P.; Kurz, C.; Lafon, M.; LaFortune, K. N.; MacGowan, B. J.; Mackinnon, A. J.; MacPhee, A. G.; McCrory, R. L.; McKenty, P. W.; Meeker, J. F.; Meyerhofer, D. D.; Nagel, S. R.; Nikroo, A.; Obenschain, S.; Petrasso, R. D.; Ralph, J. E.; Rinderknecht, H. G.; Rosenberg, M. J.; Schmitt, A. J.; Wallace, R. J.; Weaver, J.; Widmayer, C.; Skupsky, S.; Solodov, A. A.; Stoeckl, C.; Yaakobi, B.; Zuegel, J. D.

    2015-05-11

    To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drive–specific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beam geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D₂ gas were imploded with total drive energies ranging from ~500 to 750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 10¹⁴ to 1.2 10¹⁵W/cm². Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport and cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data.

  13. Polar-direct-drive experiments on the National Ignition Facility

    SciTech Connect (OSTI)

    Hohenberger, M.; Radha, P. B.; Myatt, J. F.; LePape, S.; Marozas, J. A.; Marshall, F. J.; Michel, D. T.; Regan, S. P.; Seka, W.; Shvydky, A.; Sangster, T. C.; Bates, J. W.; Betti, R.; Boehly, T. R.; Bonino, M. J.; Casey, D. T.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Fiksel, G.; Fitzsimmons, P.; Frenje, J. A.; Froula, D. H.; Goncharov, V. N.; Harding, D. R.; Kalantar, D. H.; Karasik, M.; Kessler, T. J.; Kilkenny, J. D.; Knauer, J. P.; Kurz, C.; Lafon, M.; LaFortune, K. N.; MacGowan, B. J.; Mackinnon, A. J.; MacPhee, A. G.; McCrory, R. L.; McKenty, P. W.; Meeker, J. F.; Meyerhofer, D. D.; Nagel, S. R.; Nikroo, A.; Obenschain, S.; Petrasso, R. D.; Ralph, J. E.; Rinderknecht, H. G.; Rosenberg, M. J.; Schmitt, A. J.; Wallace, R. J.; Weaver, J.; Widmayer, C.; Skupsky, S.; Solodov, A. A.; Stoeckl, C.; Yaakobi, B.; Zuegel, J. D.

    2015-05-01

    To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drive–specific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beam geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D2 gas were imploded with total drive energies ranging from ~500-750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 x 1014 to 1.2 x 1015 W/cm2. Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport and cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data.

  14. Configuring the National Ignition Facility for direct-drive experiments

    SciTech Connect (OSTI)

    Eimerl, D.

    1995-07-01

    The National Ignition Facility (NIF) is a project whose primary mission is to provide an above-ground experimental capability for maintaining nuclear competence and weapons effects simulation, and to pursue the achievement of fusion ignition utilizing solid state lasers as the energy driver. In this facility a large number of laser beams are focused onto a small target located at the center of a spherical target chamber. The laser energy is delivered in a few billionths of a second, raising the temperature and density of the nuclear materials in the target to levels where significant thermonuclear energy is released. The thermonuclear reaction proceeds very rapidly, so that the target materials remain confined by their own inertia during the thermonuclear reaction. This type of approach is called inertial confinement fusion (ICF). The proposed project is described in a conceptual design report (CDR) that was released in May 1994. Early in FY95, a collaboration between the University of Rochester and the Lawrence Livermore National Laboratory was established to study reconfiguring the NIF to accommodate direct-drive experiments. The present paper is a report to the scientific community, primarily the scientists and engineers working on the design of the NIF. It represents results from work in progress, specifically work completed by the end of the second quarter FY95. This report has two main sections. The first describes the target requirements on the laser drive, and the second part describes how the NIF laser can be configured to accommodate both indirect and direct drive. The report includes a description of the scientific basis for these conclusions. Though a complete picture does not exist, the present understanding is sufficient to conclude that the primary target requirements and laser functional requirements for indirect and direct drive are quite compatible. It is evidently straightforward to reconfigure the NIF to accommodate direct and indirect drive.

  15. Fragmentation, underlying event and jet shapes at the Tevatron...

    Office of Scientific and Technical Information (OSTI)

    Conference: Fragmentation, underlying event and jet shapes at the Tevatron Citation Details In-Document Search Title: Fragmentation, underlying event and jet shapes at the Tevatron...

  16. Boron nitride ablation studies in arc jet facilities (Conference...

    Office of Scientific and Technical Information (OSTI)

    Conference: Boron nitride ablation studies in arc jet facilities Citation Details In-Document Search Title: Boron nitride ablation studies in arc jet facilities You are ...

  17. Sustainable Alternative Jet Fuels | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Jim Hileman, U.S. Federal Aviation Administration, presentation at the Industry Roundtable on Life-Cycle GHG Emissions Modeling 9_hileman_roundtable.pdf (637.68 KB) More Documents & Publications An Update on FAA Alternative Jet Fuel Efforts Sustainable Alternative Jet Fuels Vehicle Technologies Office Merit Review 2015: Emissions Modeling: GREET Life Cycle Analysis

  18. Atmospheric-pressure plasma jet

    DOE Patents [OSTI]

    Selwyn, Gary S.

    1999-01-01

    Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

  19. Fuel Effects on Ignition and Their Impact on Advanced Combustion Engines (Poster)

    SciTech Connect (OSTI)

    Taylor, J.; Li, H.; Neill, S.

    2006-08-01

    The objective of this report is to develop a pathway to use easily measured ignition properties as metrics for characterizing fuels in advanced combustion engine research--correlate IQT{trademark} measured parameters with engine data. In HCCL engines, ignition timing depends on the reaction rates throughout compression stroke: need to understand sensitivity to T, P, and [O{sub 2}]; need to rank fuels based on more than one set of conditions; and need to understand how fuel composition (molecular species) affect ignition properties.

  20. A low cost igniter utilizing an SCB and titanium sub-hydride potassium perchlorate pyrotechnic

    SciTech Connect (OSTI)

    Bickes, R.W. Jr.; Grubelich, M.C.; Hartman, J.K.; McCampbell, C.B.; Churchill, J.K.

    1993-12-31

    A conventional NSI (NASA standard initiator) normally employs a hot-wire ignition element to ignite ZPP (zirconium potassium perchlorate). With minor modifications to the interior of a header similar to an NSI device to accommodate an SCB (semiconductor bridge), a low cost initiator was obtained. In addition, the ZPP was replaced with THKP (titanium subhydride potassium perchlorate) to obtain increased overall gas production and reduced static-charge sensitivity. This paper reports on the all-fire and no-fire levels obtained and on a dual mix device that uses THKP as the igniter mix and a thermite as the output mix.

  1. THE ODTX SYSTEM FOR THERMAL IGNITION AND THERMAL SAFETY STUDY OF ENERGETIC MATERIALS

    SciTech Connect (OSTI)

    Hsu, P C; Hust, G; Howard, M; Maienschein, J L

    2010-03-03

    Understanding the response of energetic material to thermal event is very important for the storage and handling of energetic materials. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory (LLNL) can precisely measure times to explosion and minimum ignition temperatures of energetic materials at elevated temperatures. These measurements provide insight into the relative ease of thermal ignition and allow for the determination of kinetic parameters. The ODTX system can potentialy be a good tool to measure violence of the thermal ignition by monitoring the size of anvil cavity. Recent ODTX experimental data on various energetic materials (solid and liquids) are reported in this paper.

  2. VLBA AND CHANDRA OBSERVATIONS OF JETS IN FRI RADIO GALAXIES: CONSTRAINTS ON JET EVOLUTION

    SciTech Connect (OSTI)

    Kharb, P.; O'Dea, C. P.; Tilak, A.; Baum, S. A.; Haynes, E.; Noel-Storr, J.; Fallon, C.; Christiansen, K.

