National Library of Energy BETA

Sample records for modes mode fraction

  1. Damped Modes

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

    ... . . . . . . . . 95 4.4 Percentage of electromagnetic energy in total energy of POD modes . ... 102 4.9 Nonlinear energy transfer k ' y spectrum of POD modes . . . . . . . . . . . . . . ...

  2. Mode Analyses

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

    Mode Analyses of Gyrokinetic Simulations of Plasma Microturbulence by David R. Hatch A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Physics) at The University of Wisconsin - Madison 2010 c Copyright by David R. Hatch 2010 All Rights Reserved i For Jen and Owen ii ACKNOWLEDGEMENTS I would like to thank my advisor, Paul Terry, who provided me with a research topic which I have found engaging and challenging, and has also offered an ideal

  3. Cluster Compatibility Mode

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

    Hopper Cluster Compatibility Mode Cluster Compatibility Mode Overview Hopper compute nodes run a stripped down Linux operating system called compute node Linux (CNL). Some...

  4. Cluster Compatibility Mode

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

    Cluster Compatibility Mode Cluster Compatibility Mode Edison compute nodes run a stripped-down Linux operating system called Compute Node Linux (CNL). Some standard Linux services,...

  5. List mode multichannel analyzer

    DOE Patents [OSTI]

    Archer, Daniel E.; Luke, S. John; Mauger, G. Joseph; Riot, Vincent J.; Knapp, David A.

    2007-08-07

    A digital list mode multichannel analyzer (MCA) built around a programmable FPGA device for onboard data analysis and on-the-fly modification of system detection/operating parameters, and capable of collecting and processing data in very small time bins (<1 millisecond) when used in histogramming mode, or in list mode as a list mode MCA.

  6. Kink modes in pedestal

    SciTech Connect (OSTI)

    Wang, Z. T.; College of Physics Science and Technology, Sichuan University, Chengdu 610065 ; He, Z. X.; Dong, J. Q.; Wang, Z. H.; Xu, M.; Xu, X. L.; Mou, M. L.; Sun, T. T.; Huang, J.; Chen, S. Y.; Tang, C. J.

    2014-03-15

    Kink modes are investigated in pedestal for shaped tokamaks. An analytic combining criterion is presented. It lies on the middle of the sufficient criterion of Lortz and necessary criterion of Mercier giving a more restricted necessary criterion. Growth rates and mode structure are calculated. For large poloidal mode number, the modes are highly localized in both poloidal and radial directions. The modes increase rapidly when they approach to the resonant surface. They are typical of edge localized modes (ELMs). It is assumed that the modes vanish inside the next resonant surface, then, there seems to be a second stable region. Several mitigation methods for controlling ELMs are proposed.

  7. Cluster Compatibility Mode

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

    the needed runtime environment. Users can also compile codes for CCM on Hopper. All compilers available to Hopper's native programming environment (Extreme Scalability Mode, ESM...

  8. Zero-mode waveguides

    DOE Patents [OSTI]

    Levene, Michael J.; Korlach, Jonas; Turner, Stephen W.; Craighead, Harold G.; Webb, Watt W.

    2007-02-20

    The present invention is directed to a method and an apparatus for analysis of an analyte. The method involves providing a zero-mode waveguide which includes a cladding surrounding a core where the cladding is configured to preclude propagation of electromagnetic energy of a frequency less than a cutoff frequency longitudinally through the core of the zero-mode waveguide. The analyte is positioned in the core of the zero-mode waveguide and is then subjected, in the core of the zero-mode waveguide, to activating electromagnetic radiation of a frequency less than the cut-off frequency under conditions effective to permit analysis of the analyte in an effective observation volume which is more compact than if the analysis were carried out in the absence of the zero-mode waveguide.

  9. The electron geodesic acoustic mode

    SciTech Connect (OSTI)

    Chakrabarti, N. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Calcutta 700 064 (India); Guzdar, P. N. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Kaw, P. K. [Institute for Plasma Research Bhat, Gandhinagar 382428 (India)

    2012-09-15

    In this report, a novel new mode, named the electron geodesic acoustic mode, is presented. This mode can occur in toroidal plasmas like the conventional geodesic acoustic mode (GAM). The frequency of this new mode is much larger than that of the conventional GAM by a factor equal to the square root of the ion to electron mass ratio.

  10. Synthesize Modes and Correlate

    Energy Science and Technology Software Center (OSTI)

    2005-10-01

    SMAC is an automated experimental modal parameter extraction package which determines the natural frequencies of vibration, viscous damping ratios and mode shapes from experimental accelerance frequency response functions (FRFs). It is written in the MATLAB interpretive matrix language and has a graphical user interface.

  11. Constraining primordial vector mode from B-mode polarization

    SciTech Connect (OSTI)

    Saga, Shohei; Ichiki, Kiyotomo; Shiraishi, Maresuke E-mail: maresuke.shiraishi@pd.infn.it

    2014-10-01

    The B-mode polarization spectrum of the Cosmic Microwave Background (CMB) may be the smoking gun of not only the primordial tensor mode but also of the primordial vector mode. If there exist nonzero vector-mode metric perturbations in the early Universe, they are known to be supported by anisotropic stress fluctuations of free-streaming particles such as neutrinos, and to create characteristic signatures on both the CMB temperature, E-mode, and B-mode polarization anisotropies. We place constraints on the properties of the primordial vector mode characterized by the vector-to-scalar ratio r{sub v} and the spectral index n{sub v} of the vector-shear power spectrum, from the Planck and BICEP2 B-mode data. We find that, for scale-invariant initial spectra, the ?CDM model including the vector mode fits the data better than the model including the tensor mode. The difference in ?{sup 2} between the vector and tensor models is ??{sup 2}=3.294, because, on large scales the vector mode generates smaller temperature fluctuations than the tensor mode, which is preferred for the data. In contrast, the tensor mode can fit the data set equally well if we allow a significantly blue-tilted spectrum. We find that the best-fitting tensor mode has a large blue tilt and leads to an indistinct reionization bump on larger angular scales. The slightly red-tilted vector mode supported by the current data set can also create O(10{sup -22})-Gauss magnetic fields at cosmological recombination. Our constraints should motivate research that considers models of the early Universe that involve the vector mode.

  12. Elemental Modes of Occurrence in an Illinois #6 Coal and Fractions Prepared by Physical Separation Techniques at a Coal Preparation Plant

    SciTech Connect (OSTI)

    Huggins, F.; Seidu, L; Shah, N; Huffman, G; Honaker, R; Kyger, J; Higgins, B; Robertson, J; Pal, S; Seehra, M

    2009-01-01

    In order to gain better insight into elemental partitioning between clean coal and tailings, modes of occurrence have been determined for a number of major and trace elements (S, K, Ca, V, Cr, Mn, Fe, Zn, As, Se, Pb) in an Illinois No.6 coal and fractions prepared by physical separation methods at a commercial coal preparation plant. Elemental modes of occurrence were largely determined directly by XAFS or Moessbauer spectroscopic methods because the concentrations of major minerals and wt.% ash were found to be highly correlated for this coal and derived fractions, rendering correlations between individual elements and minerals ambiguous for inferring elemental modes of occurrence. Of the major elements investigated, iron and potassium are shown to be entirely inorganic in occurrence. Most (90%) of the iron is present as pyrite, with minor fractions in the form of clays and sulfates. All potassium is present in illitic clays. Calcium in the original coal is 80-90% inorganic and is divided between calcite, gypsum, and illite, with the remainder of the calcium present as carboxyl-bound calcium. In the clean coal fraction, organically associated Ca exceeds 50% of the total calcium. This organically-associated form of Ca explains the poorer separation of Ca relative to both K and ash. Among the trace elements, V and Cr are predominantly inorganically associated with illite, but minor amounts (5-15% Cr, 20-30% V) of these elements are also organically associated. Estimates of the V and Cr contents of illite are 420 ppm and 630 ppm, respectively, whereas these elements average 20 and 8 ppm in the macerals. Arsenic in the coal is almost entirely associated with pyrite, with an average As content of about 150 ppm, but some As ({approx} 10%) is present as arsenate due to minor oxidation of the pyrite. The mode of occurrence of Zn, although entirely inorganic, is more complex than normally noted for Illinois basin coals; about 2/3 is present in sphalerite, with lesser amounts associated with illite and a third form yet to be conclusively identified. The non-sulfide zinc forms are removed predominantly by the first stage of separation (rotary breaker), whereas the sphalerite is removed by the second stage (heavy media). Germanium is the only trace element determined to have a predominantly organic association.

  13. Electron geodesic acoustic modes in electron temperature gradient mode turbulence

    SciTech Connect (OSTI)

    Anderson, Johan; Nordman, Hans [Department of Earth and Space Sciences, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Singh, Raghvendra; Kaw, Predhiman [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2012-08-15

    In this work, the first demonstration of an electron branch of the geodesic acoustic mode (el-GAM) driven by electron temperature gradient (ETG) modes is presented. The work is based on a fluid description of the ETG mode retaining non-adiabatic ions and the dispersion relation for el-GAMs driven nonlinearly by ETG modes is derived. A new saturation mechanism for ETG turbulence through the interaction with el-GAMs is found, resulting in a significantly enhanced ETG turbulence saturation level compared to the mixing length estimate.

  14. Waveguides having patterned, flattened modes

    DOE Patents [OSTI]

    Messerly, Michael J.; Pax, Paul H.; Dawson, Jay W.

    2015-10-27

    Field-flattening strands may be added to and arbitrarily positioned within a field-flattening shell to create a waveguide that supports a patterned, flattened mode. Patterning does not alter the effective index or flattened nature of the mode, but does alter the characteristics of other modes. Compared to a telecom fiber, a hexagonal pattern of strands allows for a three-fold increase in the flattened mode's area without reducing the separation between its effective index and that of its bend-coupled mode. Hexagonal strand and shell elements prove to be a reasonable approximation, and, thus, to be of practical benefit vis-a-vis fabrication, to those of circular cross section. Patterned flattened modes offer a new and valuable path to power scaling.

  15. Waveguides having patterned, flattened modes

    DOE Patents [OSTI]

    Messerly, Michael J; Pax, Paul H; Dawson, Jay W

    2015-11-05

    Field-flattening strands may be added to and arbitrarily positioned within a field-flattening shell to create a waveguide that supports a patterned, flattened mode. Patterning does not alter the effective index or flattened nature of the mode, but does alter the characteristics of other modes. Compared to a telecom fiber, a hexagonal pattern of strands allows for a three-fold increase in the flattened mode's area without reducing the separation between its effective index and that of its bend-coupled mode. Hexagonal strand and shell elements prove to be a reasonable approximation, and, thus, to be of practical benefit vis-a-vis fabrication, to those of circular cross section. Patterned flattened modes offer a new and valuable path to power scaling.

  16. Mode synthesizing atomic force microscopy and mode-synthesizing sensing

    DOE Patents [OSTI]

    Passian, Ali; Thundat, Thomas George; Tetard, Laurene

    2013-05-17

    A method of analyzing a sample that includes applying a first set of energies at a first set of frequencies to a sample and applying, simultaneously with the applying the first set of energies, a second set of energies at a second set of frequencies, wherein the first set of energies and the second set of energies form a multi-mode coupling. The method further includes detecting an effect of the multi-mode coupling.

  17. Multi-mode radio frequency device

    DOE Patents [OSTI]

    Gilbert, Ronald W.; Carrender, Curtis Lee; Anderson, Gordon A.; Steele, Kerry D.

    2007-02-13

    A transponder device having multiple modes of operation, such as an active mode and a passive mode, wherein the modes of operation are selected in response to the strength of a received radio frequency signal. A communication system is also provided having a transceiver configured to transmit a radio frequency signal and to receive a responsive signal, and a transponder configured to operate in a plurality of modes and to activate modes of operation in response to the radio frequency signal. Ideally, each mode of operation is activated and deactivated independent of the other modes, although two or more modes may be concurrently operational.

  18. Current Mode Logic Fan Out

    Energy Science and Technology Software Center (OSTI)

    2011-05-07

    Current mode logic is used in high speed timing systems for particle accelerators due to the fast rise time of the electrical signal. This software provides the necessary documentation to produce multiple copies of a single input for distribution to multiple devices. This software supports the DOE mission by providing a method for producing high speed signals in accelerator timing systems.

  19. Dual-cavity mode converter for a fundamental mode output in an over-moded relativistic backward-wave oscillator

    SciTech Connect (OSTI)

    Li, Jiawei; Huang, Wenhua; Xiao, Renzhen; Bai, Xianchen; Zhang, Yuchuan; Zhang, Xiaowei; Shao, Hao; Chen, Changhua; Zhu, Qi

    2015-03-16

    A dual-cavity TM{sub 02}–TM{sub 01} mode converter is designed for a dual-mode operation over-moded relativistic backward-wave oscillator. With the converter, the fundamental mode output is achieved. Particle-in-cell simulation shows that the efficiency of beam-wave conversion was over 46% and a pureTM{sub 01} mode output was obtained. Effects of end reflection provided by the mode converter were studied. Adequate TM{sub 01} mode feedback provided by the converter enhances conversion efficiency. The distance between the mode converter and extraction cavity critically affect the generation of microwaves depending on the reflection phase of TM{sub 01} mode feedback.

  20. Continuous scanning mode for ptychography

    SciTech Connect (OSTI)

    Clark, Jesse N.; Huang, Xiaojing; Harder, Ross J.; Robinson, Ian K.

    2014-10-15

    We outline how ptychographic imaging can be performed without the need for discrete scan positions. Through an idealized experiment, we demonstrate how a discrete-position scan regime can be replaced with a continuously scanned one with suitable modification of the reconstruction scheme based on coherent modes. The impact of this is that acquisition times can be reduced, significantly aiding ptychographic imaging with x rays, electrons, or visible light.

  1. Properties of solar gravity mode signals in total irradiance observations

    SciTech Connect (OSTI)

    Kroll, R.J.; Chen, J.; Hill, H.A.

    1988-01-01

    Further evidence has been found that a significant fraction of the gravity mode power density in the total irradiance observations appears in sidebands of classified eigenfrequencies. These sidebands whose amplitudes vary from year to year are interpreted as harmonics of the rotational frequencies of the nonuniform solar surface. These findings are for non axisymmetric modes and corroborate the findings of Kroll, Hill and Chen for axisymmetric modes. It is demonstrated the the generation of the sidebands lifts the usual restriction on the parity of the eigenfunctions for modes detectable in total irradiance observations. 14 refs.

  2. Path planning during combustion mode switch

    DOE Patents [OSTI]

    Jiang, Li; Ravi, Nikhil

    2015-12-29

    Systems and methods are provided for transitioning between a first combustion mode and a second combustion mode in an internal combustion engine. A current operating point of the engine is identified and a target operating point for the internal combustion engine in the second combustion mode is also determined. A predefined optimized transition operating point is selected from memory. While operating in the first combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion engine to approach the selected optimized transition operating point. When the engine is operating at the selected optimized transition operating point, the combustion mode is switched from the first combustion mode to the second combustion mode. While operating in the second combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion to approach the target operating point.

  3. Waveguide mode converter and method using same

    DOE Patents [OSTI]

    Moeller, Charles P.

    1990-01-01

    A waveguide mode converter converts electromagnetic power being transmitted in a TE.sub.0n or a TM.sub.0n mode, where n is an integer, to an HE.sub.11 mode. The conversion process occurs in a single stage without requiring the power to pass through any intermediate modes. The converter comprises a length of circular corrugated waveguide formed in a multiperiod periodic curve. The period of the curve is selected to couple the desired modes and decouple undesired modes. The corrugation depth is selected to control the phase propagation constant, or wavenumbers, of the input and output modes, thereby preventing coherent coupling to competing modes. In one embodiment, both the period and amplitude of the curve may be selectively adjusted, thereby allowing the converter to be tuned to maximize the conversion efficiency.

  4. Optical waveguides having flattened high order modes

    DOE Patents [OSTI]

    Messerly, Michael Joseph; Beach, Raymond John; Heebner, John Edward; Dawson, Jay Walter; Pax, Paul Henry

    2014-08-05

    A deterministic methodology is provided for designing optical fibers that support field-flattened, ring-like higher order modes. The effective and group indices of its modes can be tuned by adjusting the widths of the guide's field-flattened layers or the average index of certain groups of layers. The approach outlined here provides a path to designing fibers that simultaneously have large mode areas and large separations between the propagation constants of its modes.

  5. Sandia National Laboratories: Mode Stirred Chamber

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

    Mode Stirred Chamber The Mode Stirred chamber is essentially a large microwave oven. It consists of a metal room that serves as a high-Q chamber and a metal paddle wheel to "stir" the chamber modes. Mixing the modes in this manner allows test objects, in a single orientation to be exposed to EM energy in many different angles of incidence and polarization. Electronic susceptibility tests can be performed, or test object electromagnetic transfer functions can be determined through

  6. Transverse Mode Coupling Instability with Space Charge (Journal...

    Office of Scientific and Technical Information (OSTI)

    Transverse Mode Coupling Instability with Space Charge Citation Details In-Document Search Title: Transverse Mode Coupling Instability with Space Charge Transverse mode coupling ...

  7. Using X-mode L, R and O-mode reflectometry cutoffs to measure...

    Office of Scientific and Technical Information (OSTI)

    Using X-mode L, R and O-mode reflectometry cutoffs to measure scrape-off-layer density profiles for upgraded ORNL reflectometer on NSTX-U Citation Details In-Document Search Title:...

  8. Mode suppression means for gyrotron cavities

    DOE Patents [OSTI]

    Chodorow, Marvin; Symons, Robert S.

    1983-08-09

    In a gyrotron electron tube of the gyro-klystron or gyro-monotron type, having a cavity supporting an electromagnetic mode with circular electric field, spurious resonances can occur in modes having noncircular electric field. These spurious resonances are damped and their frequencies shifted by a circular groove in the cavity parallel to the electric field.

  9. Mixed Mode Fuel Injector And Injection System

    DOE Patents [OSTI]

    Stewart, Chris Lee; Tian, Ye; Wang, Lifeng; Shafer, Scott F.

    2005-12-27

    A fuel injector includes a homogenous charge nozzle outlet set and a conventional nozzle outlet set that are controlled respectively by first and second three way needle control valves. Each fuel injector includes first and second concentric needle valve members. One of the needle valve members moves to an open position for a homogenous charge injection event, while the other needle valve member moves to an open position for a conventional injection event. The fuel injector has the ability to operate in a homogenous charge mode with a homogenous charge spray pattern, a conventional mode with a conventional spray pattern or a mixed mode.

  10. Whispering-gallery-mode-based seismometer

    SciTech Connect (OSTI)

    Fourguette, Dominique Claire; Otugen, M Volkan; Larocque, Liane Marie; Ritter, Greg Aan; Meeusen, Jason Jeffrey; Ioppolo, Tindaro

    2014-06-03

    A whispering-gallery-mode-based seismometer provides for receiving laser light into an optical fiber, operatively coupling the laser light from the optical fiber into a whispering-gallery-mode-based optical resonator, operatively coupling a spring of a spring-mass assembly to a housing structure; and locating the whispering-gallery-mode-based optical resonator between the spring-mass assembly and the housing structure so as to provide for compressing the whispering-gallery-mode-based optical resonator between the spring-mass assembly and the housing structure responsive to a dynamic compression force from the spring-mass assembly responsive to a motion of the housing structure relative to an inertial frame of reference.

  11. Single mode pulsed dye laser oscillator

    DOE Patents [OSTI]

    Hackel, Richard P.

    1992-01-01

    A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability.

  12. Rotary Mode Core Sample System availability improvement

    SciTech Connect (OSTI)

    Jenkins, W.W.; Bennett, K.L.; Potter, J.D.; Cross, B.T.; Burkes, J.M.; Rogers, A.C.

    1995-02-28

    The Rotary Mode Core Sample System (RMCSS) is used to obtain stratified samples of the waste deposits in single-shell and double-shell waste tanks at the Hanford Site. The samples are used to characterize the waste in support of ongoing and future waste remediation efforts. Four sampling trucks have been developed to obtain these samples. Truck I was the first in operation and is currently being used to obtain samples where the push mode is appropriate (i.e., no rotation of drill). Truck 2 is similar to truck 1, except for added safety features, and is in operation to obtain samples using either a push mode or rotary drill mode. Trucks 3 and 4 are now being fabricated to be essentially identical to truck 2.

  13. Single mode pulsed dye laser oscillator

    DOE Patents [OSTI]

    Hackel, R.P.

    1992-11-24

    A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability. 6 figs.

  14. Failure modes in surface micromachined microelectromechanical actuators

    SciTech Connect (OSTI)

    Miller, S.L.; Rodgers, M.S.; LaVigne, G.; Sniegowski, J.J.; Clews, P.; Tanner, D.M.; Peterson, K.A.

    1998-03-01

    In order for the rapidly emerging field of MicroElectroMechanical Systems (MEMS) to meet its extraordinary expectations regarding commercial impact, issues pertaining to how they fail must be understood. The authors identify failure modes common to a broad range of MEMS actuators, including adhesion (stiction) and friction induced failures caused by improper operational methods, mechanical instabilities, and electrical instabilities. Demonstrated methods to mitigate these failure modes include implementing optimized designs, model based operational methods, and chemical surface treatments.

  15. ToF-SIMS Depth Profiling Of Insulating Samples, Interlaced Mode Or Non-interlaced Mode?

    SciTech Connect (OSTI)

    Wang, Zhaoying; Jin, Ke; Zhang, Yanwen; Wang, Fuyi; Zhu, Zihua

    2014-11-01

    Dual beam depth profiling strategy has been widely adopted in ToF-SIMS depth profiling, in which two basic operation modes, interlaced mode and non-interlaced mode, are commonly used. Generally, interlaced mode is recommended for conductive or semi-conductive samples, whereas non-interlaced mode is recommended for insulating samples, where charge compensation can be an issue. Recent publications, however, show that the interlaced mode can be used effectively for glass depth profiling, despite the fact that glass is an insulator. In this study, we provide a simple guide for choosing between interlaced mode and non-interlaced mode for insulator depth profiling. Two representative cases are presented: (1) depth profiling of a leached glass sample, and (2) depth profiling of a single crystal MgO sample. In brief, the interlaced mode should be attempted first, because (1) it may provide reasonable-quality data, and (2) it is time-saving for most cases, and (3) it introduces low H/C/O background. If data quality is the top priority and measurement time is flexible, non-interlaced mode is recommended because interlaced mode may suffer from low signal intensity and poor mass resolution. A big challenge is tracking trace H/C/O in a highly insulating sample (e.g., MgO), because non-interlaced mode may introduce strong H/C/O background but interlaced mode may suffer from low signal intensity. Meanwhile, a C or Au coating is found to be very effective to improve the signal intensity. Surprisingly, the best analyzing location is not on the C or Au coating, but at the edge (outside) of the coating.

  16. Particle Distribution Modification by Low Amplitude Modes

    SciTech Connect (OSTI)

    White, R. B.; Gorelenkov, N.; Heidbrink, W. W.; Van Zeeland, M. A.

    2009-08-28

    Modification of a high energy particle distribution by a spectrum of low amplitude modes is investigated using a guiding center code. Only through resonance are modes effective in modifying the distribution. Diagnostics are used to illustrate the mode-particle interaction and to find which effects are relevant in producing significant resonance, including kinetic Poincare plots and plots showing those orbits with time averaged mode-particle energy transfer. Effects of pitch angle scattering and drag are studied, as well as plasma rotation and time dependence of the equilibrium and mode frequencies. A specific example of changes observed in a DIII-D deuterium beam distribution in the presence of low amplitude experimentally validated Toroidal Alfven (TAE) eigenmodes and Reversed Shear Alfven (RSAE) eigenmodes is examined in detail. Comparison with experimental data shows that multiple low amplitude modes can account for significant modification of high energy beam particle distributions. It is found that there is a stochastic threshold for beam profile modification, and that the experimental amplitudes are only slightly above this threshold.

  17. Edge-localized-modes in tokamaks

    SciTech Connect (OSTI)

    Leonard, A. W.

    2014-09-15

    Edge-localized-modes (ELMs) are a ubiquitous feature of H-mode in tokamaks. When gradients in the H-mode transport barrier grow to exceed the MHD stability limit the ELM instability grows explosively, rapidly transporting energy and particles onto open field lines and material surfaces. Though ELMs provide additional particle and impurity transport through the H-mode transport barrier, enabling steady operation, the resulting heat flux transients to plasma facing surfaces project to large amplitude in future low collisionality burning plasma tokamaks. Measurements of the ELM heat flux deposition onto material surfaces in the divertor and main chamber indicate significant broadening compared to inter-ELM heat flux, with a timescale for energy deposition that is consistent with sonic ion flow and numerical simulation. Comprehensive ELM simulation is highlighting the important physics processes of ELM transport including parallel transport due to magnetic reconnection and turbulence resulting from collapse of the H-mode transport barrier. Encouraging prospects for ELM control and/or suppression in future tokamaks include intrinsic modes of ELM free operation, ELM triggering with frequent small pellet injection and the application of 3D magnetic fields.

  18. Mode Initialization for On-line Estimation of Power System Electromechanical Modes

    SciTech Connect (OSTI)

    Zhou, Ning; Trudnowski, Daniel; Pierre, John W.

    2009-03-18

    Measurement-based mode estimation methods are utilized to estimate electromechanical modes of a power system using phasor measurement units (PMU) data. These methods need to extract a certain amount of information before they can give useable mode estimation. Traditionally, the information is gathered solely from measurement data. Priori mode information from other resources (e.g. model eigenvalue analysis, engineering knowledge) are not fully utilized. For real time application, this means that mode estimation takes time to converge. By adding a mode regularization term in the objective function, this paper proposes a mode initialization method to include priori mode information in a regularized robust recursive least squares (R3LS) algorithm for on-line mode estimation. The proposed method is tested using a simple model, a 17 machine model and is shown to be able to shorten the convergence period of the R3LS algorithm. The proposed method is also applied on the measurement data recorded right before a major power outage in the western North American Grid on August 10th 1996 to show its potential applica-tion in detecting an approaching small signal stability problem.

  19. Transverse Mode Coupling Instability with Space Charge (Journal...

    Office of Scientific and Technical Information (OSTI)

    Transverse Mode Coupling Instability with Space Charge Citation Details In-Document Search Title: Transverse Mode Coupling Instability with Space Charge You are accessing a ...

  20. Fact #636: August 16, 2010 Transportation Energy Use by Mode...

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

    Transportation Energy Use by Mode, 2008 Bar graph showing the transportation energy use by mode (buses, rail, pipeline, water, air, mediumheavy trucks, and light vehicles) for ...

  1. Sequestering Uranium from Seawater: Binding Strength and Modes...

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

    Sequestering Uranium from Seawater: Binding Strength and Modes of Uranyl Complexes with Glutarimidedioxime Sequestering Uranium from Seawater: Binding Strength and Modes of Uranyl...

  2. Fact #602: December 21, 2009 Freight Statistics by Mode, 2007...

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

    2: December 21, 2009 Freight Statistics by Mode, 2007 Commodity Flow Survey Fact 602: December 21, 2009 Freight Statistics by Mode, 2007 Commodity Flow Survey Results from the ...

  3. Mixed-mode diesel HCCI with External Mixture Formation: Preliminary...

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

    Mixed-mode diesel HCCI with External Mixture Formation: Preliminary Results Mixed-mode diesel HCCI with External Mixture Formation: Preliminary Results 2003 DEER Conference ...

  4. Pairing Nambu-Goldstone Modes within Nuclear Density Functional...

    Office of Scientific and Technical Information (OSTI)

    Pairing Nambu-Goldstone Modes within Nuclear Density Functional Theory Citation Details ... Title: Pairing Nambu-Goldstone Modes within Nuclear Density Functional Theory Authors: ...

  5. Adaptive Particle Filtering for Mode Tracking: A Shallow Ocean...

    Office of Scientific and Technical Information (OSTI)

    Adaptive Particle Filtering for Mode Tracking: A Shallow Ocean Application Citation Details In-Document Search Title: Adaptive Particle Filtering for Mode Tracking: A Shallow Ocean ...

  6. Unbalanced edge modes and topological phase transition in gated...

    Office of Scientific and Technical Information (OSTI)

    Unbalanced edge modes and topological phase transition in gated trilayer graphene Title: Unbalanced edge modes and topological phase transition in gated trilayer graphene Authors: ...

  7. Polarization mode control of long-wavelength VCSELs by intracavity...

    Office of Scientific and Technical Information (OSTI)

    Polarization mode control of long-wavelength VCSELs by intracavity patterning Citation Details In-Document Search Title: Polarization mode control of long-wavelength VCSELs by ...

  8. Observation of Spontaneous Neoclassical Tearing Modes

    SciTech Connect (OSTI)

    E.D. Fredrickson

    2001-10-03

    We present data in this paper from the Tokamak Fusion Test Reactor (TFTR) which challenges the commonly held belief that extrinsic MHD events such as sawteeth or ELMs [edge localized modes] are required to provide the seed islands that trigger Neoclassical Tearing Modes (NTMs). While sawteeth are reported to provide the trigger for most of the NTMs on DIII-D [at General Atomics in San Diego, California] and ASDEX-U [at Max-Planck-Institut fuer Plasmaphysik in Garching, Germany], the majority of NTMs seen in TFTR occur in plasmas without sawteeth, that is which are above the beta threshold for sawtooth stabilization. Examples of NTMs appearing in the absence of any detectable extrinsic MHD activity will be shown. Conversely, large n=1 modes in plasmas above the NTM beta threshold generally do not trigger NTMs. An alternative mechanism for generating seed islands will be discussed.

  9. Hydrogen local vibrational modes in semiconductors

    SciTech Connect (OSTI)

    McCluskey, M D

    1997-06-01

    Following, a review of experimental techniques, theory, and previous work, the results of local vibrational mode (LVM) spectroscopy on hydrogen-related complexes in several different semiconductors are discussed. Hydrogen is introduced either by annealing in a hydrogen ambient. exposure to a hydrogen plasma, or during growth. The hydrogen passivates donors and acceptors in semiconductors, forming neutral complexes. When deuterium is substituted for hydrogen. the frequency of the LVM decreases by approximately the square root of two. By varying the temperature and pressure of the samples, the microscopic structures of hydrogen-related complexes are determined. For group II acceptor-hydrogen complexes in GaAs, InP, and GaP, hydrogen binds to the host anion in a bond-centered orientation, along the [111] direction, adjacent to the acceptor. The temperature dependent shift of the LVMs are proportional to the lattice thermal energy U(T), a consequence of anharmonic coupling between the LVM and acoustical phonons. In the wide band gap semiconductor ZnSe, epilayers grown by metalorganic chemical vapor phase epitaxy (MOCVD) and doped with As form As-H complexes. The hydrogen assumes a bond-centered orientation, adjacent to a host Zn. In AlSb, the DX centers Se and Te are passivated by hydrogen. The second, third, and fourth harmonics of the wag modes are observed. Although the Se-D complex has only one stretch mode, the Se-H stretch mode splits into three peaks. The anomalous splitting is explained by a new interaction between the stretch LVM and multi-phonon modes of the lattice. As the temperature or pressure is varied, and anti-crossing is observed between LVM and phonon modes.

  10. ISSUANCE 2016-02-09: Energy Conservation Program: Energy Conservation Standards for Standby Mode and Off Mode for Microwave Ovens; Correction

    Broader source: Energy.gov [DOE]

    Energy Conservation Program: Energy Conservation Standards for Standby Mode and Off Mode for Microwave Ovens; Correction

  11. Head-Tail Modes for Strong Space Charge

    SciTech Connect (OSTI)

    Burov, Alexey

    2008-12-01

    Head-tail modes are described here for the space charge tune shift significantly exceeding the synchrotron tune. General equation for the modes is derived. Spatial shapes of the modes, their frequencies, and coherent growth rates are explored. The Landau damping rates are also found. Suppression of the transverse mode coupling instability by the space charge is explained.

  12. High confinement mode and edge localized mode characteristics in a near-unity aspect ratio tokamak

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

    Thome, Kathreen E.; Bongard, Michael W.; Barr, Jayson L.; Bodner, Grant M.; Burke, Marcus G.; Fonck, Raymond J.; Kriete, David M.; Perry, Justin M.; Schlossberg, David J.

    2016-04-27

    Tokamak experiments at near-unity aspect ratio A ≲ 1.2 offer new insights into the self-organized H-mode plasma confinement regime. In contrast to conventional A ~ 3 plasmas, the L–H power threshold PLH is ~15× higher than scaling predictions, and it is insensitive to magnetic topology, consistent with modeling. Edge localized mode (ELM) instabilities shift to lower toroidal mode numbers as A decreases. Furthermore, these ultralow-A operations enable heretofore inaccessible Jedge(R,t) measurements through an ELM that show a complex multimodal collapse and the ejection of a current-carrying filament.

  13. Mode-synthesizing atomic force microscopy and mode-synthesizing sensing

    DOE Patents [OSTI]

    Passain, Ali; Thundat, Thomas George; Tetard, Laurene

    2014-07-22

    A method of analyzing a sample that includes applying a first set of energies at a first set of frequencies to a sample and applying, simultaneously with the applying the first set of energies, a second set of energies at a second set of frequencies, wherein the first set of energies and the second set of energies form a multi-mode coupling. The method further includes detecting an effect of the multi-mode coupling.

  14. Dynamical dipole mode in fusion reactions

    SciTech Connect (OSTI)

    Pierroutsakou, D.; Boiano, A.; Romoli, M.; Martin, B.; Inglima, G.; La Commara, M.; Sandoli, M.; Agodi, C.; Alba, R.; Coniglione, R.; Zoppo, A. Del; Maiolino, C.; Piattelli, P.; Santonocito, D.; Sapienza, P.; Baran, V.; Glodariu, T.; Cardella, G.; De Filippo, E.; Pagano, A.

    2009-05-04

    We investigated the dynamical dipole mode, related with entrance channel charge asymmetry effects, in the {sup 40}Ar+{sup 92}Zr and {sup 36}Ar+{sup 96}Zr fusion reactions at E{sub lab} = 15.1 A and 16 A MeV, respectively. These reactions populate, through entrance channels having different charge asymmetries, a compound nucleus in the A = 126 mass energy region, identical spin distribution at an average excitation energy of about 280 MeV. The compound nucleus average excitation energy and average mass were deduced by the analysis of the light charged particle energy spectra. By studying the {gamma}-ray energy spectra and the {gamma}-ray angular distributions of the considered reactions, the dynamical nature of the prompt radiation related to the dynamical dipole mode was evidenced. The data are compared with calculations based on a collective bremsstrahlung analysis of the reaction dynamics.

  15. Mode Selective Excitation Using Coherent Control Spectroscopy

    SciTech Connect (OSTI)

    Singh, Ajay K.; Konradi, Jakow; Materny, Arnulf; Sarkar, Sisir K.

    2008-11-14

    Femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) gives access to ultrafast molecular dynamics. However, femtosecond laser pulses are spectrally broad and therefore coherently excite several molecular modes. While the temporal resolution is high, usually no mode-selective excitation is possible. This paper demonstrates the feasibility of selectively exciting specific molecular vibrations in solution phase with shaped fs laser excitation using a feedback-controlled optimization technique guided by an evolutionary algorithm. This approach is also used to obtain molecule-specific CARS spectra from a mixture of different substances. The optimized phase structures of the fs pulses are characterized to get insight into the control process. Possible applications of the spectrum control are discussed.

  16. Electron acceleration by Z-mode and whistler-mode waves

    SciTech Connect (OSTI)

    Lee, K. H.; Omura, Y.; Lee, L. C.; Institute of Earth Science, Academia Sinica, Nankang, Taiwan

    2013-11-15

    We carried out a series of particle simulations to study electron acceleration by Z-mode and whistler-mode waves generated by an electron ring distribution. The electron ring distribution leads to excitations of X-mode waves mainly in the perpendicular direction, Z-mode waves in the perpendicular and parallel directions, and whistler-mode waves mainly in the parallel direction. The parallel Z- and whistler-mode waves can lead to an effective acceleration of ring electrons. The electron acceleration is mainly determined by the wave amplitude and phase velocity, which in turn is affected by the ratio of electron plasma to cyclotron frequencies. For the initial kinetic energy ranging from 100 to 500 keV, the peak energy of the accelerated electrons is found to reach 28 times the initial kinetic energy. We further study the acceleration process by test-particle calculations in which electrons interact with one, two, or four waves. The electron trajectories in the one-wave case are simple diffusion curves. In the multi-wave cases, electrons are accelerated simultaneously by counter-propagating waves and can have a higher final energy.

  17. Stabilizing windings for tilting and shifting modes

    DOE Patents [OSTI]

    Jardin, Stephen C.; Christensen, Uffe R.

    1984-01-01

    This invention relates to passive conducting loops for stabilizing a plasma ring against unstable tilting and/or shifting modes. To this end, for example, plasma ring in a spheromak is stabilized by a set of four figure-8 shaped loops having one pair on one side of the plasma and one pair on the other side with each pair comprising two loops whose axes are transverse to each other.

  18. Electromagnetic Transport From Microtearing Mode Turbulence

    SciTech Connect (OSTI)

    Guttenfelder, W; Kaye, S M; Nevins, W M; Wang, E; Bell, R E; Hammett, G W; LeBlanc, B P; Mikkelsen, D R

    2011-03-23

    This Letter presents non-linear gyrokinetic simulations of microtearing mode turbulence. The simulations include collisional and electromagnetic effects and use experimental parameters from a high beta discharge in the National Spherical Torus Experiment (NSTX). The predicted electron thermal transport is comparable to that given by experimental analysis, and it is dominated by the electromagnetic contribution of electrons free streaming along the resulting stochastic magnetic field line trajectories. Experimental values of flow shear can significantly reduce the predicted transport.

  19. Failure Mode and Effect Analysis (FMEA) Tutorial

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

    Mode and Effect Analysis (FMEA) Tutorial - 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 Fuel Cycle Defense Waste Management

  20. Measurements of Time-Dependent CP-Asymmetry Parameters in B Meson Decays to \\eta^{\\prime} K^0 and of Branching Fractions of SU(3) Related Modes with BaBar Experiment at SLAC

    SciTech Connect (OSTI)

    Biassoni, Pietro; /Milan U.

    2009-01-22

    In this thesis work we have measured the following upper limits at 90% of confidence level, for B meson decays (in units of 10{sup -6}), using a statistics of 465.0 x 10{sup 6} B{bar B} pairs: {Beta}(B{sup 0} {yields} {eta}K{sup 0}) < 1.6 {Beta}(B{sup 0} {yields} {eta}{eta}) < 1.4 {Beta}(B{sup 0} {yields} {eta}{prime}{eta}{prime}) < 2.1 {Beta}(B{sup 0} {yields} {eta}{phi}) < 0.52 {Beta}(B{sup 0} {yields} {eta}{omega}) < 1.6 {Beta}(B{sup 0} {yields} {eta}{prime}{phi}) < 1.2 {Beta}(B{sup 0} {yields} {eta}{prime}{omega}) < 1.7 We have no observation of any decay mode, statistical significance for our measurements is in the range 1.3-3.5 standard deviation. We have a 3.5{sigma} evidence for B {yields} {eta}{omega} and a 3.1 {sigma} evidence for B {yields} {eta}{prime}{omega}. The absence of observation of the B{sup 0} {yields} {eta}K{sup 0} open an issue related to the large difference compared to the charged mode B{sup +} {yields} {eta}K{sup +} branching fraction, which is measured to be 3.7 {+-} 0.4 {+-} 0.1 [118]. Our results represent substantial improvements of the previous ones [109, 110, 111] and are consistent with theoretical predictions. All these results were presented at Flavor Physics and CP Violation (FPCP) 2008 Conference, that took place in Taipei, Taiwan. They will be soon included into a paper to be submitted to Physical Review D. For time-dependent analysis, we have reconstructed 1820 {+-} 48 flavor-tagged B{sup 0} {yields} {eta}{prime}K{sup 0} events, using the final BABAR statistic of 467.4 x 10{sup 6} B{bar B} pairs. We use these events to measure the time-dependent asymmetry parameters S and C. We find S = 0.59 {+-} 0.08 {+-} 0.02, and C = -0.06 {+-} 0.06 {+-} 0.02. A non-zero value of C would represent a directly CP non-conserving component in B{sup 0} {yields} {eta}{prime}K{sup 0}, while S would be equal to sin2{beta} measured in B{sup 0} {yields} J/{psi}K{sub s}{sup 0} [108], a mixing-decay interference effect, provided the decay is dominated by amplitudes of a single weak phase. The new measured value of S can be considered in agreement with the expectations of the 'Standard Model', inside the experimental and theoretical uncertainties. Inconsistency of our result for S with CP conservation (S = 0) has a significance of 7.1 standard deviations (statistical and systematics included). Our result for the direct-CP violation parameter C is 0.9 standard deviations from zero (statistical and systematics included). Our results are in agreement with the previous ones [18]. Despite the statistics is only 20% larger than the one used in previous measurement, we improved of 20% the error on S and of 14% the error on C. This error is the smaller ever achieved, by both BABAR and Belle, in Time-Dependent CP Violation Parameters measurement is a b {yields} s transition.

  1. High frequency pacing of edge localized modes by injection of...

    Office of Scientific and Technical Information (OSTI)

    High frequency pacing of edge localized modes by injection of lithium granules in DIII-D ... Title: High frequency pacing of edge localized modes by injection of lithium granules in ...

  2. Investigation of NO2 Oxidation Kinetics and Burning Mode for...

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

    NO2 Oxidation Kinetics and Burning Mode for Medium Duty Diesel Particulate: Contrasting O2 and NO2 Oxidation Investigation of NO2 Oxidation Kinetics and Burning Mode for Medium ...

  3. Diagnostic for two-mode variable valve activation device

    DOE Patents [OSTI]

    Fedewa, Andrew M

    2014-01-07

    A method is provided for diagnosing a multi-mode valve train device which selectively provides high lift and low lift to a combustion valve of an internal combustion engine having a camshaft phaser actuated by an electric motor. The method includes applying a variable electric current to the electric motor to achieve a desired camshaft phaser operational mode and commanding the multi-mode valve train device to a desired valve train device operational mode selected from a high lift mode and a low lift mode. The method also includes monitoring the variable electric current and calculating a first characteristic of the parameter. The method also includes comparing the calculated first characteristic against a predetermined value of the first characteristic measured when the multi-mode valve train device is known to be in the desired valve train device operational mode.

  4. Commute Mode Switching Impact Tool | Department of Energy

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

    Commute Mode Switching Impact Tool Commute Mode Switching Impact Tool Excel tool helps agencies project the impact that changes in employee commute modes would have on its employee commute emissions. The tool is designed to be used at the worksite level and summed up at the agency level. The output of this tool can help agencies establish appropriate greenhouse gas reduction targets for major worksites or clusters of worksites in common metropolitan areas. File Download the Commute Mode

  5. Viscoelastic modes in a strongly coupled, cold, magnetized dusty plasma

    SciTech Connect (OSTI)

    Banerjee, Debabrata; Mylavarapu, Janaki Sita; Chakrabarti, Nikhil

    2010-11-15

    A generalized hydrodynamical model has been used to study the low frequency modes in a strongly coupled, cold, magnetized dusty plasma. Such plasmas exhibit elastic properties due to the strong correlations among dust particles and the tensile stresses imparted by the magnetic field. It has been shown that longitudinal compressional Alfven modes and elasticity modified transverse shear mode exist in such a medium. The features of these collective modes are established and discussed.

  6. Controlling guided modes in plasmonic metal/dielectric multilayer waveguides

    SciTech Connect (OSTI)

    Wickremasinghe, N.; Wang, X.; Wagner, H. P.; Thompson, J.; Schmitzer, H.

    2015-06-07

    We investigate the mode properties of planar dielectric aluminum-quinoline (Alq{sub 3}) multilayer waveguides comprising one single or three equally spaced embedded nanometer-thin (∼10 nm thick) Alq{sub 3}-Mg{sub 0.9}:Ag{sub 0.1} composite metal-island layers. The plasmonic waveguides were fabricated by organic molecular beam deposition. Transverse magnetic (TM) and transverse electric (TE) modes were selectively excited using the m-line method. The symmetric plasmonic TM{sub 0} mode was launched in all waveguides and—in addition—two higher order plasmonic TM{sub 1} and TM{sub 2} modes were generated in waveguides comprising three metal layers. Other TM modes have hybrid dielectric-plasmonic characters, showing an increased effective refractive index when one electric field antinode is close to a metallic layer. TM modes which have all their antinode(s) in the dielectric layers propagate essentially like dielectric modes. TE modes with antinode(s) at the position of the metal layer(s) are strongly damped while the losses are low for TE modes comprising a node at the position of the composite metal film(s). The possibility to control the effective refractive index and the losses for individual hybrid plasmonic-dielectric TM and dielectric TE modes opens new design opportunities for mode selective waveguides and TM-TE mode couplers.

  7. Multi-mode ultrasonic welding control and optimization

    DOE Patents [OSTI]

    Tang, Jason C.H.; Cai, Wayne W

    2013-05-28

    A system and method for providing multi-mode control of an ultrasonic welding system. In one embodiment, the control modes include the energy of the weld, the time of the welding process and the compression displacement of the parts being welded during the welding process. The method includes providing thresholds for each of the modes, and terminating the welding process after the threshold for each mode has been reached, the threshold for more than one mode has been reached or the threshold for one of the modes has been reached. The welding control can be either open-loop or closed-loop, where the open-loop process provides the mode thresholds and once one or more of those thresholds is reached the welding process is terminated. The closed-loop control provides feedback of the weld energy and/or the compression displacement so that the weld power and/or weld pressure can be increased or decreased accordingly.

  8. Mode trap for absorbing transverse modes of an accelerated electron beam

    DOE Patents [OSTI]

    Chojnacki, E.P.

    1994-05-31

    A mode trap to trap and absorb transverse modes formed by a beam in a linear accelerator includes a waveguide having a multiplicity of electrically conductive (preferably copper) irises and rings, each iris and ring including an aperture, and the irises and rings being stacked in a side-by-side, alternating fashion such that the apertures of the irises and rings are concentrically aligned. An absorbing material layer such as a dielectric is embedded in each iris and ring, and this absorbing material layer encircles, but is circumferentially spaced from its respective aperture. Each iris and ring includes a plurality of circumferentially spaced slots around its aperture and extending radially out toward its absorbing material layer. 9 figs.

  9. Mode trap for absorbing transverse modes of an accelerated electron beam

    DOE Patents [OSTI]

    Chojnacki, Eric P.

    1994-01-01

    A mode trap to trap and absorb transverse modes formed by a beam in a linear accelerator includes a waveguide having a multiplicity of electrically conductive (preferably copper) irises and rings, each iris and ring including an aperture, and the irises and rings being stacked in a side-by-side, alternating fashion such that the apertures of the irises and rings are concentrically aligned. An absorbing material layer such as a dielectric is embedded in each iris and ring, and this absorbing material layer encircles, but is circumferentially spaced from its respective aperture. Each iris and ring includes a plurality of circumferentially spaced slots around its aperture and extending radially out toward its absorbing material layer.

  10. Mode locking and island suppression by resonant magnetic perturbations in

    Office of Scientific and Technical Information (OSTI)

    Rutherford regime (Journal Article) | SciTech Connect Mode locking and island suppression by resonant magnetic perturbations in Rutherford regime Citation Details In-Document Search Title: Mode locking and island suppression by resonant magnetic perturbations in Rutherford regime We demonstrate in theory that tearing mode locking and magnetic island suppression by resonant magnetic perturbations (RMPs) can correspond to different states of a same dynamic system governed by the torque balance

  11. Spatiotemporal localized modes in PT-symmetric optical media (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Spatiotemporal localized modes in PT-symmetric optical media Citation Details In-Document Search Title: Spatiotemporal localized modes in PT-symmetric optical media We firstly obtain spatiotemporal localized mode solutions of a (3+1)-dimensional nonlinear Schrödinger equation in PT-symmetric potentials, and then discuss the linear stability of LMs, which are also tested by means of direct simulations. Moreover, phase switches and transverse power-flow density

  12. Simulation and Analysis of the Hybrid Operating Mode in ITER

    SciTech Connect (OSTI)

    Kessel, C.E.; Budny, R.V.; Indireshkumar, K.

    2005-09-22

    The hybrid operating mode in ITER is examined with 0D systems analysis, 1.5D discharge scenario simulations using TSC and TRANSP, and the ideal MHD stability is discussed. The hybrid mode has the potential to provide very long pulses and significant neutron fluence if the physics regime can be produced in ITER. This paper reports progress in establishing the physics basis and engineering limitation for the hybrid mode in ITER.

  13. Microwave mode shifting antenna system for regenerating particulate filters

    DOE Patents [OSTI]

    Gonze, Eugene V [Pinckney, MI; Kirby, Kevin W [Calabasas Hills, CA; Phelps, Amanda [Malibu, CA; Gregoire, Daniel J [Thousand Oaks, CA

    2011-04-26

    A regeneration system comprises a particulate matter (PM) filter including a microwave energy absorbing surface, and an antenna system comprising N antennas and an antenna driver module that sequentially drives the antenna system in a plurality of transverse modes of the antenna system to heat selected portions of the microwave absorbing surface to regenerate the PM filter, where N is an integer greater than one. The transverse modes may include transverse electric (TE) and/or transverse magnetic (TM) modes.

  14. Strong ''Quantum'' Chaos in the Global Ballooning Mode Spectrum of

    Office of Scientific and Technical Information (OSTI)

    Three-dimensional Plasmas (Technical Report) | SciTech Connect Technical Report: Strong ''Quantum'' Chaos in the Global Ballooning Mode Spectrum of Three-dimensional Plasmas Citation Details In-Document Search Title: Strong ''Quantum'' Chaos in the Global Ballooning Mode Spectrum of Three-dimensional Plasmas The spectrum of ideal magnetohydrodynamic (MHD) pressure-driven (ballooning) modes in strongly nonaxisymmetric toroidal systems is difficult to analyze numerically owing to the singular

  15. Optimization to reduce fuel consumption in charge depleting mode

    SciTech Connect (OSTI)

    Roos, Bryan Nathaniel; Martini, Ryan D.

    2014-08-26

    A powertrain includes an internal combustion engine, a motor utilizing electrical energy from an energy storage device, and a plug-in connection. A Method for controlling the powertrain includes monitoring a fuel cut mode, ceasing a fuel flow to the engine based upon the fuel cut mode, and through a period of operation including acceleration of the powertrain, providing an entirety of propelling torque to the powertrain with the electrical energy from the energy storage device based upon the fuel cut mode.

  16. Advancing the Physics Basis of Quiescent H-mode through Exploration of ITER Relevant Parameters

    SciTech Connect (OSTI)

    Solomon, W. M.; Burrell, K. H.; Fenstermacher, M. E.; Garofalo, A. M.; Grierson, B. A.; Loarte, A.; McKee, G. R.; Nazikian, R.; Snyder, B. P.

    2014-09-01

    Recent experiments on DIII-D have overcome a long-standing limitation in accessing quiescent H-mode (QH-mode), a high confinement state of the plasma that does not exhibit the explosive instabilities associated with edge localized modes (ELMs). In the past, QH-mode was associated with low density operation, but has now been extended to high normalized densities compatible with operation envisioned for ITER. Through the use of strong shaping, QH-mode plasmas have been maintained at high densities, both absolute (?e ? 7 1019 m3) and normalized Greenwald fraction (?e/?G > 0:7) . In these plasmas, the pedestal can evolve to very high pressures and current as the density is increased. Calculations of the pedestal height and width from the EPED model are quantitatively consistent with the experimental observed evolution with density. The comparison of the dependence of the maximum density threshold for QH-mode with plasma shape help validate the underlying theoretical peeling-ballooning models describing ELM stability. High density QH-mode operation with strong shaping has allowed stable access to a previously predicted regime of very high pedestal dubbed \\Super H-mode". In general, QH-mode is found to achieve ELM-stable operation while maintaining adequate impurity exhaust, due to the enhanced impurity transport from an edge harmonic oscillation, thought to be a saturated kink- peeling mode driven by rotation shear. In addition, the impurity confinement time is not affected by rotation, even though the energy confinement time and measured E ? B shear is observed to increase at low toroidal rotation. Together with demonstrations of high beta, high confinement and low q95 for many energy confinement times, these results suggest QH-mode as a potentially attractive operating scenario for ITER's Q=10 mission.

  17. Dual mode stereotactic localization method and application

    DOE Patents [OSTI]

    Keppel, Cynthia E.; Barbosa, Fernando Jorge; Majewski, Stanislaw

    2002-01-01

    The invention described herein combines the structural digital X-ray image provided by conventional stereotactic core biopsy instruments with the additional functional metabolic gamma imaging obtained with a dedicated compact gamma imaging mini-camera. Before the procedure, the patient is injected with an appropriate radiopharmaceutical. The radiopharmaceutical uptake distribution within the breast under compression in a conventional examination table expressed by the intensity of gamma emissions is obtained for comparison (co-registration) with the digital mammography (X-ray) image. This dual modality mode of operation greatly increases the functionality of existing stereotactic biopsy devices by yielding a much smaller number of false positives than would be produced using X-ray images alone. The ability to obtain both the X-ray mammographic image and the nuclear-based medicine gamma image using a single device is made possible largely through the use of a novel, small and movable gamma imaging camera that permits its incorporation into the same table or system as that currently utilized to obtain X-ray based mammographic images for localization of lesions.

  18. Asymmetric modes decomposition in an overmoded relativistic backward wave oscillator

    SciTech Connect (OSTI)

    Zhang, Dian; Zhang, Jun Zhong, Huihuang; Jin, Zhenxing; Ju, Jinchuan

    2014-09-15

    Most of the investigated overmoded relativistic backward wave oscillators (RBWOs) are azimuthally symmetric; thus, they are designed through two dimensional (2-D) particle-in-cell (PIC) simulations. However, 2-D PIC simulations cannot reveal the effect of asymmetric modes on beam-wave interaction. In order to investigate whether asymmetric mode competition needs to be considered in the design of overmoded RBWOs, a numerical method of determining the composition of both symmetric and asymmetric modes in three dimensional (3-D) PIC simulations is introduced in this paper. The 2-D and 3-D PIC simulation results of an X-band overmoded RBWO are analyzed. Our analysis indicates that the 2-D and 3-D PIC simulation results of our device are quite different due to asymmetric mode competition. In fact, asymmetric surface waves, especially EH{sub 11} mode, can lead to serious mode competition when electron beam propagates near the surface of slow wave structures (SWSs). Therefore, additional method of suppressing asymmetric mode competition, such as adjusting the reflections at both ends of SWSs to decrease the Q-factor of asymmetric modes, needs to be utilized in the design of overmoded RBWOs. Besides, 3-D PIC simulation and modes decomposition are essential for designing overmoded RBWOs.

  19. Pair breaking versus symmetry breaking: Origin of the Raman modes...

    Office of Scientific and Technical Information (OSTI)

    Pair breaking versus symmetry breaking: Origin of the Raman modes in superconducting cuprates Citation Details In-Document Search Title: Pair breaking versus symmetry breaking:...

  20. Modeling Combustion Control for High Power Diesel Mode Switching...

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

    Modeling Combustion Control for High Power Diesel Mode Switching Poster presentation given at the 16th Directions in Engine-Efficiency and Emissions Research (DEER) Conference in ...

  1. Unregulated Emissions from High-Efficiency Clean Combustion Modes...

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

    Unregulated Emissions from High-Efficiency Clean Combustion Modes - ORNL-FEERC Poster presentation at the 2007 Diesel Engine-Efficiency & Emissions Research Conference (DEER 2007). ...

  2. Strong ''Quantum'' Chaos in the Global Ballooning Mode Spectrum...

    Office of Scientific and Technical Information (OSTI)

    modes in strongly nonaxisymmetric toroidal systems is difficult to analyze numerically owing to the singular nature of ideal MHD caused by lack of an inherent scale length. ...

  3. Defense against common mode failures in protection system design

    SciTech Connect (OSTI)

    Wyman, R.H.; Johnson, G.L.

    1997-08-27

    The introduction of digital instrumentation and control into reactor safety systems creates a heightened concern about common-mode failure. This paper discusses the concern and methods to cope with the concern. Common-mode failures have been a ``fact-of-life`` in existing systems. The informal introduction of defense-in-depth and diversity (D-in-D&D)-coupled with the fact that hardware common-mode failures are often distributed in time-has allowed systems to deal with past common-mode failures. However, identical software operating in identical redundant systems presents the potential for simultaneous failure. Consequently, the use of digital systems raises the concern about common-mode failure to a new level. A more methodical approach to mitigating common-mode failure is needed to address these concerns. Purposeful introduction of D-in-D&D has been used as a defense against common-mode failure in reactor protection systems. At least two diverse systems are provided to mitigate any potential initiating event. Additionally, diverse displays and controls are provided to allow the operator to monitor plant status and manually initiate engineered safety features. A special form of conimon-mode failure analysis called ``defense-in-depth and diversity analysis`` has been developed to identify possible conimon-mode failure vulnerabilities in digital systems. An overview of this analysis technique is provided.

  4. Stability of coupled tearing and twisting modes in tokamaks

    SciTech Connect (OSTI)

    Fitzpatrick, R.

    1994-03-01

    A dispersion relation is derived for resistive modes of arbitrary parity in a tokamak plasma. At low mode amplitude, tearing and twisting modes which have nonideal MHD behavior at only one rational surface at a time in the plasma are decoupled via sheared rotation and diamagnetic flows. At higher amplitude, more unstable {open_quote}compound{close_quote} modes develop which have nonideal behavior simultaneously at many surfaces. Such modes possess tearing parity layers at some of the nonideal surfaces, and twisting parity layers at others, but mixed parity layers are generally disallowed. At low mode number, {open_quote}compound{close_quote} modes are likely to have tearing parity layers at all of the nonideal surfaces in a very low-{beta} plasma, but twisting parity layers become more probable as the plasma {beta} is increased. At high mode number, unstable twisting modes which exceed a critical amplitude drive conventional magnetic island chains on alternate rational surfaces, to form an interlocking structure in which the O-points and X-points of neighboring chains line up.

  5. Evidence for breathing modes in direct current, pulsed, and high...

    Office of Scientific and Technical Information (OSTI)

    Evidence for breathing modes in direct current, pulsed, and high power impulse magnetron sputtering plasmas Citation Details In-Document Search This content will become publicly...

  6. Sandia Energy - Turbulent Mixed-Mode Combustion Studied in a...

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

    Turbulent Mixed-Mode Combustion Studied in a New Piloted Burner Home Transportation Energy CRF Office of Science Capabilities News News & Events Research & Capabilities Fuel...

  7. Adaptive Wavenumber Estimation for Mode Tracking in a Shallow...

    Office of Scientific and Technical Information (OSTI)

    Tracking in a Shallow Ocean Environment Citation Details In-Document Search Title: Adaptive Wavenumber Estimation for Mode Tracking in a Shallow Ocean Environment You are ...

  8. Plasmon modes of metallic nanowires including quantum nonlocal effects

    SciTech Connect (OSTI)

    Moradi, Afshin

    2015-03-15

    The properties of electrostatic surface and bulk plasmon modes of cylindrical metallic nanowires are investigated, using the quantum hydrodynamic theory of plasmon excitation which allows an analytical study of quantum tunneling effects through the Bohm potential term. New dispersion relations are obtained for each type of mode and their differences with previous treatments based on the standard hydrodynamic model are analyzed in detail. Numerical results show by considering the quantum effects, as the value of wave number increases, the surface modes are slightly red-shifted first and then blue-shifted while the bulk modes are blue-shifted.

  9. Sandia Energy - Failure Mode and Effect Analysis (FMEA) Tutorial

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

    Failure Mode and Effect Analysis (FMEA) Tutorial Home Stationary Power Energy Conversion Efficiency Solar Energy Photovoltaics PV Systems Reliability Tutorial on FMEA Process...

  10. Auroral Signatures of Ballooning Mode Near Substorm Onset: Open...

    Office of Scientific and Technical Information (OSTI)

    Onset: Open Geospace General Circulation Model Simulations Citation Details In-Document Search Title: Auroral Signatures of Ballooning Mode Near Substorm Onset: Open Geospace ...

  11. Implementing the DC Mode in Cosmological Simulations with Supercomoving Variables

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

    Gnedin, Nickolay Y; Kravtsov, Andrey V; Rudd, Douglas H

    2011-06-02

    As emphasized by previous studies, proper treatment of the density fluctuation on the fundamental scale of a cosmological simulation volume - the 'DC mode' - is critical for accurate modeling of spatial correlations on scales ~> 10% of simulation box size. We provide further illustration of the effects of the DC mode on the abundance of halos in small boxes and show that it is straightforward to incorporate this mode in cosmological codes that use the 'supercomoving' variables. The equations governing evolution of dark matter and baryons recast with these variables are particularly simple and include the expansion factor, andmorehence the effect of the DC mode, explicitly only in the Poisson equation.less

  12. Spatiotemporal localized modes in PT-symmetric optical media...

    Office of Scientific and Technical Information (OSTI)

    We firstly obtain spatiotemporal localized mode solutions of a (3+1)-dimensional nonlinear Schrdinger equation in PT-symmetric potentials, and then discuss the linear stability ...

  13. Stabilization of tearing modes by oscillating the resonant surface

    SciTech Connect (OSTI)

    Yang Xiaoqing; Wang Shaojie; Yang Weihong

    2012-07-15

    The effects of the plasma current modulation on the linear instability of the tearing mode are numerically investigated. It is found that the tearing mode can be stabilized if the frequency of the modulation is suitable and the oscillation amplitude of the resonant surface position is large enough. The power needed for the lower-hybrid-current-drive to stabilize the tearing mode by oscillating the position of the resonant surface is comparable to the power consumption of the conventional method of tearing mode stabilization by using the electron-cyclotron-current-drive.

  14. Special purpose modes in photonic band gap fibers

    DOE Patents [OSTI]

    Spencer, James; Noble, Robert; Campbell, Sara

    2013-04-02

    Photonic band gap fibers are described having one or more defects suitable for the acceleration of electrons or other charged particles. Methods and devices are described for exciting special purpose modes in the defects including laser coupling schemes as well as various fiber designs and components for facilitating excitation of desired modes. Results are also presented showing effects on modes due to modes in other defects within the fiber and due to the proximity of defects to the fiber edge. Techniques and devices are described for controlling electrons within the defect(s). Various applications for electrons or other energetic charged particles produced by such photonic band gap fibers are also described.

  15. Resonant absorption in semiconductor nanowires and nanowire arrays: Relating leaky waveguide modes to Bloch photonic crystal modes

    SciTech Connect (OSTI)

    Fountaine, Katherine T.; Whitney, William S.; Atwater, Harry A.

    2014-10-21

    We present a unified framework for resonant absorption in periodic arrays of high index semiconductor nanowires that combines a leaky waveguide theory perspective and that of photonic crystals supporting Bloch modes, as array density transitions from sparse to dense. Full dispersion relations are calculated for each mode at varying illumination angles using the eigenvalue equation for leaky waveguide modes of an infinite dielectric cylinder. The dispersion relations along with symmetry arguments explain the selectivity of mode excitation and spectral red-shifting of absorption for illumination parallel to the nanowire axis in comparison to perpendicular illumination. Analysis of photonic crystal band dispersion for varying array density illustrates that the modes responsible for resonant nanowire absorption emerge from the leaky waveguide modes.

  16. Normal-mode coupling of rare-earth-metal ions in a crystal to a macroscopic optical cavity mode

    SciTech Connect (OSTI)

    Ichimura, Kouichi; Goto, Hayato

    2006-09-15

    We demonstrated coupling of rare-earth-metal ions in a crystal to a macroscopic cavity mode by observing optical bistability and normal-mode peaks due to sweeping-laser-induced population redistribution of the ions. The experimentally evaluated coupling constant between the individual ions and the single cavity mode is 15 kHz, which is comparable with or larger than the dissipation of the ions and will exceed the cavity dissipation with a narrowing of the mode waist of the cavity to the wavelength. The results advance the application of a coupled system of rare-earth-metal ions in a crystal and an optical cavity for quantum information processing.

  17. Localized radio frequency communication using asynchronous transfer mode protocol

    DOE Patents [OSTI]

    Witzke, Edward L.; Robertson, Perry J.; Pierson, Lyndon G.

    2007-08-14

    A localized wireless communication system for communication between a plurality of circuit boards, and between electronic components on the circuit boards. Transceivers are located on each circuit board and electronic component. The transceivers communicate with one another over spread spectrum radio frequencies. An asynchronous transfer mode protocol controls communication flow with asynchronous transfer mode switches located on the circuit boards.

  18. Nonlinear dynamics of multiple neoclassical tearing modes in tokamaks

    SciTech Connect (OSTI)

    Chandra, D.; Sen, A. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Agullo, O.; Benkadda, S. [France-Japan Magnetic Fusion Lab, LIA 336, CNRS/Lab PIIM, UMR 6633, CNRS-Universite de Provence, 13397 Marseille (France); Garbet, X. [Association Euratom-CEA, DRFC, CEA Cadarache, 13108 St-Paul-Lez-Durance (France)

    2013-04-15

    Numerical simulations investigating the interaction of co-existent 2/1 and 3/1 neoclassical tearing modes are presented. The results obtained from an initial value 3D toroidal code that solves a set of generalized reduced MHD equations exhibit a host of complex phenomena arising from the coupling of the two modes. These include a modification of the island saturation widths of the two modes, a significant modification in the perpendicular flow patterns in the vicinity of the islands, and the excitation of geodesic acoustic mode like oscillations that lead to concomitant oscillations in the kinetic and magnetic energies of the islands. These oscillations only occur in the presence of the neoclassical stress tensor contribution and are absent for two coupled classical tearing modes.

  19. B-mode polarization in Einstein-aether theory

    SciTech Connect (OSTI)

    Nakashima, Masahiro; Kobayashi, Tsutomu

    2011-10-15

    We study how the dynamical vector degree of freedom in modified gravity affects the CMB B-mode polarization in terms of the Einstein-aether theory. In this theory, vector perturbations can be generated from inflation, which can grow on superhorizon scales in the subsequent epochs and thereby leaves imprints on the CMB B-mode polarization. We derive the linear perturbation equations in a covariant formalism, and compute the CMB B-mode polarization using the CAMB code modified so as to incorporate the effect of the aether vector field. We find that the amplitude of the B-mode signal from the aether field can be larger than the contribution from the inflationary gravitational waves for reasonable initial conditions and for a viable range of model parameters, in which perturbation modes propagate superluminally. We also give an analytic argument explaining the shape of the spectrum based on the tight coupling approximation.

  20. Deep Borehole Emplacement Mode Hazard Analysis Revision 0

    SciTech Connect (OSTI)

    Sevougian, S. David

    2015-08-07

    This letter report outlines a methodology and provides resource information for the Deep Borehole Emplacement Mode Hazard Analysis (DBEMHA). The main purpose is identify the accident hazards and accident event sequences associated with the two emplacement mode options (wireline or drillstring), to outline a methodology for computing accident probabilities and frequencies, and to point to available databases on the nature and frequency of accidents typically associated with standard borehole drilling and nuclear handling operations. Risk mitigation and prevention measures, which have been incorporated into the two emplacement designs (see Cochran and Hardin 2015), are also discussed. A key intent of this report is to provide background information to brief subject matter experts involved in the Emplacement Mode Design Study. [Note: Revision 0 of this report is concentrated more on the wireline emplacement mode. It is expected that Revision 1 will contain further development of the preliminary fault and event trees for the drill string emplacement mode.

  1. Gyrokinetics for high-frequency modes in tokamaks

    SciTech Connect (OSTI)

    Wang, Z. T.; Long, L. X.; Dong, J. Q.; He, Zhixiong; Wang, L.; Liu, Y.; Tang, C. J.

    2012-07-15

    Gyrokinetics for high-frequency modes in tokamaks is developed. It is found that the breakdown of the invariants by perturbed electromagnetic fields drives microinstability. The obtained diamagnetic frequency, {omega}{sup *}, is proportional to only the toroidal mode number rather than transverse mode numbers. Therefore, there is no nonadiabatic drive for axisymmetrical modes in gyrokinetics. Meanwhile, the conventional eikonal Ansatz breaks down for the axisymmetrical modes. The ion drift-cyclotron instability discovered in a mirror machine is found for the first time in the toroidal system. The growth rates are proportional to {rho}{sub i}/L{sub n}, and the slope changes with magnetic curvature. In spherical torus, where magnetic curvature is greater than that of traditional tokamaks, instability poses a potential danger to such devices.

  2. Harmonic gyrotrons operating in high-order symmetric modes

    SciTech Connect (OSTI)

    Nusinovich, Gregory S.; Kashyn, Dmytro G.; Antonsen, T. M.

    2015-01-05

    It is shown that gyrotrons operating at cyclotron harmonics can be designed for operation in symmetric TE{sub 0,p}-modes. Such operation in fundamental harmonic gyrotrons is possible only at small radial indices (p≤3) because of the severe mode competition with TE{sub 2,p}-modes, which are equally coupled to annular beams as the symmetric modes. At cyclotron harmonics, however, this “degeneracy” of coupling is absent, and there is a region in the parameter space where harmonic gyrotrons can steadily operate in symmetric modes. This fact is especially important for sub-THz and THz-range gyrotrons where ohmic losses limit the power achievable in continuous-wave and high duty cycle regimes.

  3. Spontaneous Lorentz and diffeomorphism violation, massive modes, and gravity

    SciTech Connect (OSTI)

    Bluhm, Robert; Fung Shuhong; Kostelecky, V. Alan

    2008-03-15

    Theories with spontaneous local Lorentz and diffeomorphism violation contain massless Nambu-Goldstone modes, which arise as field excitations in the minimum of the symmetry-breaking potential. If the shape of the potential also allows excitations above the minimum, then an alternative gravitational Higgs mechanism can occur in which massive modes involving the metric appear. The origin and basic properties of the massive modes are addressed in the general context involving an arbitrary tensor vacuum value. Special attention is given to the case of bumblebee models, which are gravitationally coupled vector theories with spontaneous local Lorentz and diffeomorphism violation. Mode expansions are presented in both local and spacetime frames, revealing the Nambu-Goldstone and massive modes via decomposition of the metric and bumblebee fields, and the associated symmetry properties and gauge fixing are discussed. The class of bumblebee models with kinetic terms of the Maxwell form is used as a focus for more detailed study. The nature of the associated conservation laws and the interpretation as a candidate alternative to Einstein-Maxwell theory are investigated. Explicit examples involving smooth and Lagrange-multiplier potentials are studied to illustrate features of the massive modes, including their origin, nature, dispersion laws, and effects on gravitational interactions. In the weak static limit, the massive mode and Lagrange-multiplier fields are found to modify the Newton and Coulomb potentials. The nature and implications of these modifications are examined.

  4. Bunch mode specific rate corrections for PILATUS3 detectors

    SciTech Connect (OSTI)

    Trueb, P.; Dejoie, C.; Kobas, M.; Pattison, P.; Peake, D. J.; Radicci, V.; Sobott, B. A.; Walko, D. A.; Broennimann, C.

    2015-04-09

    PILATUS X-ray detectors are in operation at many synchrotron beamlines around the world. This article reports on the characterization of the new PILATUS3 detector generation at high count rates. As for all counting detectors, the measured intensities have to be corrected for the dead-time of the counting mechanism at high photon fluxes. The large number of different bunch modes at these synchrotrons as well as the wide range of detector settings presents a challenge for providing accurate corrections. To avoid the intricate measurement of the count rate behaviour for every bunch mode, a Monte Carlo simulation of the counting mechanism has been implemented, which is able to predict the corrections for arbitrary bunch modes and a wide range of detector settings. This article compares the simulated results with experimental data acquired at different synchrotrons. It is found that the usage of bunch mode specific corrections based on this simulation improves the accuracy of the measured intensities by up to 40% for high photon rates and highly structured bunch modes. For less structured bunch modes, the instant retrigger technology of PILATUS3 detectors substantially reduces the dependency of the rate correction on the bunch mode. The acquired data also demonstrate that the instant retrigger technology allows for data acquisition up to 15 million photons per second per pixel.

  5. Competition between modes with different axial structures in gyrotrons

    SciTech Connect (OSTI)

    Khutoryan, Eduard M.; Nusinovich, Gregory S.; Sinitsyn, Oleksandr V.

    2014-09-15

    This study was motivated by some experiments in which it was found that during the voltage rise, instead of expected excitation of a high-frequency parasitic mode, the excitation of a lower-frequency parasitic mode takes place in a certain range of voltages. For explaining this fact, the dependence of start currents of possible competing modes on the beam voltage was carried out in the cold-cavity approximation and by using the self-consistent approach. It was found that in the case of cavities, which consist of the combination of a section of constant radius waveguide and a slightly uptapered waveguide, these two approaches yield completely different results. Thus, experimentally observed excitation of the low-frequency parasitic mode can be explained by the self-consistent modification of the axial profile of the excited field, which has strong influence on the diffractive quality factor of competing modes. This modification is especially pronounced in the case of excitation of modes with many axial variations which can be excited in the region of beam interaction with the backward-wave component of such modes.

  6. Bunch mode specific rate corrections for PILATUS3 detectors

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

    Trueb, P.; Dejoie, C.; Kobas, M.; Pattison, P.; Peake, D. J.; Radicci, V.; Sobott, B. A.; Walko, D. A.; Broennimann, C.

    2015-04-09

    PILATUS X-ray detectors are in operation at many synchrotron beamlines around the world. This article reports on the characterization of the new PILATUS3 detector generation at high count rates. As for all counting detectors, the measured intensities have to be corrected for the dead-time of the counting mechanism at high photon fluxes. The large number of different bunch modes at these synchrotrons as well as the wide range of detector settings presents a challenge for providing accurate corrections. To avoid the intricate measurement of the count rate behaviour for every bunch mode, a Monte Carlo simulation of the counting mechanismmore » has been implemented, which is able to predict the corrections for arbitrary bunch modes and a wide range of detector settings. This article compares the simulated results with experimental data acquired at different synchrotrons. It is found that the usage of bunch mode specific corrections based on this simulation improves the accuracy of the measured intensities by up to 40% for high photon rates and highly structured bunch modes. For less structured bunch modes, the instant retrigger technology of PILATUS3 detectors substantially reduces the dependency of the rate correction on the bunch mode. The acquired data also demonstrate that the instant retrigger technology allows for data acquisition up to 15 million photons per second per pixel.« less

  7. CMB hemispherical asymmetry: long mode modulation and non-Gaussianity

    SciTech Connect (OSTI)

    Namjoo, Mohammad Hossein; Baghram, Shant; Firouzjahi, Hassan; Abolhasani, Ali Akbar E-mail: abolhasani@ipm.ir E-mail: firouz@ipm.ir

    2014-08-01

    The observed hemispherical asymmetry in CMB map can be explained by modulation from a long wavelength super horizon mode which non-linearly couples to the CMB modes. We address the criticism in [1] about the role of non-Gaussianities in squeezed and equilateral configurations in generating hemispherical asymmetry from the long mode modulation. We stress that the modulation is sensitive to the non-Gaussianity in the squeezed limit. In addition, we demonstrate the validity of our approach in providing a consistency condition relating the amplitude of dipole asymmetry to f{sub NL} in the squeezed limit.

  8. Separating and combining single-mode and multimode optical beams

    DOE Patents [OSTI]

    Ruggiero, Anthony J; Masquelier, Donald A; Cooke, Jeffery B; Kallman, Jeffery S

    2013-11-12

    Techniques for combining initially separate single mode and multimode optical beams into a single "Dual Mode" fiber optic have been developed. Bi-directional propagation of two beams that are differentiated only by their mode profiles (i.e., wavefront conditions) is provided. The beams can be different wavelengths and or contain different modulation information but still share a common aperture. This method allows the use of conventional micro optics and hybrid photonic packaging techniques to produce small rugged packages suitable for use in industrial or military environments.

  9. Simulation of peeling-ballooning modes with pellet injection

    SciTech Connect (OSTI)

    Chen, S. Y.; Huang, J.; Sun, T. T.; Tang, C. J.; Wang, Z. H.

    2014-11-15

    The influence of pellet ablation on the evolution of peeling-ballooning (P-B) modes is studied with BOUT++ code. The atoms coming from pellet ablation can significantly reshape the plasma pressure profile, so the behaviors of P-B modes and edge localized mode (ELM) are modified dramatically. This paper shows that the energy loss associated with an ELM increases substantially over that without the pellet, if the pellet is deposited at the top of the pedestal. On the contrary, for pellet deposition in the middle of the pedestal region the ELM energy loss can be less.

  10. Multiprocessor system with multiple concurrent modes of execution

    DOE Patents [OSTI]

    Ahn, Daniel; Ceze, Luis H; Chen, Dong; Gara, Alan; Heidelberger, Philip; Ohmacht, Martin

    2013-12-31

    A multiprocessor system supports multiple concurrent modes of speculative execution. Speculation identification numbers (IDs) are allocated to speculative threads from a pool of available numbers. The pool is divided into domains, with each domain being assigned to a mode of speculation. Modes of speculation include TM, TLS, and rollback. Allocation of the IDs is carried out with respect to a central state table and using hardware pointers. The IDs are used for writing different versions of speculative results in different ways of a set in a cache memory.

  11. Investigation of dominant spin wave modes by domain walls collision

    SciTech Connect (OSTI)

    Ramu, M.; Purnama, I.; Goolaup, S.; Chandra Sekhar, M.; Lew, W. S.

    2014-06-28

    Spin wave emission due to field-driven domain wall (DW) collision has been investigated numerically and analytically in permalloy nanowires. The spin wave modes generated are diagonally symmetric with respect to the collision point. The non-propagating mode has the highest amplitude along the middle of the width. The frequency of this mode is strongly correlated to the nanowire geometrical dimensions and is independent of the strength of applied field within the range of 0.1?mT to 1?mT. For nanowire with film thickness below 5?nm, a second spin wave harmonic mode is observed. The decay coefficient of the spin wave power suggests that the DWs in a memory device should be at least 300?nm apart for them to be free of interference from the spin waves.

  12. Stability of short wavelength tearing and twisting modes

    SciTech Connect (OSTI)

    Waelbroeck, F.L.

    1998-09-22

    The stability and mutual interaction of tearing and twisting modes in a torus is governed by matrices that generalize the well-known {Delta}{prime} stability index. The diagonal elements of these matrices determine the intrinsic stability of modes that reconnect the magnetic field at a single resonant surface. The off-diagonal elements indicate the strength of the coupling between the different modes. The author shows how the elements of these matrices can be evaluated, in the limit of short wavelength, from the free energy driving radially extended ballooning modes. The author applies the results by calculating the tearing and twisting {Delta}{prime} for a model high-beta equilibrium with circular flux surfaces.

  13. High-Power Microwave Transmission and Mode Conversion Program

    SciTech Connect (OSTI)

    Vernon, Ronald J.

    2015-08-14

    This is a final technical report for a long term project to develop improved designs and design tools for the microwave hardware and components associated with the DOE Plasma Fusion Program. We have developed basic theory, software, fabrication techniques, and low-power measurement techniques for the design of microwave hardware associated gyrotrons, microwave mode converters and high-power microwave transmission lines. Specifically, in this report we discuss our work on designing quasi-optical mode converters for single and multiple frequencies, a new method for the analysis of perturbed-wall waveguide mode converters, perturbed-wall launcher design for TE0n mode gyrotrons, quasi-optical traveling-wave resonator design for high-power testing of microwave components, and possible improvements to the HSX microwave transmission line.

  14. Combustion mode switching with a turbocharged/supercharged engine

    DOE Patents [OSTI]

    Mond, Alan; Jiang, Li

    2015-09-22

    A method for switching between low- and high-dilution combustion modes in an internal combustion engine having an intake passage with an exhaust-driven turbocharger, a crankshaft-driven positive displacement supercharger downstream of the turbocharger and having variable boost controllable with a supercharger bypass valve, and a throttle valve downstream of the supercharger. The current combustion mode and mass air flow are determined. A switch to the target combustion mode is commanded when an operating condition falls within a range of predetermined operating conditions. A target mass air flow to achieve a target air-fuel ratio corresponding to the current operating condition and the target combustion mode is determined. The degree of opening of the supercharger bypass valve and the throttle valve are controlled to achieve the target mass air flow. The amount of residual exhaust gas is manipulated.

  15. Coherence area profiling in multi-spatial-mode squeezed states

    SciTech Connect (OSTI)

    Lawrie, Benjamin J.; Pooser, Raphael C.; Otterstrom, Nils T.

    2015-09-12

    The presence of multiple bipartite entangled modes in squeezed states generated by four-wave mixing enables ultra-trace sensing, imaging, and metrology applications that are impossible to achieve with single-spatial-mode squeezed states. For Gaussian seed beams, the spatial distribution of these bipartite entangled modes, or coherence areas, across each beam is largely dependent on the spatial modes present in the pump beam, but it has proven difficult to map the distribution of these coherence areas in frequency and space. We demonstrate an accessible method to map the distribution of the coherence areas within these twin beams. In addition, we also show that the pump shape can impart different noise properties to each coherence area, and that it is possible to select and detect coherence areas with optimal squeezing with this approach.

  16. Gearbox Typical Failure Modes, Detection, and Mitigation Methods (Presentation)

    SciTech Connect (OSTI)

    Sheng, S.

    2014-01-01

    This presentation was given at the AWEA Operations & Maintenance and Safety Seminar and focused on what the typical gearbox failure modes are, how to detect them using detection techniques, and strategies that help mitigate these failures.

  17. Ordinary mode instability associated with thermal ring distribution

    SciTech Connect (OSTI)

    Hadi, F.; Qamar, A.; Yoon, P. H.

    2015-02-15

    The purely growing ordinary (O) mode instability driven by excessive parallel temperature anisotropy has recently received renewed attention owing to its potential applicability to the solar wind plasma. Previous studies of O mode instability have assumed either bi-Maxwellian or counter-streaming velocity distributions. For solar wind plasma trapped in magnetic mirror-like geometry such as magnetic clouds or in the vicinity of the Earth's collisionless bow shock environment, however, the velocity distribution function may possess a loss-cone feature. The O-mode instability in such a case may be excited for cyclotron harmonics as well as the purely growing branch. The present paper investigates the O-mode instability for plasmas characterized by the parallel Maxwellian distribution and perpendicular thermal ring velocity distribution in order to understand the general stability characteristics.

  18. Slant-hole collimator, dual mode sterotactic localization method

    DOE Patents [OSTI]

    Weisenberger, Andrew G.

    2002-01-01

    The use of a slant-hole collimator in the gamma camera of dual mode stereotactic localization apparatus allows the acquisition of a stereo pair of scintimammographic images without repositioning of the gamma camera between image acquisitions.

  19. Charging system with galvanic isolation and multiple operating modes

    DOE Patents [OSTI]

    Kajouke, Lateef A.; Perisic, Milun; Ransom, Ray M.

    2013-01-08

    Systems and methods are provided for operating a charging system with galvanic isolation adapted for multiple operating modes. A vehicle charging system comprises a DC interface, an AC interface, a first conversion module coupled to the DC interface, and a second conversion module coupled to the AC interface. An isolation module is coupled between the first conversion module and the second conversion module. The isolation module comprises a transformer and a switching element coupled between the transformer and the second conversion module. The transformer and the switching element are cooperatively configured for a plurality of operating modes, wherein each operating mode of the plurality of operating modes corresponds to a respective turns ratio of the transformer.

  20. Dose Rate Calculations for Rotary Mode Core Sampling Exhauster

    SciTech Connect (OSTI)

    FOUST, D.J.

    2000-10-26

    This document provides the calculated estimated dose rates for three external locations on the Rotary Mode Core Sampling (RMCS) exhauster HEPA filter housing, per the request of Characterization Field Engineering.