    2012-07-20

    We present here the results from new Very Long Baseline Array (VLBA) observations at 1.6 and 5 GHz of 19 galaxies of a complete sample of 21 Uppasala General Catalog (UGC) Fanaroff-Riley type I (FRI) radio galaxies. New Chandra data of two sources, viz., UGC 00408 and UGC 08433, are combined with the Chandra archival data of 13 sources. The 5 GHz observations of 10 'core-jet' sources are polarization-sensitive, while the 1.6 GHz observations constitute second-epoch total intensity observations of nine 'core-only' sources. Polarized emission is detected in the jets of seven sources at 5 GHz, but the cores are essentially unpolarized, except in M87. Polarization is detected at the jet edges in several sources, and the inferred magnetic field is primarily aligned with the jet direction. This could be indicative of magnetic field 'shearing' due to jet-medium interaction, or the presence of helical magnetic fields. The jet peak intensity I{sub {nu}} falls with distance d from the core, following the relation, I{sub {nu}}{proportional_to}d{sup a} , where a is typically {approx} - 1.5. Assuming that adiabatic expansion losses are primarily responsible for the jet intensity 'dimming,' two limiting cases are considered: (1) the jet has a constant speed on parsec scales and is expanding gradually such that the jet radius r{proportional_to}d 0{sup .4}; this expansion is, however, unobservable in the laterally unresolved jets at 5 GHz, and (2) the jet is cylindrical and is accelerating on parsec scales. Accelerating parsec-scale jets are consistent with the phenomenon of 'magnetic driving' in Poynting-flux-dominated jets. While slow jet expansion as predicted by case (1) is indeed observed in a few sources from the literature that are resolved laterally, on scales of tens or hundreds of parsecs, case (2) cannot be ruled out in the present data, provided the jets become conical on scales larger than those probed by VLBA. Chandra observations of 15 UGC FRIs detect X-ray jets in

  3. Development of High Efficiency Clean Combustion Engine Designs for Spark-Ignition and Compression-Ignition Internal Combustion Engines

    SciTech Connect (OSTI)

    Marriott, Craig; Gonzalez, Manual; Russell, Durrett

    2011-06-30

    This report summarizes activities related to the revised STATEMENT OF PROJECT OBJECTIVES (SOPO) dated June 2010 for the Development of High-Efficiency Clean Combustion engine Designs for Spark-Ignition and Compression-Ignition Internal Combustion Engines (COOPERATIVE AGREEMENT NUMBER DE-FC26-05NT42415) project. In both the spark- (SI) and compression-ignition (CI) development activities covered in this program, the goal was to develop potential production-viable internal combustion engine system technologies that both reduce fuel consumption and simultaneously met exhaust emission targets. To be production-viable, engine technologies were also evaluated to determine if they would meet customer expectations of refinement in terms of noise, vibration, performance, driveability, etc. in addition to having an attractive business case and value. Prior to this activity, only proprietary theoretical / laboratory knowledge existed on the combustion technologies explored The research reported here expands and develops this knowledge to determine series-production viability. Significant SI and CI engine development occurred during this program within General Motors, LLC over more than five years. In the SI program, several engines were designed and developed that used both a relatively simple multi-lift valve train system and a Fully Flexible Valve Actuation (FFVA) system to enable a Homogeneous Charge Compression Ignition (HCCI) combustion process. Many technical challenges, which were unknown at the start of this program, were identified and systematically resolved through analysis, test and development. This report documents the challenges and solutions for each SOPO deliverable. As a result of the project activities, the production viability of the developed clean combustion technologies has been determined. At this time, HCCI combustion for SI engines is not considered production-viable for several reasons. HCCI combustion is excessively sensitive to control variables

  4. Supercomputers Capture Turbulence in the Solar Wind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the solar wind occurring down to electron scales. This is a phenomenon common in fluid dynamics-turbulent energy ... he created tools to filter out the "noise" in the datasets. ...

  5. TIDAL TURBULENCE SPECTRA FROM A COMPLIANT MOORING

    SciTech Connect (OSTI)

    Thomson, Jim; Kilcher, Levi; Richmond, Marshall C.; Talbert, Joe; deKlerk, Alex; Polagye, Brian; Guerra, Maricarmen; Cienfuegos, Rodrigo

    2013-06-13

    A compliant mooring to collect high frequency turbulence data at a tidal energy site is evaluated in a series of short demon- stration deployments. The Tidal Turbulence Mooring (TTM) improves upon recent bottom-mounted approaches by suspend- ing Acoustic Doppler Velocimeters (ADVs) at mid-water depths (which are more relevant to tidal turbines). The ADV turbulence data are superior to Acoustic Doppler Current Profiler (ADCP) data, but are subject to motion contamination when suspended on a mooring in strong currents. In this demonstration, passive stabilization is shown to be sufficient for acquiring bulk statistics of the turbulence, without motion correction. With motion cor- rection (post-processing), data quality is further improved; the relative merits of direct and spectral motion correction are dis- cussed.

  6. Effects of Coaxial Air on Nitrogen-Diluted Hydrogen Jet Diffusion Flame Length and NOx Emission

    SciTech Connect (OSTI)

    Weiland, N.T.; Chen, R.-H.; Strakey, P.A.

    2007-10-01

    Turbulent nitrogen-diluted hydrogen jet diffusion flames with high velocity coaxial air flows are investigated for their NOx emission levels. This study is motivated by the DOE turbine programs goal of achieving 2 ppm dry low NOx from turbine combustors running on nitrogen-diluted high-hydrogen fuels. In this study, effects of coaxial air velocity and momentum are varied while maintaining low overall equivalence ratios to eliminate the effects of recirculation of combustion products on flame lengths, flame temperatures, and resulting NOx emission levels. The nature of flame length and NOx emission scaling relationships are found to vary, depending on whether the combined fuel and coaxial air jet is fuel-rich or fuel-lean. In the absence of differential diffusion effects, flame lengths agree well with predicted trends, and NOx emissions levels are shown to decrease with increasing coaxial air velocity, as expected. Normalizing the NOx emission index with a flame residence time reveals some interesting trends, and indicates that a global flame strain based on the difference between the fuel and coaxial air velocities, as is traditionally used, is not a viable parameter for scaling the normalized NOx emissions of coaxial air jet diffusion flames.

  7. Electrical studies and plasma characterization of an atmospheric pressure plasma jet operated at low frequency

    SciTech Connect (OSTI)

    Giuliani, L.; Xaubet, M.; Grondona, D.; Minotti, F.; Kelly, H.

    2013-06-15

    Low-temperature, high-pressure plasma jets have an extensive use in medical and biological applications. Much work has been devoted to study these applications while comparatively fewer studies appear to be directed to the discharge itself. In this work, in order to better understand the kind of electrical discharge and the plasma states existing in those devices, a study of the electrical characteristics of a typical plasma jet, operated at atmospheric pressure, using either air or argon, is reported. It is found that the experimentally determined electrical characteristics are consistent with the model of a thermal arc discharge, with a highly collisional cathode sheet. The only exception is the case of argon at the smallest electrode separation studied, around 1 mm in which case the discharge is better modeled as either a non-thermal arc or a high-pressure glow. Also, variations of the electrical behavior at different gas flow rates are interpreted, consistently with the arc model, in terms of the development of fluid turbulence in the external jet.

  8. Reaction and diffusion in turbulent combustion

    SciTech Connect (OSTI)

    Pope, S.B.

    1993-12-01

    The motivation for this project is the need to obtain a better quantitative understanding of the technologically-important phenomenon of turbulent combustion. In nearly all applications in which fuel is burned-for example, fossil-fuel power plants, furnaces, gas-turbines and internal-combustion engines-the combustion takes place in a turbulent flow. Designers continually demand more quantitative information about this phenomenon-in the form of turbulent combustion models-so that they can design equipment with increased efficiency and decreased environmental impact. For some time the PI has been developing a class of turbulent combustion models known as PDF methods. These methods have the important virtue that both convection and reaction can be treated without turbulence-modelling assumptions. However, a mixing model is required to account for the effects of molecular diffusion. Currently, the available mixing models are known to have some significant defects. The major motivation of the project is to seek a better understanding of molecular diffusion in turbulent reactive flows, and hence to develop a better mixing model.

  9. Advanced Concept Exploration for Fast Ignition Science Program, Final Report

    SciTech Connect (OSTI)

    Stephens, Richard Burnite; McLean, Harry M.; Theobald, Wolfgang; Akli, Kramer U.; Beg, Farhat N.; Sentoku, Yasuhiko; Schumacher, Douglass W.; Wei, Mingsheng

    2013-09-04

    The Fast Ignition (FI) Concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy reactors. FI differs from conventional “central hot spot” (CHS) target ignition by decoupling compression from heating: using a laser (or heavy ion beam or Z pinch) drive pulse (10’s of nanoseconds) to create a dense fuel and a second, much shorter (~10 picoseconds) high intensity pulse to ignite a small volume within the dense fuel. The physics of fast ignition process was the focus of our Advanced Concept Exploration (ACE) program. Ignition depends critically on two major issues involving Relativistic High Energy Density (RHED) physics: The laser-induced creation of fast electrons and their propagation in high-density plasmas. Our program has developed new experimental platforms, diagnostic packages, computer modeling analyses, and taken advantage of the increasing energy available at laser facilities to advance understanding of the fundamental physics underlying these issues. Our program had three thrust areas: • Understand the production and characteristics of fast electrons resulting from FI relevant laser-plasma interactions and their dependence on laser prepulse and laser pulse length. • Investigate the subsequent fast electron transport in solid and through hot (FI-relevant) plasmas. • Conduct and understand integrated core-heating experiments by comparison to simulations. Over the whole period of this project (three years for this contract), we have greatly advanced our fundamental understanding of the underlying properties in all three areas: • Comprehensive studies on fast electron source characteristics have shown that they are controlled by the laser intensity distribution and the topology and plasma density gradient. Laser pre-pulse induced pre-plasma in front of a solid surface results in increased stand-off distances from the electron origin to the high density

  10. Intra-jet shocks in two counter-streaming, weakly collisional plasma jets

    SciTech Connect (OSTI)

    Ryutov, D. D.; Kugland, N. L.; Park, H.-S.; Plechaty, C.; Remington, B. A.; Ross, J. S.

    2012-07-15

    Counterstreaming laser-generated plasma jets can serve as a test-bed for the studies of a variety of astrophysical phenomena, including collisionless shock waves. In the latter problem, the jet's parameters have to be chosen in such a way as to make the collisions between the particles of one jet with the particles of the other jet very rare. This can be achieved by making the jet velocities high and the Coulomb cross-sections correspondingly low. On the other hand, the intra-jet collisions for high-Mach-number jets can still be very frequent, as they are determined by the much lower thermal velocities of the particles of each jet. This paper describes some peculiar properties of intra-jet hydrodynamics in such a setting: the steepening of smooth perturbations and shock formation affected by the presence of the 'stiff' opposite flow; the role of a rapid electron heating in shock formation; ion heating by the intrajet shock. The latter effect can cause rapid ion heating which is consistent with recent counterstreaming jet experiments by Ross et al.[Phys. Plasmas 19, 056501 (2012)].

  11. Method and apparatus for igniting an in situ oil shale retort

    DOE Patents [OSTI]

    Burton, Robert S.; Rundberg, Sten I.; Vaughn, James V.; Williams, Thomas P.; Benson, Gregory C.

    1981-01-01

    A technique is provided for igniting an in situ oil shale retort having an open void space over the top of a fragmented mass of particles in the retort. A conduit is extended into the void space through a hole in overlying unfragmented formation and has an open end above the top surface of the fragmented mass. A primary air pipe having an open end above the open end of the conduit and a liquid atomizing fuel nozzle in the primary air pipe above the open end of the primary air pipe are centered in the conduit. Fuel is introduced through the nozzle, primary air through the pipe, and secondary air is introduced through the conduit for vortical flow past the open end of the primary air pipe. The resultant fuel and air mixture is ignited for combustion within the conduit and the resultant heated ignition gas impinges on the fragmented mass for heating oil shale to an ignition temperature.

  12. X-ray area backlighter development at the National Ignition Facility...

    Office of Scientific and Technical Information (OSTI)

    the National Ignition Facility (invited) 1D spectral imaging was used to characterize the K-shell emission of Z 30-35 and Z 40-42 laser-irradiated foils at the National...

  13. Effects of Ignition Quality and Fuel Composition on Critical Equivalence Ratio

    Broader source: Energy.gov [DOE]

    Our research shows that fuel can be blended to have a low ignition quality, which is desirable for high-efficiency advanced combustion, and with a high n-paraffin content to reduce CO and THC.

  14. Alignment of an x-Ray Imager Line of Sight in the National Ignition...

    Office of Scientific and Technical Information (OSTI)

    Conference: Alignment of an x-Ray Imager Line of Sight in the National Ignition Facility ... Citation Details In-Document Search Title: Alignment of an x-Ray Imager Line of Sight in ...

  15. X-ray area backlighter development at the National Ignition Facility...

    Office of Scientific and Technical Information (OSTI)

    Title: X-ray area backlighter development at the National Ignition Facility (NIF) Authors: Barrios, M A ; Regan, S P ; Fournier, K B ; Epstein, R ; Smith, R ; Lazicki, A ; Rygg, R ...

  16. Tungsten bridge for the low energy ignition of explosive and energetic materials

    DOE Patents [OSTI]

    Benson, David A.; Bickes, Jr., Robert W.; Blewer, Robert S.

    1990-01-01

    A tungsten bridge device for the low energy ignition of explosive and energetic materials is disclosed. The device is fabricated on a silicon-on-sapphire substrate which has an insulating bridge element defined therein using standard integrated circuit fabrication techniques. Then, a thin layer of tungsten is selectively deposited on the silicon bridge layer using chemical vapor deposition techniques. Finally, conductive lands are deposited on each end of the tungsten bridge layer to form the device. It has been found that this device exhibits substantially shorter ignition times than standard metal bridges and foil igniting devices. In addition, substantially less energy is required to cause ignition of the tungsten bridge device of the present invention than is required for common metal bridges and foil devices used for the same purpose.

  17. Qualitative assessment of the ignition of highly flammable fuels by primary explosives

    SciTech Connect (OSTI)

    Elischer, P.P.; De Yong, L.

    1983-06-01

    An assessment of the ignition of fuel/air mixtures and of fabrics soaked with different fuels (ethanol, n-hexane and diethyl ether) by primary explosives has been carried out.

  18. Radiation Hardening of Gated X-ray Imagers for the National Ignition...

    Office of Scientific and Technical Information (OSTI)

    Radiation Hardening of Gated X-ray Imagers for the National Ignition Facility Citation Details In-Document Search Title: Radiation Hardening of Gated X-ray Imagers for the National ...

  19. Tungsten bridge for the low energy ignition of explosive and energetic materials

    DOE Patents [OSTI]

    Benson, D.A.; Bickes, R.W. Jr.; Blewer, R.S.

    1990-12-11

    A tungsten bridge device for the low energy ignition of explosive and energetic materials is disclosed. The device is fabricated on a silicon-on-sapphire substrate which has an insulating bridge element defined therein using standard integrated circuit fabrication techniques. Then, a thin layer of tungsten is selectively deposited on the silicon bridge layer using chemical vapor deposition techniques. Finally, conductive lands are deposited on each end of the tungsten bridge layer to form the device. It has been found that this device exhibits substantially shorter ignition times than standard metal bridges and foil igniting devices. In addition, substantially less energy is required to cause ignition of the tungsten bridge device of the present invention than is required for common metal bridges and foil devices used for the same purpose. 2 figs.

  20. Effect of ignition conditions on upward flame spread on a composite material in a corner configuration

    SciTech Connect (OSTI)

    Ohlemiller, T.; Cleary, T.; Shields, J.

    1996-12-31

    This paper focuses on the issue of fire growth on composite materials beyond the region immediately subjected to an ignition source. Suppression of this growth is one of the key issues in realizing the safe usage of composite structural materials. A vinyl ester/glass composite was tested in the form of a 90{degrees} comer configuration with an inert ceiling segment 2.44 m above the top of the fire source. The igniter was a propane burner, either 23 or 38 cm in width with power output varied from 30 to 150 Kw. Upward flame spread rate and heat release rate were measured mainly for a brominated vinyl ester resin but limited results were also obtained for a non-flame retarded vinyl ester and a similar composite coated with an intumescent paint. Rapid fire growth beyond the igniter region was seen for the largest igniter power case; the intumescent coating successfully prevented fire growth for this case.

  1. National Ignition Facility fires 300th laser target shot of fiscal year

    National Nuclear Security Administration (NNSA)

    2015 | National Nuclear Security Administration | (NNSA) Ignition Facility fires 300th laser target shot of fiscal year 2015 August 18, 2015 WASHINGTON - Last week, the National Ignition Facility (NIF) fired its 300th laser target shot in fiscal year (FY) 2015, meeting the year's goal more than six weeks early. In comparison, the facility completed 191 target shots in FY 2014. Located at Lawrence Livermore National Laboratory (LLNL), the NIF is the world's most energetic laser. Increasing

  2. Status of the US inertial fusion program and the National Ignition Facility

    SciTech Connect (OSTI)

    Crandall, D.H.

    1997-04-01

    Research programs supported by the United States Office of Inertial Fusion and the NIF are summarized. The US inertial fusion program has developed an approach to high energy density physics and fusion ignition in the laboratory relying on the current physics basis of capsule drive by lasers and on the National Ignition Facility which is under construction. (AIP) {copyright} {ital 1997 American Institute of Physics.}

  3. Reactivity-controlled compression ignition drive cycle emissions and fuel economy estimations using vehicle system simulations

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Curran, Scott J.; Gao, Zhiming; Wagner, Robert M.