  1. Coherence area profiling in multi-spatial-mode squeezed states

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

    Lawrie, Benjamin J.; Pooser, Raphael C.; Otterstrom, Nils T.

    2015-09-12

    The presence of multiple bipartite entangled modes in squeezed states generated by four-wave mixing enables ultra-trace sensing, imaging, and metrology applications that are impossible to achieve with single-spatial-mode squeezed states. For Gaussian seed beams, the spatial distribution of these bipartite entangled modes, or coherence areas, across each beam is largely dependent on the spatial modes present in the pump beam, but it has proven difficult to map the distribution of these coherence areas in frequency and space. We demonstrate an accessible method to map the distribution of the coherence areas within these twin beams. In addition, we also show thatmore » the pump shape can impart different noise properties to each coherence area, and that it is possible to select and detect coherence areas with optimal squeezing with this approach.« less

  2. Dual sensitivity mode system for monitoring processes and sensors

    DOE Patents [OSTI]

    Wilks, Alan D.; Wegerich, Stephan W.; Gross, Kenneth C.

    2000-01-01

    A method and system for analyzing a source of data. The system and method involves initially training a system using a selected data signal, calculating at least two levels of sensitivity using a pattern recognition methodology, activating a first mode of alarm sensitivity to monitor the data source, activating a second mode of alarm sensitivity to monitor the data source and generating a first alarm signal upon the first mode of sensitivity detecting an alarm condition and a second alarm signal upon the second mode of sensitivity detecting an associated alarm condition. The first alarm condition and second alarm condition can be acted upon by an operator and/or analyzed by a specialist or computer program.

  3. Growth Mode and Substrate Symmetry Dependent Strain in Epitaxial Graphene.

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Growth Mode and Substrate Symmetry Dependent Strain in Epitaxial Graphene. Citation Details In-Document Search Title: Growth Mode and Substrate Symmetry Dependent Strain in Epitaxial Graphene. Abstract not provided. Authors: Ohta, Taisuke ; Biedermann, Laura Butler ; Beechem Iii, Thomas Edwin ; Howell, Stephen Wayne ; Schmidt, Diedrich A. Publication Date: 2010-06-01 OSTI Identifier: 1123545 Report Number(s): SAND2010-3581J 492436 DOE Contract Number:

  4. Stabilization of the Vertical Mode in Tokamaks by Localized Nonaxisymmetric

    Office of Scientific and Technical Information (OSTI)

    Fields (Journal Article) | SciTech Connect Journal Article: Stabilization of the Vertical Mode in Tokamaks by Localized Nonaxisymmetric Fields Citation Details In-Document Search Title: Stabilization of the Vertical Mode in Tokamaks by Localized Nonaxisymmetric Fields Vertical instability of a tokamak plasma can be controlled by nonaxisymmetric magnetic fields localized near the plasma edge at the bottom and top of the torus. The required magnetic fields can be produced by a relatively

  5. Adaptive Particle Filtering for Mode Tracking: A Shallow Ocean Application

    Office of Scientific and Technical Information (OSTI)

    (Conference) | SciTech Connect Adaptive Particle Filtering for Mode Tracking: A Shallow Ocean Application Citation Details In-Document Search Title: Adaptive Particle Filtering for Mode Tracking: A Shallow Ocean Application Authors: Candy, J V Publication Date: 2011-07-12 OSTI Identifier: 1117989 Report Number(s): LLNL-CONF-491045 DOE Contract Number: W-7405-ENG-48 Resource Type: Conference Resource Relation: Conference: Presented at: OCEANS'11, Kona, HI, United States, Sep 19 - Sep 22, 2011

  6. Adaptive Wavenumber Estimation for Mode Tracking in a Shallow Ocean

    Office of Scientific and Technical Information (OSTI)

    Environment (Conference) | SciTech Connect Adaptive Wavenumber Estimation for Mode Tracking in a Shallow Ocean Environment Citation Details In-Document Search Title: Adaptive Wavenumber Estimation for Mode Tracking in a Shallow Ocean Environment Authors: Candy, J V Publication Date: 2012-06-28 OSTI Identifier: 1059076 Report Number(s): LLNL-CONF-563556 DOE Contract Number: W-7405-ENG-48 Resource Type: Conference Resource Relation: Conference: Presented at: IEEE OCEANS '12, Hampton Roads, VA,

  7. Pairing Nambu-Goldstone Modes within Nuclear Density Functional Theory

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Pairing Nambu-Goldstone Modes within Nuclear Density Functional Theory Citation Details In-Document Search This content will become publicly available on April 11, 2017 Title: Pairing Nambu-Goldstone Modes within Nuclear Density Functional Theory Authors: Hinohara, Nobuo ; Nazarewicz, Witold Publication Date: 2016-04-11 OSTI Identifier: 1246764 Grant/Contract Number: SC0013365; SC0008511 Type: Publisher's Accepted Manuscript Journal Name: Physical Review

  8. Parametrically Adaptive Wavenumber Processing for Mode Tracking in a

    Office of Scientific and Technical Information (OSTI)

    Shallow Ocean Environment (Conference) | SciTech Connect Parametrically Adaptive Wavenumber Processing for Mode Tracking in a Shallow Ocean Environment Citation Details In-Document Search Title: Parametrically Adaptive Wavenumber Processing for Mode Tracking in a Shallow Ocean Environment Authors: Candy, J V Publication Date: 2013-08-05 OSTI Identifier: 1096593 Report Number(s): LLNL-CONF-642197 DOE Contract Number: W-7405-ENG-48 Resource Type: Conference Resource Relation: Conference:

  9. Auroral Signatures of Ballooning Mode Near Substorm Onset: Open Geospace

    Office of Scientific and Technical Information (OSTI)

    General Circulation Model Simulations (Journal Article) | SciTech Connect Auroral Signatures of Ballooning Mode Near Substorm Onset: Open Geospace General Circulation Model Simulations Citation Details In-Document Search Title: Auroral Signatures of Ballooning Mode Near Substorm Onset: Open Geospace General Circulation Model Simulations Authors: Raeder, J ; Zhu, P ; Ge, Y ; Siscoe, G Publication Date: 2012-01-01 OSTI Identifier: 1211702 Resource Type: Journal Article Resource Relation:

  10. Rotary mode core sampling approved checklist: 241-TX-113

    SciTech Connect (OSTI)

    Fowler, K.D.

    1998-08-03

    The safety assessment for rotary mode core sampling was developed using certain bounding assumptions, however, those assumptions were not verified for each of the existing or potential flammable gas tanks. Therefore, a Flammable Gas/Rotary Mode Core Sampling Approved Checklist has been completed for tank 241-TX-113 prior to sampling operations. This transmittal documents the dispositions of the checklist items from the safety assessment.

  11. Rotary mode core sampling approved checklist: 241-TX-116

    SciTech Connect (OSTI)

    FOWLER, K.D.

    1999-02-24

    The safety assessment for rotary mode core sampling was developed using certain bounding assumptions, however, those assumptions were not verified for each of the existing or potential flammable gas tanks. Therefore, a Flammable Gas/Rotary Mode Core Sampling Approved Checklist has been completed for tank 241-TX-116 prior to sampling operations. This transmittal documents the dispositions of the checklist items from the safety assessment.

  12. Sequestering Uranium from Seawater: Binding Strength and Modes of Uranyl

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

    Complexes with Glutarimidedioxime Sequestering Uranium from Seawater: Binding Strength and Modes of Uranyl Complexes with Glutarimidedioxime Sequestering Uranium from Seawater: Binding Strength and Modes of Uranyl Complexes with Glutarimidedioxime Print Sunday, 14 October 2012 00:00 The ocean is an important source of uranium if it can be extracted economically. Extraction of uranium from seawater is very challenging, not only because it is in an extremely low concentration, but also because

  13. Adaptive sliding mode control for a class of chaotic systems

    SciTech Connect (OSTI)

    Farid, R.; Ibrahim, A.; Zalam, B.

    2015-03-30

    Chaos control here means to design a controller that is able to mitigating or eliminating the chaos behavior of nonlinear systems that experiencing such phenomenon. In this paper, an Adaptive Sliding Mode Controller (ASMC) is presented based on Lyapunov stability theory. The well known Chua's circuit is chosen to be our case study in this paper. The study shows the effectiveness of the proposed adaptive sliding mode controller.

  14. Mode dependent lattice thermal conductivity of single layer graphene

    SciTech Connect (OSTI)

    Wei, Zhiyong; Yang, Juekuan; Bi, Kedong; Chen, Yunfei

    2014-10-21

    Molecular dynamics simulation is performed to extract the phonon dispersion and phonon lifetime of single layer graphene. The mode dependent thermal conductivity is calculated from the phonon kinetic theory. The predicted thermal conductivity at room temperature exhibits important quantum effects due to the high Debye temperature of graphene. But the quantum effects are reduced significantly when the simulated temperature is as high as 1000 K. Our calculations show that out-of-plane modes contribute about 41.1% to the total thermal conductivity at room temperature. The relative contribution of out-of-plane modes has a little decrease with the increase of temperature. Contact with substrate can reduce both the total thermal conductivity of graphene and the relative contribution of out-of-plane modes, in agreement with previous experiments and theories. Increasing the coupling strength between graphene and substrate can further reduce the relative contribution of out-of-plane modes. The present investigations also show that the relative contribution of different mode phonons is not sensitive to the grain size of graphene. The obtained phonon relaxation time provides useful insight for understanding the phonon mean free path and the size effects in graphene.

  15. Rouse mode analysis of chain relaxation in homopolymer melts

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

    Kalathi, Jagannathan T.; Kumar, Sanat K.; Rubinstein, Michael; Grest, Gary S.

    2014-09-15

    We use molecular dynamics simulations of the Kremer–Grest (KG) bead–spring model of polymer chains of length between 10 and 500, and a closely related analogue that allows for chain crossing, to clearly delineate the effects of entanglements on the length-scale-dependent chain relaxation in polymer melts. We analyze the resulting trajectories using the Rouse modes of the chains and find that entanglements strongly affect these modes. The relaxation rates of the chains show two limiting effective monomeric frictions, with the local modes experiencing much lower effective friction than the longer modes. The monomeric relaxation rates of longer modes vary approximately inverselymore » with chain length due to kinetic confinement effects. The time-dependent relaxation of Rouse modes has a stretched exponential character with a minimum of stretching exponent in the vicinity of the entanglement chain length. None of these trends are found in models that allow for chain crossing. As a result, these facts, in combination, argue for the confined motion of chains for time scales between the entanglement time and their ultimate free diffusion.« less

  16. Microsoft PowerPoint - 15.1500_Michael Deane [Compatibility Mode...

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

    00Michael Deane Compatibility Mode Microsoft PowerPoint - 15.1500Michael Deane Compatibility Mode PDF icon Microsoft PowerPoint - 15.1500Michael Deane Compatibility Mode...

  17. Microsoft PowerPoint - 16.0805_Tom Fox [Compatibility Mode] ...

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

    05Tom Fox Compatibility Mode Microsoft PowerPoint - 16.0805Tom Fox Compatibility Mode PDF icon Microsoft PowerPoint - 16.0805Tom Fox Compatibility Mode More Documents &...

  18. AXISYMMETRIC SCATTERING OF p MODES BY THIN MAGNETIC TUBES

    SciTech Connect (OSTI)

    Hindman, Bradley W.; Jain, Rekha

    2012-02-10

    We examine the scattering of acoustic p-mode waves from a thin magnetic fibril embedded in a gravitationally stratified atmosphere. The scattering is mediated through the excitation of slow sausage waves on the magnetic tube, and only the scattering of the monopole component of the wave field is considered. Since such tube waves are not confined by the acoustic cavity and may freely propagate along the field lines removing energy from the acoustic wave field, the excitation of fibril oscillations is a source of acoustic wave absorption as well as scattering. We compute the mode mixing that is achieved and the absorption coefficients and phase shifts. We find that for thin tubes the mode mixing is weak and the absorption coefficient is small and is a smooth function of frequency over the physically relevant band of observed frequencies. The prominent absorption resonances seen in previous studies of unstratified tubes are absent. Despite the relatively small absorption, the phase shift induced can be surprisingly large, reaching values as high as 15 Degree-Sign for f modes. Further, the phase shift can be positive or negative depending on the incident mode order and the frequency.

  19. Magnetic antenna excitation of whistler modes. II. Antenna arrays

    SciTech Connect (OSTI)

    Stenzel, R. L.; Urrutia, J. M.

    2014-12-15

    The excitation of whistler modes from magnetic loop antennas has been investigated experimentally. The field topology of the excited wave driven by a single loop antenna has been measured for different loop orientations with respect to the uniform background field. The fields from two or more antennas at different locations are then created by superposition of the single-loop data. It is shown that an antenna array can produce nearly plane waves which cannot be achieved with single antennas. By applying a phase shift along the array, oblique wave propagation is obtained. This allows a meaningful comparison with plane wave theory. The Gendrin mode and oblique cyclotron resonance are demonstrated. Wave helicity and polarization in space and time are demonstrated and distinguished from the magnetic helicity of the wave field. The superposition of two oblique plane whistler modes produces in a “whistler waveguide” mode whose polarization and helicity properties are explained. The results show that single point measurements cannot properly establish the wave character of wave packets. The laboratory observations are relevant for excitation and detection of whistler modes in space plasmas.

  20. Suppression and nonlinear excitation of parasitic modes in second harmonic gyrotrons operating in a very high order mode

    SciTech Connect (OSTI)

    Nusinovich, Gregory S.; Pu, Ruifeng; Granatstein, Victor L.

    2015-07-06

    In recent years, there was an active development of high-power, sub-terahertz (sub-THz) gyrotrons for numerous applications. For example, a 0.67 THz gyrotron delivering more than 200 kW with about 20% efficiency was developed. This record high efficiency was achieved because the gyrotron operated in a high-order TE{sub 31,8}-mode with the power of ohmic losses less than 10% of the power of outgoing radiation. That gyrotron operated at the fundamental cyclotron resonance, and a high magnetic field of about 27 T was created by a pulse solenoid. For numerous applications, it is beneficial to use gyrotrons at cyclotron harmonics which can operate in available cryomagnets with fields not exceeding 15 T. However, typically, the gyrotron operation at harmonics faces severe competition from parasitic modes at the fundamental resonance. In the present paper, we consider a similar 0.67 THz gyrotron designed for operation in the same TE{sub 31,8}-mode, but at the second harmonic. We focus on two nonlinear effects typical for interaction between the fundamental and second harmonic modes, viz., the mode suppression and the nonlinear excitation of the mode at the fundamental harmonic by the second harmonic oscillations. Our study includes both the analytical theory and numerical simulations performed with the self-consistent code MAGY. The simulations show that stable second harmonic operation in the TE{sub 31,8} mode is possible with only modest sacrifice of efficiency and power.

  1. Nonlinear gyrofluid computation of edge localized ideal ballooning modes

    SciTech Connect (OSTI)

    Kendl, Alexander; Scott, Bruce D.; Ribeiro, Tiago T.

    2010-07-15

    Three-dimensional electromagnetic gyrofluid simulations of the ideal ballooning mode blowout scenario for tokamak edge localized modes are presented. Special emphasis is placed on diagnosis of the linear, overshoot, and decay phases. The saturation process is energy transfer to self-generated edge turbulence, which exhibits an ion temperature gradient mode structure. Convergence in the decay phase is found only if the spectrum reaches the ion gyroradius. The equilibrium is a self-consistent background whose evolution is taken into account. Approximately two-thirds of the total energy in the edge layer is liberated in the blowout. Parameter dependence with respect to plasma pressure and the ion gyroradius is studied. Despite the violent nature of the short-lived process, the transition to nonlinearity is very similar to that found in generic tokamak edge turbulence.

  2. Lasing modes in polycrystalline and amorphous photonic structures

    SciTech Connect (OSTI)

    Yang, Jin-Kyu; Noh, Heeso; Liew, Seng Fatt; Rooks, Michael J.; Solomon, Glenn S.; Cao Hui

    2011-09-15

    We systematically studied the lasing characteristics in photonic polycrystalline and amorphous structures. 2D arrays of air holes were fabricated in a GaAs membrane. InAs quantum dots embedded in the membrane provide gain for lasing under optical pumping. The lasing modes are spatially localized, and blue shift as the structural order becomes short ranged. Our three-dimensional numerical simulations reveal that the out-of-plane leakage of the lasing mode dominates over the in-plane leakage. The lasing modes in a photonic polycrystalline move away from the center frequency of the photonic band gap to reduce the out-of-plane leakage. In a photonic amorphous structure, the short-range order improves optical confinement and enhances the quality factor of resonances. Understanding the behavior of photonic polycrystalline laser and amorphous laser opens the possibility of controlling lasing characteristic by varying the degree of structural order.

  3. Overview of Common Mode Outages in Power Systems

    SciTech Connect (OSTI)

    Papic, Milorad; Awodele , Kehinde; Billinton, Roy; Dent, Chris; Eager, Dan; Hamoud, Gomaa; Jirutitijaroen, Panida; Kumbale, Murali; Mitra, Joydeep; Samaan, Nader A.; Schneider, Alex; Singh, Chanan

    2012-11-10

    This paper is a result of ongoing activity carried out by Probability Applications for Common Mode Events (PACME) Task Force under the Reliability Risk and Probability Applications (RRPA) Subcommittee. The paper is intended to constitute a valid source of information and references about dealing with common-mode outages in power systems reliability analysis. This effort involves reviewing published literature and presenting state-of-the-art research and practical applications in the area of common-mode outages. Evaluation of available outage statistics show that there is a definite need for collective effort from academia and industry to not only recommended procedures for data collection and monitoring but also to provide appropriate mathematical models to assess such events.

  4. Scissors mode of Gd nuclei studied from resonance neutron capture

    SciTech Connect (OSTI)

    Kroll, J.; Baramsai, B.; Becker, J. A.; and others

    2012-10-20

    Spectra of {gamma} rays following the neutron capture at isolated resonances of stable Gd nuclei were measured. The objectives were to get new information on photon strength of {sup 153,155-159}Gd with emphasis on the role of the M1 scissors-mode vibration. An analysis of the data obtained clearly indicates that the scissors mode is coupled not only to the ground state, but also to all excited levels of the nuclei studied. The specificity of our approach ensures unbiasedness in estimating the sumed scissors-mode strength {Sigma}B(M1){up_arrow}, even for odd product nuclei, for which conventional nuclear resonance fluorescence measurements yield only limited information. Our analysis indicates that for these nuclei the sum {Sigma}B(M1){up_arrow} increases with A and for {sup 157,159}Gd it is significantly higher compared to {sup 156,158}Gd.

  5. Asymmetric tearing mode in the presence of viscosity

    SciTech Connect (OSTI)

    Militello, F.; Grasso, D.; Marchetto, C.; Ottaviani, M.

    2011-11-15

    The linear stability of the tearing mode (TM) in a plasma column is investigated in the presence of viscosity and finite equilibrium current density gradients (i.e., asymmetries). It is shown that for low {beta}, both effects are essential in order to properly describe the mode behaviour close to marginality. In particular, the theory introduces a critical threshold for the destabilization, such that the perturbation grows only if {Delta}'>{Delta}'{sub cr}. The value of {Delta}'{sub cr} depends on the equilibrium configuration and on the plasma parameters. Most importantly, {Delta}'{sub cr} can take negative values, thus allowing unstable tearing modes for {Delta}' < 0 (even in the absence of bootstrap current).

  6. Linear mode conversion of Langmuir/z-mode waves to radiation in plasmas with various magnetic field strength

    SciTech Connect (OSTI)

    Kim, Eun-Hwa; Johnson, Jay R.; Cairns, Iver H.

    2013-12-15

    Linear mode conversion of Langmuir/z waves to electromagnetic radiation near the plasma and upper hybrid frequency in the presence of density gradients is potentially relevant to type II and III solar radio bursts, ionospheric radar experiments, pulsars, and continuum radiation for planetary magnetospheres. Here, we study mode conversion in warm, magnetized plasmas using a numerical electron fluid simulation code when the density gradient has a wide range of angle, δ, to the ambient magnetic field, B{sub 0}, for a range of incident Langmuir/z wavevectors. Our results include: (1) Left-handed polarized ordinary (oL) and right-handed polarized extraordinary (xR) mode waves are produced in various ranges of δ for Ω{sub 0} = (ωL/c){sup 1/3}(ω{sub ce}/ω) < 1.5, where ω{sub ce} is the (angular) electron cyclotron frequency, ω is the angular wave frequency, L is the length scale of the (linear) density gradient, and c is the speed of light; (2) the xR mode is produced most strongly in the range, 40° < δ < 60°, for intermediately magnetized plasmas with Ω{sub 0} = 1.0 and 1.5, while it is produced over a wider range, 0° ≤ δ ≤ 90°, for weakly magnetized plasmas with Ω{sub 0} = 0.1 and 0.7; (3) the maximum total conversion efficiencies for wave power from the Langmuir/z mode to radiation are of order 50%–99% and the corresponding energy conversion efficiencies are 5%–14% (depending on the adiabatic index γ and β = T{sub e}/m{sub e}c{sup 2}, where T{sub e} is the electron temperature and m{sub e} is the electron) for various Ω{sub 0}; (4) the mode conversion window becomes wider as Ω{sub 0} and δ increase. Hence, the results in this paper confirm that linear mode conversion under these conditions can explain the weak total circular polarization of interplanetary type II and III solar radio bursts because a strong xR mode can be generated via linear mode conversion near δ ∼ 45°.

  7. Non-linear mode interaction between spin torque driven and damped modes in spin torque nano-oscillators

    SciTech Connect (OSTI)

    Romera, M.; Monteblanco, E.; Garcia-Sanchez, F.; Buda-Prejbeanu, L. D.; Ebels, U.; Delaët, B.

    2015-05-11

    The influence of dynamic coupling in between magnetic layers of a standard spin torque nano-oscillator composed of a synthetic antiferromagnet (SyF) as a polarizer and an in-plane magnetized free layer has been investigated. Experiments on spin valve nanopillars reveal non-continuous features such as kinks in the frequency field dependence that cannot be explained without such interactions. Comparison of experiments to numerical macrospin simulations shows that this is due to non-linear interaction between the spin torque (STT) driven mode and a damped mode that is mediated via the third harmonics of the STT mode. It only occurs at large applied currents and thus at large excitation amplitudes of the STT mode. Under these conditions, a hybridized mode characterized by a strong reduction of the linewidth appears. The reduced linewidth can be explained by a reduction of the non-linear contribution to the linewidth via an enhanced effective damping. Interestingly, the effect depends also on the exchange interaction within the SyF. An enhancement of the current range of reduced linewidth by a factor of two and a reduction of the minimum linewidth by a factor of two are predicted from simulation when the exchange interaction strength is reduced by 30%. These results open directions to optimize the design and microwave performances of spin torque nano-oscillators taking advantage of the coupling mechanisms.

  8. Wavelength meter having single mode fiber optics multiplexed inputs

    DOE Patents [OSTI]

    Hackel, Richard P.; Paris, Robert D.; Feldman, Mark

    1993-01-01

    A wavelength meter having a single mode fiber optics input is disclosed. The single mode fiber enables a plurality of laser beams to be multiplexed to form a multiplexed input to the wavelength meter. The wavelength meter can provide a determination of the wavelength of any one or all of the plurality of laser beams by suitable processing. Another aspect of the present invention is that one of the laser beams could be a known reference laser having a predetermined wavelength. Hence, the improved wavelength meter can provide an on-line calibration capability with the reference laser input as one of the plurality of laser beams.

  9. Wavelength meter having single mode fiber optics multiplexed inputs

    DOE Patents [OSTI]

    Hackel, R.P.; Paris, R.D.; Feldman, M.

    1993-02-23

    A wavelength meter having a single mode fiber optics input is disclosed. The single mode fiber enables a plurality of laser beams to be multiplexed to form a multiplexed input to the wavelength meter. The wavelength meter can provide a determination of the wavelength of any one or all of the plurality of laser beams by suitable processing. Another aspect of the present invention is that one of the laser beams could be a known reference laser having a predetermined wavelength. Hence, the improved wavelength meter can provide an on-line calibration capability with the reference laser input as one of the plurality of laser beams.

  10. LOCAL MEASUREMENTS OF TEARING MODE FLOWS AND THE MHD DYNAMO

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

    LOCAL MEASUREMENTS OF TEARING MODE FLOWS AND THE MHD DYNAMO IN THE MST REVERSED-FIELD PINCH by David A. Ennis A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Physics) at the University of Wisconsin-Madison 2008 i Local Measurements of Tearing Mode Flows and the MHD Dynamo in the MST Reversed-Field Pinch David A. Ennis Under the supervision of Dr. Darren J. G. Craig and Professor Stewart C. Prager At the University of Wisconsin-Madison

  11. Edge Plasma Boundary Layer Generated By Kink Modes in Tokamaks

    SciTech Connect (OSTI)

    L.E. Zakharov

    2010-11-22

    This paper describes the structure of the electric current generated by external kink modes at the plasma edge using the ideally conducting plasma model. It is found that the edge current layer is created by both wall touching and free boundary kink modes. Near marginal stability, the total edge current has a universal expression as a result of partial compensation of the ?-functional surface current by the bulk current at the edge. The resolution of an apparent paradox with the pressure balance across the plasma boundary in the presence of the surface currents is provided.

  12. Accelerator-mode-based technique for studying quantum chaos

    SciTech Connect (OSTI)

    D'Arcy, M.B.; Godun, R.M.; Cassettari, D. [Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Summy, G.S. [Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States)

    2003-02-01

    We experimentally demonstrate a method for selecting small regions of phase space for kicked rotor quantum chaos experiments with cold atoms. Our technique uses quantum accelerator modes to selectively accelerate atomic wave packets with localized spatial and momentum distributions. The potential used to create the accelerator mode and subsequently realize the kicked rotor system is formed by a set of off-resonant standing-wave light pulses. We also propose a method for testing whether a selected region of phase space exhibits chaotic or regular behavior using a Ramsey type separated field experiment.

  13. Feedback stabilization system for pulsed single longitudinal mode tunable lasers

    DOE Patents [OSTI]

    Esherick, Peter; Raymond, Thomas D.

    1991-10-01

    A feedback stabilization system for pulse single longitudinal mode tunable lasers having an excited laser medium contained within an adjustable length cavity and producing a laser beam through the use of an internal dispersive element, including detection of angular deviation in the output laser beam resulting from detuning between the cavity mode frequency and the passband of the internal dispersive element, and generating an error signal based thereon. The error signal can be integrated and amplified and then applied as a correcting signal to a piezoelectric transducer mounted on a mirror of the laser cavity for controlling the cavity length.

  14. Nonlinear normal modes modal interactions and isolated resonance curves

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

    Kuether, Robert J.; Renson, L.; Detroux, T.; Grappasonni, C.; Kerschen, G.; Allen, M. S.

    2015-05-21

    The objective of the present study is to explore the connection between the nonlinear normal modes of an undamped and unforced nonlinear system and the isolated resonance curves that may appear in the damped response of the forced system. To this end, an energy balance technique is used to predict the amplitude of the harmonic forcing that is necessary to excite a specific nonlinear normal mode. A cantilever beam with a nonlinear spring at its tip serves to illustrate the developments. Furthermore, the practical implications of isolated resonance curves are also discussed by computing the beam response to sine sweepmore » excitations of increasing amplitudes.« less

  15. Enforcement Policy Statement: Off Mode Standards for Central Air Conditioners

    Energy Savers [EERE]

    Enforcement Policy Statement: Off Mode Standards for Central Air Conditioners and Central Air Conditioning Heat Pumps July 8, 2014 On June 27, 2011, the Department of Energy (DOE) published in the Federal Register a direct final rule (DFR) under the Energy Policy and Conservation Act (EPCA), 42 U.S.C. §§ 6291-6309, which set forth amended energy conservation standards for central air conditioners and central air conditioning heat pumps (CAC/HP), including a new standard for off mode electrical

  16. Wind Turbine Gearbox Failure Modes - A Brief (Presentation)

    SciTech Connect (OSTI)

    Sheng, S.; McDade, M.; Errichello, R.

    2011-10-01

    Wind turbine gearboxes are not always meeting 20-year design life. Premature failure of gearboxes increases cost of energy, turbine downtime, unplanned maintenance, gearbox replacement and rebuild, and increased warranty reserves. The problem is widespread, affects most Original Equipment Manufacturers, and is not caused by manufacturing practices. There is a need to improve gearbox reliability and reduce turbine downtime. The topics of this presentation are: GRC (Gearbox Reliability Collaborative) technical approach; Gearbox failure database; Recorded incidents summary; Top failure modes for bearings; Top failure modes for gears; GRC test gearbox; Bearing nomenclature; Test history; Real damage; Gear sets; Bearings; Observations; and Summary. 5 refs.

  17. Nonlinear normal modes modal interactions and isolated resonance curves

    SciTech Connect (OSTI)

    Kuether, Robert J.; Renson, L.; Detroux, T.; Grappasonni, C.; Kerschen, G.; Allen, M. S.

    2015-05-21

    The objective of the present study is to explore the connection between the nonlinear normal modes of an undamped and unforced nonlinear system and the isolated resonance curves that may appear in the damped response of the forced system. To this end, an energy balance technique is used to predict the amplitude of the harmonic forcing that is necessary to excite a specific nonlinear normal mode. A cantilever beam with a nonlinear spring at its tip serves to illustrate the developments. Furthermore, the practical implications of isolated resonance curves are also discussed by computing the beam response to sine sweep excitations of increasing amplitudes.

  18. Mechanism of force mode dip-pen nanolithography

    SciTech Connect (OSTI)

    Yang, Haijun E-mail: swguo@sjtu.edu.cn; Xie, Hui; Rong, Weibin; Sun, Lining; Wu, Haixia; Guo, Shouwu E-mail: swguo@sjtu.edu.cn

    2014-05-07

    In this work, the underlying mechanism of the force mode dip-pen nanolithography (FMDPN) is investigated in depth by analyzing force curves, tapping mode deflection signals, and Z-scan voltage variations during the FMDPN. The operation parameters including the relative trigger threshold and surface delay parameters are vital to control the loading force and dwell time for ink deposition during FMDPN. A model is also developed to simulate the interactions between the atomic force microscope tip and soft substrate during FMDPN, and verified by its good performance in fitting our experimental data.

  19. TM01-mode microwave propagation property analysis for plasmas with

    Office of Scientific and Technical Information (OSTI)

    disk-plate windows by a finite-difference time-domain method (Journal Article) | SciTech Connect TM01-mode microwave propagation property analysis for plasmas with disk-plate windows by a finite-difference time-domain method Citation Details In-Document Search Title: TM01-mode microwave propagation property analysis for plasmas with disk-plate windows by a finite-difference time-domain method Numerical studies of microwave propagation properties in a conical horn and an adjustable

  20. Unusual Layer-Dependent Charge Distribution, Collective Mode Coupling, and

    Office of Scientific and Technical Information (OSTI)

    Superconductivity in Multilayer Cuprate Ba2Ca3Cu4O8F2 (Journal Article) | SciTech Connect Layer-Dependent Charge Distribution, Collective Mode Coupling, and Superconductivity in Multilayer Cuprate Ba2Ca3Cu4O8F2 Citation Details In-Document Search Title: Unusual Layer-Dependent Charge Distribution, Collective Mode Coupling, and Superconductivity in Multilayer Cuprate Ba2Ca3Cu4O8F2 Low energy ultrahigh momentum resolution angle resolved photoemission spectroscopy study on four-layer self-doped

  1. Unusual layer-dependent charge distribution, collective mode coupling, and

    Office of Scientific and Technical Information (OSTI)

    superconductivity in multilayer cuprate Ba2Ca3Cu4O8F2 (Journal Article) | SciTech Connect layer-dependent charge distribution, collective mode coupling, and superconductivity in multilayer cuprate Ba2Ca3Cu4O8F2 Citation Details In-Document Search Title: Unusual layer-dependent charge distribution, collective mode coupling, and superconductivity in multilayer cuprate Ba2Ca3Cu4O8F2 Low energy ultrahigh momentum resolution angle resolved photoemission spectroscopy study on four-layer self-doped

  2. Nonlinear simulations of peeling-ballooning modes with anomalous electron viscosity and their role in edge localized mode crashes

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

    Xu, X. Q.; Dudson, B.; Snyder, P. B.; Umansky, M. V.; Wilson, H.

    2010-10-22

    A minimum set of equations based on the peeling-ballooning (P-B) model with nonideal physics effects (diamagnetic drift, E×B drift, resistivity, and anomalous electron viscosity) is found to simulate pedestal collapse when using the new BOUT++ simulation code, developed in part from the original fluid edge code BOUT. Nonlinear simulations of P-B modes demonstrate that the P-B modes trigger magnetic reconnection, which leads to the pedestal collapse. With the addition of a model of the anomalous electron viscosity under the assumption that the electron viscosity is comparable to the anomalous electron thermal diffusivity, it is found from simulations using a realisticmore » high-Lundquist number that the pedestal collapse is limited to the edge region and the edge localized mode (ELM) size is about 5–10% of the pedestal stored energy. Furthermore, this is consistent with many observations of large ELMs.« less

  3. Effects of a random spatial variation of the plasma density on the mode conversion in cold, unmagnetized, and stratified plasmas

    SciTech Connect (OSTI)

    Jung Yu, Dae; Kim, Kihong

    2013-12-15

    We study the effects of a random spatial variation of the plasma density on the mode conversion of electromagnetic waves into electrostatic oscillations in cold, unmagnetized, and stratified plasmas. Using the invariant imbedding method, we calculate precisely the electromagnetic field distribution and the mode conversion coefficient, which is defined to be the fraction of the incident wave power converted into electrostatic oscillations, for the configuration where a numerically generated random density variation is added to the background linear density profile. We repeat similar calculations for a large number of random configurations and take an average of the results. We obtain a peculiar nonmonotonic dependence of the mode conversion coefficient on the strength of randomness. As the disorder increases from zero, the maximum value of the mode conversion coefficient decreases initially, then increases to a maximum, and finally decreases towards zero. The range of the incident angle in which mode conversion occurs increases monotonically as the disorder increases. We present numerical results suggesting that the decrease of mode conversion mainly results from the increased reflection due to the Anderson localization effect originating from disorder, whereas the increase of mode conversion of the intermediate disorder regime comes from the appearance of many resonance points and the enhanced tunneling between the resonance points and the cutoff point. We also find a very large local enhancement of the magnetic field intensity for particular random configurations. In order to obtain high mode conversion efficiency, it is desirable to restrict the randomness close to the resonance region.

  4. Localized Ballooning Modes in Compact Quasiaxially Symmetric Stellarators

    SciTech Connect (OSTI)

    M.H. Redi; J. Canik; R.L. Dewar; E.D. Fredrickson; W.A. Cooper; J.L. Johnson; S. Klasky

    2001-06-14

    Understanding of ballooning mode stability boundaries may lead to performance improvement of toroidal devices through control of plasma disruptions. Toroidally localized ballooning modes have been found as precursors to high-beta plasma disruptions on the Tokamak Fusion Test Reactor (TFTR) arising in conditions of n=1 kink mode asymmetry. Recent optimization has shown that magnetohydrodynamic (MHD) stability as well as good particle confinement are likely to be achievable in the National Compact Stellarator Experiment (NCSX), a compact, quasiaxially symmetric stellarator (QAS) for values of the plasma near beta = 4%. The configuration, with a major radius of 1.42 m, an aspect ratio of 4.4, a toroidal magnetic field 1.2-1.7 T and 6 MW of neutral-beam heating, is stable to MHD instabilities, and is expected to be limited by high-n kink and ballooning modes. This paper describes the ballooning eigenvalue isosurfaces for NCSX, the first step in an examination of the kinetic stabilization of the ballooning beta limit using a hybrid WKB approach.

  5. Nonlinear dynamics of large amplitude modes in a magnetized plasma

    SciTech Connect (OSTI)

    Brodin, G.; Stenflo, L.

    2014-12-15

    We derive two equations describing the coupling between electromagnetic and electrostatic oscillations in one-dimensional geometry in a magnetized cold and non-relativistic plasma. The nonlinear interaction between the wave modes is studied numerically. The effects of the external magnetic field strength and the initial electromagnetic polarization are of particular interest here. New results can, thus, be identified.

  6. Stress Induced Degradation Modes in CIGSS Minimodules (Presentation)

    SciTech Connect (OSTI)

    Kempe, M. D.; Terwilliger, K.; Tarrant, D.

    2008-05-01

    The experimental objectives of this report are: (1) compare the performance of modules exposed to high temperature and humidity; (2) determine the effects of different encapsulants on long term stability of CIGSS modules; and (3) analyze failure modes to determine areas in need of improvement.

  7. Critical {delta}{sup '} for stability of viscoresistive tearing modes

    SciTech Connect (OSTI)

    Grasso, D.; Hastie, R. J.; Porcelli, F.; Tebaldi, C.

    2008-07-15

    An analytic expression for the stability threshold of linear tearing modes is derived. The magnetized plasma is described in terms of a standard viscoresistive magnetohydrodynamic model. The analytic derivation requires an extension of the standard layer equation that represents an approximation of the full model in the vicinity of the reconnecting layer. The analytic result is checked against numerical simulations, showing excellent agreement.

  8. Cosmic super-strings and Kaluza-Klein modes

    SciTech Connect (OSTI)

    Dufaux, Jean-Franois

    2012-09-01

    Cosmic super-strings interact generically with a tower of relatively light and/or strongly coupled Kaluza-Klein (KK) modes associated with the geometry of the internal space. In this paper, we study the production of spin-2 KK particles by cusps on loops of cosmic F- and D-strings. We consider cosmic super-strings localized either at the bottom of a warped throat or in a flat internal space with large volume. The total energy emitted by cusps in KK modes is comparable in both cases, although the number of produced KK modes may differ significantly. We then show that KK emission is constrained by the photo-dissociation of light elements and by observations of the diffuse gamma ray background. We show that this rules out regions of the parameter space of cosmic super-strings that are complementary to the regions that can be probed by current and upcoming gravitational wave experiments. KK modes are also expected to play an important role in the friction-dominated epoch of cosmic super-string evolution.

  9. Northwest Energy Innovations (TRL 5 6 System)- WETNZ MtiMode Wave Energy Converter Advancement Project

    Broader source: Energy.gov [DOE]

    Northwest Energy Innovations (TRL 5 6 System) - WETNZ MtiMode Wave Energy Converter Advancement Project

  10. Axisymmetric oscillation modes of a double droplet system

    SciTech Connect (OSTI)

    Ramalingam, Santhosh K.; Basaran, Osman A.

    2010-11-15

    A double droplet system (DDS) consists of a sessile and a pendant drop that are coupled through a liquid filled cylindrical hole in a plate of thickness d. For a small hole radius R, equilibrium shapes of both drops are sections of spheres. While DDSs have a number of applications in microfluidics, a DDS oscillating about its equilibrium state can be used as a fast focusing liquid lens. Here, a DDS consisting of an isothermal, incompressible Newtonian fluid of constant density p and constant viscosity u that is surrounded by a gas is excited by oscillating in time (a) the pressure in the gas surrounding either drop (pressure excitation), (b) the plate perpendicular to its plane (axial excitation), and (c) the hole radius (radial excitation). In contrast to previous works that assumed transient drop shapes are spherical, they are determined here by simulation and used to identify the natural modes of axisymmetric oscillations from resonances observed during frequency sweeps with DDSs for which the combined volume V of the two drops is less than (4/3)?R3. Pressure and axial excitations are found to have identical responses but axial and radial excitations are shown to excite different modes. These modes are compared to those exhibited by single pendant (sessile) drop systems. In particular, while a single pendant (sessile) drop has one additional oscillation mode compared to a free drop, a DDS is found to exhibit roughly twice as many oscillation modes as a pendant (sessile) drop. The effects of dimensionless volume V/R3, dimensionless plate thickness d/R, and Ohnesorge number Oh =?/??R? , where ? is the surface tension of the DDS-gas interface, on the resonance frequencies are also investigated.

  11. Axisymmetric oscillation modes of a double droplet system

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

    Ramalingam, Santhosh K.; Basaran, Osman A.

    2010-11-15

    A double droplet system (DDS) consists of a sessile and a pendant drop that are coupled through a liquid filled cylindrical hole in a plate of thickness d. For a small hole radius R, equilibrium shapes of both drops are sections of spheres. While DDSs have a number of applications in microfluidics, a DDS oscillating about its equilibrium state can be used as a fast focusing liquid lens. Here, a DDS consisting of an isothermal, incompressible Newtonian fluid of constant density p and constant viscosity u that is surrounded by a gas is excited by oscillating in time (a) themore » pressure in the gas surrounding either drop (pressure excitation), (b) the plate perpendicular to its plane (axial excitation), and (c) the hole radius (radial excitation). In contrast to previous works that assumed transient drop shapes are spherical, they are determined here by simulation and used to identify the natural modes of axisymmetric oscillations from resonances observed during frequency sweeps with DDSs for which the combined volume V of the two drops is less than (4/3)πR3. Pressure and axial excitations are found to have identical responses but axial and radial excitations are shown to excite different modes. These modes are compared to those exhibited by single pendant (sessile) drop systems. Specifically, while a single pendant (sessile) drop has one additional oscillation mode compared to a free drop, a DDS is found to exhibit roughly twice as many oscillation modes as a pendant (sessile) drop. The effects of dimensionless volume V/R3, dimensionless plate thickness d/R, and Ohnesorge number Oh =μ/√ρRσ , where σ is the surface tension of the DDS-gas interface, on the resonance frequencies are also investigated.« less

  12. FAST MODES AND DUSTY HORSESHOES IN TRANSITIONAL DISKS

    SciTech Connect (OSTI)

    Mittal, Tushar; Chiang, Eugene

    2015-01-01

    The brightest transitional protoplanetary disks are often azimuthally asymmetric: their millimeter-wave thermal emission peaks strongly on one side. Dust overdensities can exceed ?100:1, while gas densities vary by factors less than a few. We propose that these remarkable ALMA observationswhich may bear on how planetesimals formreflect a gravitational global mode in the gas disk. The mode is (1) fastits pattern speed equals the disk's mean Keplerian frequency; (2) of azimuthal wavenumber m = 1, displacing the host star from the barycenter; and (3) Toomre-stable. We solve for gas streamlines including the indirect stellar potential in the frame rotating with the pattern speed, under the drastic simplification that gas does not feel its own gravity. Near corotation, the gas disk takes the form of a horseshoe-shaped annulus. Dust particles with aerodynamic stopping times much shorter or much longer than the orbital period are dragged by gas toward the horseshoe center. For intermediate stopping times, dust converges toward a ?45 wide arc on the corotation circle. Particles that do not reach their final accumulation points within disk lifetimes, either because of gas turbulence or long particle drift times, conform to horseshoe-shaped gas streamlines. Our mode is not self-consistent because we neglect gas self-gravity; still, we expect that trends between accumulation location and particle size, similar to those we have found, are generically predicted by fast modes and are potentially observable. Unlike vortices, global modes are not restricted in radial width to the pressure scale height; their large radial and azimuthal extents may better match observations.