    2014-12-22

    In-cylinder blending of gasoline and diesel to achieve reactivity-controlled compression ignition has been shown to reduce NOX and soot emissions while maintaining or improving brake thermal efficiency as compared with conventional diesel combustion. The reactivity-controlled compression ignition concept has an advantage over many advanced combustion strategies in that the fuel reactivity can be tailored to the engine speed and load, allowing stable low-temperature combustion to be extended over more of the light-duty drive cycle load range. In this paper, a multi-mode reactivity-controlled compression ignition strategy is employed where the engine switches from reactivity-controlled compression ignition to conventional diesel combustion whenmore » speed and load demand are outside of the experimentally determined reactivity-controlled compression ignition range. The potential for reactivity-controlled compression ignition to reduce drive cycle fuel economy and emissions is not clearly understood and is explored here by simulating the fuel economy and emissions for a multi-mode reactivity-controlled compression ignition–enabled vehicle operating over a variety of US drive cycles using experimental engine maps for multi-mode reactivity-controlled compression ignition, conventional diesel combustion, and a 2009 port-fuel injected gasoline engine. Drive cycle simulations are completed assuming a conventional mid-size passenger vehicle with an automatic transmission. Multi-mode reactivity-controlled compression ignition fuel economy simulation results are compared with the same vehicle powered by a representative 2009 port-fuel injected gasoline engine over multiple drive cycles. Finally, engine-out drive cycle emissions are compared with conventional diesel combustion, and observations regarding relative gasoline and diesel tank sizes needed for the various drive cycles are also summarized.« less

  4. Reactivity-controlled compression ignition drive cycle emissions and fuel economy estimations using vehicle system simulations

    SciTech Connect (OSTI)

    Curran, Scott J.; Gao, Zhiming; Wagner, Robert M.

    2014-12-22

    In-cylinder blending of gasoline and diesel to achieve reactivity-controlled compression ignition has been shown to reduce NOX and soot emissions while maintaining or improving brake thermal efficiency as compared with conventional diesel combustion. The reactivity-controlled compression ignition concept has an advantage over many advanced combustion strategies in that the fuel reactivity can be tailored to the engine speed and load, allowing stable low-temperature combustion to be extended over more of the light-duty drive cycle load range. In this paper, a multi-mode reactivity-controlled compression ignition strategy is employed where the engine switches from reactivity-controlled compression ignition to conventional diesel combustion when speed and load demand are outside of the experimentally determined reactivity-controlled compression ignition range. The potential for reactivity-controlled compression ignition to reduce drive cycle fuel economy and emissions is not clearly understood and is explored here by simulating the fuel economy and emissions for a multi-mode reactivity-controlled compression ignition–enabled vehicle operating over a variety of US drive cycles using experimental engine maps for multi-mode reactivity-controlled compression ignition, conventional diesel combustion, and a 2009 port-fuel injected gasoline engine. Drive cycle simulations are completed assuming a conventional mid-size passenger vehicle with an automatic transmission. Multi-mode reactivity-controlled compression ignition fuel economy simulation results are compared with the same vehicle powered by a representative 2009 port-fuel injected gasoline engine over multiple drive cycles. Finally, engine-out drive cycle emissions are compared with conventional diesel combustion, and observations regarding relative gasoline and diesel tank sizes needed for the various drive cycles are also summarized.

  5. "New Results from the National Ignition Facility", Dr. John Lindl, Lawrence

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Livermore National Laboratory | Princeton Plasma Physics Lab November 7, 2012, 4:15pm Colloquia MBG Auditorium "New Results from the National Ignition Facility", Dr. John Lindl, Lawrence Livermore National Laboratory Since completion of the NIF construction project in March 2009, a wide variety of diagnostics, facility infrastructure, and experimental platforms have been qualified. NIF reached its design goal of 1.8 MJ and 500 TW of ultraviolet light in 2012. The Ignition Campaign

  6. Utilizing the Rapid Ignition Region of HCCI to Attain > 60% BTE |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy Utilizing the Rapid Ignition Region of HCCI to Attain > 60% BTE Utilizing the Rapid Ignition Region of HCCI to Attain > 60% BTE HCCI is inherently able to produce such rapid combustion (10 … 100µs) that it is effectively constant volume combustion. Constant volume combustion offers significant opportunity for dramatically improving ICRE BTE. However, to be used with conventional ICRE slider-crank kinematics, HCCI must transformed to a moderated mode of combustion

  7. Heavy Alcohols as a Fuel Blending Agent for Compression Ignition Engine

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Applications | Department of Energy Alcohols as a Fuel Blending Agent for Compression Ignition Engine Applications Heavy Alcohols as a Fuel Blending Agent for Compression Ignition Engine Applications Blends of Phytol and diesel (by volume) were compared against baseline diesel experiments and simulations p-21_ramirez.pdf (351.23 KB) More Documents & Publications HD Applications of Significantly Downsized SI Engines Using Alcohol DI for Knock Avoidance Characterization of Dual-Fuel

  8. Homogeneous Charge Compression Ignition (HCCI) R&D | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Homogeneous Charge Compression Ignition (HCCI) R&D Homogeneous Charge Compression Ignition (HCCI) R&D 2002 DEER Conference Presentation: Lawrence Livermore National Laboratory 2002_deer_aceves.pdf (753.26 KB) More Documents & Publications Detailed Modeling of HCCI and PCCI combustion and Multi-cylinder HCCI Engine Control Bridging the Gap between Fundamental Physics and Chemistry and Applied Models for HCCI Engines Modeling of HCCI and PCCI Combustion Processes

  9. Comparison between kinetic-ballooning-mode-driven turbulence and ion-temperature-gradient-driven turbulence

    SciTech Connect (OSTI)

    Maeyama, S. Nakata, M.; Miyato, N.; Yagi, M.; Ishizawa, A.; Watanabe, T.-H.; Idomura, Y.

    2014-05-15

    Electromagnetic turbulence driven by kinetic ballooning modes (KBMs) in high-? plasma is investigated based on the local gyrokinetic model. Analysis of turbulent fluxes, norms, and phases of fluctuations shows that KBM turbulence gives narrower spectra and smaller phase factors than those in ion-temperature-gradient (ITG)-driven turbulence. This leads to the smaller transport fluxes in KBM turbulence than those in ITG turbulence even when they have similar linear growth rates. From the analysis of the entropy balance relation, it is found that the entropy transfer from ions to electrons through the field-particle interactions mainly drives electron perturbations, which creates radial twisted modes by rapid parallel motions of electrons in a sheared magnetic geometry. The nonlinear coupling between the dominant unstable mode and its twisted modes is important for the saturation of KBM turbulence, in contrast to the importance of zonal flow shearing in ITG turbulence. The coupling depends on the flux-tube domain with the one-poloidal-turn parallel length and on the torus periodicity constraint.

  10. On the Fielding of a High Gain, Shock-Ignited Target on the National Ignitiion Facility in the Near Term

    SciTech Connect (OSTI)

    Perkins, L J; Betti, R; Schurtz, G P; Craxton, R S; Dunne, A M; LaFortune, K N; Schmitt, A J; McKenty, P W; Bailey, D S; Lambert, M A; Ribeyre, X; Theobald, W R; Strozzi, D J; Harding, D R; Casner, A; Atzemi, S; Erbert, G V; Andersen, K S; Murakami, M; Comley, A J; Cook, R C; Stephens, R B

    2010-04-12

    Shock ignition, a new concept for igniting thermonuclear fuel, offers the possibility for a near-term ({approx}3-4 years) test of high gain inertial confinement fusion on the National Ignition Facility at less than 1MJ drive energy and without the need for new laser hardware. In shock ignition, compressed fusion fuel is separately ignited by a strong spherically converging shock and, because capsule implosion velocities are significantly lower than those required for conventional hotpot ignition, fusion energy gains of {approx}60 may be achievable on NIF at laser drive energies around {approx}0.5MJ. Because of the simple all-DT target design, its in-flight robustness, the potential need for only 1D SSD beam smoothing, minimal early time LPI preheat, and use of present (indirect drive) laser hardware, this target may be easier to field on NIF than a conventional (polar) direct drive hotspot ignition target. Like fast ignition, shock ignition has the potential for high fusion yields at low drive energy, but requires only a single laser with less demanding timing and spatial focusing requirements. Of course, conventional symmetry and stability constraints still apply. In this paper we present initial target performance simulations, delineate the critical issues and describe the immediate-term R&D program that must be performed in order to test the potential of a high gain shock ignition target on NIF in the near term.

  11. Jet spoiler arrangement for wind turbine

    DOE Patents [OSTI]

    Cyrus, J.D.; Kadlec, E.G.; Klimas, P.C.

    1983-09-15

    An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the end thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby including stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

  12. Jet spoiler arrangement for wind turbine

    DOE Patents [OSTI]

    Cyrus, Jack D.; Kadlec, Emil G.; Klimas, Paul C.

    1985-01-01

    An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the ends thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby inducing stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

  13. THE RHIC HYDROGEN JET LUMINESCENCE MONITOR.

    SciTech Connect (OSTI)

    RUSSO,T.; BELLAVIA, S.; GASSNER, D.; THIEBERGER, P.; TRBOJEVIC, D.; TSANG, T.