  13. Coupler for coupling gyrotron whispering gallery mode RF into HE11 waveguide

    DOE Patents [OSTI]

    Neilson, Jeffrey M

    2015-02-24

    A cylindrical waveguide with a mode converter transforms a whispering gallery mode from a gyrotron cylindrical waveguide with a helical cut launch edge to a quasi-Gaussian beam suitable for conveyance through a corrugated waveguide. This quasi-Gaussian beam is radiated away from the waveguide using a spiral cut launch edge, which is in close proximity to a first mode converting reflector. The first mode converting reflector is coupled to a second mode converting reflector which provides an output free-space HE11 mode wave suitable for direct coupling into a corrugated waveguide. The radiated beam produced at the output of the second mode converting reflector is substantially circular.

  14. Pulsation modes of long-period variables in the period-luminosity plane

    SciTech Connect (OSTI)

    Soszyński, I.; Udalski, A.; Wood, P. R. E-mail: udalski@astrouw.edu.pl

    2013-12-20

    We present a phenomenological analysis of long-period variables (LPVs) in the Large Magellanic Cloud with the aim of detecting pulsation modes associated with different period-luminosity (PL) relations. Among brighter LPVs, we discover a group of triple-mode semi-regular variables with the fundamental, first-overtone, and second-overtone modes simultaneously excited, which fall on PL sequences C, C', and B, respectively. The mode identification in the fainter red giants is more complicated. We demonstrate that the fundamental-mode pulsators partly overlap with the first-overtone modes. We show a possible range of fundamental mode and first overtone periods in the PL diagram.

  15. Mode-locked solid state lasers using diode laser excitation

    DOE Patents [OSTI]

    Holtom, Gary R.

    2012-03-06

    A mode-locked laser employs a coupled-polarization scheme for efficient longitudinal pumping by reshaped laser diode bars. One or more dielectric polarizers are configured to reflect a pumping wavelength having a first polarization and to reflect a lasing wavelength having a second polarization. An asymmetric cavity provides relatively large beam spot sizes in gain medium to permit efficient coupling to a volume pumped by a laser diode bar. The cavity can include a collimation region with a controlled beam spot size for insertion of a saturable absorber and dispersion components. Beam spot size is selected to provide stable mode locking based on Kerr lensing. Pulse durations of less than 100 fs can be achieved in Yb:KGW.

  16. Compact representation of radiation patterns using spherical mode expansions

    SciTech Connect (OSTI)

    Simpson, T.L.; Chen, Yinchao . Dept. of Electrical and Computer Engineering)

    1990-07-15

    This report presents the results of an investigation of SM (Spherical Mode) expansions as a compact and efficient alternative to the use of current distributions for generating radiation patterns. The study included three areas: (1) SM expansion from the radiation pattern; (2) SM expansion from the antenna current; and (3) Literature search. SM expansions were obtained from radiation patterns during the initial phase of this study. Although straightforward in principal, however, this technique was found to be awkward for the treatment on theoretical radiation patterns. It is included here for completeness and for possible use to summarize experimental results in a more meaningful way than with an exhaustive display of amplitude with azimuth and elevation angles. In essence, the work in this area served as as warm-up problem to develop our skills in computing and manipulating spherical modes as mathematical entities. 6 refs., 21 figs., 6 tabs.

  17. Active/passive mode-locked laser oscillator

    DOE Patents [OSTI]

    Fountain, William D.; Johnson, Bertram C.

    1977-01-01

    A Q-switched/mode-locked Nd:YAG laser oscillator employing simultaneous active (electro-optic) and passive (saturable absorber) loss modulation within the optical cavity is described. This "dual modulation" oscillator can produce transform-limited pulses of duration ranging from about 30 psec to about 5 nsec with greatly improved stability compared to other mode-locked systems. The pulses produced by this system lack intrapulse frequency or amplitude modulation, and hence are idealy suited for amplification to high energies and for other applications where well-defined pulses are required. Also, the pulses of this system have excellent interpulse characteristics, wherein the optical noise between the individual pulses of the pulse train has a power level well below the power of the peak pulse of the train.

  18. Theoretic base of Edge Local Mode triggering by vertical displacements

    SciTech Connect (OSTI)

    Wang, Z. T.; He, Z. X.; Wang, Z. H.; Wu, N.; Tang, C. J.

    2015-05-15

    Vertical instability is studied with R-dependent displacement. For Solovev's configuration, the stability boundary of the vertical instability is calculated. The pressure gradient is a destabilizing factor which is contrary to Rebhan's result. Equilibrium parallel current density, j{sub //}, at plasma boundary is a drive of the vertical instability similar to Peeling-ballooning modes; however, the vertical instability cannot be stabilized by the magnetic shear which tends towards infinity near the separatrix. The induced current observed in the Edge Local Mode (ELM) triggering experiment by vertical modulation is derived. The theory provides some theoretic explanation for the mitigation of type-I ELMS on ASDEX Upgrade. The principle could be also used for ITER.

  19. Present and Future Modes of Low Frequency Climate Variability

    SciTech Connect (OSTI)

    Cane, Mark A.

    2014-02-20

    This project addressed area (1) of the FOA, “Interaction of Climate Change and Low Frequency Modes of Natural Climate Variability”. Our overarching objective is to detect, describe and understand the changes in low frequency variability between model simulations of the preindustrial climate and simulations of a doubled CO2 climate. The deliverables are a set of papers providing a dynamical characterization of interannual, decadal, and multidecadal variability in coupled models with attention to the changes in this low frequency variability between pre-industrial concentrations of greenhouse gases and a doubling of atmospheric concentrations of CO2. The principle mode of analysis, singular vector decomposition, is designed to advance our physical, mechanistic understanding. This study will include external natural variability due to solar and volcanic aerosol variations as well as variability internal to the climate system. An important byproduct is a set of analysis tools for estimating global singular vector structures from the archived output of model simulations.

  20. The whistler mode refractive index as a function of gyrofrequency

    SciTech Connect (OSTI)

    Albert, J. M.

    2011-08-15

    The refractive index for a constant-frequency whistler mode wave in an electron-proton plasma is considered as a function of position, through the local gyrofrequencies {Omega}{sub e,i}. The full cold plasma dispersion relation is used. The wave frequency can take any value up to the smaller of {Omega}{sub e} and the plasma frequency {omega}{sub pe}, but {omega}{sub pe} is allowed to take any fixed value, as is the wavenormal angle. It is rigorously established that the refractive index is a decreasing function of {Omega}{sub e}. One application of this is to finding locations of Landau and cyclotron resonances, to evaluate the effects of whistler mode waves on radiation belt electrons.

  1. Scissors Mode of 162 Dy Studied from Resonance Neutron Capture

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

    Baramsai, B.; Bečvář, F.; Bredeweg, T. A.; Haight, R. C.; Jandel, M.; Kroll, J.; Krtička, M.; Mitchell, G. E.; O’Donnell, J. M.; Rundberg, R. S.; et al

    2015-05-28

    Multi-step cascade γ-ray spectra from the neutron capture at isolated resonances of 161Dy nucleus were measured at the LANSCE/DANCE time-of-flight facility in Los Alamos National Laboratory. The objectives of this experiment were to confirm and possibly extend the spin assignment of s-wave neutron resonances and get new information on photon strength functions with emphasis on the role of the M1 scissors mode vibration. The preliminary results show that the scissors mode plays a significant role in all transitions between accessible states of the studied nucleus. The photon strength functions describing well our data are compared to results from 3He-induced reactions,more » (n,γ) experiments on Gd isotopes, and (γ,γ’) reactions.« less

  2. Staggered fermions, zero modes, and flavor-singlet mesons

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

    Donald, Gordon C; Davies, Christine T.H.; Follana, Eduardo; Kronfeld, Andreas S.

    2011-09-12

    We examine the taste structure of eigenvectors of the staggered-fermion Dirac operator. We derive a set of conditions on the eigenvectors of modes with small eigenvalues (near-zero modes), such that staggered fermions reproduce the 't Hooft vertex in the continuum limit. We also show that, assuming these conditions, the correlators of flavor-singlet mesons are free of contributions singular in 1/m, where m is the quark mass. This conclusion holds also when a single flavor of sea quark is represented by the fourth root of the staggered-fermion determinant. We then test numerically, using the HISQ action, whether these conditions hold onmore » realistic lattice gauge fields. We find that the needed structure does indeed emerge.« less

  3. Development and Use of the Dual-Mode Plasma Torch

    SciTech Connect (OSTI)

    Womack, R.; Shuey, M.

    2002-02-26

    After several years of development, a commercially available high-temperature treatment system has been developed and installed that treats heterogeneous low-level radioactive waste. High temperature plasma processing, unique torch design and operating features make it feasible to achieve a volume reduced, permanent, high integrity waste form while eliminating the personnel exposure and costs associated with conventional sorting, characterizing and handling. Plasma technology can also be used to treat previous conditioned waste packages that no longer meet the current acceptance criteria for final disposal. Plasma treatment can result, in many cases, in a substantial volume reduction, which lowers the final disposal costs. This paper covers the recently patented dual mode plasma torch design(1), the lessons learned that fostered its development and the advantages it brings to radioactive waste processing. This paper also provides current full scale Plasma Arc Centrifugal Treatment (PACT) project status and how the dual mode torch is being used in the PACT system.

  4. Development of magnetohydrodynamic modes during sawteeth in tokamak plasmas

    SciTech Connect (OSTI)

    Firpo, M.-C.; Ettoumi, W.; Farengo, R.; Ferrari, H. E.; Consejo Nacional de Investigaciones Cientficas y Tcnicas , Bariloche ; Garca-Martnez, P. L.; Lifschitz, A. F.

    2013-07-15

    A dynamical analysis applied to a reduced resistive magnetohydrodynamics model is shown to explain the chronology of the nonlinear destabilization of modes observed in tokamak sawteeth. A special emphasis is put on the nonlinear self-consistent perturbation of the axisymmetric m = n = 0 mode that manifests through the q-profile evolution. For the very low fusion-relevant resistivity values, the q-profile is shown to remain almost unchanged on the early nonlinear timescale within the central tokamak region, which supports a partial reconnection scenario. Within the resistive region, indications for a local flattening or even a local reversed-shear of the q-profile are given. The impact of this ingredient in the occurrence of the sawtooth crash is discussed.

  5. Understanding the H-Mode Pedestal, Gyrokinetic Simulations and Their

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

    Implications | Princeton Plasma Physics Lab January 7, 2016, 10:30am to 11:45am Colloquia MBG AUDITORIUM Understanding the H-Mode Pedestal, Gyrokinetic Simulations and Their Implications Dr. Mike Kotschenreuther University of Texas, Austin ThC07Jan2016_MKotschenreuther Colloquium Committee: The Princeton Plasma Physics Laboratory 2015-2016 Colloquium Committee is comprised of the following people. Please feel free to contact them by e-mail regarding any possible speakers or topics for future

  6. Dynamical dipole mode in fusion reactions with exotic nuclear beams

    SciTech Connect (OSTI)

    Baran, V.; Rizzo, C.; Colonna, M.; Toro, M. Di; Pierroutsakou, D.

    2009-02-15

    We report the properties of the prompt dipole radiation, produced via a collective bremsstrahlung mechanism, in fusion reactions with exotic beams. We show that the {gamma} yield is sensitive to the density dependence of the symmetry energy below/around saturation. Moreover, we find that the angular distribution of the emitted photons from such fast collective mode can represent a sensitive probe of its excitation mechanism and of fusion dynamics in the entrance channel.

  7. Raman scattering in a whispering mode optical waveguide

    DOE Patents [OSTI]

    Kurnit, Norman A.

    1982-01-01

    A device and method for Raman scattering in a whispering mode optical waveguide. Both a helical ribbon and cylinder are disclosed which incorporate an additional curvature .rho. p for confining the beam to increase intensity. A Raman scattering medium is disposed in the optical path of the beam as it propagates along the waveguide. Raman scattering is enhanced by the high intensities of the beam and long interaction path lengths which are achieved in a small volume.

  8. with multiple torsional modes and when there are

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

    multiple torsional modes and when there are hydrogen bonds formed for some of the geometries. The presence of hydrogen bonds particularly compli- cates things by coupling some of the other vibrational motions to the torsional motions. In particular, many of the bending frequencies become quite strongly de- pendent on the torsional geometry. Truhlar has devel- oped a method that treats this difficulty by explicitly considering the contributions from each of the differ- ent torsional minima. The

  9. Composite slip table of dissimilar materials for damping longitudinal modes

    DOE Patents [OSTI]

    Gregory, Danny L. (Albuquerque, NM); Priddy, Tommy G. (Albuquerque, NM); Smallwood, David O. (Albuquerque, NM); Woodall, Tommy D. (Albuquerque, NM)

    1991-01-01

    A vibration slip table for use in a vibration testing apparatus. The table s comprised of at least three composite layers of material; a first metal layer, a second damping layer, and a third layer having a high acoustic velocity relative to the first layer. The different acoustic velocities between the first and third layers cause relative shear displacements between the layers with the second layer damping the displacements between the first and third layers to reduce the table longitudinal vibration modes.

  10. Sandia and EMCORE: Solar Photovoltaics, Fiber Optics, MODE, and Energy

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

    Efficiency EMCORE: Solar Photovoltaics, Fiber Optics, MODE, and Energy Efficiency - 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

  11. Mode and Intermediate Waters in Earth System Models

    SciTech Connect (OSTI)

    Gnanadesikan, Anand; Sarmiento, Jorge L.

    2015-12-22

    This report describes work done as part of a joint Princeton-Johns Hopkins project to look at the impact of mode and intermediate waters in Earth System Models. The Johns Hopkins portion of this work focussed on the role of lateral mixing in ventilating such waters, with important implications for hypoxia, the uptake of anthropogenic carbon, the dynamics of El Nino and carbon pumps. The Johns Hopkins group also collaborated with the Princeton Group to help develop a watermass diagnostics framework.

  12. Optical pumping in a whispering mode optical waveguide

    DOE Patents [OSTI]

    Kurnit, Norman A.

    1984-01-01

    A device and method for optical pumping in a whispering mode optical waveguide. Both a helical ribbon and cylinder are disclosed which incorporate an additional curvature for confining the beam to increase intensity. An optical pumping medium is disposed in the optical path of the beam as it propagates along the waveguide. Optical pumping is enhanced by the high intensities of the beam and long interaction pathlengths which are achieved in a small volume.

  13. BES Web Highlight: Single-mode gallium nitride nanowire lasers

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

    Web Highlight: Single-mode gallium nitride nanowire lasers - 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 Fuel Cycle Defense

  14. Optical pumping in a whispering-mode optical waveguide

    DOE Patents [OSTI]

    Kurnit, N.A.

    1981-08-11

    A device and method for optical pumping in a whispering mode optical waveguide are described. Both a helical ribbon and cylinder are disclosed which incorporate an additional curvature for confining the beam to increase intensity. An optical pumping medium is disposed in the optical path of the beam as it propagates along the waveguide. Optical pumping is enhanced by the high intensities of the beam and long interaction path lengths which are achieved in a small volume.

  15. Vibrational modes of ultrathin carbon nanomembrane mechanical resonators

    SciTech Connect (OSTI)

    Zhang, Xianghui E-mail: elke.scheer@uni-konstanz.de; Angelova, Polina; Gölzhäuser, Armin; Waitz, Reimar; Yang, Fan; Lutz, Carolin; Scheer, Elke E-mail: elke.scheer@uni-konstanz.de

    2015-02-09

    We report measurements of vibrational mode shapes of mechanical resonators made from ultrathin carbon nanomembranes (CNMs) with a thickness of approximately 1 nm. CNMs are prepared from electron irradiation induced cross-linking of aromatic self-assembled monolayers and the variation of membrane thickness and/or density can be achieved by varying the precursor molecule. Single- and triple-layer freestanding CNMs were made by transferring them onto Si substrates with square/rectangular orifices. The vibration of the membrane was actuated by applying a sinusoidal voltage to a piezoelectric disk on which the sample was glued. The vibrational mode shapes were visualized with an imaging Mirau interferometer using a stroboscopic light source. Several mode shapes of a square membrane can be readily identified and their dynamic behavior can be well described by linear response theory of a membrane with negligible bending rigidity. By applying Fourier transformations to the time-dependent surface profiles, the dispersion relation of the transverse membrane waves can be obtained and its linear behavior verifies the membrane model. By comparing the dispersion relation to an analytical model, the static stress of the membranes was determined and found to be caused by the fabrication process.

  16. A Prescription for List-Mode Data Processing Conventions

    SciTech Connect (OSTI)

    Beddingfield, David H.; Swinhoe, Martyn Thomas; Huszti, Jozsef; Newell, Matthew R.

    2015-10-08

    There are a variety of algorithmic approaches available to process list-mode pulse streams to produce multiplicity histograms for subsequent analysis. In the development of the INCC v6.0 code to include the processing of this data format, we have noted inconsistencies in the “processed time” between the various approaches. The processed time, tp, is the time interval over which the recorded pulses are analyzed to construct multiplicity histograms. This is the time interval that is used to convert measured counts into count rates. The observed inconsistencies in tp impact the reported count rate information and the determination of the error-values associated with the derived singles, doubles, and triples counting rates. This issue is particularly important in low count-rate environments. In this report we will present a prescription for the processing of list-mode counting data that produces values that are both correct and consistent with traditional shift-register technologies. It is our objective to define conventions for list mode data processing to ensure that the results are physically valid and numerically aligned with the results from shift-register electronics.

  17. Kink modes and surface currents associated with vertical displacement events

    SciTech Connect (OSTI)

    Manickam, Janardhan; Boozer, Allen; Gerhardt, Stefan

    2012-08-15

    The fast termination phase of a vertical displacement event (VDE) in a tokamak is modeled as a sequence of shrinking equilibria, where the core current profile remains constant so that the safety-factor at the axis, q{sub axis}, remains fixed and the q{sub edge} systematically decreases. At some point, the n = 1 kink mode is destabilized. Kink modes distort the magnetic field lines outside the plasma, and surface currents are required to nullify the normal component of the B-field at the plasma boundary and maintain equilibrium at finite pressure. If the plasma touches a conductor, the current can be transferred to the conductor, and may be measurable by the halo current monitors. This report describes a practical method to model the plasma as it evolves during a VDE, and determine the surface currents, needed to maintain equilibrium. The main results are that the onset conditions for the disruption are that the growth-rate of the n = 1 kink exceeds half the Alfven time and the associated surface current needed to maintain equilibrium exceeds one half of the core plasma current. This occurs when q{sub edge} drops below a low integer, usually 2. Application to NSTX provides favorable comparison with non-axisymmetric halo-current measurements. The model is also applied to ITER and shows that the 2/1 mode is projected to be the most likely cause of the final disruption.

  18. Proposal for efficient mode converter based on cavity quantum electrodynamics dark mode in a semiconductor quantum dot coupled to a bimodal microcavity

    SciTech Connect (OSTI)

    Li, Jiahua; Yu, Rong; Ma, Jinyong; Wu, Ying

    2014-10-28

    The ability to engineer and convert photons between different modes in a solid-state approach has extensive technological implications not only for classical communication systems but also for future quantum networks. In this paper, we put forward a scheme for coherent mode conversion of optical photons by utilizing the intermediate coupling between a single quantum dot and a bimodal photonic crystal microcavity via a waveguide. Here, one mode of the photonic crystal microcavity is coherently driven by an external single-frequency continuous-wave laser field and the two cavity modes are not coupled to each other due to their orthogonal polarizations. The undriven cavity mode is thus not directly coupled to the input driving laser and the only way it can get light is via the quantum dot. The influences of the system parameters on the photon-conversion efficiency are analyzed in detail in the limit of weak probe field and it is found that high photon-conversion efficiency can be achieved under appropriate conditions. It is shown that the cavity dark mode, which is a superposition of the two optical modes and is decoupled from the quantum dot, can appear in such a hybrid optical system. We discuss the properties of the dark mode and indicate that the formation of the dark mode enables the efficient transfer of optical fields between the two cavity modes.

  19. Multi-Mode RCCI Has Great Potential to Improve Fuel Economy in...

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

    Mode RCCI Has Great Potential to Improve Fuel Economy in Light-Duty Diesel Engines Multi-Mode RCCI Has Great Potential to Improve Fuel Economy in Light-Duty Diesel Engines February ...

  20. MIT's Plasma Science Fusion Center: I-Mode Powers Up on Alcator...

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

    I-Mode Powers Up on Alcator C-Mod Tokamak American Fusion News Category: Massachusetts Institute of Technology (MIT) Link: MIT's Plasma Science Fusion Center: I-Mode Powers Up on...

  1. Toward a Single Mode Free Electron Laser for Coherent Hard X...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Toward a Single Mode Free Electron Laser for Coherent Hard X-Ray Experiments Citation Details In-Document Search Title: Toward a Single Mode Free Electron Laser...

  2. Divertor Heat Flux Mitigation in High-Performance H-mode Plasmas...

    Office of Scientific and Technical Information (OSTI)

    H-mode Plasmas in the National Spherical Torus Experiment. Citation Details In-Document Search Title: Divertor Heat Flux Mitigation in High-Performance H-mode Plasmas ...

  3. In-gap collective mode spectrum of the topological Kondo insulator...

    Office of Scientific and Technical Information (OSTI)

    In-gap collective mode spectrum of the topological Kondo insulator SmB 6 Title: In-gap collective mode spectrum of the topological Kondo insulator SmB 6 Authors: Fuhrman, W. T. ; ...

  4. Spin-polarized and valley helical edge modes in graphene nanoribbons...

    Office of Scientific and Technical Information (OSTI)

    Spin-polarized and valley helical edge modes in graphene nanoribbons Citation Details In-Document Search Title: Spin-polarized and valley helical edge modes in graphene nanoribbons ...

  5. Report 20.5: Chromaticity Shift Modes of LED PAR38 Lamps Operated...

    Energy Savers [EERE]

    5: Chromaticity Shift Modes of LED PAR38 Lamps Operated in Steady-State Conditions Report 20.5: Chromaticity Shift Modes of LED PAR38 Lamps Operated in Steady-State Conditions PDF ...

  6. Plasmonic modes and extinction properties of a random nanocomposite cylinder

    SciTech Connect (OSTI)

    Moradi, Afshin

    2014-04-15

    We study the properties of surface plasmon-polariton waves of a random metal-dielectric nanocomposite cylinder, consisting of bulk metal embedded with dielectric nanoparticles. We use the Maxwell-Garnett formulation to model the effective dielectric function of the composite medium and show that there exist two surface mode bands. We investigate the extinction properties of the system, and obtain the dependence of the extinction spectrum on the nanoparticles shape and concentration as well as the cylinder radius and the incidence angle for both TE and TM polarization.

  7. Curvature effect on tearing modes in presence of neoclassical friction

    SciTech Connect (OSTI)

    Maget, Patrick; Mellet, Nicolas; Meshcheriakov, Dmytro; Garbet, Xavier; Lütjens, Hinrich

    2013-11-15

    Neoclassical physics (here associated to the poloidal variation of the magnetic field strength along field lines in a tokamak) is well known for driving self-generated plasma current and nonlinear magnetic islands associated to it in high performance, ITER relevant plasma discharges. It is demonstrated that the neoclassical friction between a magnetic perturbation and plasma flow already impacts magnetic islands in the linear regime, by inducing a weakening of curvature stabilization for tearing modes. This conclusion holds in particular for regimes where convection is influencing the pressure dynamics, as shown using a simple analytical model and confirmed in full Magneto-Hydro-Dynamics simulations.

  8. Active control of the resistive wall mode with power saturation

    SciTech Connect (OSTI)

    Li Li; Liu Yue [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, 116024 (China); Liu Yueqiang [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

    2012-01-15

    An analytic model of non-linear feedback stabilization of the resistive wall mode is presented. The non-linearity comes from either the current or the voltage saturation of the control coil power supply. For the so-called flux-to-current control, the current saturation of active coils always results in the loss of control. On the contrary, the flux-to-voltage control scheme tolerates certain degree of the voltage saturation. The minimal voltage limit is calculated, below which the control will be lost.

  9. Entropy mode loops and cosmological correlations during perturbative reheating

    SciTech Connect (OSTI)

    Kaya, Ali; Kutluk, Emine Seyma E-mail: seymakutluk@gmail.com

    2015-01-01

    Recently, it has been shown that during preheating the entropy modes circulating in the loops, which correspond to the inflaton decay products, meaningfully modify the cosmological correlation functions at superhorizon scales. In this paper, we determine the significance of the same effect when reheating occurs in the perturbative regime. In a typical two scalar field model, the magnitude of the loop corrections are shown to depend on several parameters like the background inflaton amplitude in the beginning of reheating, the inflaton decay rate and the inflaton mass. Although the loop contributions turn out to be small as compared to the preheating case, they still come out larger than the loop effects during inflation.

  10. Electron plasma dynamics during autoresonant excitation of the diocotron mode

    SciTech Connect (OSTI)

    Baker, C. J. Danielson, J. R. Hurst, N. C. Surko, C. M.

    2015-02-15

    Chirped-frequency autoresonant excitation of the diocotron mode is used to move electron plasmas confined in a Penning-Malmberg trap across the magnetic field for advanced plasma and antimatter applications. Plasmas of 10{sup 8} electrons, with radii small compared to that of the confining electrodes, can be moved from the magnetic axis to ?90% of the electrode radius with near unit efficiency and reliable angular positioning. Translations of ?70% of the wall radius are possible for a wider range of plasma parameters. Details of this process, including phase and displacement oscillations in the plasma response and plasma expansion, are discussed, as well as possible extensions of the technique.

  11. Composite slip table of dissimilar materials for damping longitudinal modes

    DOE Patents [OSTI]

    Gregory, D.L.; Priddy, T.G.; Smallwood, D.O.; Woodall, T.D.

    1991-06-18

    A vibration slip table for use in a vibration testing apparatus is disclosed. The tables comprised of at least three composite layers of material; a first metal layer, a second damping layer, and a third layer having a high acoustic velocity relative to the first layer. The different acoustic velocities between the first and third layers cause relative shear displacements between the layers with the second layer damping the displacements between the first and third layers to reduce the table longitudinal vibration modes. 6 figures.

  12. Mixed mode control method and engine using same

    DOE Patents [OSTI]

    Kesse, Mary L.; Duffy, Kevin P.

    2007-04-10

    A method of mixed mode operation of an internal combustion engine includes the steps of controlling a homogeneous charge combustion event timing in a given engine cycle, and controlling a conventional charge injection event to be at least a predetermined time after the homogeneous charge combustion event. An internal combustion engine is provided, including an electronic controller having a computer readable medium with a combustion timing control algorithm recorded thereon, the control algorithm including means for controlling a homogeneous charge combustion event timing and means for controlling a conventional injection event timing to be at least a predetermined time from the homogeneous charge combustion event.

  13. Exotic modes of excitation in proton rich nuclei

    SciTech Connect (OSTI)

    Paar, N.

    2011-11-30

    The framework of relativistic energy density functional has been applied in description of excitation phenomena in nuclei close to the proton drip line. In particular, low-lying dipole excitations have been studied using relativistic quasiparticle random phase approximation, based on effective Lagrangians with density dependent meson nucleon couplings. In the isovector dipole channel, the occurrence of pronounced low-lying dipole peaks is predicted, corresponding to the proton pygmy dipole resonance. Since this exotic mode still awaits its experimental confirmation, systematic calculations have been conducted within a pool of neutron deficient nuclei, in order to identify the best possible candidates for measurements.

  14. Diffractive optical elements for transformation of modes in lasers

    DOE Patents [OSTI]

    Sridharan, Arun K.; Pax, Paul H.; Heebner, John E.; Drachenberg, Derrek R.; Armstrong, James P.; Dawson, Jay W.

    2015-09-01

    Spatial mode conversion modules are described, with the capability of efficiently transforming a given optical beam profile, at one plane in space into another well-defined optical beam profile at a different plane in space, whose detailed spatial features and symmetry properties can, in general, differ significantly. The modules are comprised of passive, high-efficiency, low-loss diffractive optical elements, combined with Fourier transform optics. Design rules are described that employ phase retrieval techniques and associated algorithms to determine the necessary profiles of the diffractive optical components. System augmentations are described that utilize real-time adaptive optical techniques for enhanced performance as well as power scaling.

  15. Tunable dark modes in one-dimensional diatomic dielectric gratings

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

    Zeng, Bo; Majumdar, Arka; Wang, Feng

    2015-05-04

    Recently researchers have demonstrated ultra high quality factor (Q) resonances in one-dimensional (1D) dielectric gratings. Here we theoretically investigate a new class of subwavelength 1D gratings, namely diatomic gratings with two nonequivalent subcells in one period, and utilize their intrinsic dark modes to achieve robust ultra high Q resonances. Such diatomic gratings provide extra design flexibility, and enable high Q resonators using thinner geometry with smaller filling factors compared to conventional designs like the high contrast gratings (HCGs). More importantly, we show that these high Q resonances can be efficiently tuned in situ, making the design appealing in various applicationsmoreincluding optical sensing, filtering and displays.less

  16. Nonlinear gyrokinetic simulations of the I-mode high confinement regime and

    Office of Scientific and Technical Information (OSTI)

    comparisons with experiment (Journal Article) | SciTech Connect Nonlinear gyrokinetic simulations of the I-mode high confinement regime and comparisons with experiment Citation Details In-Document Search Title: Nonlinear gyrokinetic simulations of the I-mode high confinement regime and comparisons with experiment For the first time, nonlinear gyrokinetic simulations of I-mode plasmas are performed and compared with experiment. I-mode is a high confinement regime, featuring energy confinement

  17. Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects

    SciTech Connect (OSTI)

    Pankin, Alexei Y.; Kritz, Arnold H.

    2011-07-19

    Topics covered are: anomalous transport and E x B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies.

  18. Magnetic dipole excitations in nuclei: Elementary modes of nucleonic motion

    SciTech Connect (OSTI)

    Heyde, Kris; Neumann-Cosel, Peter von; Richter, Achim

    2010-07-15

    The nucleus is one of the most multifaceted many-body systems in the Universe. It exhibits a multitude of responses depending on the way one ''probes'' it. With increasing technical advancements of beams at the various accelerators and of detection systems the nucleus has, over and over again, surprised us by expressing always new ways of ''organized'' structures and layers of complexity. Nuclear magnetism is one of those fascinating faces of the atomic nucleus discussed in the present review. We shall not just limit ourselves to presenting the by now large data set that has been obtained in the past two decades using various probes, electromagnetic and hadronic alike and that presents ample evidence for a low-lying orbital scissors mode around 3 MeV, albeit fragmented over an energy interval of the order of 1.5 MeV, and higher-lying spin-flip strength in the energy region 5-9 MeV in deformed nuclei nor to the presently discovered evidence for low-lying proton-neutron isovector quadrupole excitations in spherical nuclei. To the contrary, the experimental evidence is put in the perspectives of understanding the atomic nucleus and its various structures of well-organized modes of motion and thus enlarges the discussion to more general fermion and bosonic many-body systems.

  19. Variational principles with Pad approximants for tearing mode analysis

    SciTech Connect (OSTI)

    Cole, Andrew J.; Finn, John M.

    2014-03-15

    Tearing modes occur in several distinct physical regimes, and it is often important to compute the inner layer response for these modes with various effects. There is a need for an approximate and efficient method of solving the inner layer equations in all these regimes. In this paper, we introduce a method of solving the inner layer equations based on using a variational principle with Pad approximants. For all the regimes considered, the main layer equations to be solved are inhomogeneous, and Pad approximants give a convenient and efficient method of satisfying the correct asymptotic behavior at the edge of the layer. Results using this variational principlePad approximant method in three of these regimes is presented. These regimes are the constant-? resistive-inertial (RI) regime, the constant-? viscoresistive regime, and the non-constant-? inviscid tearing regime. The last regime includes the constant-? RI regime and the inertial regime. The results show that reasonable accuracy can be obtained very efficiently with Pad approximants having a small number of parameters.

  20. Concentric core optical fiber with multiple-mode signal transmission

    DOE Patents [OSTI]

    Muhs, J.D.

    1997-05-06

    A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion. 3 figs.

  1. Concentric core optical fiber with multiple-mode signal transmission

    DOE Patents [OSTI]

    Muhs, Jeffrey D.

    1997-01-01

    A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion.

  2. Strong electron dissipation by a mode converted ion hybrid (Bernstein) wave

    SciTech Connect (OSTI)

    Lashmore-Davies, C.N.; Ram, A.K.

    1996-02-01

    The fast wave approximation, extended to include the effects of electron dissipation, is used to calculate the power mode converted to the ion hybrid (Bernstein) wave in the vicinity of the ion hybrid resonance. The power absorbed from the fast wave by ion cyclotron damping and by electron Landau and transit time damping (including cross terms) is also calculated. The fast wave equation is solved for either the Budden configuration of a cut-off-resonance pair or the triplet configuration of cut-off-resonance-cut-off. The fraction mode converted is compared for the triplet case and the Budden multi-pass situation. The electron damping rate of the ion hybrid wave is obtained from the local dispersion relation and a ray tracing code is used to calculate the damping of the mode converted ion hybrid wave by the electrons as it propagates away from the resonance. Quantitative results for a range of conditions relevant to JET, TFTR and ITER are given. {copyright} {ital 1996 American Institute of Physics.}

  3. Search for invisible decays of Higgs bosons in the vector boson fusion and associated ZH production modes

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

    Chatrchyan, Serguei

    2014-08-01

    A search for invisible decays of Higgs bosons is performed using the vector boson fusion and associated ZH production modes. In the ZH mode, the Z boson is required to decay to a pair of charged leptons or a b b-bar quark pair. The searches use the 8 TeV pp collision dataset collected by the CMS detector at the LHC, corresponding to an integrated luminosity of up to 19.7 inverse femtobarns. Certain channels include data from 7 TeV collisions corresponding to an integrated luminosity of 4.9 inverse femtobarns. The searches are sensitive to non-standard-model invisible decays of the recently observedmore » Higgs boson, as well as additional Higgs bosons with similar production modes and large invisible branching fractions. In all channels, the observed data are consistent with the expected standard model backgrounds. Limits are set on the production cross section times invisible branching fraction, as a function of the Higgs boson mass, for the vector boson fusion and ZH production modes. By combining all channels, and assuming standard model Higgs boson cross sections and acceptances, the observed (expected) upper limit on the invisible branching fraction at m[H] = 125 GeV is found to be 0.58 (0.44) at 95% confidence level. We interpret this limit in terms of a Higgs-portal model of dark matter interactions.« less

  4. Search for invisible decays of Higgs bosons in the vector boson fusion and associated ZH production modes

    SciTech Connect (OSTI)

    Chatrchyan, Serguei

    2014-08-01

    A search for invisible decays of Higgs bosons is performed using the vector boson fusion and associated ZH production modes. In the ZH mode, the Z boson is required to decay to a pair of charged leptons or a b b-bar quark pair. The searches use the 8 TeV pp collision dataset collected by the CMS detector at the LHC, corresponding to an integrated luminosity of up to 19.7 inverse femtobarns. Certain channels include data from 7 TeV collisions corresponding to an integrated luminosity of 4.9 inverse femtobarns. The searches are sensitive to non-standard-model invisible decays of the recently observed Higgs boson, as well as additional Higgs bosons with similar production modes and large invisible branching fractions. In all channels, the observed data are consistent with the expected standard model backgrounds. Limits are set on the production cross section times invisible branching fraction, as a function of the Higgs boson mass, for the vector boson fusion and ZH production modes. By combining all channels, and assuming standard model Higgs boson cross sections and acceptances, the observed (expected) upper limit on the invisible branching fraction at m[H] = 125 GeV is found to be 0.58 (0.44) at 95% confidence level. We interpret this limit in terms of a Higgs-portal model of dark matter interactions.

  5. High frequency pacing of edge localized modes by injection of lithium

    Office of Scientific and Technical Information (OSTI)

    granules in DIII-D H-mode discharges (Journal Article) | SciTech Connect High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges Citation Details In-Document Search This content will become publicly available on April 8, 2017 Title: High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges Authors: Bortolon, A. ; Maingi, R. ; Mansfield, D. K. ; Nagy, A. ; Roquemore, A. L. ; Baylor, L. R. ;

  6. Enforcement Policy Statement: Off Mode Standards for CAC/HP | Department of

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

    Energy Policy Statement: Off Mode Standards for CAC/HP Enforcement Policy Statement: Off Mode Standards for CAC/HP July 8, 2014 DOE will not seek civil penalties for violation of the off mode electrical power consumption standard for central air conditioners or central air conditioning heat pumps (CAC/HP) until 180 days following publication of a final rule establishing a test method for measuring off mode electrical power consumption for CAC/HP. PDF icon Enforcement Policy: Off Mode

  7. Limits of ultrashort pulse generation in cw mode-locked dye lasers

    SciTech Connect (OSTI)

    Petrov, V.; Rudolph, W.; Stamm, U.; Wilhelmi, B.

    1989-08-01

    Essential mechanisms limiting the achievable pulse duration in synchronously pumped, hybrid-mode-locked, and passively mode-locked cw subpicosecond dye lasers are analyzed. The action of spontaneously emitted light is shown to be the detrimental factor in synchronous mode locking. The influence of this factor can be suppressed by a saturable absorber in the hybrid-mode-locked lasers. In this case as well as in the case of passive mode locking the combined action of group-velocity dispersion and Kerr-effect-type nonlinearity, though serving as an additional shortening mechanism, causes fluctuations of the pulse parameters and determines the limit of the steady-state regime.

  8. Double Beta Decay in Xenon-136: Measuring the Neutrino-Emitting Mode and

    Office of Scientific and Technical Information (OSTI)

    Searching for Majoron-Emitting Modes (Thesis/Dissertation) | SciTech Connect Double Beta Decay in Xenon-136: Measuring the Neutrino-Emitting Mode and Searching for Majoron-Emitting Modes Citation Details In-Document Search Title: Double Beta Decay in Xenon-136: Measuring the Neutrino-Emitting Mode and Searching for Majoron-Emitting Modes Authors: Herrin, Steven ; /Stanford U., Phys. Dept. /SLAC Publication Date: 2013-08-23 OSTI Identifier: 1091528 Report Number(s): SLAC-R-1034 DOE Contract

  9. Microsoft PowerPoint - 16.1330_Rimando 110316 rev3 [Compatibility Mode] |

    Office of Environmental Management (EM)

    Department of Energy 16.1330_Rimando 110316 rev3 [Compatibility Mode] Microsoft PowerPoint - 16.1330_Rimando 110316 rev3 [Compatibility Mode] PDF icon Microsoft PowerPoint - 16.1330_Rimando 110316 rev3 [Compatibility Mode] More Documents & Publications Microsoft PowerPoint - 01 Bosco PM Workshop BOSCO Feb22_2010PB final rcvd 5 Mar [Compatibility Mode] Microsoft PowerPoint - 16.0805_Tom Fox [Compatibility Mode] Microsoft PowerPoint - 15.1500_Michael Deane [Compatibility Mod

  10. Eddy current inspection tool which is selectively operable in a discontinuity detection mode and a discontinuity magnitude mode

    DOE Patents [OSTI]

    Petrini, Richard R.; Van Lue, Dorin F.

    1983-01-01

    A miniaturized inspection tool, for testing and inspection of metal objects in locations with difficult accessibility, which comprises eddy current sensing equipment (12) with a probe coil (11), and associated coaxial coil cable (13), coil energizing means (21), and circuit means (21, 12) responsive to impedance changes in the coil as effected by induced eddy currents in a test object to produce a data output signal proportional to such changes. The coil and cable are slideably received in the utility channel of the flexible insertion tube 17 of fiberoptic scope 10. The scope 10 is provided with light transmitting and receiving fiberoptics for viewing through the flexible tube, and articulation means (19, 20) for articulating the distal end of the tube and permitting close control of coil placement relative to a test object. The eddy current sensing equipment includes a tone generator 30 for generating audibly signals responsive to the data output signal. In one selected mode of operation, the tone generator responsive to the output signal above a selected level generates a constant single frequency tone for signalling detection of a discontinuity and, in a second selected mode, generates a tone whose frequency is proportional to the difference between the output signal and a predetermined selected threshold level.

  11. Eddy current inspection tool which is selectively operable in a discontinuity detection mode and a discontinuity magnitude mode

    DOE Patents [OSTI]

    Petrini, R.R.; Van Lue, D.F.

    1983-10-25

    A miniaturized inspection tool, for testing and inspection of metal objects in locations with difficult accessibility, which comprises eddy current sensing equipment with a probe coil, and associated coaxial coil cable, coil energizing means, and circuit means responsive to impedance changes in the coil as effected by induced eddy currents in a test object to produce a data output signal proportional to such changes. The coil and cable are slideably received in the utility channel of the flexible insertion tube of fiberoptic scope. The scope is provided with light transmitting and receiving fiberoptics for viewing through the flexible tube, and articulation means for articulating the distal end of the tube and permitting close control of coil placement relative to a test object. The eddy current sensing equipment includes a tone generator 30 for generating audibly signals responsive to the data output signal. In one selected mode of operation, the tone generator responsive to the output signal above a selected level generates a constant single frequency tone for signaling detection of a discontinuity and, in a second selected mode, generates a tone whose frequency is proportional to the difference between the output signal and a predetermined selected threshold level. 5 figs.