    2007-06-25

    A hydrogen jet polarimeter was developed for the RHIC accelerator to improve the process of measuring polarization. Particle beams intersecting with gas molecules can produce light by the process known as luminescence. This light can then be focused, collected, and processed giving important information such as size, position, emittance, motion, and other parameters. The RHIC hydrogen jet polarimeter was modified in 2005 with specialized optics, vacuum windows, light transport, and a new camera system making it possible to monitor the luminescence produced by polarized protons intersecting the hydrogen beam. This paper describes the configuration and preliminary measurements taken using the RHIC hydrogen jet polarimeter as a luminescence monitor.

  14. Ignition properties of n-butane and iso-butane in a rapid compression machine

    SciTech Connect (OSTI)

    Gersen, S.; Darmeveil, J.H.; Mokhov, A.V.; Levinsky, H.B.

    2010-02-15

    Autoignition delay times of n-butane and iso-butane have been measured in a Rapid Compression Machine in the temperature range 660-1010 K, at pressures varying from 14 to 36 bar and at equivalence ratios {phi} = 1.0 and {phi} = 0.5. Both butane isomers exhibit a negative-temperature-coefficient (NTC) region and, at low temperatures, two-stage ignition. At temperatures below {proportional_to}900 K, the delay times for iso-butane are longer than those for the normal isomer, while above this temperature both butanes give essentially the same results. At temperatures above {proportional_to}720 K the delay times of the lean mixtures are twice those for stoichiometric compositions; at T < 720 K, the equivalence ratio is seen to have little influence on the ignition behavior. Increasing the pressure from 15 bar to 30 bar decreases the amplitude of the NTC region, and reduces the ignition delay time for both isomers by roughly a factor of 3. In the region in which two-stage ignition is observed, 680-825 K, the duration of the first ignition stage decreases sharply in the range 680-770 K, but is essentially flat above 770 K. Good quantitative agreement is found between the measurements and calculations for n-butane using a comprehensive model for butane ignition, including both delay times in the two-stage region, with substantial differences being observed for iso-butane, particularly in the NTC region. (author)

  15. A photographic study of fuel spray ignition in a rapid compression machine

    SciTech Connect (OSTI)

    Solomon, A.S.P.

    1986-01-01

    The process of spark ignition of fuel sprays in a rapid compression machine was analyzed using high-speed schlieren photography and pressure-time data. The combustion chamber studied simulates in a two-dimensional sense the three-dimensional arrangement of the piston bowl, injector and spark plug in a typical direct-injection stratified-charge (DISC) engine. The test hardware included a flat-seat straight-hole injector, a high-energy ignition system and an extended-electrode spark plug. The influence of amount of fuel injected, ignition dwell period (time between start of injection and start of ignition), swirl rate and direction, and spark-plug electrode-tip location on the ignition process was examined. For the test conditions studied, excessive spray penetration and fuel impingement on the walls was observed. The ignition process was observed to be governed by the delayed formation, growth and transport of a flame kernel which spreads to complete the major portion of the burn only after the injection process has been completed. The factors found to influence the evolution of the flame kernel could be possible mechanisms for the high cyclic variability and high hydrocarbon emissions observed for DISC engines of the type simulated.

  16. Relativistic MHD simulations of collision-induced magnetic dissipation in poynting-flux-dominated jets/outflows

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Deng, Wei; Li, Hui; Zhang, Bing; Li, Shengtai

    2015-05-29

    We perform 3D relativistic ideal MHD simulations to study the collisions between high-σ (Poynting- ux-dominated) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable Poynting- ux-dominated jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvenic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in themore » relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini-jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. In conclusion, our results give support to the proposed astrophysical models that invoke signi cant magnetic energy dissipation in Poynting- ux-dominated jets, such as the internal collision-induced magnetic reconnection and turbulence (ICMART) model for GRBs, and reconnection triggered mini-jets model for AGNs.« less

  17. Dynamic control of a homogeneous charge compression ignition engine

    DOE Patents [OSTI]

    Duffy, Kevin P.; Mehresh, Parag; Schuh, David; Kieser, Andrew J.; Hergart, Carl-Anders; Hardy, William L.; Rodman, Anthony; Liechty, Michael P.

    2008-06-03

    A homogenous charge compression ignition engine is operated by compressing a charge mixture of air, exhaust and fuel in a combustion chamber to an autoignition condition of the fuel. The engine may facilitate a transition from a first combination of speed and load to a second combination of speed and load by changing the charge mixture and compression ratio. This may be accomplished in a consecutive engine cycle by adjusting both a fuel injector control signal and a variable valve control signal away from a nominal variable valve control signal. Thereafter in one or more subsequent engine cycles, more sluggish adjustments are made to at least one of a geometric compression ratio control signal and an exhaust gas recirculation control signal to allow the variable valve control signal to be readjusted back toward its nominal variable valve control signal setting. By readjusting the variable valve control signal back toward its nominal setting, the engine will be ready for another transition to a new combination of engine speed and load.

  18. Direct drive: Simulations and results from the National Ignition Facility

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Radha, P. B.; Hohenberger, M.; Edgell, D. H.; Marozas, J. A.; Marshall, F. J.; Michel, D. T.; Rosenberg, M. J.; Seka, W.; Shvydky, A.; Boehly, T. R.; et al

    2016-04-19

    Here, the direct-drive implosion physics is being investigated at the National Ignition Facility. The primary goal of the experiments is twofold: to validate modeling related to implosion velocity and to estimate the magnitude of hot-electron preheat. Implosion experiments indicate that the energetics is well-modeled when cross-beam energy transfer (CBET) is included in the simulation and an overall multiplier to the CBET gain factor is employed; time-resolved scattered light and scattered-light spectra display the correct trends. Trajectories from backlit images are well modeled, although those from measured self-emission images indicate increased shell thickness and reduced shell density relative to simulations. Sensitivitymore » analyses indicate that the most likely cause for the density reduction is nonuniformity growth seeded by laser imprint and not laser-energy coupling. Hot-electron preheat is at tolerable levels in the ongoing experiments, although it is expected to increase after the mitigation of CBET. Future work will include continued model validation, imprint measurements, and mitigation of CBET and hot-electron preheat.« less

  19. Method for fabricating an ignitable heterogeneous stratified metal structure

    DOE Patents [OSTI]

    Barbee, T.W. Jr.; Weihs, T.

    1996-08-20

    A multilayer structure has a selectable: (1) propagating reaction front velocity V; (2) reaction initiation temperature attained by application of external energy; and (3) amount of energy delivered by a reaction of alternating unreacted layers of the multilayer structure. Because V is selectable and controllable, a variety of different applications for the multilayer structures are possible, including but not limited to their use as igniters, in joining applications, in fabrication of new materials, as smart materials and in medical applications and devices. The multilayer structure has a period D, and an energy release rate constant K. Two or more alternating unreacted layers are made of different materials and separated by reacted zones. The period D is equal to a sum of the widths of each single alternating reaction layer of a particular material, and also includes a sum of reacted zone widths, t{sub i}, in the period D. The multilayer structure has a selectable propagating reaction front velocity V, where V=K(1/D{sup n}){times}[1-(t{sub i}/D)] and n is about 0.8 to 1.2. 8 figs.

  20. Preliminary hazards analysis for the National Ignition Facility

    SciTech Connect (OSTI)

    Brereton, S.J.

    1993-10-01

    This report documents the Preliminary Hazards Analysis (PHA) for the National Ignition Facility (NIF). In summary, it provides: a general description of the facility and its operation; identification of hazards at the facility; and details of the hazards analysis, including inventories, bounding releases, consequences, and conclusions. As part of the safety analysis procedure set forth by DOE, a PHA must be performed for the NIF. The PHA characterizes the level of intrinsic potential hazard associated with a facility, and provides the basis for hazard classification. The hazard classification determines the level of safety documentation required, and the DOE Order governing the safety analysis. The hazard classification also determines the level of review and approval required for the safety analysis report. The hazards of primary concern associated with NIF are radiological and toxicological in nature. The hazard classification is determined by comparing facility inventories of radionuclides and chemicals with threshold values for the various hazard classification levels and by examining postulated bounding accidents associated with the hazards of greatest significance. Such postulated bounding accidents cannot take into account active mitigative features; they must assume the unmitigated consequences of a release, taking into account only passive safety features. In this way, the intrinsic hazard level of the facility can be ascertained.

  1. Nuclear imaging of the fuel assembly in ignition experiments

    SciTech Connect (OSTI)

    Grim, G. P.; Guler, N.; Merrill, F. E.; Morgan, G. L.; Danly, C. R.; Volegov, P. L.; Wilde, C. H.; Wilson, D. C.; Clark, D. S.; Hinkel, D. E.; Jones, O. S.; Raman, K. S.; Izumi, N.; Fittinghoff, D. N.; Drury, O. B.; Alger, E. T.; Arnold, P. A.; Ashabranner, R. C.; Atherton, L. J.; Barrios, M. A.; Batha, S.; Bell, P. M.; Benedetti, L. R.; Berger, R. L.; Bernstein, L. A.; Berzins, L. V.; Betti, R.; Bhandarkar, S. D.; Bionta, R. M.; Bleuel, D. L.; Boehly, T. R.; Bond, E. J.; Bowers, M. W.; Bradley, D. K.; Brunton, G. K.; Buckles, R. A.; Burkhart, S. C.; Burr, R. F.; Caggiano, J. A.; Callahan, D. A.; Casey, D. T.; Castro, C.; Celliers, P. M.; Cerjan, C. J.; Chandler, G. A.; Choate, C.; Cohen, S. J.; Collins, G. W.; Cooper, G. W.; Cox, J. R.; Cradick, J. R.; Datte, P. S.; Dewald, E. L.; Di Nicola, P.; Di Nicola, J. M.; Divol, L.; Dixit, S. N.; Dylla-Spears, R.; Dzenitis, E. G.; Eckart, M. J.; Eder, D. C.; Edgell, D. H.; Edwards, M. J.; Eggert, J. H.; Ehrlich, R. B.; Erbert, G. V.; Fair, J.; Farley, D. R.; Felker, B.; Fortner, R. J.; Frenje, J. A.; Frieders, G.; Friedrich, S.; Gatu-Johnson, M.; Gibson, C. R.; Giraldez, E.; Glebov, V. Y.; Glenn, S. M.; Glenzer, S. H.; Gururangan, G.; Haan, S. W.; Hahn, K. D.; Hammel, B. A.; Hamza, A. V.; Hartouni, E. P.; Hatarik, R.; Hatchett, S. P.; Haynam, C.; Hermann, M. R.; Herrmann, H. W.; Hicks, D. G.; Holder, J. P.; Holunga, D. M.; Horner, J. B.; Hsing, W. W.; Huang, H.; Jackson, M. C.; Jancaitis, K. S.; Kalantar, D. H.; Kauffman, R. L.; Kauffman, M. I.; Khan, S. F.; Kilkenny, J. D.; Kimbrough, J. R.; Kirkwood, R.; Kline, J. L.; Knauer, J. P.; Knittel, K. M.; Koch, J. A.; Kohut, T. R.; Kozioziemski, B. J.; Krauter, K.; Krauter, G. W.; Kritcher, A. L.; Kroll, J.; Kyrala, G. A.; Fortune, K. N. La; LaCaille, G.; Lagin, L. J.; Land, T. A.; Landen, O. L.; Larson, D. W.; Latray, D. A.; Leeper, R. J.; Lewis, T. L.; LePape, S.; Lindl, J. D.; Lowe-Webb, R. R.; Ma, T.; MacGowan, B. J.; MacKinnon, A. J.; MacPhee, A. G.; Malone, R. M.; Malsbury, T. N.; Mapoles, E.; Marshall, C. D.; Mathisen, D. G.; McKenty, P.; McNaney, J. M.; Meezan, N. B.; Michel, P.; Milovich, J. L.; Moody, J. D.; Moore, A. S.; Moran, M. J.; Moreno, K.; Moses, E. I.; Munro, D. H.; Nathan, B. R.; Nelson, A. J.; Nikroo, A.; Olson, R. E.; Orth, C.; Pak, A. E.; Palma, E. S.; Parham, T. G.; Patel, P. K.; Patterson, R. W.; Petrasso, R. D.; Prasad, R.; Ralph, J. E.; Regan, S. P.; Rinderknecht, H.; Robey, H. F.; Ross, G. F.; Ruiz, C. L.; Se?guin, F. H.; Salmonson, J. D.; Sangster, T. C.; Sater, J. D.; Saunders, R. L.; Schneider, M. B.; Schneider, D. H.; Shaw, M. J.; Simanovskaia, N.; Spears, B. K.; Springer, P. T.; Stoeckl, C.; Stoeffl, W.; Suter, L. J.; Thomas, C. A.; Tommasini, R.; Town, R. P.; Traille, A. J.; Wonterghem, B. Van; Wallace, R. J.; Weaver, S.; Weber, S. V.; Wegner, P. J.; Whitman, P. K.; Widmann, K.; Widmayer, C. C.; Wood, R. D.; Young, B. K.; Zacharias, R. A.; Zylstra, A.

    2013-01-01

    First results from the analysis of neutron image data collected on implosions of cryogenically layered deuterium-tritium capsules during the 2011-2012 National Ignition Campaign are reported. The data span a variety of experimental designs aimed at increasing the stagnation pressure of the central hotspot and areal density of the surrounding fuel assembly. Images of neutrons produced by deuteriumtritium fusion reactions in the hotspot are presented, as well as images of neutrons that scatter in the surrounding dense fuel assembly. The image data are compared with 1D and 2D model predictions, and consistency checked using other diagnostic data. The results indicate that the size of the fusing hotspot is consistent with the model predictions, as well as other imaging data, while the overall size of the fuel assembly, inferred from the scattered neutron images, is systematically smaller than models prediction. Preliminary studies indicate these differences are consistent with a significant fraction (20%25%) of the initial deuterium-tritium fuel mass outside the compact fuel assembly, due either to low mode mass asymmetry or high mode 3D mix effects at the ablator-ice interface.

  2. String model for spinning quark jets

    SciTech Connect (OSTI)

    Artru, X.; Belghobsi, Z.

    2012-06-27

    A string model of quark hadronization, taking the quark spin degree of freedom into account, is proposed. The method for using the model in a Monte-Carlo code for jet generation is given.

  3. Jet-images — deep learning edition

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    de Oliveira, Luke; Kagan, Michael; Mackey, Lester; Nachman, Benjamin; Schwartzman, Ariel

    2016-07-13

    Building on the notion of a particle physics detector as a camera and the collimated streams of high energy particles, or jets, it measures as an image, we investigate the potential of machine learning techniques based on deep learning architectures to identify highly boosted W bosons. Modern deep learning algorithms trained on jet images can out-perform standard physically-motivated feature driven approaches to jet tagging. We develop techniques for visualizing how these features are learned by the network and what additional information is used to improve performance. Finally, this interplay between physicallymotivated feature driven tools and supervised learning algorithms is generalmore » and can be used to significantly increase the sensitivity to discover new particles and new forces, and gain a deeper understanding of the physics within jets.« less

  4. Flux-driven simulations of turbulence collapse

    SciTech Connect (OSTI)

    Park, G. Y.; Kim, S. S.; Jhang, Hogun; Rhee, T.; Diamond, P. H.; Xu, X. Q.

    2015-03-15

    Using three-dimensional nonlinear simulations of tokamak turbulence, we show that an edge transport barrier (ETB) forms naturally once input power exceeds a threshold value. Profiles, turbulence-driven flows, and neoclassical coefficients are evolved self-consistently. A slow power ramp-up simulation shows that ETB transition is triggered by the turbulence-driven flows via an intermediate phase which involves coherent oscillation of turbulence intensity and E×B flow shear. A novel observation of the evolution is that the turbulence collapses and the ETB transition begins when R{sub T} > 1 at t = t{sub R} (R{sub T}: normalized Reynolds power), while the conventional transition criterion (ω{sub E×B}>γ{sub lin} where ω{sub E×B} denotes mean flow shear) is satisfied only after t = t{sub C} ( >t{sub R}), when the mean flow shear grows due to positive feedback.

  5. Gap between jets at the LHC

    SciTech Connect (OSTI)

    Royon, Christophe

    2013-04-15

    We describe a NLL BFKL calculation implemented in the HERWIG MC of the gap between jets cross section, that represent a test of BFKL dynamics. We compare the predictions with recent measurements at the Tevatron and present predictions for the LHC. We also discuss the interesting process of looking for gap between jets in diffractive events when protons are detected in the ATLAS Forward Physics (AFP) detectors.