  12. System and methods for determining masking signals for applying empirical mode decomposition (EMD) and for demodulating intrinsic mode functions obtained from application of EMD

    DOE Patents [OSTI]

    Senroy, Nilanjan; Suryanarayanan, Siddharth

    2011-03-15

    A computer-implemented method of signal processing is provided. The method includes generating one or more masking signals based upon a computed Fourier transform of a received signal. The method further includes determining one or more intrinsic mode functions (IMFs) of the received signal by performing a masking-signal-based empirical mode decomposition (EMD) using the at least one masking signal.

  13. Theoretical study on mode competition between fundamental and second harmonic modes in a 0.42 THz gyrotron with gradually tapered complex cavity

    SciTech Connect (OSTI)

    Zhao, Qixiang Yu, Sheng; Zhang, Tianzhong; Li, Xiang

    2015-10-15

    In this paper, the nonlinear dynamics of mode competition in the complex cavity gyrotron are studied by using multi-frequency, time-dependent theory with the cold-cavity longitudinal profile approximation. Based on the theory, a code is written to simulate the mode competition in the gradually tapered complex cavity gyrotron operating at second harmonic oscillation. The simulations tracking seven competition modes show that single mode oscillation of the desired mode TE{sub 17.4} at 150 kW level can be expected with proper choice of operating parameters. Through studying on mode competition, it is proved that the complex cavity has a good capability for suppressing the mode competition. Meanwhile, it is found that TE{sub 17.3} could be excited in the first cavity as a competition mode when the gyrotron operating at large beam current, which leads to that TE{sub 17.3} and TE{sub 17.4} with different frequencies can coexist stably in the complex cavity gyrotron with very close amplitudes. Thus, the complex cavity might be used for multi-frequency output gyrotron.

  14. Mixed mode fuel injector with individually moveable needle valve members

    DOE Patents [OSTI]

    Stewart, Chris; Chockley, Scott A.; Ibrahim, Daniel R.; Lawrence, Keith; Tomaseki, Jay; Azam, Junru H.; Tian, Steven Ye; Shafer, Scott F.

    2004-08-03

    A fuel injector includes a homogenous charge nozzle outlet set and a conventional nozzle outlet set controlled respectively, by first and second needle valve members. One of the needle valve members moves to an open position while the other needle valve member remains stationary for a homogeneous charge injection event. The former needle valve member stays stationary while the other needle valve member moves to an open position for a conventional injection event. One of the needle valve members is at least partially positioned in the other needle valve member. Thus, the injector can perform homogeneous charge injection events, conventional injection events, or even a mixed mode having both types of injection events in a single engine cycle.

  15. Security technologies and protocols for Asynchronous Transfer Mode networks

    SciTech Connect (OSTI)

    Tarman, T.D.

    1996-06-01

    Asynchronous Transfer Mode (ATM) is a new data communications technology that promises to integrate voice, video, and data traffic into a common network infrastructure. In order to fully utilize ATM`s ability to transfer real-time data at high rates, applications will start to access the ATM layer directly. As a result of this trend, security mechanisms at the ATM layer will be required. A number of research programs are currently in progress which seek to better understand the unique issues associated with ATM security. This paper describes some of these issues, and the approaches taken by various organizations in the design of ATM layer security mechanisms. Efforts within the ATM Forum to address the user communities need for ATM security are also described.

  16. Beam dynamics studies for transverse electromagnetic mode type rf deflectors

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

    Ahmed, Shahid; Krafft, Geoffrey A.; Deitrick, Kirsten; De Silva, Subashini U.; Delayen, Jean R.; Spata, Mike; Tiefenback, Michael; Hofler, Alicia; Beard, Kevin

    2012-02-14

    We have performed three-dimensional simulations of beam dynamics for transverse electromagnetic mode (TEM) type rf deflectors: normal and superconducting. The compact size of these cavities as compared to the conventional TM110 type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of six 2-cell normal conducting cavities or a single cell superconducting structure is enough to produce the required vertical displacement at the target point. Both the normal and superconducting structures show very small emittance dilution due to the verticalmore » kick of the beam.« less

  17. Roughness Optimization at High Modes for GDP CHx Microshells

    SciTech Connect (OSTI)

    Theobald, M.; Dumay, B.; Chicanne, C.; Barnouin, J.; Legaie, O.; Baclet, P.

    2004-03-15

    For the ''Megajoule'' Laser (LMJ) facility of the CEA, amorphous hydrogenated carbon (a-C:H) is the nominal ablator to be used for inertial confinement fusion (ICF) experiments. These capsules contain the fusible deuterium-tritium mixture to achieve ignition. Coatings are prepared by glow discharge polymerization (GDP) with trans-2-butene and hydrogen. The films properties have been investigated. Laser fusion targets must have optimized characteristics: a diameter of about 2.4 mm for LMJ targets, a thickness up to 175 {mu}m, a sphericity and a thickness concentricity better than 99% and an outer and an inner roughness lower than 20 nm at high modes. The surface finish of these laser fusion targets must be extremely smooth to minimize hydrodynamic instabilities.Movchan and Demchishin, and later Thornton introduced a structure zone model (SZM) based on both evaporated and sputtered metals. They investigated the influence of base temperature and the sputtering gas pressure on structure and properties of thick polycrystalline coatings of nickel, titanium, tungsten, aluminum oxide. An original cross-sectional analysis by atomic force microscopy (AFM) allows amorphous materials characterization and permits to make an analogy between the amorphous GDP material and the existing model (SZM). The purpose of this work is to understand the relationship between the deposition parameters, the growing structures and the surface roughness.The coating structure as a function of deposition parameters was first studied on plane silicon substrates and then optimized on PAMS shells. By adjusting the coating parameters, the structures are modified, and in some case, the high modes roughness decreases dramatically.

  18. Atomic nuclei decay modes by spontaneous emission of heavy ions

    SciTech Connect (OSTI)

    Poenaru, D.N.; Ivascu, M.; Sndulescu, A.; Greiner, W.

    1985-08-01

    The great majority of the known nuclides with Z>40, including the so-called stable nuclides, are metastable with respect to several modes of spontaneous superasymmetric splitting. A model extended from the fission theory of alpha decay allows one to estimate the lifetimes and the branching ratios relative to the alpha decay for these natural radioactivities. From a huge amount of systematic calculations it is concluded that the process should proceed with maximum intensity in the trans-lead nuclei, where the minimum lifetime is obtained from parent-emitted heavy ion combinations leading to a magic (/sup 208/Pb) or almost magic daughter nucleus. More than 140 nuclides with atomic number smaller than 25 are possible candidates to be emitted from heavy nuclei, with half-lives in the range of 10/sup 10/--10/sup 30/ s: /sup 5/He, /sup 8en-dash10/Be, /sup 11,12/B, /sup 12en-dash16/C, /sup 13en-dash17/N, /sup 15en-dash22/O, /sup 18en-dash23/F, /sup 20en-dash26/Ne, /sup 23en-dash28/Na, /sup 23en-dash30/Mg, /sup 27en-dash32/Al, /sup 28en-dash36/Si, /sup 31en-dash39/P, /sup 32en-dash42/S, /sup 35en-dash45/Cl, /sup 37en-dash47/Ar, /sup 40en-dash49/ K, . .Ca, /sup 44en-dash53/ Sc, /sup 46en-dash53/Ti, /sup 48en-dash54/V, and /sup 49en-dash55/ Cr. The shell structure and the pairing effects are clearly manifested in these new decay modes.

  19. Benchmarking kinetic calculations of resistive wall mode stability

    SciTech Connect (OSTI)

    Berkery, J. W.; Sabbagh, S. A.; Liu, Y. Q.; Betti, R.

    2014-05-15

    Validating the calculations of kinetic resistive wall mode (RWM) stability is important for confidently predicting RWM stable operating regions in ITER and other high performance tokamaks for disruption avoidance. Benchmarking the calculations of the Magnetohydrodynamic Resistive SpectrumKinetic (MARS-K) [Y. Liu et al., Phys. Plasmas 15, 112503 (2008)], Modification to Ideal Stability by Kinetic effects (MISK) [B. Hu et al., Phys. Plasmas 12, 057301 (2005)], and Perturbed Equilibrium Nonambipolar Transport (PENT) [N. Logan et al., Phys. Plasmas 20, 122507 (2013)] codes for two Solov'ev analytical equilibria and a projected ITER equilibrium has demonstrated good agreement between the codes. The important particle frequencies, the frequency resonance energy integral in which they are used, the marginally stable eigenfunctions, perturbed Lagrangians, and fluid growth rates are all generally consistent between the codes. The most important kinetic effect at low rotation is the resonance between the mode rotation and the trapped thermal particle's precession drift, and MARS-K, MISK, and PENT show good agreement in this term. The different ways the rational surface contribution was treated historically in the codes is identified as a source of disagreement in the bounce and transit resonance terms at higher plasma rotation. Calculations from all of the codes support the present understanding that RWM stability can be increased by kinetic effects at low rotation through precession drift resonance and at high rotation by bounce and transit resonances, while intermediate rotation can remain susceptible to instability. The applicability of benchmarked kinetic stability calculations to experimental results is demonstrated by the prediction of MISK calculations of near marginal growth rates for experimental marginal stability points from the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)].

  20. Failure modes and effects analysis of fusion magnet systems

    SciTech Connect (OSTI)

    Zimmermann, M; Kazimi, M S; Siu, N O; Thome, R J

    1988-12-01

    A failure modes and consequence analysis of fusion magnet system is an important contributor towards enhancing the design by improving the reliability and reducing the risk associated with the operation of magnet systems. In the first part of this study, a failure mode analysis of a superconducting magnet system is performed. Building on the functional breakdown and the fault tree analysis of the Toroidal Field (TF) coils of the Next European Torus (NET), several subsystem levels are added and an overview of potential sources of failures in a magnet system is provided. The failure analysis is extended to the Poloidal Field (PF) magnet system. Furthermore, an extensive analysis of interactions within the fusion device caused by the operation of the PF magnets is presented in the form of an Interaction Matrix. A number of these interactions may have significant consequences for the TF magnet system particularly interactions triggered by electrical failures in the PF magnet system. In the second part of this study, two basic categories of electrical failures in the PF magnet system are examined: short circuits between the terminals of external PF coils, and faults with a constant voltage applied at external PF coil terminals. An electromagnetic model of the Compact Ignition Tokamak (CIT) is used to examine the mechanical load conditions for the PF and the TF coils resulting from these fault scenarios. It is found that shorts do not pose large threats to the PF coils. Also, the type of plasma disruption has little impact on the net forces on the PF and the TF coils. 39 refs., 30 figs., 12 tabs.

  1. Global gyrokinetic stability of collisionless microtearing modes in large aspect ratio tokamaks

    SciTech Connect (OSTI)

    Swamy, Aditya K.; Ganesh, R., E-mail: ganesh@ipr.res.in [Institute for Plasma Research, Bhat, Gandhinagar (India); Chowdhury, J. [Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Brunner, S.; Vaclavik, J.; Villard, L. [CRPP, EPFL, 1015 Lausanne (Switzerland)

    2014-08-15

    Linear full radius gyrokinetic calculations show the existence of unstable microtearing modes (MTMs) in purely collisionless, high temperature, large aspect ratio tokamak plasmas. The present study takes into account fully gyrokinetic highly passing ions and electrons. The global 2-D structures of the collisionless mode with full radius coupling of the poloidal modes is obtained and compared with another electromagnetic mode, namely, the Alfvn Ion Temperature Gradient (AITG) mode (or Kinetic Ballooning Mode, KBM) for the same equilibrium profile. Several important characteristics of the modes are brought out and compared, such as a clear signature in the symmetry properties of the two modes, the plasma? dependence, and radial and poloidal length scales of the electrostatic and magnetic vector potential fluctuations. Extensive parameter scans for this collisionless microtearing mode reveal the scaling of the growth rate with ? and the electron temperature gradient ?{sub e}. Scans at different ? values show an inverse relationship between the ?{sub e} threshold and ?, leading to a stability diagram, and implying that the mode might exist at moderate to strong temperature gradients for finite ? plasmas in large aspect ratio tokamaks. In contrast to small aspect ratio tokamaks where the trapped electron magnetic drift resonance is found to be important, in large aspect ratio tokamaks, a strong destabilization due to the magnetic drift resonance of passing electrons is observed and is identified as a possible collisionless drive mechanism for the collisionless MTM.

  2. Phonon-roton modes of liquid 4He beyond the roton in MCM-41

    SciTech Connect (OSTI)

    Azuah, Richard T NIST Center for Neutron Research , Gaithersburg, MD; Omar Diallo, Souleymane ORNL; Adams, Mark A. ISIS Facility, Rutherford Appleton Laboratory; Kirichek, Oleg ISIS Facility, Rutherford Appleton Laboratory; Glyde, Henry R University of Delaware

    2013-01-01

    We present neutron scattering measurements of the phonon-roton (P-R) mode of superfluid 4He confined in 47 A MCM-41 at T = 0.5 K at wave vectors, Q, beyond the roton wave vector (QR = 1.92 A-1). Measurements beyond the roton require access to high wave vectors (up to Q = 4 A-1) with excellent energy resolution and high statistical precision. The present results show for the first time that at T = 0.5 K the P-R mode in MCM-41 extends out to wave-vector Q 3.6 A-1 with the same energy and zero width (within precision) as observed in bulk superfluid 4He. Layer modes in the roton region are also observed. Specifically, the P-R mode energy, !Q, increases with Q for Q > QR and reaches a plateau at a maximum energy !Q = 2 where is the roton energy, = 0.74 0.01 meV in MCM-41. This upper limit means the P-R mode decays to two rotons when its energy exceeds 2 . It also means that the P-R mode does not decay to two layers modes. If the P-R could decay to two layer modes, !Q would plateau at a lower energy, !Q = 2 L where L = 0.60 meV is the energy of the roton like minimum of the layer mode. The observation of the P-R mode with energy up to 2 shows that the P-R mode and the layer modes are independent modes with apparently little interaction between them.

  3. An experimental study of CTOD for Mode I/Mode II stable crack growth in thin 2024-T3 aluminum specimens

    SciTech Connect (OSTI)

    Amstutz, B.E.; Sutton, M.A.; Dawicke, D.S.; Newman, J.C.

    1995-12-31

    An experimental study of crack tip opening displacement (CTOD) for Mode I/Mode II stable crack growth in thin sheet 2024-T3 aluminum has been conducted. To perform the experiments, an Arcan specimen and fixture was modified so that (1) slippage in the grips was eliminated, (2) large rotations of the fixture components were achievable and (3) bending stresses were minimized. Defining {Theta} to be the angle between the Mode I loading direction (perpendicular to the crack line) and the direction of applied loading, experimental results indicate that (a) for large amounts of crack extension, a {ge} 10mm, the value of CTOD at 1 mm behind the crack tip appears to approach a constant value of 0.1 mm for all modes of loading, (b) the direction of crack extension varied with applied mixed mode loading, (c) Mode I crack extension is predominant for 0{degree} {le} {Theta} {le} 60{degree}, (d) Mode II crack extension is predominant for 75{degree} {le} {Theta} {le} 90{degree} and (e) a transition zone exists for angles {Theta} near 75{degree}.

  4. Electromagnetic coupling and array packing induce exchange of dominance on complex modes in 3D periodic arrays of spheres with large permittivity

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

    Campione, Salvatore; Capolino, Filippo

    2016-01-25

    In this study, we investigate the effect on wave propagation of array packing and electromagnetic coupling between spheres in a three-dimensional (3D) lattice of microspheres with large permittivity that exhibit strong magnetic polarizability. We report on the complex wavenumber of Bloch waves in the lattice when each sphere is assumed to possess both electric and magnetic dipoles and full electromagnetic coupling is accounted for. While for small material-filling fractions we always determine one dominant mode with low attenuation constant, the same does not happen for large filling fractions, when electromagnetic coupling is included. In the latter case we peculiarly observemore » two dominant modes with low attenuation constant, dominant in different frequency ranges. The filling fraction threshold for which two dominant modes appear varies for different metamaterial constituents, as proven by considering spheres made by either titanium dioxide or lead telluride. As further confirmation of our findings, we retrieve the complex propagation constant of the dominant mode(s) via a field fitting procedure employing two sets of waves (direct and reflected) pertaining to two distinct modes, strengthening the presence of the two distinct dominant modes for increasing filling fractions. However, given that one mode only, with transverse polarization, at any given frequency, is dominant and able to propagate inside the lattice, we are able to accurately treat the metamaterial that is known to exhibit artificial magnetism as a homogeneous material with effective parameters, such as the refractive index. Results clearly show that the account of both electric and magnetic scattering processes in evaluating all electromagnetic intersphere couplings is essential for a proper description of the electromagnetic propagation in lattices.« less

  5. Low-frequency Interlayer Breathing Modes in Few-layer Black Phosphorus

    SciTech Connect (OSTI)

    Huang, Shengxi; Puretzky, Alexander A; Geohegan, David B; Sumpter, Bobby G; Kong, Jing; Dresselhaus, M; Meunier, V.; Liang, Liangbo; Ling, Xi

    2015-01-01

    As a new two-dimensional layered material, black phosphorus (BP) is a very promising material for nanoelectronics and nano-optoelectronics. We use Raman spectroscopy and first-principles theory to characterize and understand low-frequency (LF) interlayer breathing modes (<100 cm-1) in few-layer BP for the first time. Using laser polarization dependence study and group theory analysis the breathing modes are assigned to Ag symmetry. Compared to the high-frequency (HF) Raman modes, the LF breathing modes are considerably more sensitive to interlayer coupling and thus their frequencies show stronger dependence on the number of layers. Hence, they constitute an effective means to probe both the crystalline orientation and thickness of few-layer BP. Furthermore, the temperature dependence shows that the breathing modes have a harmonic behavior, in contrast to HF Raman modes which exhibit anharmonicity.

  6. Low-Frequency Interlayer Breathing Modes in Few-Layer Black Phosphorus

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

    Ling, Xi; Liang, Liangbo; Huang, Shengxi; Puretzky, Alexander A.; Geohegan, David B.; Sumpter, Bobby G.; Kong, Jing; Meunier, Vincent; Dresselhaus, Mildred S.

    2015-05-08

    As a new two-dimensional layered material, black phosphorus (BP) is a very promising material for nanoelectronics and nano-optoelectronics. We use Raman spectroscopy and first-principles theory to characterize and understand low-frequency (LF) interlayer breathing modes (<100 cm-1) in few-layer BP for the first time. Using laser polarization dependence study and group theory analysis the breathing modes are assigned to Ag symmetry. Compared to the high-frequency (HF) Raman modes, the LF breathing modes are considerably more sensitive to interlayer coupling and thus their frequencies show stronger dependence on the number of layers. Hence, they constitute an effective means to probe both themore » crystalline orientation and thickness of few-layer BP. Furthermore, the temperature dependence shows that the breathing modes have a harmonic behavior, in contrast to HF Raman modes which exhibit anharmonicity.« less

  7. Effect of toroidal magnetic field on n = 1 mode stability in rotamak plasmas

    SciTech Connect (OSTI)

    Yang, X.; Goss, J.; Kalaria, D.; Huang, T. S.

    2011-08-15

    To study the effect of toroidal magnetic field on n = 1 mode stability, a series of experiments with linearly ramping the axial current I{sub z}, which makes field-reversed configuration (FRC) to spherical tokamak (ST) transition, have been conducted in rotamak. Results clearly demonstrate that the tilt mode can be completely suppressed by small I{sub z} around 0.4 kA (in comparison with 2.0 kA plasma current). An unknown new mode with larger magnetic perturbations is triggered when I{sub z} reaches 0.5 kA. This instability mode keeps saturation while plasma current is boosted when I{sub z} is in the range of 0.6-1.4 kA. When I{sub z} exceeds 1.6 kA, the new mode suddenly disappears and discharge is free from instability modes.

  8. Magneto-hydrodynamics simulation study of deflagration mode in co-axial plasma accelerators

    SciTech Connect (OSTI)

    Sitaraman, Hariswaran; Raja, Laxminarayan L.

    2014-01-15

    Experimental studies by Poehlmann et al. [Phys. Plasmas 17(12), 123508 (2010)] on a coaxial electrode magnetohydrodynamic (MHD) plasma accelerator have revealed two modes of operation. A deflagration or stationary mode is observed for lower power settings, while higher input power leads to a detonation or snowplow mode. A numerical modeling study of a coaxial plasma accelerator using the non-ideal MHD equations is presented. The effect of plasma conductivity on the axial distribution of radial current is studied and found to agree well with experiments. Lower conductivities lead to the formation of a high current density, stationary region close to the inlet/breech, which is a characteristic of the deflagration mode, while a propagating current sheet like feature is observed at higher conductivities, similar to the detonation mode. Results confirm that plasma resistivity, which determines magnetic field diffusion effects, is fundamentally responsible for the two modes.

  9. Harmonic mode competition in a terahertz gyrotron backward-wave oscillator

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Harmonic mode competition in a terahertz gyrotron backward-wave oscillator Citation Details In-Document Search Title: Harmonic mode competition in a terahertz gyrotron backward-wave oscillator Electron cyclotron maser interactions at terahertz (THz) frequencies require a high-order-mode structure to reduce the wall loss to a tolerable level. To generate THz radiation, it is also essential to employ cyclotron harmonic resonances to reduce the required

  10. Reduction of the beam breakup mode Q values in the ETA/ATA Accelerating Cells

    SciTech Connect (OSTI)

    Birx, D.L.

    1980-05-20

    Earlier Microwave Measurements of the ETA Accelerating Cells has uncovered eleven resonances in the frequency range of 0 > 850 MHz. The Q values of these modes ranged from 14 to 70. A three phase program directed at substantially reducing these Q values is reported. In particular the dampening methods described below resulted in a decrease of Q value from 40 to 5 for the beam breakup mode (TM/sub 110/) with a corresponding reduction for most of the other cavity modes.

  11. A possibility for using an APPLE undulator to generate a photon beam with transverse optical modes.

    SciTech Connect (OSTI)

    Sasaki, S.; McNulty, I.; Shimada, T.; JAEA

    2008-01-01

    We investigate use of an APPLE-type undulator for generating Laguerre-Gaussian (LG) and Hermite-Gaussian (HG) mode beams. We find that the second harmonic radiation in the circular mode corresponds to an LG beam with l=1, and the second harmonic in the linear mode corresponds to an HG beam with l=1. The combination of an APPLE undulator and conventional monochromator optics may provide an opportunity for a new type of experimental research in the synchrotron radiation community.

  12. Dynamic control of polarization-inverted modes in three-dimensionally

    Office of Scientific and Technical Information (OSTI)

    trapped multiple nanogaps (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Dynamic control of polarization-inverted modes in three-dimensionally trapped multiple nanogaps Citation Details In-Document Search Title: Dynamic control of polarization-inverted modes in three-dimensionally trapped multiple nanogaps We propose a guiding principle for the dynamic control of polarization-inverted modes in multiple nanogaps for unconventional optical transitions of

  13. MULTI-MODE ERROR FIELD CORRECTION ON THE DIII-D TOKAMAK

    SciTech Connect (OSTI)

    SCOVILLE, JT; LAHAYE, RJ

    2002-10-01

    OAK A271 MULTI-MODE ERROR FIELD CORRECTION ON THE DIII-D TOKAMAK. Error field optimization on DIII-D tokamak plasma discharges has routinely been done for the last ten years with the use of the external ''n = 1 coil'' or the ''C-coil''. The optimum level of correction coil current is determined by the ability to avoid the locked mode instability and access previously unstable parameter space at low densities. The locked mode typically has toroidal and poloidal mode numbers n = 1 and m = 2, respectively, and it is this component that initially determined the correction coil current and phase. Realization of the importance of nearby n = 1 mode components m = 1 and m = 3 has led to a revision of the error field correction algorithm. Viscous and toroidal mode coupling effects suggested the need for additional terms in the expression for the radial ''penetration'' field B{sub pen} that can induce a locked mode. To incorporate these effects, the low density locked mode threshold database was expanded. A database of discharges at various toroidal fields, plasma currents, and safety factors was supplement4ed with data from an experiment in which the fields of the n = 1 coil and C-coil were combined, allowing the poloidal mode spectrum of the error field to be varied. A multivariate regression analysis of this new low density locked mode database was done to determine the low density locked mode threshold scaling relationship n{sub e} {proportional_to} B{sub T}{sup -0.01} q{sub 95}{sup -0.79} B{sub pen} and the coefficients of the poloidal mode components in the expression for B{sub pen}. Improved plasma performance is achieved by optimizing B{sub pen} by varying the applied correction coil currents.

  14. Mode-locked terahertz quantum cascade laser by direct phase synchronization

    SciTech Connect (OSTI)

    Maussang, K.; Maysonnave, J.; Jukam, N.; Freeman, J. R.; Cavali, P.; Dhillon, S. S.; Tignon, J.; Khanna, S. P.; Linfield, E. H.; Davies, A. G.; Beere, H. E.; Ritchie, D. A.

    2013-12-04

    Mode-locking of a terahertz quantum cascade laser is achieved using multimode injection seeding. Contrary to standard methods that rely on gain modulation, here a fixed phase relationship is directly imprinted to the laser modes. In this work, we demonstrate the generation of 9 ps phase mode-locked pulses around 2.75 THz. A direct measurement of the emitted field phase shows that it results from the phase of the initial injection.

  15. DISCHARGE IMPROVEMENT THROUGH CONTROL OF NEOCLASSICAL TEARING MODES BY LOCALIZED ECCD IN DIII-D

    SciTech Connect (OSTI)

    PRATER,R; LAHAYE,RJ; LOHR,J; LUCE,TC; PETTY,CC; FERRON,JR; HUMPHREYS,DA; STRAIT,EJ; PERKINS,FW; HARVEY,RW

    2002-10-01

    A271 DISCHARGE IMPROVEMENT THROUGH CONTROL OF NEOCLASSICAL TEARING MODES BY LOCALIZED ECCD IN DIII-D. Neoclassical tearing modes (NTMs) are MHD modes which can limit the performance of high beta discharges in tokamaks, in some cases leading to a major disruption. The destabilizing effect which results in NTM growth is a helical decrease in the bootstrap current caused by a local reduction of the plasma pressure gradient by seed magnetic islands. The NTM is particularly well suited to control since the mode is linearly stable although nonlinearly unstable, so if the island amplitude can be decreased below a threshold size the mode will decay and vanish. One means of shrinking the island is the replacement of the missing bootstrap current by a localized current generated by electron cyclotron current drive (ECCD). This method has been applied to the m=3/n=2 neoclassical tearing mode in DIII-D, in H-mode plasmas with ongoing ELMs and sawteeth, both of which generate seed islands periodically. In the case of the 3/2 mode, full suppression was obtained robustly by applying about 1.5 MW of ECCD very near the rational surface of the mode. When the mode first appears in the plasma the stored energy decreases by 20%, but after the mode is stabilized by the ECCD the beta may be raised above the initial threshold pressure by 20% by additional neutral beam heating, thereby generating an improvement in the limiting beta of nearly a factor 2. An innovative automated search algorithm was implemented to find and retain the optimum location for the ECCD in the presence of the mode.

  16. Rouse mode analysis of chain relaxation in polymer nanocomposites

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

    Kalathi, Jagannathan T.; Kumar, Sanat K.; Rubinstein, Michael; Grest, Gary S.

    2015-04-20

    Large-scale molecular dynamics simulations are used to study the internal relaxations of chains in nanoparticle (NP)/polymer composites. We examine the Rouse modes of the chains, a quantity that is closest in spirit to the self-intermediate scattering function, typically determined in an (incoherent) inelastic neutron scattering experiment. Our simulations show that for weakly interacting mixtures of NPs and polymers, the effective monomeric relaxation rates are faster than in a neat melt when the NPs are smaller than the entanglement mesh size. In this case, the NPs serve to reduce both the monomeric friction and the entanglements in the polymer melt, asmore » in the case of a polymer–solvent system. However, for NPs larger than half the entanglement mesh size, the effective monomer relaxation is essentially unaffected for low NP concentrations. Even in this case, we observe a strong reduction in chain entanglements for larger NP loadings. Furthermore, the role of NPs is to always reduce the number of entanglements, with this effect only becoming pronounced for small NPs or for high concentrations of large NPs. Our studies of the relaxation of single chains resonate with recent neutron spin echo (NSE) experiments, which deduce a similar entanglement dilution effect.« less

  17. Parameter spaces for linear and nonlinear whistler-mode waves

    SciTech Connect (OSTI)

    Summers, Danny; School of Space Research, Kyung Hee University, Yongin, Gyeonggi ; Tang, Rongxin; Institute of Space Science and Technology, Nanchang University, Nanchang; State Key Laboratory of Space Weather, Chinese Academy of Sciences, Beijing ; Omura, Yoshiharu; Lee, Dong-Hun

    2013-07-15

    We examine the growth of magnetospheric whistler-mode waves which comprises a linear growth phase followed by a nonlinear growth phase. We construct time-profiles for the wave amplitude that smoothly match at the transition between linear and nonlinear wave growth. This matching procedure can only take place over a limited “matching region” in (N{sub h}/N{sub 0},A{sub T})-space, where A{sub T} is the electron thermal anisotropy, N{sub h} is the hot (energetic) electron number density, and N{sub 0} is the cold (background) electron number density. We construct this matching region and determine how the matching wave amplitude varies throughout the region. Further, we specify a boundary in (N{sub h}/N{sub 0},A{sub T})-space that separates a region where only linear chorus wave growth can occur from the region in which fully nonlinear chorus growth is possible. We expect that this boundary should prove of practical use in performing computationally expensive full-scale particle simulations, and in interpreting experimental wave data.

  18. Intermittent bursts induced by double tearing mode reconnection

    SciTech Connect (OSTI)

    Wei, Lai; Wang, Zheng-Xiong, E-mail: zxwang@dlut.edu.cn [Key Laboratory of Materials Modification by Beams of the Ministry of Education, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2014-06-15

    Reversed magnetic shear (RMS) configuration is assumed to be the steady-state operation scenario for the future advanced tokamaks like International Thermonuclear Experimental Reactor. In this work, we numerically discover a phenomenon of violent intermittent bursts induced by self-organized double tearing mode (DTM) reconnection in the RMS configuration during the very long evolution, which may continuously lead to annular sawtooth crashes and thus badly impact the desired steady-state operation of the future advanced RMS tokamaks. The key process of the intermittent bursts in the off-axis region is similar to that of the typical sawtooth relaxation oscillation in the positive magnetic shear configuration. It is interestingly found that in the decay phase of the DTM reconnection, the zonal field significantly counteracts equilibrium field to make the magnetic shear between the two rational surfaces so weak that the residual self-generated vortices of the previous DTM burst are able to trigger a reverse DTM reconnection by curling the field lines.

  19. Real-time multi-mode neutron multiplicity counter

    DOE Patents [OSTI]

    Rowland, Mark S; Alvarez, Raymond A

    2013-02-26

    Embodiments are directed to a digital data acquisition method that collects data regarding nuclear fission at high rates and performs real-time preprocessing of large volumes of data into directly useable forms for use in a system that performs non-destructive assaying of nuclear material and assemblies for mass and multiplication of special nuclear material (SNM). Pulses from a multi-detector array are fed in parallel to individual inputs that are tied to individual bits in a digital word. Data is collected by loading a word at the individual bit level in parallel, to reduce the latency associated with current shift-register systems. The word is read at regular intervals, all bits simultaneously, with no manipulation. The word is passed to a number of storage locations for subsequent processing, thereby removing the front-end problem of pulse pileup. The word is used simultaneously in several internal processing schemes that assemble the data in a number of more directly useable forms. The detector includes a multi-mode counter that executes a number of different count algorithms in parallel to determine different attributes of the count data.

  20. Rouse mode analysis of chain relaxation in polymer nanocomposites

    SciTech Connect (OSTI)

    Kalathi, Jagannathan T.; Kumar, Sanat K.; Rubinstein, Michael; Grest, Gary S.

    2015-04-20

    Large-scale molecular dynamics simulations are used to study the internal relaxations of chains in nanoparticle (NP)/polymer composites. We examine the Rouse modes of the chains, a quantity that is closest in spirit to the self-intermediate scattering function, typically determined in an (incoherent) inelastic neutron scattering experiment. Our simulations show that for weakly interacting mixtures of NPs and polymers, the effective monomeric relaxation rates are faster than in a neat melt when the NPs are smaller than the entanglement mesh size. In this case, the NPs serve to reduce both the monomeric friction and the entanglements in the polymer melt, as in the case of a polymer–solvent system. However, for NPs larger than half the entanglement mesh size, the effective monomer relaxation is essentially unaffected for low NP concentrations. Even in this case, we observe a strong reduction in chain entanglements for larger NP loadings. Furthermore, the role of NPs is to always reduce the number of entanglements, with this effect only becoming pronounced for small NPs or for high concentrations of large NPs. Our studies of the relaxation of single chains resonate with recent neutron spin echo (NSE) experiments, which deduce a similar entanglement dilution effect.

  1. Non-gaussian mode coupling and the statistical cosmological principle

    SciTech Connect (OSTI)

    LoVerde, Marilena; Nelson, Elliot; Shandera, Sarah E-mail: eln121@psu.edu

    2013-06-01

    Local-type primordial non-Gaussianity couples statistics of the curvature perturbation ? on vastly different physical scales. Because of this coupling, statistics (i.e. the polyspectra) of ? in our Hubble volume may not be representative of those in the larger universe that is, they may be biased. The bias depends on the local background value of ?, which includes contributions from all modes with wavelength k?

  2. Magnetic antenna excitation of whistler modes. I. Basic properties

    SciTech Connect (OSTI)

    Urrutia, J. M.; Stenzel, R. L.

    2014-12-15

    Properties of magnetic loop antennas for exciting electron whistler modes have been investigated in a large laboratory plasma. The parameter regime is that of large plasma frequency compared to the cyclotron frequency and signal frequency below half the cyclotron frequency. The antenna diameter is smaller than the wavelength. Different directions of the loop antenna relative to the background magnetic field have been measured for small amplitude waves. The differences in the topology of the wave magnetic field are shown from measurements of the three field components in three spatial directions. The helicity of the wave magnetic field and of the hodogram of the magnetic vector in space and time are clarified. The superposition of wave fields is used to investigate the properties of two antennas for small amplitude waves. Standing whistler waves are produced by propagating two wave packets in opposite directions. Directional radiation is obtained with two phased loops separated by a quarter wavelength. Rotating antenna fields, produced with phased orthogonal loops at the same location, do not produce directionality. The concept of superposition is extended in a Paper II to generate antenna arrays for whistlers. These produce nearly plane waves, whose propagation angle can be varied by the phase shifting the currents in the array elements. Focusing of whistlers is possible. These results are important for designing antennas on spacecraft or diagnosing and heating of laboratory plasmas.

  3. Optothermal transport behavior in whispering gallery mode optical cavities

    SciTech Connect (OSTI)

    Soltani, Soheil; Armani, Andrea M.

    2014-08-04

    Over the past century, whispering gallery mode optical cavities have enabled numerous advances in science and engineering, such as discoveries in quantum mechanics and non-linear optics, as well as the development of optical gyroscopes and add drop filters. One reason for their widespread appeal is their ability to confine light for long periods of time, resulting in high circulating intensities. However, when sufficiently large amounts of optical power are coupled into these cavities, they begin to experience optothermal or photothermal behavior, in which the optical energy is converted into heat. Above the optothermal threshold, the resonance behavior is no longer solely defined by electromagnetics. Previous work has primarily focused on the role of the optothermal coefficient of the material in this instability. However, the physics of this optothermal behavior is significantly more complex. In the present work, we develop a predictive theory based on a generalizable analytical expression in combination with a geometry-specific COMSOL Multiphysics finite element method model. The simulation couples the optical and thermal physics components, accounting for geometry variations as well as the temporal and spatial profile of the optical field. To experimentally verify our theoretical model, the optothermal thresholds of a series of silica toroidal resonant cavities are characterized at different wavelengths (visible through near-infrared) and using different device geometries. The silica toroid offers a particularly rigorous case study for the developed optothermal model because of its complex geometrical structure which provides multiple thermal transport paths.

  4. Kinetic neoclassical transport in the H-mode pedestal

    SciTech Connect (OSTI)

    Battaglia, D. J.; Chang, C. S.; Ku, S.; Grierson, B. A.; Burrell, K. H.; Grassie, J. S. de

    2014-07-15

    Multi-species kinetic neoclassical transport through the QH-mode pedestal and scrape-off layer on DIII-D is calculated using XGC0, a 5D full-f particle-in-cell drift-kinetic solver with self-consistent neutral recycling and sheath potentials. Quantitative agreement between the flux-driven simulation and the experimental electron density, impurity density, and orthogonal measurements of impurity temperature and flow profiles is achieved by adding random-walk particle diffusion to the guiding-center drift motion. The radial electric field (E{sub r}) that maintains ambipolar transport across flux surfaces and to the wall is computed self-consistently on closed and open magnetic field lines and is in excellent agreement with experiment. The E{sub r} inside the separatrix is the unique solution that balances the outward flux of thermal tail deuterium ions against the outward neoclassical electron flux and inward pinch of impurity and colder deuterium ions. Particle transport in the pedestal is primarily due to anomalous transport, while the ion heat and momentum transport are primarily due to the neoclassical transport. The full-f treatment quantifies the non-Maxwellian energy distributions that describe a number of experimental observations in low-collisionallity pedestals on DIII-D, including intrinsic co-I{sub p} parallel flows in the pedestal, ion temperature anisotropy, and large impurity temperatures in the scrape-off layer.

  5. Power Supply Changes for NSTX Resistive Wall Mode Coils

    SciTech Connect (OSTI)

    Ramakrishnan, S S.

    2013-06-28

    The National Spherical Torus Experiment (NSTX) has been designed and installed in the existing facilities at Princeton Plasma Physics Laboratory (PPPL). Most of the hardware, plant facilities, auxiliary sub-systems, and power systems originally used for the Tokamak Fusion Test Reactor (TFTR) have been used with suitable modifications to reflect NSTX needs. Prior to 2004, the NSTX power system was feeding twelve (12) circuits in the machine. In 2004 the Resistive Wall Mode (RWM) Coils were installed on the machine to correct error fields. There are six of these coils installed around the machine in the mid-plane. Since these coils need fast and accurate controls, a Switching Power Amplifier (SPA) with three sub-units was procured, installed and commissioned along with other power loop components. Two RWM Coils were connected in series and fed from one SPA sub-unit. After the initial RWM campaign, operational requirements evolved such that each of the RWM coils now requires separate power and control. Hence a second SPA with three sub-units has been procured and installed. The second unit is of improved design and has the controls and power components completely isolated. The existing thyristor rectifier is used as DC Link to both of the Switching Power Amplifiers. The controls for the RWM are integrated into the overall computer control of the DC Power systems for NSTX. This paper describes the design changes in the RWM Power system for NSTX.

  6. Ultrafast spectroscopy of super high frequency mechanical modes of doubly clamped beams

    SciTech Connect (OSTI)

    Ristow, Oliver; Merklein, Moritz; Grossmann, Martin; Hettich, Mike; Schubert, Martin; Bruchhausen, Axel; Scheer, Elke; Dekorsy, Thomas; Barretto, Elaine C. S.; Grebing, Jochen; Erbe, Artur; Mounier, Denis; Gusev, Vitalyi

    2013-12-02

    We use ultrafast pump-probe spectroscopy to study the mechanical vibrations in the time domain of doubly clamped silicon nitride beams. Beams with two different clamping conditions are investigated. Finite element method calculations are performed to analyse the mode spectra of both structures. By calculating the strain integral on the surface of the resonators, we are able to reproduce the effect of the detection mechanism and identify all the measured modes. We show that our spectroscopy technique combined with our modelling tools allow the investigation of several different modes in the super high frequency range (3-30?GHz) and above, bringing more information about the vibration modes of nanomechanical resonators.

  7. Progress in understanding the enhanced pedestal H-mode in NSTX

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

    Gerhardt, S. P.; Canik, J. M.; Maingi, R.; Battaglia, D.; Bell, R. E.; Guttenfelder, W.; LeBlanc, B. P.; Smith, D. R.; Yuh, H.; Sabbagh, S.

    2014-08-01

    The paper describes the enhanced pedestal (EP) H-mode observed in the National Spherical Torus Experiment (NSTX). The defining characteristics of EP H-mode are given, namely i)transition after the L- to H-mode transition, ii) region of very steep ion temperature gradient, and iii) associated region of strong rotational shear. A newly observed long-pulse EP H-mode example shows quiescent behavior for as long as the heating and current drive sources are maintained. Cases are shown where the region of steep ion temperature gradient is located at the very edge, and cases where it is shifted up to 10 cm inward from themore » plasma edge; these cases are united by a common dependence of the ion temperature gradient on the toroidal rotation frequency shear. EP H-mode examples have been observed across a wide range of q95 and pedestal collisionality. No strong changes in the fluctuation amplitudes have been observed following the eP H-mode transition, and transport analysis indicates that the ion t hermal transport is comparable to or less than anticipated from a simple neoclassical transport model. Cases are shown where EP H-modes were reliably generated, through these low-q95 examples were difficult to sustain. A case where an externally triggered ELM precipitates the transition to EP H-mode is also shown, though an initial experiment designed to trigger EP-H-modes in this fashion was successful.« less

  8. A simple cohesive zone model that generates a mode-mixity dependent toughness

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

    Reedy, Jr., E. D.; Emery, J. M.