  6. Santa Fe Jets and Heavy Flavor Workshop

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Santa Fe Jets and Heavy Flavor Workshop Santa Fe Jets and Heavy Flavor Workshop WHEN: Jan 11, 2016 8:30 AM - Jan 13, 2016 5:30 PM WHERE: Inn and Spa at Loretto 211 Old Santa Fe Trail Santa Fe, New Mexico 87501 USA CONTACT: Ivan Vitev CATEGORY: Science TYPE: Conference INTERNAL: Calendar Login Event Description This workshop will bring together senior researchers, postdoctoral fellows and talented graduate students to discuss the exciting recent developments and future directions in high energy

  7. Estimation of k-e parameters using surrogate models and jet-in-crossflow data.

    SciTech Connect (OSTI)

    Lefantzi, Sophia; Ray, Jaideep; Arunajatesan, Srinivasan; Dechant, Lawrence

    2015-02-01

    We demonstrate a Bayesian method that can be used to calibrate computationally expensive 3D RANS (Reynolds Av- eraged Navier Stokes) models with complex response surfaces. Such calibrations, conditioned on experimental data, can yield turbulence model parameters as probability density functions (PDF), concisely capturing the uncertainty in the parameter estimates. Methods such as Markov chain Monte Carlo (MCMC) estimate the PDF by sampling, with each sample requiring a run of the RANS model. Consequently a quick-running surrogate is used instead to the RANS simulator. The surrogate can be very difficult to design if the model's response i.e., the dependence of the calibration variable (the observable) on the parameter being estimated is complex. We show how the training data used to construct the surrogate can be employed to isolate a promising and physically realistic part of the parameter space, within which the response is well-behaved and easily modeled. We design a classifier, based on treed linear models, to model the "well-behaved region". This classifier serves as a prior in a Bayesian calibration study aimed at estimating 3 k [?] e parameters ( C u , C e 2 , C e 1 ) from experimental data of a transonic jet-in-crossflow interaction. The robustness of the calibration is investigated by checking its predictions of variables not included in the cal- ibration data. We also check the limit of applicability of the calibration by testing at off-calibration flow regimes. We find that calibration yield turbulence model parameters which predict the flowfield far better than when the nomi- nal values of the parameters are used. Substantial improvements are still obtained when we use the calibrated RANS model to predict jet-in-crossflow at Mach numbers and jet strengths quite different from those used to generate the ex- perimental (calibration) data. Thus the primary reason for poor predictive skill of RANS, when using nominal values of the turbulence model

  8. JET ROTATION DRIVEN BY MAGNETOHYDRODYNAMIC SHOCKS IN HELICAL MAGNETIC FIELDS

    SciTech Connect (OSTI)

    Fendt, Christian

    2011-08-10

    In this paper, we present a detailed numerical investigation of the hypothesis that a rotation of astrophysical jets can be caused by magnetohydrodynamic (MHD) shocks in a helical magnetic field. Shock compression of the helical magnetic field results in a toroidal Lorentz force component that will accelerate the jet material in the toroidal direction. This process transforms magnetic angular momentum (magnetic stress) carried along the jet into kinetic angular momentum (rotation). The mechanism proposed here only works in a helical magnetic field configuration. We demonstrate the feasibility of this mechanism by axisymmetric MHD simulations in 1.5 and 2.5 dimensions using the PLUTO code. In our setup, the jet is injected into the ambient gas with zero kinetic angular momentum (no rotation). We apply different dynamical parameters for jet propagation such as the jet internal Alfven Mach number and fast magnetosonic Mach number, the density contrast of the jet to the ambient medium, and the external sonic Mach number of the jet. The mechanism we suggest should work for a variety of jet applications, e.g., protostellar or extragalactic jets, and internal jet shocks (jet knots) or external shocks between the jet and the ambient gas (entrainment). For typical parameter values for protostellar jets, the numerically derived rotation feature looks consistent with the observations, i.e., rotational velocities of 0.1%-1% of the jet bulk velocity.

  9. Study of jet properties at the Tevatron

    SciTech Connect (OSTI)

    Martinez, Mario; /Barcelona, IFAE

    2005-05-01

    The Run II at the Tevatron will define a new level of precision for QCD studies in hadron collisions. Both collider experiments, CDF and D0, expect to collect up to 8 fb{sup -1} of data in this new run period. The increase in instantaneous luminosity, center-of-mass energy (from 1.8 TeV to 2 TeV) and the improved acceptance of the detectors will allow stringent tests of the Standard Model (SM) predictions in extended regions of jet transverse momentum, P{sub T}{sup jet}, and jet rapidity, Y{sup jet}. The hadronic final states in hadron-hadron collisions are characterized by the presence of soft contributions (the so-called underlying event) from initial-state gluon radiation and multiple parton interactions between remnants, in addition to the jets of hadrons originated by the hard interaction. A proper comparison with pQCD predictions at the parton level requires an adequate modeling of these soft contributions which become important at low P{sub T}{sup jet}. In this letter, a review of some of the most important QCD results from Run II is presented.

  10. Structure and Dynamics of Colliding Plasma Jets

    SciTech Connect (OSTI)

    Li, C.; Ryutov, D.; Hu, S.; Rosenberg, M.; Zylstra, A.; Seguin, F.; Frenje, J.; Casey, D.; Gatu Johnson, M.; Manuel, M.; Rinderknecht, H.; Petrasso, R.; Amendt, P.; Park, H.; Remington, B.; Wilks, S.; Betti, R.; Froula, D.; Knauer, J.; Meyerhofer, D.; Drake, R.; Kuranz, C.; Young, R.; Koenig, M.

    2013-12-01

    Monoenergetic-proton radiographs of laser-generated, high-Mach-number plasma jets colliding at various angles shed light on the structures and dynamics of these collisions. The observations compare favorably with results from 2D hydrodynamic simulations of multistream plasma jets, and also with results from an analytic treatment of electron flow and magnetic field advection. In collisions of two noncollinear jets, the observed flow structure is similar to the analytic model’s prediction of a characteristic feature with a narrow structure pointing in one direction and a much thicker one pointing in the opposite direction. Spontaneous magnetic fields, largely azimuthal around the colliding jets and generated by the well-known ∇Te ×∇ne Biermann battery effect near the periphery of the laser spots, are demonstrated to be “frozen in” the plasma (due to high magnetic Reynolds number RM ~5×10⁴) and advected along the jet streamlines of the electron flow. These studies provide novel insight into the interactions and dynamics of colliding plasma jets.

  11. Structure and Dynamics of Colliding Plasma Jets

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, C.; Ryutov, D.; Hu, S.; Rosenberg, M.; Zylstra, A.; Seguin, F.; Frenje, J.; Casey, D.; Gatu Johnson, M.; Manuel, M.; et al

    2013-12-01

    Monoenergetic-proton radiographs of laser-generated, high-Mach-number plasma jets colliding at various angles shed light on the structures and dynamics of these collisions. The observations compare favorably with results from 2D hydrodynamic simulations of multistream plasma jets, and also with results from an analytic treatment of electron flow and magnetic field advection. In collisions of two noncollinear jets, the observed flow structure is similar to the analytic model’s prediction of a characteristic feature with a narrow structure pointing in one direction and a much thicker one pointing in the opposite direction. Spontaneous magnetic fields, largely azimuthal around the colliding jets and generatedmore » by the well-known ∇Te ×∇ne Biermann battery effect near the periphery of the laser spots, are demonstrated to be “frozen in” the plasma (due to high magnetic Reynolds number RM ~5×10⁴) and advected along the jet streamlines of the electron flow. These studies provide novel insight into the interactions and dynamics of colliding plasma jets.« less

  12. The National Ignition Facility (NIF) Diagnostic Set at the Completion of the National Ignition Campaign (NIC) September 2013

    SciTech Connect (OSTI)

    Kilkenny, J.; Bell, P. E.; Bradley, D. K.; Bleuel, D. L.; Caggiano, J. A.; Dewald, E. L.; Hsing, W.; Kalantar, H.; Kauffman, R.; Moody, J. D.; Schneider, M. B.; Shaughnessy, D. A.; Shelton, R. T.; Yeamans, C. B.; Batha, S. H.; Grim, G. P.; Herrmann, H. W.; Merrill, F. E.; Leeper, R. J.; Sangster, T. C.; Edgell, D. H.; Glebov, V. Y.; Regan, S. P.; Frenje, J. A.; Gatu-Johnson, M.; Petrasso, R. D.; Rindernecht, H. G.; Zylstra, A. B.; Cooper, G. W.; Ruiz, C.

    2015-01-05

    At the completion of the National Ignition Campaign NIF had about 36 different types of diagnostics. These were based on several decades of development on Nova and OMEGA and involved the whole US ICF community. A plan for a limited of NIF Diagnostics was documented by the Joint Central Diagnostic Team in the NIF Conceptual Design Report in 1994. These diagnostics and many more were installed diagnostics by two decades later. We give a short description of each of the 36 different types of NIC diagnostics grouped by the function of the diagnostics, namely target drive, target response and target assembly, stagnation and burn. A comparison of NIF diagnostics with the Nova diagnostics shows that the NIF diagnostic capability is broadly equivalent to that of Nova’s in 1999. NIF diagnostics have a much greater degree of automation and rigor than Nova’s and the NIF diagnostic suite incorporates some scientific innovation compared to Nova and OMEGA namely one much higher speed x-ray imager. Directions for future NIF diagnostics are discussed.

  13. Formative time of breakdown modeled for the ignition of air and n-butane mixtures using effective ionization coefficients

    SciTech Connect (OSTI)

    Kudryavtsev, A. A.; Popugaev, S. D.; Demidov, V. I.; Adams, S. F.; Jiao, C. Q.