    2014-07-24

    A simple, mode-mixity dependent toughness cohesive zone model (MDGc CZM) is described. This phenomenological cohesive zone model has two elements. Mode I energy dissipation is defined by a traction–separation relationship that depends only on normal separation. Mode II (III) dissipation is generated by shear yielding and slip in the cohesive surface elements that lie in front of the region where mode I separation (softening) occurs. The nature of predictions made by analyses that use the MDGc CZM is illustrated by considering the classic problem of an elastic layer loaded by rigid grips. This geometry, which models a thin adhesive bondmore » with a long interfacial edge crack, is similar to that which has been used to measure the dependence of interfacial toughness on crack-tip mode-mixity. The calculated effective toughness vs. applied mode-mixity relationships all display a strong dependence on applied mode-mixity with the effective toughness increasing rapidly with the magnitude of the mode-mixity. The calculated relationships also show a pronounced asymmetry with respect to the applied mode-mixity. As a result, this dependence is similar to that observed experimentally, and calculated results for a glass/epoxy interface are in good agreement with published data that was generated using a test specimen of the same type as analyzed here.« less

  9. Mode transition in CF{sub 4} + Ar inductively coupled plasma

    SciTech Connect (OSTI)

    Liu, Wei; Gao, Fei; Zhao, Shu-Xia; Li, Xue-Chun; Wang, You-Nian [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2013-12-15

    The E to H mode transitions are studied by a hairpin probe and optical emission spectroscopy in inductively coupled CF{sub 4} + Ar plasmas. Electron density, optical emission intensity of Ar, and the voltage and current are measured during the E to H mode transitions. It is found that the electron density and plasma emission intensity increase continuously at low pressure during the E to H mode transition, while they jump up discontinuously at high pressure. Meanwhile, the transition threshold power and ?P (the power interval between E and H mode) increase by increasing the pressure. When the ratio of CF{sub 4} increases, the E to H mode transition happens at higher applied power, and meanwhile, the ?P also significantly increases. Besides, the effects of CF{sub 4} gas ratio on the plasma properties and the circuit electrical properties in both pure E and H modes were also investigated. The electron density and plasma emission intensity both decrease upon increasing the ratio of CF{sub 4} at the two modes, due to the stronger electrons loss scheme. The applied voltages at E and H modes both increase as increasing the CF{sub 4} gas ratio, however the applied current at two modes behave just oppositely with the gas ratio.

  10. Progress In Understanding The Enhanced Petestal H-mode In NSTX

    SciTech Connect (OSTI)

    Gerhardt, S. P.; Canik, J. M.; Maingi, R.; Battaglia, D.; Bell, R. E.; Guttenfelder, W.; LeBlanc, B. P.; Smith, D. R.; Yuh, H.; Sabbagh, S.

    2014-06-26

    ThIS paper describes the enhanced pedestal (EP) H-mode observed in the National Spherical Torus Experiment (NSTX). The defining characteristics of EP H-mode are given, namely i)transition after the L- to H-mode transition, ii) region of very steep ion temperature gradient, and iii) associated region of strong rotational shear. A newly observed long-pulse EP H-mode example shows quiescent behavior for as long as the heating and current drive sources are maintained. Cases are shown where the region of steep ion temperature gradient is located at the very edge, and cases where it is shifted up to 10 cm inward from the plasma edge; these cases are united by a common dependence of the ion temperature gradient on the toroidal rotation frequency shear. EP H-mode examples have been observed across a wide range of q95 and pedestal collisionality. No strong changes in the fluctuation amplitudes have been observed following the eP H-mode transition, and transport analysis indicates that the ion t hermal transport is comparable to or less than anticipated from a simple neoclassical transport model. Cases are shown where EP H-modes were reliably generated, through these low-q95 examples were difficult to sustain. A case where an externally triggered ELM precipitates the transition to EP H-mode is also shown, though an initial experiment designed to trigger EP-H-modes in this fashion was successful.

  11. Progress in understanding the enhanced pedestal H-mode in NSTX

    SciTech Connect (OSTI)

    Gerhardt, S. P.; Canik, J. M.; Maingi, R.; Battaglia, D.; Bell, R. E.; Guttenfelder, W.; LeBlanc, B. P.; Smith, D. R.; Yuh, H.; Sabbagh, S.

    2014-08-01

    The paper describes the enhanced pedestal (EP) H-mode observed in the National Spherical Torus Experiment (NSTX). The defining characteristics of EP H-mode are given, namely i)transition after the L- to H-mode transition, ii) region of very steep ion temperature gradient, and iii) associated region of strong rotational shear. A newly observed long-pulse EP H-mode example shows quiescent behavior for as long as the heating and current drive sources are maintained. Cases are shown where the region of steep ion temperature gradient is located at the very edge, and cases where it is shifted up to 10 cm inward from the plasma edge; these cases are united by a common dependence of the ion temperature gradient on the toroidal rotation frequency shear. EP H-mode examples have been observed across a wide range of q95 and pedestal collisionality. No strong changes in the fluctuation amplitudes have been observed following the eP H-mode transition, and transport analysis indicates that the ion t hermal transport is comparable to or less than anticipated from a simple neoclassical transport model. Cases are shown where EP H-modes were reliably generated, through these low-q95 examples were difficult to sustain. A case where an externally triggered ELM precipitates the transition to EP H-mode is also shown, though an initial experiment designed to trigger EP-H-modes in this fashion was successful.

  12. Poor fluorinated graphene sheets carboxymethylcellulose polymer composite mode locker for erbium doped fiber laser

    SciTech Connect (OSTI)

    Mou, Chengbo E-mail: a.rozhin@aston.ac.uk; Turitsyn, Sergei; Rozhin, Aleksey E-mail: a.rozhin@aston.ac.uk; Arif, Raz; Lobach, Anatoly S.; Spitsina, Nataliya G.; Khudyakov, Dmitry V.; Kazakov, Valery A.

    2015-02-09

    We report poor fluorinated graphene sheets produced by thermal exfoliation embedding in carboxymethylcellulose polymer composite (GCMC) as an efficient mode locker for erbium doped fiber laser. Two GCMC mode lockers with different concentration have been fabricated. The GCMC based mode locked fiber laser shows stable soliton output pulse shaping with repetition rate of 28.5?MHz and output power of 5.5 mW was achieved with the high concentration GCMC, while a slightly higher output power of 6.9 mW was obtained using the low concentration GCMC mode locker.

  13. Systems acceptance and operability testing for rotary mode core sampling in flammable gas tanks

    SciTech Connect (OSTI)

    Corbett, J.E., Westinghouse Hanford

    1996-07-29

    This document provides instructions for the system acceptance and operability testing of the rotary mode core sampling system, modified for use in flammable gas tanks.

  14. G-band harmonic multiplying gyrotron traveling-wave amplifier with a mode-selective circuit

    SciTech Connect (OSTI)

    Yeh, Y. S.; Chen, Chang-Hong; Wang, Z. W.; Kao, B. H.; Chen, Chien-Hsiang; Lin, T. Y.; Guo, Y. W.

    2014-12-15

    Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) permit for magnetic field reduction and frequency multiplication. A high-order-mode harmonic multiplying gyro-TWA with large circuit dimensions and low ohmic loss can achieve a high average power. By amplifying a fundamental harmonic TE{sub 01} drive wave, the second harmonic component of the beam current initiates a TE{sub 02} wave to be amplified. Wall losses can suppress some competing modes because they act as an effective sink of the energy of the modes. However, such wall losses do not suppress all competing modes as the fields are contracted in the copper section in the gyro-TWA. An improved mode-selective circuit, using circular waveguides with the specified radii, can provide the rejection points within the frequency range to suppress the competing modes. The simulated results reveal that the mode-selective circuit can provide an attenuation of more than 10 dB to suppress the competing modes (TE{sub 21}, TE{sub 51}, TE{sub 22}, and TE{sub 03}). A G-band second harmonic multiplying gyro-TWA with the mode-selective circuit is predicted to yield a peak output power of 50 kW at 198.8 GHz, corresponding to a saturated gain of 55 dB at an interaction efficiency of 10%. The full width at half maximum bandwidth is 5 GHz.

  15. Frequencies of the geodesic acoustic mode and Alfvn gap modes in high-q{sup 2}? plasmas with non-circular cross section

    SciTech Connect (OSTI)

    Fesenyuk, O. P.; Kolesnichenko, Ya. I.; Yakovenko, Yu. V.; National University of Kyiv Mohyla Academy, Vul. Skovorody 2, Kyiv 04070

    2013-12-15

    This work generalizes recent results [O. P. Fesenyuk et al., Plasma Phys. Controlled Fusion 54, 085014 (2012)] to plasmas with elongated cross section. It suggests new expressions for the frequencies of the geodesic acoustic mode and Alfvn gap modes in tokamaks, with a large ratio of the plasma pressure to the magnetic field pressure and a large safety factor (q?1, which takes place in discharges with reversed-shear configuration and, especially, in hollow-current discharges)

  16. A Preliminary Cost Study of the Dual Mode Inverter Controller

    SciTech Connect (OSTI)

    McKeever, J.W.

    2005-01-28

    In 1998, the Power Electronics and Electric Machinery Research Center (PEEMRC) at the Oak Ridge National Laboratory (ORNL) started a program to investigate alternate field weakening schemes for permanent magnet (PM) motors. The adjective ''alternate'' was used because at that time, outside research emphasis was on motors with interior-mounted PMs (IPMs). The PEEMRC emphasis was placed on motors with surface-mounted PMs (SPMs) because of the relative ease of manufacturing SPM motors compared with the IPM motors. Today the PEEMRC is continuing research on SPMs while examining the IPMs that have been developed by industry. Out of this task--the goal of which was to find ways to drive PM motors that inherently have low inductance at high speeds where their back-emf exceeds the supply voltage--ORNL developed and demonstrated the dual mode inverter control (DMIC) [1,2] method of field weakening for SPM motors. The predecessor of DMIC is conventional phase advance (CPA), which was developed by UQM Technologies, Inc. [3]. Fig. 1 shows the three sets of anti-parallel thyristors in the dashed box that comprise the DMIC. If one removes the dashed box by shorting each set of anti-parallel thyristors, the configuration becomes a conventional full bridge inverter on the left driving a three phase motor on the right. CPA may be used to drive this configuration ORNL's initial analyses of CPA and DMIC were based on driving motors with trapezoidal back-emfs [4-6], obtained using double layer lapped stator windings with one slot per pole per phase. A PM motor with a sinusoidal back-emf obtained with two poles per slot per phase has been analyzed under DMIC operation as a University of Tennessee-Knoxville (UTK) doctoral dissertation [7]. In the process of this research, ORNL has completed an analysis that explains and quantifies the role of inductance in these methods of control. The Appendix includes information on the equations for the three components of phase inductance, L{sub gap}, L{sub slot}, and L{sub endturns}. PM motors inherently have a lower inductance because of the increase in effective air gap caused by the magnet, which is in the denominator of the equation for L{sub gap}. L{sub gap} accounts for about half of the phase inductance. Because of the low inductance, there is a propensity for currents to exceed the motor's rated value. DMIC solves this problem for low-inductance PM motors and, in addition, provides a number of safety features that protect against uncontrolled generator mode operation [8,9]; however, the DMIC topology adds a pair of anti-parallel thyristors in each of the three phases, thereby introducing additional silicon costs as well as additional voltage drops during operation. It poses the tradeoff question; under what conditions can the beneficial features of DMIC offset its additional silicon cost and voltage drop losses? The purpose of this report is to address the tradeoff question. Sections of the report will: (1) review the role of self-inductance in performance and control of PM motors, (2) discuss the bounding inductances for motors with trapezoidal back-emfs under CPA control, (3) discuss the bounding inductances for trapezoidal back-emfs under DMIC, (4) discuss the bounding inductances for the PM synchronous motor (PMSM), (5) present the analysis showing how DMIC minimizes current in PMSMs, (6) present the results of a cost study conducted for two motors driven using a CPA inverter and for two motors driven using DMIC, (7) discuss estimating life cycle cost benefits, and (8) present conclusions.

  17. Classification of US hydropower dams by their modes of operation

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

    McManamay, Ryan A.; Oigbokie, II, Clement O.; Kao, Shih -Chieh; Bevelhimer, Mark S.

    2016-02-19

    A key challenge to understanding ecohydrologic responses to dam regulation is the absence of a universally transferable classification framework for how dams operate. In the present paper, we develop a classification system to organize the modes of operation (MOPs) for U.S. hydropower dams and powerplants. To determine the full diversity of MOPs, we mined federal documents, open-access data repositories, and internet sources. W then used CART classification trees to predict MOPs based on physical characteristics, regulation, and project generation. Finally, we evaluated how much variation MOPs explained in sub-daily discharge patterns for stream gages downstream of hydropower dams. After reviewingmore » information for 721 dams and 597 power plants, we developed a 2-tier hierarchical classification based on 1) the storage and control of flows to powerplants, and 2) the presence of a diversion around the natural stream bed. This resulted in nine tier-1 MOPs representing a continuum of operations from strictly peaking, to reregulating, to run-of-river, and two tier-2 MOPs, representing diversion and integral dam-powerhouse configurations. Although MOPs differed in physical characteristics and energy production, classification trees had low accuracies (<62%), which suggested accurate evaluations of MOPs may require individual attention. MOPs and dam storage explained 20% of the variation in downstream subdaily flow characteristics and showed consistent alterations in subdaily flow patterns from reference streams. Lastly, this standardized classification scheme is important for future research including estimating reservoir operations for large-scale hydrologic models and evaluating project economics, environmental impacts, and mitigation.« less

  18. Search for the decay modes B±→h±τl

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

    Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Milanes, D. A.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; et al

    2012-07-16

    We present a search for the lepton flavor violating decay modes B±→h±τl (h=K, π; l=e, μ) using the BABAR data sample, which corresponds to 472×10⁶ BB¯¯¯ pairs. The search uses events where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and l candidates, we are able to fully determine the τ four-momentum. The resulting τ candidate mass is our main discriminant against combinatorial background. We see no evidence for B±→h±τl decays and set a 90% confidence level upper limit on each branching fraction at the level ofmore » a few times 10⁻⁵.« less

  19. Search for the decay modes D??e?e?, D??????, and D??e??

    SciTech Connect (OSTI)

    Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Palano, A.; Eigen, G.; Stugu, B.; Brown, D. N.; Kerth, L. T.; Kolomensky, Yu. G.; Lynch, G.; Koch, H.; Schroeder, T.; Asgeirsson, D. J.; Hearty, C.; Mattison, T. S.; McKenna, J. A.; So, R. Y.; Khan, A.; Blinov, V. E.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Kravchenko, E. A.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Todyshev, K. Yu.; Yushkov, A. N.; Bondioli, M.; Kirkby, D.; Lankford, A. J.; Mandelkern, M.; Atmacan, H.; Gary, J. W.; Liu, F.; Long, O.; Mullin, E.; Vitug, G. M.; Campagnari, C.; Hong, T. M.; Kovalskyi, D.; Richman, J. D.; West, C. A.; Eisner, A. M.; Kroseberg, J.; Lockman, W. S.; Martinez, A. J.; Schumm, B. A.; Seiden, A.; Chao, D. S.; Cheng, C. H.; Echenard, B.; Flood, K. T.; Hitlin, D. G.; Ongmongkolkul, P.; Porter, F. C.; Rakitin, A. Y.; Andreassen, R.; Huard, Z.; Meadows, B. T.; Sokoloff, M. D.; Sun, L.; Bloom, P. C.; Ford, W. T.; Gaz, A.; Nauenberg, U.; Smith, J. G.; Wagner, S. R.; Ayad, R.; Toki, W. H.; Spaan, B.; Schubert, K. R.; Schwierz, R.; Bernard, D.; Verderi, M.; Clark, P. J.; Playfer, S.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Cibinetto, G.; Fioravanti, E.; Garzia, I.; Luppi, E.; Munerato, M.; Piemontese, L.; Santoro, V.; Baldini-Ferroli, R.; Calcaterra, A.; de Sangro, R.; Finocchiaro, G.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Rama, M.; Zallo, A.; Contri, R.; Guido, E.; Lo Vetere, M.; Monge, M. R.; Passaggio, S.; Patrignani, C.; Robutti, E.; Bhuyan, B.; Prasad, V.; Lee, C. L.; Morii, M.; Edwards, A. J.; Adametz, A.; Uwer, U.; Lacker, H. M.; Lueck, T.; Dauncey, P. D.; Mallik, U.; Chen, C.; Cochran, J.; Meyer, W. T.; Prell, S.; Rubin, A. E.; Gritsan, A. V.; Guo, Z. J.; Arnaud, N.; Davier, M.; Derkach, D.; Grosdidier, G.; Le Diberder, F.; Lutz, A. M.; Malaescu, B.; Roudeau, P.; Schune, M. H.; Stocchi, A.; Wormser, G.; Lange, D. J.; Wright, D. M.; Chavez, C. A.; Coleman, J. P.; Fry, J. R.; Gabathuler, E.; Hutchcroft, D. E.; Payne, D. J.; Touramanis, C.; Bevan, A. J.; Di Lodovico, F.; Sacco, R.; Sigamani, M.; Cowan, G.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Griessinger, K.; Hafner, A.; Prencipe, E.; Barlow, R. J.; Jackson, G.; Lafferty, G. D.; Behn, E.; Cenci, R.; Hamilton, B.; Jawahery, A.; Roberts, D. A.; Dallapiccola, C.; Cowan, R.; Dujmic, D.; Sciolla, G.; Cheaib, R.; Lindemann, D.; Patel, P. M.; Robertson, S. H.; Biassoni, P.; Neri, N.; Palombo, F.; Stracka, S.; Cremaldi, L.; Godang, R.; Kroeger, R.; Sonnek, P.; Summers, D. J.; Nguyen, X.; Simard, M.; Taras, P.; De Nardo, G.; Monorchio, D.; Onorato, G.; Sciacca, C.; Martinelli, M.; Raven, G.; Jessop, C. P.; LoSecco, J. M.; Wang, W. F.; Honscheid, K.; Kass, R.; Brau, J.; Frey, R.; Sinev, N. B.; Strom, D.; Torrence, E.; Feltresi, E.; Gagliardi, N.; Margoni, M.; Morandin, M.; Posocco, M.; Rotondo, M.; Simi, G.; Simonetto, F.; Stroili, R.; Akar, S.; Ben-Haim, E.; Bomben, M.; Bonneaud, G. R.; Briand, H.; Calderini, G.; Chauveau, J.; Hamon, O.; Leruste, Ph.; Marchiori, G.; Ocariz, J.; Sitt, S.; Biasini, M.; Manoni, E.; Pacetti, S.; Rossi, A.; Angelini, C.; Batignani, G.; Bettarini, S.; Carpinelli, M.; Casarosa, G.; Cervelli, A.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Oberhof, B.; Paoloni, E.; Perez, A.; Rizzo, G.; Walsh, J. J.; Lopes Pegna, D.; Olsen, J.; Smith, A. J. S.; Telnov, A. V.; Anulli, F.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gaspero, M.; Li Gioi, L.; Mazzoni, M. A.; Piredda, G.; Bnger, C.; Grnberg, O.; Hartmann, T.; Leddig, T.; Schrder, H.; Voss, C.; Waldi, R.; Adye, T.; Olaiya, E. O.; Wilson, F. F.; Emery, S.; Hamel de Monchenault, G.; Vasseur, G.; Yche, Ch.; Aston, D.; Bard, D. J.; Bartoldus, R.; Benitez, J. F.; Cartaro, C.; Convery, M. R.; Dorfan, J.; Dubois-Felsmann, G. P.; Dunwoodie, W.; Ebert, M.; Field, R. C.; Franco Sevilla, M.; Fulsom, B. G.; Gabareen, A. M.; Graham, M. T.; Grenier, P.; Hast, C.; Innes, W. R.; Kelsey, M. H.; Kim, P.; Kocian, M. L.; Leith, D. W. G. S.; Lewis, P.; Lindquist, B.; Luitz, S.; Luth, V.; Lynch, H. L.; MacFarlane, D. B.; Muller, D. R.; Neal, H.; Nelson, S.; Perl, M.; Pulliam, T.; Ratcliff, B. N.; Roodman, A.; Salnikov, A. A.; Schindler, R. H.; Snyder, A.; Su, D.; Sullivan, M. K.; Vavra, J.; Wagner, A. P.; Wisniewski, W. J.; Wittgen, M.; Wright, D. H.; Wulsin, H. W.; Young, C. C.; Ziegler, V.; Park, W.; Purohit, M. V.; White, R. M.; Wilson, J. R.; Randle-Conde, A.; Sekula, S. J.; Bellis, M.; Burchat, P. R.; Miyashita, T. S.; Puccio, E. M. T.; Alam, M. S.; Ernst, J. A.; Gorodeisky, R.; Guttman, N.; Peimer, D. R.; Soffer, A.; Lund, P.; Spanier, S. M.; Ritchie, J. L.; Ruland, A. M.; Schwitters, R. F.; Wray, B. C.; Izen, J. M.; Lou, X. C.; Bianchi, F.; Gamba, D.; Zambito, S.; Lanceri, L.; Vitale, L.; Martinez-Vidal, F.

    2012-08-01

    We present searches for the rare decay modes D??e?e?, D0?????, and D??e?? in continuum e?e??cc events recorded by the BABAR detector in a data sample that corresponds to an integrated luminosity of 468 fb?. These decays are highly GlashowIliopoulosMaiani suppressed but may be enhanced in several extensions of the standard model. Our observed event yields are consistent with the expected backgrounds. An excess is seen in the D?????? channel, although the observed yield is consistent with an upward background fluctuation at the 5% level. Using the FeldmanCousins method, we set the following 90% confidence level intervals on the branching fractions: B(D??e?e?)<1.710??, B(D??????) within [0.6,8.1]10??, and B(D??e??)<3.310??.

  20. Search for the decay modes B?h?l

    SciTech Connect (OSTI)

    Lees, J. P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Milanes, D. A.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Brown, D. N.; Kerth, L. T.; Kolomensky, Yu. G.; Lynch, G.; Koch, H.; Schroeder, T.; Asgeirsson, D. J.; Hearty, C.; Mattison, T. S.; McKenna, J. A.; Khan, A.; Blinov, V. E.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Kravchenko, E. A.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Todyshev, K. Yu.; Yushkov, A. N.; Bondioli, M.; Kirkby, D.; Lankford, A. J.; Mandelkern, M.; Stoker, D. P.; Atmacan, H.; Gary, J. W.; Liu, F.; Long, O.; Vitug, G. M.; Campagnari, C.; Hong, T. M.; Kovalskyi, D.; Richman, J. D.; West, C. A.; Eisner, A. M.; Kroseberg, J.; Lockman, W. S.; Martinez, A. J.; Schalk, T.; Schumm, B. A.; Seiden, A.; Cheng, C. H.; Doll, D. A.; Echenard, B.; Flood, K. T.; Hitlin, D. G.; Ongmongkolkul, P.; Porter, F. C.; Rakitin, A. Y.; Andreassen, R.; Huard, Z.; Meadows, B. T.; Sokoloff, M. D.; Sun, L.; Bloom, P. C.; Ford, W. T.; Gaz, A.; Nagel, M.; Nauenberg, U.; Smith, J. G.; Wagner, S. R.; Ayad, R.; Toki, W. H.; Spaan, B.; Kobel, M. J.; Schubert, K. R.; Schwierz, R.; Bernard, D.; Verderi, M.; Clark, P. J.; Playfer, S.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Cibinetto, G.; Fioravanti, E.; Garzia, I.; Luppi, E.; Munerato, M.; Negrini, M.; Piemontese, L.; Santoro, V.; Baldini-Ferroli, R.; Calcaterra, A.; de Sangro, R.; Finocchiaro, G.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Rama, M.; Zallo, A.; Contri, R.; Guido, E.; Lo Vetere, M.; Monge, M. R.; Passaggio, S.; Patrignani, C.; Robutti, E.; Bhuyan, B.; Prasad, V.; Lee, C. L.; Morii, M.; Edwards, A. J.; Adametz, A.; Marks, J.; Uwer, U.; Lacker, H. M.; Lueck, T.; Dauncey, P. D.; Behera, P. K.; Mallik, U.; Chen, C.; Cochran, J.; Meyer, W. T.; Prell, S.; Rubin, A. E.; Gritsan, A. V.; Guo, Z. J.; Arnaud, N.; Davier, M.; Derkach, D.; Grosdidier, G.; Le Diberder, F.; Lutz, A. M.; Malaescu, B.; Roudeau, P.; Schune, M. H.; Stocchi, A.; Wormser, G.; Lange, D. J.; Wright, D. M.; Bingham, I.; Chavez, C. A.; Coleman, J. P.; Fry, J. R.; Gabathuler, E.; Hutchcroft, D. E.; Payne, D. J.; Touramanis, C.; Bevan, A. J.; Di Lodovico, F.; Sacco, R.; Sigamani, M.; Cowan, G.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Hafner, A.; Prencipe, E.; Alwyn, K. E.; Bailey, D.; Barlow, R. J.; Jackson, G.; Lafferty, G. D.; Behn, E.; Cenci, R.; Hamilton, B.; Jawahery, A.; Roberts, D. A.; Simi, G.; Dallapiccola, C.; Cowan, R.; Dujmic, D.; Sciolla, G.; Lindemann, D.; Patel, P. M.; Robertson, S. H.; Schram, M.; Biassoni, P.; Neri, N.; Palombo, F.; Stracka, S.; Cremaldi, L.; Godang, R.; Kroeger, R.; Sonnek, P.; Summers, D. J.; Nguyen, X.; Simard, M.; Taras, P.; De Nardo, G.; Monorchio, D.; Onorato, G.; Sciacca, C.; Martinelli, M.; Raven, G.; Jessop, C. P.; Knoepfel, K. J.; LoSecco, J. M.; Wang, W. F.; Honscheid, K.; Kass, R.; Brau, J.; Frey, R.; Sinev, N. B.; Strom, D.; Torrence, E.; Feltresi, E.; Gagliardi, N.; Margoni, M.; Morandin, M.; Posocco, M.; Rotondo, M.; Simonetto, F.; Stroili, R.; Akar, S.; Ben-Haim, E.; Bomben, M.; Bonneaud, G. R.; Briand, H.; Calderini, G.; Chauveau, J.; Hamon, O.; Leruste, Ph.; Marchiori, G.; Ocariz, J.; Sitt, S.; Biasini, M.; Manoni, E.; Pacetti, S.; Rossi, A.; Angelini, C.; Batignani, G.; Bettarini, S.; Carpinelli, M.; Casarosa, G.; Cervelli, A.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Oberhof, B.; Paoloni, E.; Perez, A.; Rizzo, G.; Walsh, J. J.; Lopes Pegna, D.; Lu, C.; Olsen, J.; Smith, A. J. S.; Telnov, A. V.; Anulli, F.; Cavoto, G.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gaspero, M.; Li Gioi, L.; Mazzoni, M. A.; Piredda, G.; Bnger, C.; Grnberg, O.; Hartmann, T.; Leddig, T.; Schrder, H.; Voss, C.; Waldi, R.; Adye, T.; Olaiya, E. O.; Wilson, F. F.; Emery, S.; Hamel de Monchenault, G.; Vasseur, G.; Yche, Ch.; Aston, D.; Bard, D. J.; Bartoldus, R.; Cartaro, C.; Convery, M. R.; Dorfan, J.; Dubois-Felsmann, G. P.; Dunwoodie, W.; Ebert, M.; Field, R. C.; Franco Sevilla, M.; Fulsom, B. G.; Gabareen, A. M.; Graham, M. T.; Grenier, P.; Hast, C.; Innes, W. R.; Kelsey, M. H.; Kim, P.; Kocian, M. L.; Leith, D. W. G. S.; Lewis, P.; Lindquist, B.; Luitz, S.; Luth, V.; Lynch, H. L.; MacFarlane, D. B.; Muller, D. R.; Neal, H.; Nelson, S.; Perl, M.; Pulliam, T.; Ratcliff, B. N.; Roodman, A.; Salnikov, A. A.; Schindler, R. H.; Snyder, A.; Su, D.; Sullivan, M. K.; Vavra, J.; Wagner, A. P.; Weaver, M.; Wisniewski, W. J.; Wittgen, M.; Wright, D. H.; Wulsin, H. W.; Young, C. C.; Ziegler, V.; Park, W.; Purohit, M. V.; White, R. M.; Wilson, J. R.; Randle-Conde, A.; Sekula, S. J.; Bellis, M.; Benitez, J. F.; Burchat, P. R.; Miyashita, T. S.; Alam, M. S.; Ernst, J. A.; Gorodeisky, R.; Guttman, N.; Peimer, D. R.; Soffer, A.; Lund, P.; Spanier, S. M.; Eckmann, R.; Ritchie, J. L.

    2012-07-16

    We present a search for the lepton flavor violating decay modes B?h?l (h=K, ?; l=e, ?) using the BABAR data sample, which corresponds to 47210? BB pairs. The search uses events where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and l candidates, we are able to fully determine the ? four-momentum. The resulting ? candidate mass is our main discriminant against combinatorial background. We see no evidence for B?h?l decays and set a 90% confidence level upper limit on each branching fraction at the level of a few times 10??.

  1. Evaluation of the electrical contact area in contact-mode scanning probe microscopy

    SciTech Connect (OSTI)

    Celano, Umberto E-mail: u.celano@gmail.com; Chintala, Ravi Chandra; Vandervorst, Wilfried; Hantschel, Thomas; Giammaria, Guido; Conard, Thierry; Bender, Hugo

    2015-06-07

    The tunneling current through an atomic force microscopy (AFM) tip is used to evaluate the effective electrical contact area, which exists between tip and sample in contact-AFM electrical measurements. A simple procedure for the evaluation of the effective electrical contact area is described using conductive atomic force microscopy (C-AFM) in combination with a thin dielectric. We characterize the electrical contact area for coated metal and doped-diamond tips operated at low force (<200 nN) in contact mode. In both cases, we observe that only a small fraction (<10?nm{sup 2}) of the physical contact (?100?nm{sup 2}) is effectively contributing to the transport phenomena. Assuming this reduced area is confined to the central area of the physical contact, these results explain the sub-10?nm electrical resolution observed in C-AFM measurements.

  2. Variable mode bi-directional and uni-directional computer communication system

    DOE Patents [OSTI]

    Cornett, Frank N.; Jenkins, Philip N.; Bowman, Terrance L.; Placek, Joseph M.; Thorson, Gregory M.

    2004-12-14

    A variable communication systems comprising a plurality of transceivers and a control circuit connected to the transceivers to configure the transceivers to operate in a bi-directional mode and a uni-directional mode at different times using different transfer methods to transfer data.

  3. Controlling the vertical mode coupling instability with feedback in the ALS

    SciTech Connect (OSTI)

    Byrd, J.; Barry, W.

    1997-01-01

    The authors present the results of experiments to control the mode coupling instability in the vertical direction using a feedback system. Presently, they can raise the instability threshold from {approximately} 20 mA to 35 mA. The maximum current threshold is reached when the feedback is operated in a resistive mode.

  4. DETECTING GRAVITY MODES IN THE SOLAR {sup 8} B NEUTRINO FLUX

    SciTech Connect (OSTI)

    Lopes, Ildio; Turck-Chize, Sylvaine E-mail: ilopes@uevora.pt

    2014-09-10

    The detection of gravity modes produced in the solar radiative zone has been a challenge in modern astrophysics for more than 30yr and their amplitude in the core is not yet determined. In this Letter, we develop a new strategy to look for standing gravity modes through solar neutrino fluxes. We note that due to a resonance effect, the gravity modes of low degree and low order have the largest impact on the {sup 8} B neutrino flux. The strongest effect is expected to occur for the dipole mode with radial order 2, corresponding to periods of about 1.5 hr. These standing gravity waves produce temperature fluctuations that are amplified by a factor of 170 in the boron neutrino flux for the corresponding period, in consonance with the gravity modes. From current neutrino observations, we determine that the maximum temperature variation due to the gravity modes in the Sun's core is smaller than 5.8 10{sup 4}. This study clearly shows that due to their high sensitivity to the temperature, the {sup 8} B neutrino flux time series is an excellent tool to determine the properties of gravity modes in the solar core. Moreover, if gravity mode footprints are discovered in the {sup 8} B neutrino flux, this opens a new line of research to probe the physics of the solar core as non-standing gravity waves of higher periods cannot be directly detected by helioseismology but could leave their signature on boron neutrino or on other neutrino fluxes.

  5. Zero-mode clad waveguides for performing spectroscopy with confined effective observation volumes

    DOE Patents [OSTI]

    Levene, Michael J.; Korlach, Jonas; Turner, Stephen W.; Craighead, Harold G.; Webb, Watt W.

    2005-07-12

    The present invention is directed to a method and an apparatus for analysis of an analyte. The method involves providing a zero-mode waveguide which includes a cladding surrounding a core where the cladding is configured to preclude propagation of electromagnetic energy of a frequency less than a cutoff frequency longitudinally through the core of the zero-mode waveguide. The analyte is positioned in the core of the zero-mode waveguide and is then subjected, in the core of the zero-mode waveguide, to activating electromagnetic radiation of a frequency less than the cut-off frequency under conditions effective to permit analysis of the analyte in an effective observation volume which is more compact than if the analysis were carried out in the absence of the zero-mode waveguide.

  6. Dispersion relations of externally and thermally excited dust lattice modes in 2D complex plasma crystals

    SciTech Connect (OSTI)

    Yang Xuefeng; Cui Jian; Zhang Yuan [School of Mathematical Sciences, Dalian University of Technology, Dalian 116024 (China); Liu Yue [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2012-07-15

    The dispersion relations of the externally and thermally (naturally) excited dust lattice modes (both longitudinal and transverse) in two-dimensional Debye-Yukawa complex plasma crystals are investigated. The dispersion relations are calculated numerically by taking the neutral gas damping effects into account and the numerical results are in agreement with the experimental data given by Nunomura et al.[Phys. Rev. E 65, 066402 (2002)]. It is found that for the mode excited by an external disturbance with a real frequency, the dispersion properties are changed at a critical frequency near where the group velocity of the mode goes to zero. Therefore, the high frequency branch with negative dispersion cannot be reached. In contrast, for the thermally excited mode, the dispersion curve can extend all the way to the negative dispersion region, while a 'cut-off' wave number exists at the long wavelength end of the dispersion in the transverse mode.

  7. Dispersion and interaction of waveguide modes in a relativistic electron beam with ion-channel guiding

    SciTech Connect (OSTI)

    Maraghechi, Borna; Maraghechi, Behrouz

    2008-07-15

    A theory for the high-frequency eigenmodes of a cylindrical metallic waveguide partially filled with a relativistic electron beam and guided by an ion channel is presented. Equations that permit calculation of dispersion curves for five families of wave modes are derived. The dependence of the frequencies and the dispersion curves of azimuthally asymmetric modes on the ratio of the beam radius a to the waveguide radius R are studied in detail. The coupling of the dispersion curves of different modes is studied and illustrated for the partially filled waveguide. It was found that, in their course of interaction, HE modes cannot displace the betatron modes in a completely filled waveguide, which is different from the case of a magnetized electron beam. Physical and analytical explanations are presented for this difference.

  8. Surveillance and diagnostics of the beam mode vibrations of the Ringhals PWRs

    SciTech Connect (OSTI)

    Martin, C. M.; Pazsit, I.; Nylen, H.

    2012-07-01

    Surveillance of core barrel vibrations has been performed in the Swedish Ringhals PWRs for several years. This surveillance is focused mainly on the pendular motion of the core barrel, which is known as the beam mode. The monitoring of the beam mode has suggested that its amplitude increases along the cycle and decreases after refuelling. In the last 5 years several measurements have been taken in order to understand this behaviour. Besides, a non-linear fitting procedure has been implemented in order to better distinguish the different components of vibration. By using this fitting procedure, two modes of vibration have been identified in the frequency range of the beam mode. Several results coming from the trend analysis performed during these years indicate that one of the modes is due to the core barrel motion itself and the other is due to the individual flow induced vibrations of the fuel elements. In this work, the latest results of this monitoring are presented. (authors)

  9. A consistency relation for the CMB B-mode polarization in the squeezed limit

    SciTech Connect (OSTI)

    Kehagias, A.; Dizgah, A. Moradinezhad; Norea, J.; Perrier, H.; Riotto, A. E-mail: Azadeh.Moradinezhad@unige.ch E-mail: Hideki.Perrier@unige.ch

    2014-10-01

    A large-scale temperature perturbation has a non-zero correlation with the power spectrum of B-modes of cosmological origin on short scales while the corresponding correlation is expected to be zero for B-modes sourced by galactic foregrounds. We thus compute the squeezed limit of a three-point function in which one correlates the temperature fluctuations at large scales with two polarization modes at small scales. In the particular case of the B-mode polarization we obtain a relation that connects the squeezed limit of the TBB three-point function with the cosmological B-mode power spectrum, which can be used as a consistency relation. This could in principle help to distinguish a primordial signal from that induced by inter-stellar dust.

  10. Avoidance of Tearing Mode Locking and Disruption with Electro-Magnetic Torque Introduced by Feedback-based Mode Rotation Control in DIII-D and RFX-mod

    SciTech Connect (OSTI)

    Okabayashi, M.; Zanca, P.; Strait, E. J.

    2014-09-01

    Disruptions caused by tearing modes (TMs) are considered to be one of the most critical roadblocks to achieving reliable, steady-state operation of tokamak fusion reactors. Here we have demonstrated a very promising scheme to avoid such disruptions by utilizing the electro-magnetic (EM) torque produced with 3D coils that are available in many tokamaks. In this scheme, the EM torque to the modes is created by a toroidal phase shift between the externally-applied field and the excited TM fields, compensating for the mode momentum loss due to the interaction with the resistive wall and uncorrected error fields. Fine control of torque balance is provided by a feedback scheme. We have explored this approach in two vastly different devices and plasma conditions: DIII-D and RFX-mod operated in tokamak mode. In DIII-D, the plasma target was high βN plasmas in a non-circular divertor tokamak. In RFX-mod, the plasma was ohmically-heated plasma with ultralow safety factor in a circular limiter discharge of active feedback coils outside the thick resistive shell. The DIII-D and RFX-mod experiments showed remarkable consistency with theoretical predictions of torque balance. The application to ignition-oriented devices such as International Thermonuclear Experimental Reactor (ITER) would expand the horizon of its operational regime. The internal 3D coil set currently under consideration for edge localized mode suppression in ITER would be well suited to this purpose.

  11. Performance Assessment of Single Electrode-Supported Solid Oxide Cells Operating in the Steam Electrolysis Mode

    SciTech Connect (OSTI)

    X. Zhang; J. E. O'Brien; R. C. O'Brien; N. Petigny

    2011-11-01

    An experimental study is under way to assess the performance of electrode-supported solid-oxide cells operating in the steam electrolysis mode for hydrogen production. Results presented in this paper were obtained from single cells, with an active area of 16 cm{sup 2} per cell. The electrolysis cells are electrode-supported, with yttria-stabilized zirconia (YSZ) electrolytes ({approx}10 {mu}m thick), nickel-YSZ steam/hydrogen electrodes ({approx}1400 {mu}m thick), and modified LSM or LSCF air-side electrodes ({approx}90 {mu}m thick). The purpose of the present study is to document and compare the performance and degradation rates of these cells in the fuel cell mode and in the electrolysis mode under various operating conditions. Initial performance was documented through a series of voltage-current (VI) sweeps and AC impedance spectroscopy measurements. Degradation was determined through long-term testing, first in the fuel cell mode, then in the electrolysis mode. Results generally indicate accelerated degradation rates in the electrolysis mode compared to the fuel cell mode, possibly due to electrode delamination. The paper also includes details of an improved single-cell test apparatus developed specifically for these experiments.

  12. SCATTERING OF THE f-MODE BY SMALL MAGNETIC FLUX ELEMENTS FROM OBSERVATIONS AND NUMERICAL SIMULATIONS

    SciTech Connect (OSTI)

    Felipe, T.; Braun, D.; Crouch, A.; Birch, A.

    2012-10-01

    The scattering of f-modes by magnetic tubes is analyzed using three-dimensional numerical simulations. An f-mode wave packet is propagated through a solar atmosphere embedded with three different flux tube models that differ in radius and total magnetic flux. A quiet-Sun simulation without a tube present is also performed as a reference. Waves are excited inside the flux tube and propagate along the field lines, and jacket modes are generated in the surroundings of the flux tube, carrying 40% as much energy as the tube modes. The resulting scattered wave is mainly an f-mode composed of a mixture of m = 0 and m = {+-}1 modes. The amplitude of the scattered wave approximately scales with the magnetic flux. A small amount of power is scattered into the p{sub 1}-mode. We have evaluated the absorption and phase shift from a Fourier-Hankel decomposition of the photospheric vertical velocities. They are compared with the results obtained from the ensemble average of 3400 small magnetic elements observed in high-resolution MDI Doppler datacubes. The comparison shows that the observed dependence of the phase shift with wavenumber can be matched reasonably well with the simulated flux tube model. The observed variation of the phase shifts with the azimuthal order m appears to depend on details of the ensemble averaging, including possible motions of the magnetic elements and asymmetrically shaped elements.

  13. Impurity effects on short wavelength ion temperature gradient mode in elongated tokamak plasmas

    SciTech Connect (OSTI)

    Du, Huarong; Wang, Zheng-Xiong; Dong, J. Q.

    2015-02-15

    The effects of impurity ions on the short wavelength ion temperature gradient (SWITG) driven instability in elongated tokamak plasmas are numerically investigated with the gyrokinetic integral eigenmode equation. It is found that for a moderate electron density gradient, the SWITG mode is first destabilized and then stabilized with increasing elongation ?, which is different from the conventional long wavelength ITG mode. For a large electron density gradient, the elongation can effectively stabilize the SWITG mode. Moreover, the low Z impurity ions with inwardly (outwardly) peaked density profiles have stabilizing (destabilizing) effects on the SWITG modes in elongated plasmas. Interestingly, the high Z tungsten impurity ions with inwardly peaked density profiles play a stronger stabilizing role in the SWITG modes than the low Z impurity ions (such as carbon and oxygen) do. In particular, the high Z tungsten impurity ions with a weakly outwardly peaked density profile still have a stabilizing effect. Finally, the critical threshold of impurity density gradient scale length for exciting impurity mode is also numerically obtained, indicating that the impurity mode is harder to be excited in elongated plasmas than in circular ones.

  14. Energy and frequency dependence of the alpha particle redistribution produced by internal kink modes

    SciTech Connect (OSTI)

    Farengo, R.; Ferrari, H. E.; Garcia-Martinez, P. L.; Firpo, M.-C.; Ettoumi, W.; Lifschitz, A. F.

    2014-08-15

    The redistribution of alpha particles due to internal kink modes is studied. The exact particle trajectories in the total fields, equilibrium plus perturbation, are calculated. The equilibrium has circular cross section and the plasma parameters are similar to those expected in ITER. The alpha particles are initially distributed according to a slowing down distribution function and have energies between 18?keV and 3.5?MeV. The (1, 1), (2, 2), and (2, 1) modes are included and the effect of changing their amplitude and frequency is studied. When only the (1, 1) mode is included, the spreading of high energy (E?1?MeV) alpha particles increases slowly with the energy and mode frequency. At lower energies, the redistribution is more sensitive to the mode frequency and particle energy. When a (2, 1) mode is added, the spreading increases significantly and particles can reach the edge of the plasma. Trapped particles are the most affected and the redistribution parameter can have maxima above 1?MeV, depending on the mode frequency. These results can have important implications for ash removal.

  15. Injection locking of a two-mode electron oscillator with close frequencies

    SciTech Connect (OSTI)

    Starodubova, E. N.; Usacheva, S. A.; Ryskin, N. M.; Novozhilova, Y. V.; Nusinovich, G. S.

    2015-03-15

    Theory of injection locking is developed for a two-mode electron maser with close frequencies, when the driving signal affects both modes. There exist two regimes of phase locking in which either first or second mode dominates. Hard transitions between the two regimes are observed with variation of the driving frequency. The results of numerical simulations are presented for the case of driving by a signal with linear frequency chirp, as well as by a signal with sinusoidal frequency modulation. The effect of bifurcation delay is observed with the increase of chirp rate.

  16. ICRF Mode Conversion Flow Drive on Alcator C-Mod and Projections to Other

    Office of Scientific and Technical Information (OSTI)

    Tokamaks (Journal Article) | SciTech Connect ICRF Mode Conversion Flow Drive on Alcator C-Mod and Projections to Other Tokamaks Citation Details In-Document Search Title: ICRF Mode Conversion Flow Drive on Alcator C-Mod and Projections to Other Tokamaks Plasma flow drive via ICRF mode conversion (MC) has been demonstrated on Alcator C-Mod. The toroidal rotation in these D({sup 3}He) MC plasmas is typically more than twice above the empirically determined intrinsic rotation scaling in ICRF

  17. Report 20.5: Chromaticity Shift Modes of LED PAR38 Lamps Operated in

    Energy Savers [EERE]

    Steady-State Conditions | Department of Energy 5: Chromaticity Shift Modes of LED PAR38 Lamps Operated in Steady-State Conditions Report 20.5: Chromaticity Shift Modes of LED PAR38 Lamps Operated in Steady-State Conditions PDF icon Report 20.5: Chromaticity Shift Modes of LED PAR38 Lamps Operated in Steady-State Conditions More Documents & Publications Report 20.4: Lumen and Chromaticity Maintenance of LED PAR38 Lamps MARCH 2016 POSTINGS Retail Lamps Study 3.2: Lumen and Chromaticity

  18. EERE Success Story-Multi-Mode RCCI Has Great Potential to Improve Fuel

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

    Economy in Light-Duty Diesel Engines | Department of Energy Multi-Mode RCCI Has Great Potential to Improve Fuel Economy in Light-Duty Diesel Engines EERE Success Story-Multi-Mode RCCI Has Great Potential to Improve Fuel Economy in Light-Duty Diesel Engines February 26, 2015 - 11:47am Addthis Multi-mode RCCI (Reactivity-Controlled Compression Ignition), a promising advanced combustion process, has the potential to improve fuel economy of passenger cars by at least 15%, according to a recent

  19. A wide bandwidth free-electron laser with mode locking using current modulation.

    SciTech Connect (OSTI)

    Kur, E.; Dunning, D. J.; McNeil, B. W. J.; Wurtele, J.; Zholents, A. A. )

    2011-01-20

    A new scheme for mode locking a free-electron laser amplifier is proposed based on electron beam current modulation. It is found that certain properties of the original concept, based on the energy modulation of electrons, are improved including the spectral brightness of the source and the purity of the series of short pulses. Numerical comparisons are made between the new and old schemes and between a mode-locked free-electron laser and self-amplified spontaneous emission free-electron laser. Illustrative examples using a hypothetical mode-locked free-electron laser amplifier are provided. The ability to generate intense coherent radiation with a large bandwidth is demonstrated.

  20. Observation of Ion-Cyclotron-Frequency Mode-Conversion Flow Drive in

    Office of Scientific and Technical Information (OSTI)

    Tokamak Plasmas (Journal Article) | SciTech Connect Observation of Ion-Cyclotron-Frequency Mode-Conversion Flow Drive in Tokamak Plasmas Citation Details In-Document Search Title: Observation of Ion-Cyclotron-Frequency Mode-Conversion Flow Drive in Tokamak Plasmas Strong toroidal flow (V{sub {phi}}) and poloidal flow (V{sub {theta}}) have been observed in D-{sup 3}He plasmas with ion cyclotron range of frequencies (ICRF) mode-conversion (MC) heating on the Alcator C-Mod tokamak. The toroidal

  1. Spontaneous electromagnetic fluctuations in unmagnetized plasmas. VI. Transverse, collective mode for arbitrary distribution functions

    SciTech Connect (OSTI)

    Felten, T.; Schlickeiser, R.; Research Department Plasmas with Complex Interactions, Ruhr-Universität Bochum, D-44780 Bochum

    2013-10-15

    Using the general expressions for the magnetic fluctuation spectrum from uncorrelated plasma particles, it is shown that an isotropic, unmagnetized plasma with arbitrary momentum distribution function spontaneously emits an aperiodic, collective, transverse, damped mode. The collective mode with the dispersion relation γ(k) provides the strongest contribution to the magnetic field fluctuation spectrum. Its existence has been proven before for Maxwellian and Lorentzian plasma distribution functions. Here it is demonstrated that this collective aperiodic mode exists in any isotropic unmagnetized, irrespective of the explicit form of the momentum distribution of plasma particles.

  2. Mode-hopping mechanism generating colored noise in a magnetic tunnel junction based spin torque oscillator

    SciTech Connect (OSTI)

    Sharma, Raghav; Drrenfeld, P.; Iacocca, E.; Heinonen, O. G.; kerman, J.; Muduli, P. K.

    2014-09-29

    The frequency noise spectrum of a magnetic tunnel junction based spin torque oscillator is examined where multiple modes and mode-hopping events are observed. The frequency noise spectrum is found to consist of both white noise and 1/f frequency noise. We find a systematic and similar dependence of both white noise and 1/f frequency noise on bias current and the relative angle between the reference and free layers, which changes the effective damping and hence the mode-hopping behavior in this system. The frequency at which the 1/f frequency noise changes to white noise increases as the free layer is aligned away from the anti-parallel orientation w.r.t the reference layer. These results indicate that the origin of 1/f frequency noise is related to mode-hopping, which produces both white noise as well as 1/f frequency noise similar to the case of ring lasers.

  3. Expanded-mode semiconductor laser with tapered-rib adiabatic-following fiber coupler

    SciTech Connect (OSTI)

    Vawter, G.A.; Smith, R.E.; Hou, H.; Wendt, J.R.

    1997-02-01

    A new diode laser using a Tapered-Rib Adiabatic-Following Fiber Coupler to achieve 2D mode expansion and narrow, symmetric far-field emission without epitaxial regrowth or sharply-defined tips on tapered waveguides is presented.

  4. Resonance Excitation of Longitudinal High Order Modes in Project X Linac

    SciTech Connect (OSTI)

    Khabiboulline, T.N.; Sukhanov, A.AUTHOR = Awida, M.; Gonin, I.; Lunin, A.AUTHOR = Solyak, N.; Yakovlev, V.; /Fermilab

    2012-05-01

    Results of simulation of power loss due to excitation of longitudinal high order modes (HOMs) in the accelerating superconducting RF system of CW linac of Project X are presented. Beam structures corresponding to the various modes of Project X operation are considered: CW regime for 3 GeV physics program; pulsed mode for neutrino experiments; and pulsed regime, when Project X linac operates as a driver for Neutrino Factory/Muon Collider. Power loss and associated heat load due to resonance excitation of longitudinal HOMs are shown to be small in all modes of operation. Conclusion is made that HOM couplers can be removed from the design of superconducting RF cavities of Project X linac.

  5. Numerical investigation on operation mode influenced by external frequency in atmospheric pressure barrier discharge

    SciTech Connect (OSTI)

    Wang Qi [Dalian Institute of Semiconductor Technology, School of Electronics Science and Technology, Dalian University of Technology, Dalian 116023 (China); Sun Jizhong; Wang Dezhen [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China)

    2011-10-15

    The influence of external driving frequency on the discharge mode in the dielectric barrier discharge was investigated with a two-dimensional, self-consistent fluid model. The simulation results show that the helium discharge exhibits three operation modes: Townsend, homogeneous glow, and local glow discharges from the lower frequency (1 kHz) to the higher frequency (100 kHz) under discharge parameters specified in this work. The discharge operates in a Townsend mode when the driving frequency varies from 1 to about 7 kHz; while it exhibits homogenous glow characteristics in an approximate range from 7 to 65 kHz; when the external frequency exceeds 65 kHz, it turns into a local glow discharge. The effects of external driving frequency on the discharge mode were revealed and the physical reasons were discussed.

  6. Atom detection in a two-mode optical cavity with intermediate coupling: Autocorrelation studies

    SciTech Connect (OSTI)

    Norris, D. G.; Cahoon, E. J.; Orozco, L. A.

    2009-10-15

    We use an optical cavity in the regime of intermediate coupling between atom and cavity mode to detect single moving atoms. Degenerate polarization modes allow excitation of the atoms in one mode and collection of spontaneous emission in the other while keeping separate the two sources of light; we obtain a higher confidence and efficiency of detection by adding cavity-enhanced Faraday rotation. Both methods greatly benefit from coincidence detection of photons, attaining fidelities in excess of 99% in less than 1 {mu}s. Detailed studies of the second-order intensity autocorrelation function of light from the signal mode reveal evidence of antibunched photon emissions and the dynamics of single-atom transits.

  7. Isotope effect in normal-to-local transition of acetylene bending modes

    SciTech Connect (OSTI)

    Ma, Jianyi; Xu, Dingguo; Guo, Hua; Tyng, Vivian; Kellman, Michael E.

    2012-01-01

    The normal-to-local transition for the bending modes of acetylene is considered a prelude to its isomerization to vinylidene. Here, such a transition in fully deuterated acetylene is investigated using a full-dimensional quantum model. It is found that the local benders emerge at much lower energies and bending quantum numbers than in the hydrogen isotopomer HCCH. This is accompanied by a transition to a second kind of bending mode called counter-rotator, again at lower energies and quantum numbers than in HCCH. These transitions are also investigated using bifurcation analysis of two empirical spectroscopic fitting Hamiltonians for pure bending modes, which helps to understand the origin of the transitions semiclassically as branchings or bifurcations out of the trans and normal bend modes when the latter become dynamically unstable. The results of the quantum model and the empirical bifurcation analysis are in very good agreement.

  8. EERE Success Story-Multi-Mode RCCI Has Great Potential to Improve...

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

    light-duty diesel engines. Multi-mode RCCI is a form of low-temperature combustion that uses injections of both gasoline and diesel fuel in an internal combustion engine whenever ...

  9. Measurements of the ablation-front trajectory and low-mode nonuniformi...

    Office of Scientific and Technical Information (OSTI)

    trajectory and low-mode nonuniformity of a target imploded by directly illuminating a fusion capsule with laser beams. The technique uses time-resolved images of soft x-rays (> 1...

  10. On the Use of Material-Dependent Damping in ANSYS for Mode Superposition Transient Analysis

    SciTech Connect (OSTI)

    Nie, J.; Wei, X.

    2011-07-17

    The mode superposition method is often used for dynamic analysis of complex structures, such as the seismic Category I structures in nuclear power plants, in place of the less efficient full method, which uses the full system matrices for calculation of the transient responses. In such applications, specification of material-dependent damping is usually desirable because complex structures can consist of multiple types of materials that may have different energy dissipation capabilities. A recent review of the ANSYS manual for several releases found that the use of material-dependent damping is not clearly explained for performing a mode superposition transient dynamic analysis. This paper includes several mode superposition transient dynamic analyses using different ways to specify damping in ANSYS, in order to determine how material-dependent damping can be specified conveniently in a mode superposition transient dynamic analysis.

  11. THE SLOW-MODE NATURE OF COMPRESSIBLE WAVE POWER IN SOLAR WIND TURBULENCE

    SciTech Connect (OSTI)

    Howes, G. G.; Klein, K. G.; TenBarge, J. M.; Bale, S. D.; Chen, C. H. K.; Salem, C. S.

    2012-07-01

    We use a large, statistical set of measurements from the Wind spacecraft at 1 AU, and supporting synthetic spacecraft data based on kinetic plasma theory, to show that the compressible component of inertial range solar wind turbulence is primarily in the kinetic slow mode. The zero-lag cross-correlation C({delta}n, {delta}B{sub ||}) between proton density fluctuations {delta}n and the field-aligned (compressible) component of the magnetic field {delta}B{sub ||} is negative and close to -1. The typical dependence of C({delta}n, {delta}B{sub ||}) on the ion plasma beta {beta}{sub i} is consistent with a spectrum of compressible wave energy that is almost entirely in the kinetic slow mode. This has important implications for both the nature of the density fluctuation spectrum and for the cascade of kinetic turbulence to short wavelengths, favoring evolution to the kinetic Alfven wave mode rather than the (fast) whistler mode.

  12. ICRF Mode Conversion Flow Drive on Alcator C-Mod and Projections...

    Office of Scientific and Technical Information (OSTI)

    In L-mode plasmas at 3 MW ICRF power input, up to 90 kms toroidal rotation and 2 kms localized (raapprox0.4) poloidal rotation has been observed. The MC ion cyclotron wave ...

  13. Isotope effect in normal-to-local transition of acetylene bending modes

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

    Ma, Jianyi; Xu, Dingguo; Guo, Hua; Tyng, Vivian; Kellman, Michael E.

    2012-01-01

    The normal-to-local transition for the bending modes of acetylene is considered a prelude to its isomerization to vinylidene. Here, such a transition in fully deuterated acetylene is investigated using a full-dimensional quantum model. It is found that the local benders emerge at much lower energies and bending quantum numbers than in the hydrogen isotopomer HCCH. This is accompanied by a transition to a second kind of bending mode called counter-rotator, again at lower energies and quantum numbers than in HCCH. These transitions are also investigated using bifurcation analysis of two empirical spectroscopic fitting Hamiltonians for pure bending modes, which helpsmore » to understand the origin of the transitions semiclassically as branchings or bifurcations out of the trans and normal bend modes when the latter become dynamically unstable. The results of the quantum model and the empirical bifurcation analysis are in very good agreement.« less

  14. Magnetic stochasticity and transport due to nonlinearly excited subdominant microtearing modes

    SciTech Connect (OSTI)

    Hatch, D. R.; Jenko, F.; Doerk, H.; Pueschel, M. J.; Terry, P. W.; Nevins, W. M.

    2013-01-15

    Subdominant, linearly stable microtearing modes are identified as the main mechanism for the development of magnetic stochasticity and transport in gyrokinetic simulations of electromagnetic ion temperature gradient driven plasma microturbulence. The linear eigenmode spectrum is examined in order to identify and characterize modes with tearing parity. Connections are demonstrated between microtearing modes and the nonlinear fluctuations that are responsible for the magnetic stochasticity and electromagnetic transport, and nonlinear coupling with zonal modes is identified as the salient nonlinear excitation mechanism. A simple model is presented, which relates the electromagnetic transport to the electrostatic transport. These results may provide a paradigm for the mechanisms responsible for electromagnetic stochasticity and transport, which can be examined in a broader range of scenarios and parameter regimes.

  15. Higher-order mode analysis at the BNL Energy Recovery Linac

    SciTech Connect (OSTI)

    Johnson, E.C.; Ben-Zvi, I.; Hahn, H.; Hammons, L.; Xu, W.

    2011-08-03

    Understanding the prevalence and structure of higher-order modes (HOMs) in accelerator cavities is critical because their excitation can result in problematic single bunch and multi-bunch effects. Particularly hazardous are dipole modes, which are more easily excited due to their linear field nature near the beam center. During a recent superconducting test on the energy recovery linac (ERL) cavity at Brookhaven National Laboratory (BNL), 8 of the highest-Q HOMs were measured for the first time. In conjunction with analysis of CST Microwave Studio simulation results for the ERL model, one of these modes was further studied in the copper prototype ERL cavity. A method of identifying HOMs utilizing existing holes drilled in copper cavity cells was developed and used to conclude that the observed high-Q mode was a quadrupole.

  16. Verification of gyrokinetic particle simulation of current-driven instability in fusion plasmas. II. Resistive tearing mode

    SciTech Connect (OSTI)

    Liu, Dongjian; Zhang, Wenlu; McClenaghan, Joseph; Wang, Jiaqi; Lin, Zhihong

    2014-12-15

    Global gyrokinetic particle simulation of resistive tearing modes has been developed and verified in the gyrokinetic toroidal code (GTC). GTC linear simulations in the fluid limit of the kink-tearing and resistive tearing modes in the cylindrical geometry agree well with the resistive magnetohydrodynamic eigenvalue and initial value codes. Ion kinetic effects are found to reduce the radial width of the tearing modes. GTC simulations of the resistive tearing modes in the toroidal geometry find that the toroidicity reduces the growth rates.

  17. Isoscalar and neutron modes in the E 1 spectra of Ni isotopes and the

    Office of Scientific and Technical Information (OSTI)

    relevance of shell effects and the continuum (Journal Article) | SciTech Connect Isoscalar and neutron modes in the E 1 spectra of Ni isotopes and the relevance of shell effects and the continuum Citation Details In-Document Search This content will become publicly available on September 13, 2016 Title: Isoscalar and neutron modes in the E 1 spectra of Ni isotopes and the relevance of shell effects and the continuum Authors: Papakonstantinou, P. ; Hergert, H. ; Roth, R. Publication Date:

  18. Low-energy collective modes of deformed superfluid nuclei within the

    Office of Scientific and Technical Information (OSTI)

    finite-amplitude method (Journal Article) | SciTech Connect Low-energy collective modes of deformed superfluid nuclei within the finite-amplitude method Citation Details In-Document Search Title: Low-energy collective modes of deformed superfluid nuclei within the finite-amplitude method Authors: Hinohara, Nobuo ; Kortelainen, Markus ; Nazarewicz, Witold Publication Date: 2013-06-17 OSTI Identifier: 1103819 Type: Publisher's Accepted Manuscript Journal Name: Physical Review C Additional

  19. Effect of residual catalyst on the vibrational modes of single-walled carbon nanotubes

    SciTech Connect (OSTI)

    McNeil, L.E.; Park, H.; Lu, J.P.; Peters, M.J.

    2004-11-01

    Raman scattering measurements of single-walled carbon nanotubes prepared by laser ablation with Ni/Co catalyst show that samples that have not been purified have a graphitic mode frequency that is 8 cm{sup -1} lower than that of samples from which most of the catalyst has been removed. The shift is attributed to charge transfer from the catalyst particles to the nanotubes. The charge transfer from the residual catalyst also affects the temperature dependence of the radial breathing mode.

  20. Spin-polarized and valley helical edge modes in graphene nanoribbons

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Spin-polarized and valley helical edge modes in graphene nanoribbons Citation Details In-Document Search Title: Spin-polarized and valley helical edge modes in graphene nanoribbons Authors: Qiao, Zhenhua ; Yang, Shengyuan A. ; Wang, Bin ; Yao, Yugui ; Niu, Qian Publication Date: 2011-07-25 OSTI Identifier: 1100389 Type: Publisher's Accepted Manuscript Journal Name: Physical Review B Additional Journal Information: Journal Volume: 84; Journal Issue: 3;

  1. An Adaptive Particle Filtering Approach to Tracking Modes in a Varying

    Office of Scientific and Technical Information (OSTI)

    Shallow Ocean Environment (Conference) | SciTech Connect An Adaptive Particle Filtering Approach to Tracking Modes in a Varying Shallow Ocean Environment Citation Details In-Document Search Title: An Adaptive Particle Filtering Approach to Tracking Modes in a Varying Shallow Ocean Environment The shallow ocean environment is ever changing mostly due to temperature variations in its upper layers (< 100m) directly affecting sound propagation throughout. The need to develop processors that

  2. Normal Modes of Black Hole Accretion Disks (Technical Report) | SciTech

    Office of Scientific and Technical Information (OSTI)

    Connect Technical Report: Normal Modes of Black Hole Accretion Disks Citation Details In-Document Search Title: Normal Modes of Black Hole Accretion Disks × You are accessing a document from the Department of Energy's (DOE) SciTech Connect. This site is a product of DOE's Office of Scientific and Technical Information (OSTI) and is provided as a public service. Visit OSTI to utilize additional information resources in energy science and technology. A paper copy of this document is also

  3. The locking and unlocking thresholds for tearing modes in a cylindrical

    Office of Scientific and Technical Information (OSTI)

    tokamak (Journal Article) | SciTech Connect The locking and unlocking thresholds for tearing modes in a cylindrical tokamak Citation Details In-Document Search This content will become publicly available on March 10, 2017 Title: The locking and unlocking thresholds for tearing modes in a cylindrical tokamak Authors: Huang, Wenlong [1] ; Zhu, Ping [2] + Show Author Affiliations CAS Key Laboratory of Geospace Environment and Department of Modern Physics, University of Science and Technology of

  4. Tokamak error fields and locked modes (Technical Report) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Tokamak error fields and locked modes Citation Details In-Document Search Title: Tokamak error fields and locked modes The effects of externally applied, resonant magnetic field perturbations on tokamak plasmas are discussed. An analytical model assuming tokamak ordering and narrow islands clarifies the conditions under which error fields are amplified or diminished by self- consistent effects. A strong amplification of error fields near marginal tearing stability is found to broaden the range

  5. Advanced Materials for Reversible Solid Oxide Fuel Cell (RSOFC), Dual Mode

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

    Operation with Low Degradation | Department of Energy for Reversible Solid Oxide Fuel Cell (RSOFC), Dual Mode Operation with Low Degradation Advanced Materials for Reversible Solid Oxide Fuel Cell (RSOFC), Dual Mode Operation with Low Degradation Presented at the Department of Energy Fuel Cell Projects Kickoff Meeting, September 1 - October 1, 2009 PDF icon petri_versa%20_power_kickoff.pdf More Documents & Publications Reversible Fuel Cells Workshop Summary Report Progress on the

  6. Investigation of a metallic photonic crystal high power microwave mode converter

    SciTech Connect (OSTI)

    Wang, Dong Qin, Fen; Xu, Sha; Yu, Aimin; Wu, Yong

    2015-02-15

    It is demonstrated that an L band metallic photonic crystal TEM-TE{sub 11} mode converter is suitable for narrow band high power microwave application. The proposed mode converter is realized by partially filling metallic photonic crystals along azimuthal direction in a coaxial transmission line for phase-shifting. A three rows structure is designed and simulated by commercial software CST Microwave Studio. Simulation results show that its conversion efficiency is 99% at the center frequency 1.58 GHz. Over the frequency range of 1.56-1.625 GHz, the conversion efficiency exceeds 90 %, with a corresponding bandwidth of 4.1 %. This mode converter has a gigawatt level power handling capability which is suitable for narrow band high power microwave application. Using magnetically insulated transmission line oscillator(MILO) as a high power microwave source, particle-in-cell simulation is carried out to test the performance of the mode converter. The expected TE{sub 11} mode microwave output is obtained and the MILO works well. Mode conversion performance of the converter is tested by far-field measurement method. And the experimental result confirms the validity of our design. Then, high power microwave experiment is carried out on a Marx-driven Blumlein water line pulsed power accelerator. Microwave frequency, radiated pattern and power are measured in the far-field region and the results agree well with simulation results. The experiment also reveals that no microwave breakdown or pulse shortening took place in the experimental setup.

  7. Investigation of physical processes limiting plasma density in H-mode on DIII-D

    SciTech Connect (OSTI)

    Maingi, R.; Mahdavi, M.A.; Jernigan, T.C.

    1996-12-01

    A series of experiments was conducted on the DIII-D tokamak to investigate the physical processes which limit density in high confinement mode (H-mode) discharges. The typical H-mode to low confinement mode (L-mode) transition limit at high density near the empirical Greenwald density limit was avoided by divertor pumping, which reduced divertor neutral pressure and prevented formation of a high density, intense radiation zone (MARFE) near the X-point. It was determined that the density decay time after pellet injection was independent of density relative to the Greenwald limit and increased non-linearly with the plasma current. Magnetohydrodynamic (MHD) activity in pellet-fueled plasmas was observed at all power levels, and often caused unacceptable confinement degradation, except when the neutral beam injected (NBI) power was {le} 3 MW. Formation of MARFEs on closed field lines was avoided with low safety factor (q) operation but was observed at high q, qualitatively consistent with theory. By using pellet fueling and optimizing discharge parameters to avoid each of these limits, an operational space was accessed in which density {approximately} 1.5 {times} Greenwald limit was achieved for 600 ms, and good H-mode confinement was maintained for 300 ms of the density flattop. More significantly, the density was successfully increased to the limit where a central radiative collapse was observed, the most fundamental density limit in tokamaks.

  8. Quantum correlations of helicity entangled states in non-inertial frames beyond single mode approximation

    SciTech Connect (OSTI)

    Harsij, Zeynab Mirza, Behrouz

    2014-12-15

    A helicity entangled tripartite state is considered in which the degree of entanglement is preserved in non-inertial frames. It is shown that Quantum Entanglement remains observer independent. As another measure of quantum correlation, Quantum Discord has been investigated. It is explicitly shown that acceleration has no effect on the degree of quantum correlation for the bipartite and tripartite helicity entangled states. Geometric Quantum Discord as a HilbertSchmidt distance is computed for helicity entangled states. It is shown that living in non-inertial frames does not make any influence on this distance, either. In addition, the analysis has been extended beyond single mode approximation to show that acceleration does not have any impact on the quantum features in the limit beyond the single mode. As an interesting result, while the density matrix depends on the right and left Unruh modes, the Negativity as a measure of Quantum Entanglement remains constant. Also, Quantum Discord does not change beyond single mode approximation. - Highlights: The helicity entangled states here are observer independent in non-inertial frames. It is explicitly shown that Quantum Discord for these states is observer independent. Geometric Quantum Discord is also not affected by acceleration increase. Extending to beyond single mode does not change the degree of entanglement. Beyond single mode approximation the degree of Quantum Discord is also preserved.

  9. Harmonic mode competition in a terahertz gyrotron backward-wave oscillator

    SciTech Connect (OSTI)

    Kao, S. H.; Chiu, C. C.; Chang, P. C.; Wu, K. L.; Chu, K. R.

    2012-10-15

    Electron cyclotron maser interactions at terahertz (THz) frequencies require a high-order-mode structure to reduce the wall loss to a tolerable level. To generate THz radiation, it is also essential to employ cyclotron harmonic resonances to reduce the required magnetic field strength to a value within the capability of the superconducting magnets. However, much weaker harmonic interactions in a high-order-mode structure lead to serious mode competition problems. The current paper addresses harmonic mode competition in the gyrotron backward wave oscillator (gyro-BWO). We begin with a comparative study of the mode formation and oscillation thresholds in the gyro-BWO and gyromonotron. Differences in linear features result in far fewer 'windows' for harmonic operation of the gyro-BWO. Nonlinear consequences of these differences are examined in particle simulations of the multimode competition processes in the gyro-BWO, which shed light on the competition criteria between modes of different as well as the same cyclotron harmonic numbers. The viability of a harmonic gyro-BWO is assessed on the basis of the results obtained.

  10. Linear mode conversion of Langmuir/z-mode waves to radiation: Scalings of conversion efficiencies and propagation angles with temperature and magnetic field orientation

    SciTech Connect (OSTI)

    Schleyer, F.; Cairns, Iver H.; Kim, E.-H.

    2013-03-15

    Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in an inhomogeneous plasma. It is relevant to laboratory plasmas and multiple solar system radio emissions, such as continuum radiation from planetary magnetospheres and type II and III radio bursts from the solar corona and solar wind. This paper simulates LMC of waves defined by warm, magnetized fluid theory, specifically the conversion of Langmuir/z-mode waves to electromagnetic (EM) radiation. The primary focus is the calculation of the energy and power conversion efficiencies for LMC as functions of the angle of incidence {theta} of the Langmuir/z-mode wave, temperature {beta}=T{sub e}/m{sub e}c{sup 2}, adiabatic index {gamma}, and orientation angle {phi} between the ambient density gradient {nabla}N{sub 0} and ambient magnetic field B{sub 0} in a warm, unmagnetized plasma. The ratio of these efficiencies is found to agree well as a function of {theta}, {gamma}, and {beta} with an analytical relation that depends on the group speeds of the Langmuir/z and EM wave modes. The results demonstrate that the energy conversion efficiency {epsilon} is strongly dependent on {gamma}{beta}, {phi} and {theta}, with {epsilon}{proportional_to}({gamma}{beta}){sup 1/2} and {theta}{proportional_to}({gamma}{beta}){sup 1/2}. The power conversion efficiency {epsilon}{sub p}, on the other hand, is independent of {gamma}{beta} but does vary significantly with {theta} and {phi}. The efficiencies are shown to be maximum for approximately perpendicular density gradients ({phi} Almost-Equal-To 90 Degree-Sign ) and minimal for parallel orientation ({phi}=0 Degree-Sign ) and both the energy and power conversion efficiencies peak at the same {theta}.

  11. Effects of alloy disorder and confinement on phonon modes and Raman scattering in Si{sub x}Ge{sub 1−x} nanocrystals: A microscopic modeling

    SciTech Connect (OSTI)

    Vasin, A. S.; Vikhrova, O. V.; Vasilevskiy, M. I.

    2014-04-14

    Confinement and alloy disorder effects on the lattice dynamics and Raman scattering in Si{sub 1−x}Ge{sub x} nanocrystals (NCs) are investigated numerically employing two different empirical inter-atomic potentials. Relaxed NCs of different compositions (x) were built using the Molecular Dynamics method and applying rigid boundary conditions mimicking the effect of surrounding matrix. The resulting variation of bond lengths with x was checked against Vegard's law and the NC phonon modes were calculated using the same inter-atomic potential. The localization of the principal Raman-active (Si-Si, Si-Ge, and Ge-Ge) modes is investigated by analysing representative eigenvectors and their inverse participation ratio. The dependence of the position and intensity of these modes upon x and NC size is presented and compared to previous calculated results and available experimental data. In particular, it is argued that the composition dependence of the intensity of the Si-Ge and Ge-Ge modes does not follow the fraction of the corresponding nearest-neighbour bonds as it was suggested by some authors. Possible effects of alloy segregation are considered by comparing the calculated properties of random and clustered Si{sub x}Ge{sub 1−x} NCs. It is found that the Si-Si mode and Ge-Ge mode are enhanced and blue-shifted (by several cm{sup −1}for the Si-Si mode), while the intensity of the Si-Ge Raman mode is strongly suppressed by clustering.

  12. Magnetohydrodynamic slow mode with drifting He{sup ++}: Implications for coronal seismology and the solar wind

    SciTech Connect (OSTI)

    Hollweg, Joseph V.; Verscharen, Daniel; Chandran, Benjamin D. G. E-mail: daniel.verscharen@unh.edu

    2014-06-10

    The MHD slow mode wave has application to coronal seismology, MHD turbulence, and the solar wind where it can be produced by parametric instabilities. We consider analytically how a drifting ion species (e.g. He{sup ++}) affects the linear slow mode wave in a mainly electron-proton plasma, with potential consequences for the aforementioned applications. Our main conclusions are as follows. 1. For wavevectors highly oblique to the magnetic field, we find solutions that are characterized by very small perturbations of total pressure. Thus, our results may help to distinguish the MHD slow mode from kinetic Alfvn waves and non-propagating pressure-balanced structures, which can also have very small total pressure perturbations. 2. For small ion concentrations, there are solutions that are similar to the usual slow mode in an electron-proton plasma, and solutions that are dominated by the drifting ions, but for small drifts the wave modes cannot be simply characterized. 3. Even with zero ion drift, the standard dispersion relation for the highly oblique slow mode cannot be used with the Alfvn speed computed using the summed proton and ion densities, and with the sound speed computed from the summed pressures and densities of all species. 4. The ions can drive a non-resonant instability under certain circumstances. For low plasma beta, the threshold drift can be less than that required to destabilize electromagnetic modes, but damping from the Landau resonance can eliminate this instability altogether, unless T{sub e} /T{sub p} >> 1.

  13. MULTI-SPACECRAFT OBSERVATIONS OF LINEAR MODES AND SIDEBAND WAVES IN ION-SCALE SOLAR WIND TURBULENCE

    SciTech Connect (OSTI)

    Perschke, Christopher; Motschmann, Uwe; Narita, Yasuhito; Glassmeier, Karl-Heinz

    2014-10-01

    In the scenario of weak turbulence, energy is believed to be cascaded from smaller to larger wave numbers and frequencies due to weak wave-wave interactions. Based on its perturbative treatment one may regard plasma turbulence as a superposition of linear modes (or normal modes) and sideband waves (or nonlinear modes). In this study, we use magnetic field and plasma measurements of nine solar wind events obtained by the Cluster spacecraft and make extensive use of a high-resolution wave vector analysis method, the Multi-point Signal Resonator technique, to find frequencies and wave vectors of discrete modes on ion kinetic scales in the plasma rest frame. The primarily unstructured wave observations in the frequency-wave number diagram are classified into three distinct linear modes (proton Bernstein modes, helium-alpha Bernstein modes, and kinetic Alfvn waves) and the sideband waves by comparing with the dispersion relations derived theoretically from linear Vlasov theory using observational values of the plasma parameter beta and the propagation angle from the mean magnetic field. About 60% of the observed discrete modes can be explained by the linear modes, primarily as the proton Bernstein and the kinetic Alfvn waves, within the frequency uncertainties, while the rest of the population (about 40%) cannot be classified as linear modes due to the large deviation from dispersion relations. We conclude that both the linear modes and sideband wave components are needed to construct the wave picture of solar wind turbulence on ion-kinetic scales.

  14. Mode I Fracture Toughness Prediction for Multiwalled-Carbon-Nanotube Reinforced Ceramics

    SciTech Connect (OSTI)

    Nguyen, Ba Nghiep; Henager, Charles H.

    2015-08-27

    This article develops a multiscale model to predict fracture toughness of multiwalled-carbon-nanotube (MWCNT) reinforced ceramics. The model bridges different scales from the scale of a MWCNT to that of a composite domain containing a macroscopic crack. From the nano, micro to meso scales, Eshelby-Mori-Tanaka models combined with a continuum damage mechanics approach are explored to predict the elastic damage behavior of the composite as a function of MWCNT volume fraction. MWCNTs are assumed to be randomly dispersed in a ceramic matrix subject to cracking under loading. A damage variable is used to describe matrix cracking that causes reduction of the elastic modulus of the matrix. This damage model is introduced in a modified boundary layer modeling approach to capture damage initiation and development at a tip of a pre-existing crack. Damage and fracture are captured only in a process window containing the crack tip under plane strain Mode I loading. The model is validated against the published experimental fracture toughness data for a MWCNT 3 mol% yttria stabilized zirconia composite system. In addition, crack resistance curves as a function of MWCNT content are predicted and fitted by a power law as observed in the experiments on zirconia.

  15. Performance of Single Electrode-Supported Cells Operating in the Electrolysis Mode

    SciTech Connect (OSTI)

    J. E. O'Brien; G. K. Housley; D. G. Milobar

    2009-11-01

    An experimental study is under way to assess the performance of electrode-supported solid-oxide cells operating in the steam electrolysis mode for hydrogen production over a temperature range of 800 to 900C. Results presented in this paper were obtained from single cells, with an active area of 16 cm2 per cell. The electrolysis cells are electrode-supported, with yttria-stabilized zirconia (YSZ) electrolytes (~10 m thick), nickel-YSZ steam/hydrogen electrodes (~1400 m thick), and manganite (LSM) air-side electrodes. The experiments were performed over a range of steam inlet mole fractions (0.1 0.6), gas flow rates, and current densities (0 to 0.6 A/cm2). Steam consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation. On a molar basis, the steam consumption rate is equal to the hydrogen production rate. Cell performance was evaluated by performing DC potential sweeps at 800, 850, and 900C. The voltage-current characteristics are presented, along with values of area-specific resistance as a function of current density. Long-term cell performance is also assessed to evaluate cell degradation. Details of the custom single-cell test apparatus developed for these experiments are also presented.

  16. The effect of oxygen-to-fuel stoichiometry on coal ash fine-fragmentation mode formation mechanisms.

    SciTech Connect (OSTI)

    Fix, G.; Seames, W. S.; Mann, M. D.; Benson, S. A.; Miller, D. J.

    2011-04-01

    Ash particles smaller than 2.5 {micro}m in diameter generated during pulverized coal combustion are difficult to capture and may pose greater harm to the environment and human health than the discharge of larger particles. Recent research efforts on coal ash formation have revealed a middle fine-fragment mode centered around 2 {micro}m. Formation of this middle or fine-fragment mode (FFM) is less well understood compared to larger coarse and smaller ultrafine ash. This study is part of an overall effort aimed at determining the key factors that impact the formation of FFM. This work examined the effects of oxygen-to-fuel stoichiometry (OFS). Pulverized Illinois No.6 bituminous coal was combusted and the ash generated was size segregated in a Dekati low pressure inertial impactor. The mass of each fraction was measured and the ash was analyzed using scanning electron microscopy (SEM) and X-ray microanalysis. The FFM ash types were classified based on the SEM images to evaluate the significant fine-fragment ash formation mechanisms and determine any possible link between stoichiometry and formation mechanism. From the particle size distributions (PSDs), the coarse mode appears unaffected by the change in OFS, however, the OFS 1.05 lowered the fraction of ultrafine ash in relation to the higher OFS settings, and appears to increase the portion of the FFM. An intermediate minimum was found in the FFM at 1.3 {micro}m for the 1.20 and 1.35 OFS tests but was not observed in the 1.05 OFS. SEM analysis also suggests that OFS may contribute to changing formation mechanisms.

  17. The hydrogen-bond network of water supports propagating optical phonon-like modes

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

    Elton, Daniel C.; Fernández-Serra, Marivi

    2016-01-04

    The local structure of liquid water as a function of temperature is a source of intense research. This structure is intimately linked to the dynamics of water molecules, which can be measured using Raman and infrared spectroscopies. The assignment of spectral peaks depends on whether they are collective modes or single-molecule motions. Vibrational modes in liquids are usually considered to be associated to the motions of single molecules or small clusters. Using molecular dynamics simulations, here we find dispersive optical phonon-like modes in the librational and OH-stretching bands. We argue that on subpicosecond time scales these modes propagate through water’smore » hydrogen-bond network over distances of up to 2 nm. In the long wavelength limit these optical modes exhibit longitudinal–transverse splitting, indicating the presence of coherent long-range dipole–dipole interactions, as in ice. Lastly, our results indicate the dynamics of liquid water have more similarities to ice than previously thought.« less

  18. Search for Suitable ICRF Operation Window for the Shaped H-mode Operation of KSTAR

    SciTech Connect (OSTI)

    Park, B. H.; Kim, J. Y.

    2009-11-26

    KSTAR will try to achieve its 1st shaped H-mode plasma in 2010 campaign. The available power is limited by our plan for auxiliary heating system. Up to 2010, NBI with 1 MW, LHCD 0.5 MW, and ECH with 0.5 MW power will be prepared. To accomplish high beta plasma, TF magnetic field will be reduced to 2 T from rated field of 3.5 T. In this case the ECH contribution to H-mode power threshold requirement is ignorant because the 84 GHz frequency does not meet neither fundamental nor second harmonic resonance in the discharge area. Therefore the ICRF heating should carry out important roll to reach power threshold. The ICRF system of tunable frequency from 30 to 60 MHz will come with 1 MW power in 2010. To maximize the ICRF heating efficiency for H-mode purpose, we try to find suitable condition of ICRF heating parameters through the simulation using by TORIC code. Optimizations of RF frequency, toroidal modes controllable by 4 current straps, and the minority concentration are performed. Possibilities of second harmonic heating of minority and the mode converted heating near resonance layer are also studied.

  19. Evaluation of Geometrically Nonlinear Reduced Order Models with Nonlinear Normal Modes

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

    Kuether, Robert J.; Deaner, Brandon J.; Hollkamp, Joseph J.; Allen, Matthew S.

    2015-09-15

    Several reduced-order modeling strategies have been developed to create low-order models of geometrically nonlinear structures from detailed finite element models, allowing one to compute the dynamic response of the structure at a dramatically reduced cost. But, the parameters of these reduced-order models are estimated by applying a series of static loads to the finite element model, and the quality of the reduced-order model can be highly sensitive to the amplitudes of the static load cases used and to the type/number of modes used in the basis. Our paper proposes to combine reduced-order modeling and numerical continuation to estimate the nonlinearmore » normal modes of geometrically nonlinear finite element models. Not only does this make it possible to compute the nonlinear normal modes far more quickly than existing approaches, but the nonlinear normal modes are also shown to be an excellent metric by which the quality of the reduced-order model can be assessed. Hence, the second contribution of this work is to demonstrate how nonlinear normal modes can be used as a metric by which nonlinear reduced-order models can be compared. Moreover, various reduced-order models with hardening nonlinearities are compared for two different structures to demonstrate these concepts: a clamped–clamped beam model, and a more complicated finite element model of an exhaust panel cover.« less

  20. Transport effects of low (m,n) MHD modes on TFTR supershots

    SciTech Connect (OSTI)

    Chang, Z.; Callen, J.D.; Fredrickson, E.D.