    2008-12-15

    It is shown that simulations of ignition by electric arc discharge in n-butane and air mixtures have interesting features, which deviate from results obtained by simple extension of calculations based on methanelike fuels. In particular, it is demonstrated that lowering the temperature of the n-butane-air mixture before ignition under certain conditions will actually decrease the ignition stage time as well as the required electric field.

  14. THE FATE OF PLANETESIMALS IN TURBULENT DISKS WITH DEAD ZONES. I. THE TURBULENT STIRRING RECIPE

    SciTech Connect (OSTI)

    Okuzumi, Satoshi [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551 (Japan); Ormel, Chris W., E-mail: okuzumi@geo.titech.ac.jp [Astronomy Department, University of California, Berkeley, CA 94720 (United States)

    2013-07-01

    Turbulence in protoplanetary disks affects planet formation in many ways. While small dust particles are mainly affected by the aerodynamical coupling with turbulent gas velocity fields, planetesimals and larger bodies are more affected by gravitational interaction with gas density fluctuations. For the latter process, a number of numerical simulations have been performed in recent years, but a fully parameter-independent understanding has not been yet established. In this study, we present simple scaling relations for the planetesimal stirring rate in turbulence driven by magnetorotational instability (MRI), taking into account the stabilization of MRI due to ohmic resistivity. We begin with order-of-magnitude estimates of the turbulence-induced gravitational force acting on solid bodies and associated diffusion coefficients for their orbital elements. We then test the predicted scaling relations using the results of recent ohmic-resistive MHD simulations by Gressel et al. We find that these relations successfully explain the simulation results if we properly fix order-of-unity uncertainties within the estimates. We also update the saturation predictor for the density fluctuation amplitude in MRI-driven turbulence originally proposed by Okuzumi and Hirose. Combination of the scaling relations and saturation predictor allows us to know how the turbulent stirring rate of planetesimals depends on disk parameters such as the gas column density, distance from the central star, vertical resistivity distribution, and net vertical magnetic flux. In Paper II, we apply our recipe to planetesimal accretion to discuss its viability in turbulent disks.

  15. A signature for turbulence driven magnetic islands

    SciTech Connect (OSTI)

    Agullo, O.; Muraglia, M.; Benkadda, S.; Poyé, A.; Yagi, M.; Garbet, X.; Sen, A.

    2014-09-15

    We investigate the properties of magnetic islands arising from tearing instabilities that are driven by an interchange turbulence. We find that such islands possess a specific signature that permits an identification of their origin. We demonstrate that the persistence of a small scale turbulence maintains a mean pressure profile, whose characteristics makes it possible to discriminate between turbulence driven islands from those arising due to an unfavourable plasma current density gradient. We also find that the island poloidal turnover time, in the steady state, is independent of the levels of the interchange and tearing energy sources. Finally, we show that a mixing length approach is adequate to make theoretical predictions concerning island flattening in the island rotation frame.

  16. Boundary Plasma Turbulence Simulations for Tokamaks

    SciTech Connect (OSTI)

    Xu, X; Umansky, M; Dudson, B; Snyder, P

    2008-05-15

    The boundary plasma turbulence code BOUT models tokamak boundary-plasma turbulence in a realistic divertor geometry using modified Braginskii equations for plasma vorticity, density (ni), electron and ion temperature (T{sub e}; T{sub i}) and parallel momenta. The BOUT code solves for the plasma fluid equations in a three dimensional (3D) toroidal segment (or a toroidal wedge), including the region somewhat inside the separatrix and extending into the scrape-off layer; the private flux region is also included. In this paper, a description is given of the sophisticated physical models, innovative numerical algorithms, and modern software design used to simulate edge-plasmas in magnetic fusion energy devices. The BOUT code's unique capabilities and functionality are exemplified via simulations of the impact of plasma density on tokamak edge turbulence and blob dynamics.

  17. RELAXATION PROCESSES IN SOLAR WIND TURBULENCE

    SciTech Connect (OSTI)

    Servidio, S.; Carbone, V.; Gurgiolo, C.; Goldstein, M. L.

    2014-07-10

    Based on global conservation principles, magnetohydrodynamic (MHD) relaxation theory predicts the existence of several equilibria, such as the Taylor state or global dynamic alignment. These states are generally viewed as very long-time and large-scale equilibria, which emerge only after the termination of the turbulent cascade. As suggested by hydrodynamics and by recent MHD numerical simulations, relaxation processes can occur during the turbulent cascade that will manifest themselves as local patches of equilibrium-like configurations. Using multi-spacecraft analysis techniques in conjunction with Cluster data, we compute the current density and flow vorticity and for the first time demonstrate that these localized relaxation events are observed in the solar wind. Such events have important consequences for the statistics of plasma turbulence.

  18. Core density turbulence in the HSX Stellarator

    SciTech Connect (OSTI)

    Deng, C. B.; Brower, D. L.; Anderson, D. T.; Anderson, F. S. B.; Briesemeister, Alexis R.; Likin, K. M.

    2015-10-23

    Broadband turbulent density fluctuations are explored in the helically symmetric stellarator experiment (HSX) by investigating changes related to plasma heating power and location. No fluctuation response is observed to occur with large changes in electron temperature and its gradient, thereby eliminating temperature gradient as a driving mechanism. Instead, measurements reveal that density turbulence varies inversely with electron density scale length. This response is consistent with density gradient drive as one might expect for trapped electron mode (TEM) turbulence. In general, the plasma stored energy and particle confinement are higher for discharges with reduced fluctuations in the plasma core. When the density fluctuation amplitude is reduced, increased plasma rotation is also evident suggesting a role is being played by intrinsic plasma flow.

  19. PHOTOSPHERIC EMISSION FROM STRATIFIED JETS

    SciTech Connect (OSTI)

    Ito, Hirotaka; Nagataki, Shigehiro; Ono, Masaomi; Lee, Shiu-Hang; Mao, Jirong; Yamada, Shoichi; Pe'er, Asaf; Mizuta, Akira; Harikae, Seiji

    2013-11-01

    We explore photospheric emissions from stratified two-component jets, wherein a highly relativistic spine outflow is surrounded by a wider and less relativistic sheath outflow. Thermal photons are injected in regions of high optical depth and propagated until the photons escape at the photosphere. Because of the presence of shear in velocity (Lorentz factor) at the boundary of the spine and sheath region, a fraction of the injected photons are accelerated using a Fermi-like acceleration mechanism such that a high-energy power-law tail is formed in the resultant spectrum. We show, in particular, that if a velocity shear with a considerable variance in the bulk Lorentz factor is present, the high-energy part of observed gamma-ray bursts (GRBs) photon spectrum can be explained by this photon acceleration mechanism. We also show that the accelerated photons might also account for the origin of the extra-hard power-law component above the bump of the thermal-like peak seen in some peculiar bursts (e.g., GRB 090510, 090902B, 090926A). We demonstrate that time-integrated spectra can also reproduce the low-energy spectrum of GRBs consistently using a multi-temperature effect when time evolution of the outflow is considered. Last, we show that the empirical E{sub p}-L{sub p} relation can be explained by differences in the outflow properties of individual sources.

  20. Advances in Inertial Confinement Fusion at the National Ignition Facility (NIF)

    SciTech Connect (OSTI)

    Moses, E

    2009-10-15

    The 192-beam National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in Livermore, CA, is now operational and conducting experiments. NIF, the flagship facility of the U.S. Inertial Confinement Fusion (ICF) Program, will achieve high-energy-density conditions never previously obtained in the laboratory - temperatures over 100 million K, densities of 1,000 g/cm3, and pressures exceeding 100 billion atmospheres. Such conditions exist naturally only in the interiors of the stars and during thermonuclear burn. Demonstration of ignition and thermonuclear burn in the laboratory is a major NIF goal. To date, the NIF laser has demonstrated all pulse shape, beam quality, energy, and other specifications required to meet the ignition challenge. On March 10, 2009, the NIF laser delivered 1.1 MJ of ultraviolet laser energy to target chamber center, approximately 30 times more energy than any previous facility. The ignition program at NIF is the National Ignition Campaign (NIC), a national collaboration for ignition experimentation with participation from General Atomics, LLNL, Los Alamos National Laboratory (LANL), Sandia National Laboratories (SNL), and the University of Rochester Laboratory for Laser Energetics (LLE). The achievement of ignition at NIF will demonstrate the scientific feasibility of ICF and focus worldwide attention on fusion as a viable energy option. A particular energy concept under investigation is the LIFE (Laser Inertial Fusion Energy) scheme. The LIFE engine is inherently safe, minimizes proliferation concerns associated with the nuclear fuel cycle, and can provide a sustainable carbon-free energy generation solution in the 21st century. This talk will describe NIF and its potential as a user facility and an experimental platform for high-energy-density science, NIC, and the LIFE approach for clean, sustainable energy.