    1993-10-01

    Supershots in TFTR often suffer a performance deterioration characterized by a gradual decrease of the D-D fusion neutron yield and plasma stored energy after several hundred milliseconds of auxiliary heating. The correlation between this performance deterioration and the development of low m (the poloidal mode number), n (the toroidal mode number) MHD modes is studied through shot-to-shot comparisons and statistical data analyses. A good correlation is observed between performance deterioration and the appearance of strong 3/2 and 4/3 macroscopic modes (magnetic islands) in small major radius plasmas (R = 2.45 m). The magnetic island structures are observed using Mirnov and ECE diagnostics. The measured T{sub e} T{sub i} and n{sub e}, profiles show that development of the islands corresponds to a nearly constant decrement of these quantities over the core region r < r{sub s}. where r{sub s} is the mode rational surface, on a transport time scale (t > {tau}{sub E}). The observed energy deterioration scaling, {delta}W/W {approximately}w/a, where w is the magnetic island width, agrees with both a local transport model and predictive numerical simulations. For larger major radius plasmas (R = 2.52, 2.60 m), a continuous increase of edge recycling rate during the neutral beam injection phase seems to have a larger effect on the performance deterioration than does the MHD.

  1. Prediction of non-equilibrium solidification modes in austenitic stainless steel laser welds

    SciTech Connect (OSTI)

    Vitek, J.M.; David, S.A.

    1993-08-01

    A primary austenitic, non-equilibrium mode of solidification can be induced in many 300 series austenitic stainless steels by laser welding and other rapid solidification techniques. The change in solidification mode can often result in a fully austenitic microstructure compared to the two phase ferrite plus austenite microstructure that is commonly found after primary ferrite solidification. A predictive capability for the solidification mode under rapid solidification conditions such as laser welding is needed since the microstructure and properties are closely related to solidification behavior. Conventional constitutional diagrams do not predict with any reliability the change to non-equilibrium austenitic solidification mode. Several means that have been attempted to predict the solidification behavior under extreme conditions are reviewed. The Cr{sub EQ}/Ni{sub EQ} ratio is shown to be unreliable, at least with the equivalence factors commonly used. Theoretical calculations of growth rate competition between ferrite and austenite solidification show promise, but some ambiguity results from inaccuracy in thermophysical material parameters. Use of calculated thermodynamic parameters such as equilibrium and non-equilibrium liquidus and solidus temperatures also shows some promise. However, this approach is not completely satisfactory and reliable either. It is concluded that a reliable and accurate method for predicting the tendency of austenitic stainless steels to solidify in the non-equilibrium mode is not yet available.

  2. Deuterium-Tritium Simulations of the Enhanced Reversed Shear Mode in the Tokamak Fusion Test Reactor

    SciTech Connect (OSTI)

    Mikkelsen, D.R.; Manickam, J.; Scott, S.D.; Zarnstorff

    1997-04-01

    The potential performance, in deuterium-tritium plasmas, of a new enhanced con nement regime with reversed magnetic shear (ERS mode) is assessed. The equilibrium conditions for an ERS mode plasma are estimated by solving the plasma transport equations using the thermal and particle dif- fusivities measured in a short duration ERS mode discharge in the Tokamak Fusion Test Reactor [F. M. Levinton, et al., Phys. Rev. Letters, 75, 4417, (1995)]. The plasma performance depends strongly on Zeff and neutral beam penetration to the core. The steady state projections typically have a central electron density of {approx}2:5x10 20 m{sup -3} and nearly equal central electron and ion temperatures of {approx}10 keV. In time dependent simulations the peak fusion power, {approx} 25 MW, is twice the steady state level. Peak performance occurs during the density rise when the central ion temperature is close to the optimal value of {approx} 15 keV. The simulated pressure profiles can be stable to ideal MHD instabilities with toroidal mode number n = 1, 2, 3, 4 and {infinity} for {beta}{sub norm} up to 2.5; the simulations have {beta}{sub norm} {le} 2.1. The enhanced reversed shear mode may thus provide an opportunity to conduct alpha physics experiments in conditions imilar to those proposed for advanced tokamak reactors.

  3. Multifrequency spectrum analysis using fully digital G Mode-Kelvin probe force microscopy

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

    Collins, Liam F.; Jesse, Stephen; Belianinov, Alex; Somnath, Suhas; Rodriguez, Brian J.; Balke, Nina; Kalinin, Sergei V.

    2016-02-11

    Since its inception over two decades ago, Kelvin probe force microscopy (KPFM) has become the standard technique for characterizing electrostatic, electrochemical and electronic properties at the nanoscale. In this work, we present a purely digital, software-based approach to KPFM utilizing big data acquisition and analysis methods. General Mode (G-Mode) KPFM, works by capturing the entire photodetector data stream, typically at the sampling rate limit, followed by subsequent de-noising, analysis and compression of the cantilever response. We demonstrate that the G-Mode approach allows simultaneous multi-harmonic detection, combined with on-the-fly transfer function correction required for quantitative CPD mapping. The KPFM approach outlinedmore » in this work significantly simplifies the technique by avoiding cumbersome instrumentation optimization steps (i.e. lock in parameters, feedback gains etc.), while also retaining the flexibility to be implemented on any atomic force microscopy platform. We demonstrate the added advantages of G-Mode KPFM by allowing simultaneous mapping of CPD and capacitance gradient (C') channels as well as increased flexibility in data exploration across frequency, time, space, and noise domains. As a result, G-Mode KPFM is particularly suitable for characterizing voltage sensitive materials or for operation in conductive electrolytes, and will be useful for probing electrodynamics in photovoltaics, liquids and ionic conductors.« less

  4. Heralding efficiency and correlated-mode coupling of near-IR fiber-coupled photon pairs

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

    Dixon, P. Ben; Rosenberg, Danna; Stelmakh, Veronika; Grein, Matthew E.; Bennink, Ryan S.; Dauler, Eric A.; Kerman, Andrew J.; Molnar, Richard J.; Wong, Franco N. C.

    2014-10-06

    We report on a systematic experimental study of heralding efficiency and generation rate of telecom-band infrared photon pairs generated by spontaneous parametric down-conversion and coupled to single mode optical fibers. We define the correlated-mode coupling efficiency--an inherent source efficiency--and explain its relation to heralding efficiency. For our experiment, we developed a reconfigurable computer controlled pump-beam and collection-mode optical apparatus which we used to measure the generation rate and correlated-mode coupling efficiency. The use of low-noise, high-efficiency superconducting-nanowire single-photon-detectors in this setup allowed us to explore focus configurations with low overall photon flux. The measured data agree well with theory andmore » we demonstrated a correlated-mode coupling efficiency of 97%±2%, which is the highest efficiency yet achieved for this type of system. These results confirm theoretical treatments and demonstrate that very high overall heralding efficiencies can, in principle, be achieved in quantum optical systems. We expect that these results and techniques will be widely incorporated into future systems that require, or benefit from, a high heralding efficiency.« less

  5. Evaluation of Geometrically Nonlinear Reduced Order Models with Nonlinear Normal Modes

    SciTech Connect (OSTI)

    Kuether, Robert J.; Deaner, Brandon J.; Hollkamp, Joseph J.; Allen, Matthew S.

    2015-09-15

    Several reduced-order modeling strategies have been developed to create low-order models of geometrically nonlinear structures from detailed finite element models, allowing one to compute the dynamic response of the structure at a dramatically reduced cost. But, the parameters of these reduced-order models are estimated by applying a series of static loads to the finite element model, and the quality of the reduced-order model can be highly sensitive to the amplitudes of the static load cases used and to the type/number of modes used in the basis. Our paper proposes to combine reduced-order modeling and numerical continuation to estimate the nonlinear normal modes of geometrically nonlinear finite element models. Not only does this make it possible to compute the nonlinear normal modes far more quickly than existing approaches, but the nonlinear normal modes are also shown to be an excellent metric by which the quality of the reduced-order model can be assessed. Hence, the second contribution of this work is to demonstrate how nonlinear normal modes can be used as a metric by which nonlinear reduced-order models can be compared. Moreover, various reduced-order models with hardening nonlinearities are compared for two different structures to demonstrate these concepts: a clamped–clamped beam model, and a more complicated finite element model of an exhaust panel cover.

  6. Direct X-B mode conversion for high-? national spherical torus experiment in nonlinear regime

    SciTech Connect (OSTI)

    Ali Asgarian, M. E-mail: maa@msu.edu; Parvazian, A.; Abbasi, M.; Verboncoeur, J. P.

    2014-09-15

    Electron Bernstein wave (EBW) can be effective for heating and driving currents in spherical tokamak plasmas. Power can be coupled to EBW via mode conversion of the extraordinary (X) mode wave. The most common and successful approach to study the conditions for optimized mode conversion to EBW was evaluated analytically and numerically using a cold plasma model and an approximate kinetic model. The major drawback in using radio frequency waves was the lack of continuous wave sources at very high frequencies (above the electron plasma frequency), which has been addressed. A future milestone is to approach high power regime, where the nonlinear effects become significant, exceeding the limits of validity for present linear theory. Therefore, one appropriate tool would be particle in cell (PIC) simulation. The PIC method retains most of the nonlinear physics without approximations. In this work, we study the direct X-B mode conversion process stages using PIC method for incident wave frequency f{sub 0}?=?15?GHz, and maximum amplitude E{sub 0}?=?10{sup 5?}V/m in the national spherical torus experiment (NSTX). The modelling shows a considerable reduction in X-B mode conversion efficiency, C{sub modelling}?=?0.43, due to the presence of nonlinearities. Comparison of system properties to the linear state reveals predominant nonlinear effects; EBW wavelength and group velocity in comparison with linear regime exhibit an increment around ?36% and 17%, respectively.

  7. Heralding efficiency and correlated-mode coupling of near-IR fiber coupled photon pairs

    SciTech Connect (OSTI)

    Dixon, P. Ben; Rosenberg, Danna; Stelmakh, Veronika; Grein, Matthew E.; Bennink, Ryan S; Dauler, Eric A.; Kerman, Andrew J.; Molnar, Richard J.; Wong, Franco N. C.

    2014-01-01

    We report on a systematic experimental study of heralding efficiency and generation rate of telecom-band infrared photon pairs generated by spontaneous parametric down-conversion and coupled to single mode optical fibers. We define the correlated-mode coupling efficiency--an inherent source efficiency--and explain its relation to heralding efficiency. For our experiment, we developed a reconfigurable computer controlled pump-beam and collection-mode optical apparatus which we used to measure the generation rate and correlated-mode coupling efficiency. The use of low-noise, high-efficiency superconducting-nanowire single-photon-detectors in this setup allowed us to explore focus configurations with low overall photon flux. The measured data agree well with theory and we demonstrated a correlated-mode coupling efficiency of 97 +-2%, which is the highest efficiency yet achieved for this type of system. These results confirm theoretical treatments and demonstrate that very high overall heralding efficiencies can, in principle, be achieved in quantum optical systems. It is expected that these results and techniques will be widely incorporated into future systems that require, or benefit from, a high heralding efficiency.

  8. A nonlinear multi-mode wideband piezoelectric vibration-based energy harvester using compliant orthoplanar spring

    SciTech Connect (OSTI)

    Dhote, Sharvari Zu, Jean; Zhu, Yang

    2015-04-20

    In this paper, a nonlinear wideband multi-mode piezoelectric vibration-based energy harvester (PVEH) is proposed based on a compliant orthoplanar spring (COPS), which has an advantage of providing multiple vibration modes at relatively low frequencies. The PVEH is made of a tri-leg COPS flexible structure, where three fixed-guided beams are capable of generating strong nonlinear oscillations under certain base excitation. A prototype harvester was fabricated and investigated through both finite-element analysis and experiments. The frequency response shows multiple resonance which corresponds to a hardening type of nonlinear resonance. By adding masses at different locations on the COPS structure, the first three vibration modes are brought close to each other, where the three hardening nonlinear resonances provide a wide bandwidth for the PVEH. The proposed PVEH has enhanced performance of the energy harvester in terms of a wide frequency bandwidth and a high-voltage output under base excitations.

  9. The effect of an anisotropic pressure of thermal particles on resistive wall mode stability

    SciTech Connect (OSTI)

    Berkery, J. W. Sabbagh, S. A.; Betti, R.; Guazzotto, L.; Manickam, J.

    2014-11-15

    The effect of an anisotropic pressure of thermal particles on resistive wall mode stability in tokamak fusion plasmas is derived through kinetic theory and assessed through calculation with the MISK code [B. Hu et al., Phys. Plasmas 12, 0?57301 (2005)]. The fluid anisotropy is treated as a small perturbation on the plasma equilibrium and modeled with a bi-Maxwellian distribution function. A complete stability treatment without an assumption of high frequency mode rotation leads to anisotropic kinetic terms in the dispersion relation in addition to anisotropy corrections to the fluid terms. With the density and the average pressure kept constant, when thermal particles have a higher temperature perpendicular to the magnetic field than parallel, the fluid pressure-driven ballooning destabilization term is reduced. Additionally, the stabilizing kinetic effects of the trapped thermal ions can be enhanced. Together these two effects can lead to a modest increase in resistive wall mode stability.

  10. Mode specificity in bond selective reactions F + HOD ? HF + OD and DF + OH

    SciTech Connect (OSTI)

    Song, Hongwei; Guo, Hua

    2015-05-07

    The influence of vibrational excitations in the partially deuterated water (HOD) reactant on its bond selective reactions with F is investigated using a full-dimensional quantum wave packet method on an accurate global potential energy surface. Despite the decidedly early barrier of the F + H{sub 2}O reaction, reactant vibrational excitation in each local stretching mode of HOD is found to significantly enhance the reaction which breaks the excited bond. In the mean time, excitation of the HOD bending mode also enhances the reaction, but with much lower efficacy and weaker bond selectivity. Except for low collision energies, all vibrational modes are more effective in promoting the bond selective reactions than the translational energy. These results are compared with the predictions of the recently proposed sudden vector projection model.

  11. Strongly localized modes in one-dimensional defect-free magnonic quasicrystals

    SciTech Connect (OSTI)

    Chen, C. H.; Qiu, R. Z.; Chang, C. H.; Hsueh, W. J.

    2014-08-15

    Signal storage in magnonic quasicrystals using a slow spin-wave mode, rather than the quasinormal mode of traditional periodic magnonic crystals, is proposed, which is analogous to the slow light mode in the field of optics. Compared to traditional materials, richer and more wavelength-selective sharp resonances are achieved using the quasicrystals with a fewer number of layers, because of the peculiar fractal transmission spectra of quasicrystals. The number of sharp resonance and the quality factor for the sharp resonances in the transmission spectra also increases as the generation order of the magnonic quasicrystal increases. This generic nature allows the storage of signals using spin wave, for a wide range of quasiperiodic systems.

  12. The impact of pedestal turbulence and electron inertia on edge-localized-mode crashes

    SciTech Connect (OSTI)

    Xi, P. W.; Lawrence Livermore National Laboratory, Livermore, California 94550 ; Xu, X. Q.; Diamond, P. H.; Center for Astrophysics and Space Sciences and Department of Physics, University of California San Diego, La Jolla, California 92093-0429

    2014-05-15

    We demonstrate that the occurrence of Edge-Localized-Modes (ELM) crashes does not depend only on the linear peeling-ballooning threshold, but also relies on nonlinear processes. Wave-wave interaction constrains the growth time of a mode, thus inducing a shift in the criterion for triggering an ELM crash. An ELM crash requires the P-B growth rate to exceed a critical value ?>?{sub c}, where ?{sub c} is set by 1/?{sup }{sub c}, and ?{sup }{sub c} is the averaged mode phase coherence time. For 0

  13. On the marginal instability threshold condition of the aperiodic ordinary mode

    SciTech Connect (OSTI)

    Schlickeiser, R.; Yoon, P. H.

    2014-07-15

    The purely growing ordinary (O) mode instability has recently received renewed attention owing to its potential applicability to the solar wind plasma. Here, an analytical marginal instability condition is derived for counter-streaming bi-Maxwellian plasma particle distribution functions. The derived marginal instability condition as a function of the temperature anisotropy and plasma beta agrees remarkably well with the numerically determined instability condition. The existence of a new instability domain of the O-mode at small plasma beta values is confirmed with the leading A??{sub ?}{sup ?1}-dependence, if the counter-stream parameter P{sub e} exceeds a critical value. At small plasma beta values at large enough counter-stream parameter, the O-mode also operates for temperature anisotropies A?=?T{sub ?}/T{sub ?}?>?1 even larger than unity, as the parallel counter-stream free energy exceeds the perpendicular bi-Maxwellian free energy.

  14. Modes of Occurrence of Trace and Minor Elements in Some Australian Coals

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Modes of Occurrence of Trace and Minor Elements in Some Australian Coals Citation Details In-Document Search Title: Modes of Occurrence of Trace and Minor Elements in Some Australian Coals Authors: Riley K. ; French, D ; Farrell, O ; Wood, R ; Huggins, F Publication Date: 2012-05-01 OSTI Identifier: 1069931 Report Number(s): BNL--100503-2013-JA Journal ID: ISSN 0166-5162 DOE Contract Number: DE-AC02-98CH10886 Resource Type: Journal Article Resource

  15. Entanglement verification for quantum-key-distribution systems with an underlying bipartite qubit-mode structure

    SciTech Connect (OSTI)

    Rigas, Johannes; Luetkenhaus, Norbert

    2006-01-15

    We consider entanglement detection for quantum-key-distribution systems that use two signal states and continuous-variable measurements. This problem can be formulated as a separability problem in a qubit-mode system. To verify entanglement, we introduce an object that combines the covariance matrix of the mode with the density matrix of the qubit. We derive necessary separability criteria for this scenario. These criteria can be readily evaluated using semidefinite programming and we apply them to the specific quantum key distribution protocol.

  16. DOE Publishes CALiPER Report on Chromaticity Shift Modes of LED PAR38 Lamps

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

    | Department of Energy CALiPER Report on Chromaticity Shift Modes of LED PAR38 Lamps DOE Publishes CALiPER Report on Chromaticity Shift Modes of LED PAR38 Lamps March 23, 2016 - 11:33am Addthis The U.S. Department of Energy's CALiPER program has released Report 20.5, which is part of a series of investigations on LED PAR38 lamps. The new report builds on CALiPER Report 20.4 by providing a tear-down analysis of its 32 LED PAR38 lamp models and also performing additional analyses on the

  17. Strong ''Quantum'' Chaos in the Global Ballooning Mode Spectrum of Three-Dimensional Plasmas

    SciTech Connect (OSTI)

    Dewar, R. L.; Cuthbert, P.; Ball, R.

    2001-03-12

    The spectrum of ideal magnetohydrodynamic (MHD) pressure-driven (ballooning) modes in strongly nonaxisymmetric toroidal systems is difficult to analyze numerically owing to the singular nature of ideal MHD caused by lack of an inherent scale length. In this paper, ideal MHD is regularized by using a k -space cutoff, making the ray tracing for the WKB ballooning formalism a chaotic Hamiltonian billiard problem. The minimum width of the toroidal Fourier spectrum needed for resolving toroidally localized ballooning modes with a global eigenvalue code is estimated from the Weyl formula. This phase-space-volume estimation method is applied to two stellarator cases.

  18. The Theory of the Kink Mode during the Vertical Disruption Events in Tokamaks

    SciTech Connect (OSTI)

    Leonid E. Zakharov

    2008-01-14

    This paper explains the locked m/n = 1/1 kink mode during the vertical disruption event when the plasma has an electrical contact with the plasma facing conducting surfaces. It is shown that the kink perturbation can be in equilibrium state even with a stable safety factor q > 1, if the halo currents, excited by the kink mode, can flow through the conducting structure. This suggests a new explanation of the so-called sideway forces on the tokamak in-vessel components during the disruption event. __________________________________________________

  19. Irregular-regular-irregular mixed mode oscillations in a glow discharge plasma

    SciTech Connect (OSTI)

    Ghosh, Sabuj Shaw, Pankaj Kumar Saha, Debajyoti Janaki, M. S. Iyengar, A. N. Sekar

    2015-05-15

    Floating potential fluctuations of a glow discharge plasma are found to exhibit different kinds of mixed mode oscillations. Power spectrum analysis reveals that with change in the nature of the mixed mode oscillation (MMO), there occurs a transfer of power between the different harmonics and subharmonics. The variation in the chaoticity of different types of mmo was observed with the study of Lyapunov exponents. Estimates of correlation dimension and the Hurst exponent suggest that these MMOs are of low dimensional nature with an anti persistent character. Numerical modeling also reflects the experimentally found transitions between the different MMOs.

  20. Search for Majoron-emitting modes of double-beta decay of Xe 136 with

    Office of Scientific and Technical Information (OSTI)

    EXO-200 (Journal Article) | SciTech Connect Search for Majoron-emitting modes of double-beta decay of Xe 136 with EXO-200 Citation Details In-Document Search Title: Search for Majoron-emitting modes of double-beta decay of Xe 136 with EXO-200 Authors: Albert, J. B. ; Auty, D. J. ; Barbeau, P. S. ; Beauchamp, E. ; Beck, D. ; Belov, V. ; Benitez-Medina, C. ; Breidenbach, M. ; Brunner, T. ; Burenkov, A. ; Cao, G. F. ; Chambers, C. ; Chaves, J. ; Cleveland, B. ; Coon, M. ; Craycraft, A. ;

  1. Waste compatibility safety issues and final results for tank 241-T-110 push mode samples

    SciTech Connect (OSTI)

    Nuzum, J.L.

    1997-05-15

    This document is the final laboratory report for Tank 241-T-110. Push mode core segments were removed from risers 2 and 6 between January 29, 1997, and February 7, 1997. Segments were received and extruded at 222-S Laboratory. Analyses were performed in accordance with Tank 241-T-110 Push Mode Core Sampling and analysis Plan (TSAP) and Safety Screening Data Quality Objective (DQO). None of the subsamples submitted for total alpha activity (AT) or differential scanning calorimetry (DSC) analyses exceeded the notification limits stated in DQO.

  2. Vacuum-induced Berry phases in single-mode Jaynes-Cummings models

    SciTech Connect (OSTI)

    Liu, Yu; Wei, L. F.; Jia, W. Z. [Quantum Optoelectronics Laboratory, School of Physics and Technology, Southwest Jiaotong University, Chengdu 610031 (China); Liang, J. Q. [Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006 (China)

    2010-10-15

    Motivated by work [Phys. Rev. Lett. 89, 220404 (2002)] for detecting the vacuum-induced Berry phases with two-mode Jaynes-Cummings models (JCMs), we show here that, for a parameter-dependent single-mode JCM, certain atom-field states also acquired photon-number-dependent Berry phases after the parameter slowly changed and eventually returned to its initial value. This geometric effect related to the field quantization still exists, even if the field is kept in its vacuum state. Specifically, a feasible Ramsey interference experiment with a cavity quantum electrodynamics system is designed to detect the vacuum-induced Berry phase.

  3. Three-dimensional simulation of H-mode plasmas with localized divertor

    Office of Scientific and Technical Information (OSTI)

    impurity injection on Alcator C-Mod using the edge transport code EMC3-EIRENE (Journal Article) | SciTech Connect Three-dimensional simulation of H-mode plasmas with localized divertor impurity injection on Alcator C-Mod using the edge transport code EMC3-EIRENE Citation Details In-Document Search Title: Three-dimensional simulation of H-mode plasmas with localized divertor impurity injection on Alcator C-Mod using the edge transport code EMC3-EIRENE Experiments in Alcator C-Mod to assess

  4. Three-dimensional simulation of H-mode plasmas with localized divertor

    Office of Scientific and Technical Information (OSTI)

    impurity injection on Alcator C-Mod using the edge transport code EMC3-EIRENEa) (Journal Article) | SciTech Connect Three-dimensional simulation of H-mode plasmas with localized divertor impurity injection on Alcator C-Mod using the edge transport code EMC3-EIRENEa) Citation Details In-Document Search Title: Three-dimensional simulation of H-mode plasmas with localized divertor impurity injection on Alcator C-Mod using the edge transport code EMC3-EIRENEa) Authors: Lore, J. D. [1] ; Reinke,

  5. Polarization mode control of long-wavelength VCSELs by intracavity patterning

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

    Long, Christopher Michael; Mickovic, Zlatko; Dwir, Benjamin; Caliman, Andrei; Iakovlev, Vladimir; Mereuta, Alexandru; Sirbu, Alexei; Kapon, Eli

    2016-04-26

    Polarization mode control is enhanced in wafer-fused vertical-cavity surface-emitting lasers emitting at 1310 nm wavelength by etching two symmetrically arranged arcs above the gain structure within the laser cavity. The intracavity patterning introduces birefringence and dichroism, which discriminates between the two polarization states of the fundamental transverse modes. We find that the cavity modifications define the polarization angle at threshold with respect to the crystal axes, and increase the gain anisotropy and birefringence on average, leading to an increase in the polarization switching current. As a result, experimental measurements are explained using the spin-flip model of VCSEL polarization dynamics.

  6. Mode Conversion of Langmuir to Electromagnetic Waves with Parallel Inhomogeneity in the Solar Wind and the Corona

    SciTech Connect (OSTI)

    Kim, Eun-Hwa; Cairns, Iver H.; Robinson, Peter A.

    2008-06-09

    Linear mode conversion of Langmuir waves to radiation near the plasma frequency at density gradients is potentially relevant to multiple solar radio emissions, ionospheric radar experiments, laboratory plasma devices, and pulsars. Here we study mode conversion in warm magnetized plasmas using a numerical electron fluid simulation code with the density gradient parallel to the ambient magnetic field B0 for a range of incident Langmuir wavevectors. Our results include: (1) Both o- and x-mode waves are produced for ? ? (?L)1/3(?c/?) somewhat less than 1, contrary to previous ideas. Only o mode is produced for ? and somewhat greater than 1.5. Here ?c is the (angular) electron cyclotron frequency, ? the angular wave frequency, and L the length scale of the (linear) density gradient. (2) In the unmagnetized limit, equal amounts of o- and x-mode radiation are produced. (3) The mode conversion window narrows as ? increases. (4) As ? increases the total electromagnetic field changes from linear to circular polarization, with the o- and x- mode signals remaining circularly polarized. (5) The conversion efficiency to the x mode decreases monotonically as ? increases while the o-mode conversion efficiency oscillates due to an interference phenomenon between incoming and reflected Langmuir/z modes. (6) The total conversion efficiency for wave energy from the Langmuir/z mode to radiation is typically less than 10%, but the corresponding power efficiencies differ by the ratio of the group speeds for each mode and are of order 50 70%. (7) The interference effect and the disappearance of the x mode at ? somewhat greater than 1 can be accounted for semiquantitatively using a WKB-like analysis. (8) Constraints on density turbulence are developed for the x mode to be generated and be able to propagate from the source. (9) Standard parameters for the corona and the solar wind near 1 AU suggest that linear mode conversion should produce both o- and x- mode radiation for solar and interplanetary radio bursts. It is therefore possible that linear mode conversion under these conditions might explain the weak total circular polarizations of type II and III solar radio bursts.

  7. Edge radial electric field structure and its connections to H-mode confinement in Alcator C-Mod plasmas

    SciTech Connect (OSTI)

    McDermott, R. M.; Lipschultz, B.; Hughes, J. W.; Catto, P. J.; Hubbard, A. E.; Hutchinson, I. H.; Granetz, R. S.; Greenwald, M.; LaBombard, B.; Marr, K.; Reinke, M. L.; Rice, J. E.; Whyte, D.

    2009-05-15

    High-resolution charge-exchange recombination spectroscopic measurements of B{sup 5+} ions have enabled the first spatially resolved calculations of the radial electric field (E{sub r}) in the Alcator C-Mod pedestal region [E. S. Marmar, Fusion Sci. Technol. 51, 261 (2006)]. These observations offer new challenges for theory and simulation and provide for important comparisons with other devices. Qualitatively, the field structure observed on C-Mod is similar to that on other tokamaks. However, the narrow high-confinement mode (H-mode) E{sub r} well widths (5 mm) observed on C-Mod suggest a scaling with machine size, while the observed depths (up to 300 kV/m) are unprecedented. Due to the strong ion-electron thermal coupling in the C-Mod pedestal, it is possible to infer information about the main ion population in this region. The results indicate that in H-mode the main ion pressure gradient is the dominant contributor to the E{sub r} well and that the main ions have significant edge flow. C-Mod H-mode data show a clear correlation between deeper E{sub r} wells, higher confinement plasmas, and higher electron temperature pedestal heights. However, improved L-mode (I-mode) plasmas exhibit energy confinement equivalent to that observed in similar H-mode discharges, but with significantly shallower E{sub r} wells. I-mode plasmas are characterized by H-mode-like energy barriers, but with L-mode-like particle barriers. The decoupling of energy and particle barrier formation makes the I-mode an interesting regime for fusion research and provides for a low collisionality pedestal without edge localized modes.

  8. 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.

  9. Optical apparatus for conversion of whispering-gallery modes into a free space gaussian like beam

    DOE Patents [OSTI]

    Stallard, B.W.; Makowski, M.A.; Byers, J.A.

    1992-05-19

    An optical converter for efficient conversion of millimeter wavelength whispering-gallery gyrotron output into a linearly polarized, free-space Gaussian-like beam is described. The converter uses a mode-converting taper and three mirror optics. The first mirror has an azimuthal tilt to eliminate the k[sub [phi

  10. How much are Chevrolet Volts in The EV Project driven in EV Mode?

    SciTech Connect (OSTI)

    John Smart

    2013-08-01

    This report summarizes key conclusions from analysis of data collected from Chevrolet Volts participating in The EV Project. Topics include how many miles are driven in EV mode, how far vehicles are driven between charging events, and how much energy is charged from the electric grid per charging event.

  11. Structural integrity and potential failure modes of hanford high-level waste tanks

    SciTech Connect (OSTI)

    Han, F.C.

    1996-09-30

    Structural Integrity of the Hanford High-Level Waste Tanks were evaluated based on the existing Design and Analysis Documents. All tank structures were found adequate for the normal operating and seismic loads. Potential failure modes of the tanks were assessed by engineering interpretation and extrapolation of the existing engineering documents.

  12. Zonal flow dynamics in the double tearing mode with antisymmetric shear flows

    SciTech Connect (OSTI)

    Mao, Aohua [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China) [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan); Li, Jiquan, E-mail: lijq@energy.kyoto-u.ac.jp [Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan)] [Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan); Liu, Jinyuan, E-mail: jyliu@dlut.edu.cn [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Kishimoto, Yasuaki [Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan) [Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan); Institude of Advanced Energy, Kyoto University, Uji, Kyoto 6110011 (Japan)

    2014-05-15

    The generation dynamics and the structural characteristics of zonal flows are investigated in the double tearing mode (DTM) with antisymmetric shear flows. Two kinds of zonal flow oscillations are revealed based on reduced resistive magnetohydrodynamics simulations, which depend on the shear flow amplitudes corresponding to different DTM eigen mode states, elaborated by Mao et al. [Phys. Plasmas 20, 022114 (2013)]. For the weak shear flows below an amplitude threshold, v{sub c}, at which two DTM eigen states with antisymmetric or symmetric magnetic island structure are degenerated, the zonal flows grow oscillatorily in the Rutherford regime during the nonlinear evolution of the DTMs. It is identified that the oscillation mechanism results from the nonlinear interaction between the distorted islands and the zonal flows through the modification of shear flows. However, for the medium shear flows above v{sub c} but below the critical threshold of the Kelvin-Helmholtz instability, an oscillatory growing zonal flow occurs in the linear phase of the DTM evolution. It is demonstrated that the zonal flow oscillation originates from the three-wave mode coupling or a modulation instability pumped by two DTM eigen modes with the same frequency but opposite propagating direction. With the shear flows increasing, the amplitude of zonal flow oscillation increases first and then decreases, whilst the oscillation frequency as twice of the Doppler frequency shift increases. Furthermore, impacts of the oscillatory zonal flows on the nonlinear evolution of DTM islands and the global reconnection are also discussed briefly.

  13. Picosecond pulses produced by mode locking a Nd:glass laser with Kodak dye number26

    SciTech Connect (OSTI)

    Schiller, N.H.; Foresti, M.; Alfano, R.R.

    1985-05-01

    Kodak dye number26 was used to generate picosecond laser pulses by mode locking a Nd:glass laser. The intensity profiles and characteristics of the pulses were compared with those of pulses emitted using dyes number5 and number9860.

  14. Mixed-mode diesel HCCI with External Mixture Formation: Preliminary Results

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

    | Department of Energy 3 DEER Conference Presentation: The Ohio State University PDF icon 2003_deer_rizzoni.pdf More Documents & Publications Diesel HCCI with External Mixture Preparation Gasoline-like fuel effects on advanced combustion regimes A Mixed Mode HCCI/DI Engine Based on a Novel Heavy Fuel Atomizer

  15. Operability test report for rotary mode core sampling system number 3

    SciTech Connect (OSTI)

    Corbett, J.E.

    1996-03-01

    This report documents the successful completion of operability testing for the Rotary Mode Core Sampling (RMCS) system {number_sign}3. The Report includes the test procedure (WHC-SD-WM-OTP-174), exception resolutions, data sheets, and a test report summary.

  16. WET-NZ Multi-Mode Wave Energy Converter Advancement Project

    SciTech Connect (OSTI)

    Klure, Justin

    2011-11-01

    Presentation from the 2011 Water Peer Review in which the principal investigator discussed the next steps to verify a multi-mode functionality of the WET-NZ device. This included overview of the approaches taken to perform wave tank testing, open ocean deployment, synthesis and analysis.

  17. On the single-photon-counting (SPC) modes of imaging using an XFEL source

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

    Wang, Zhehui

    2015-12-14

    In this study, the requirements to achieve high detection efficiency (above 50%) and gigahertz (GHz) frame rate for the proposed 42-keV X-ray free-electron laser (XFEL) at Los Alamos are summarized. Direct detection scenarios using C (diamond), Si, Ge and GaAs semiconductor sensors are analyzed. Single-photon counting (SPC) mode and weak SPC mode using Si can potentially meet the efficiency and frame rate requirements and be useful to both photoelectric absorption and Compton physics as the photon energy increases. Multilayer three-dimensional (3D) detector architecture, as a possible means to realize SPC modes, is compared with the widely used two-dimensional (2D) hybridmore » planar electrode structure and 3D deeply entrenched electrode architecture. Demonstration of thin film cameras less than 100-μm thick with onboard thin ASICs could be an initial step to realize multilayer 3D detectors and SPC modes for XFELs.« less

  18. Experience with Aerosol Generation During Rotary Mode Core Sampling in the Hanford Single Shell Waste Tanks

    SciTech Connect (OSTI)

    SCHOFIELD, J.S.

    2000-01-24

    This document provides data on aerosol concentrations in tank head spaces, total mass of aerosols in the tank head space and mass of aerosols sent to the exhauster during Rotary Mode Core Sampling from November 1994 through June 1999. A decontamination factor for the RMCS exhauster filter housing is calculated based on operation data.

  19. Real time MHD mode control using ECCD in KSTAR: Plan and requirements

    SciTech Connect (OSTI)

    Joung, M.; Woo, M. H.; Jeong, J. H.; Hahn, S. H.; Yun, S. W.; Lee, W. R.; Bae, Y. S.; Oh, Y. K.; Kwak, J. G.; Yang, H. L.; Namkung, W.; Park, H.; Cho, M. H.; Kim, M. H.; Kim, K. J.; Na, Y. S.; Hosea, J.; Ellis, R.

    2014-02-12

    For a high-performance, advanced tokamak mode in KSTAR, we have been developing a real-time control system of MHD modes such as sawtooth and Neo-classical Tearing Mode (NTM) by ECH/ECCD. The active feedback control loop will be also added to the mirror position and the real-time detection of the mode position. In this year, for the stabilization of NTM that is crucial to plasma performance we have implemented open-loop ECH antenna control system in KSTAR Plasma Control System (PCS) for ECH mirror movement during a single plasma discharge. KSTAR 170 GHz ECH launcher which was designed and fabricated by collaboration with PPPL and POSTECH has a final mirror of a poloidally and toroidally steerable mirror. The poloidal steering motion is only controlled in the real-time NTM control system and its maximum steering speed is 10 degree/sec by DC motor. However, the latency of the mirror control system and the return period of ECH antenna mirror angle are not fast because the existing launcher mirror control system is based on PLC which is connected to the KSTAR machine network through serial to LAN converter. In this paper, we present the design of real time NTM control system, ECH requirements, and the upgrade plan.

  20. A Summary of Taxonomies of Digital System Failure Modes Provided by the DigRel Task Group

    SciTech Connect (OSTI)

    Chu T. L.; Yue M.; Postma, W.

    2012-06-25

    Recently, the CSNI directed WGRisk to set up a task group called DIGREL to initiate a new task on developing a taxonomy of failure modes of digital components for the purposes of PSA. It is an important step towards standardized digital I&C reliability assessment techniques for PSA. The objective of this paper is to provide a comparison of the failure mode taxonomies provided by the participants. The failure modes are classified in terms of their levels of detail. Software and hardware failure modes are discussed separately.

  1. Effect of the drift wave turbulence on the evolution of the low-[ital m] tearing modes

    SciTech Connect (OSTI)

    Siva Rama Prasad, P.V.; Tewari, D.P. )

    1994-01-01

    The effect of the background drift wave turbulence on the evolution of the low-[ital m] tearing modes has been studied, in the quasilinear regime, in various limiting cases. It is found, in the cases of the [ital m]=1 classical, collisionless, and drift-tearing modes, that the turbulence introduces finite real frequencies to these modes, which are otherwise purely growing ones, but reduces their instability activity. In the case of the [ital m][ge]2 classical modes, in a limit [vert bar][alpha][vert bar][sup 1/2][much gt][rho][sub [ital i

  2. Gyro-fluid and two-fluid theory and simulations of edge-localized-modes

    SciTech Connect (OSTI)

    Xu, X. Q.; Dimits, A.; Joseph, I.; Umansky, M. V.; Xi, P. W.; School of Physics, Peking University, Beijing ; Xia, T. Y.; Gui, B.; Institute of Plasma Physics, Chinese Academy of Sciences, Hefei ; Kim, S. S.; Park, G. Y.; Rhee, T.; Jhang, H.; Diamond, P. H.; Center for Astrophysics and Space Sciences and Department of Physics, University of California, San Diego, La Jolla, California 92093-0424 ; Dudson, B.; Snyder, P. B.

    2013-05-15

    This paper reports on the theoretical and simulation results of a gyro-Landau-fluid extension of the BOUT++ code, which contributes to increasing the physics understanding of edge-localized-modes (ELMs). Large ELMs with low-to-intermediate-n peeling-ballooning (P-B) modes are significantly suppressed due to finite Larmor radius (FLR) effects when the ion temperature increases. For type-I ELMs, it is found from linear simulations that retaining complete first order FLR corrections as resulting from the incomplete “gyroviscous cancellation” in Braginskii's two-fluid model is necessary to obtain good agreement with gyro-fluid results for high ion temperature cases (T{sub i}≽3 keV) when the ion density has a strong radial variation, which goes beyond the simple local model of ion diamagnetic stabilization of ideal ballooning modes. The maximum growth rate is inversely proportional to T{sub i} because the FLR effect is proportional to T{sub i}. The FLR effect is also proportional to toroidal mode number n, so for high n cases, the P-B mode is stabilized by FLR effects. Nonlinear gyro-fluid simulations show results that are similar to those from the two-fluid model, namely that the P-B modes trigger magnetic reconnection, which drives the collapse of the pedestal pressure. Due to the additional FLR-corrected nonlinear E × B convection of the ion gyro-center density, for a ballooning-dominated equilibrium the gyro-fluid model further limits the radial spreading of ELMs. In six-field two fluid simulations, the parallel thermal diffusivity is found to prevent the ELM encroachment further into core plasmas and therefore leads to steady state L-mode profiles. The simulation results show that most energy is lost via ion channel during an ELM event, followed by particle loss and electron energy loss. Because edge plasmas have significant spatial inhomogeneities and complicated boundary conditions, we have developed a fast non-Fourier method for the computation of Landau-fluid closure terms based on an accurate and tunable approximation. The accuracy and the fast computational scaling of the method have been demonstrated.

  3. Higher order mode filter design for double quarter wave crab cavity for the LHC high luminosity upgrade

    SciTech Connect (OSTI)

    Xiao, B.; Belomestnykh, S.; Ben-Zvi, I.; Burt, G.; Calaga, R.; Capatina, O.; Hall, B.; Jones, T.; Skaritka, J.; Verdu-Andres, S.; Wu, Q.

    2015-05-03

    A Double Quarter Wave Crab Cavity (DQWCC) was designed for the Large Hadron Collider (LHC) luminosity upgrade. A compact Higher Order Mode (HOM) filter with wide stop band at the deflecting mode is developed for this cavity. Multiphysics finite element simulation results are presented. The integration of this design to the cavity cryomodule is described.

  4. Roles of poloidal rotation in the q = 1 high-order harmonic tearing modes in a tokamak plasma

    SciTech Connect (OSTI)

    Wei Lai; Wang Zhengxiong

    2013-01-15

    Roles of poloidal rotation in stabilizing the m/n=1/1 kink-tearing mode and exciting its high-order harmonic tearing modes are numerically investigated by using a reduced magnetohydrodynamic model. It is found that the high-order harmonic tearing modes, such as m/n=2/2, m/n=3/3, or even much higher-m harmonics, can be destabilized so significantly by rotation shear as to be more unstable than or comparable to the m/n=1/1 mode. Moreover, the short wave-length Kelvin- Helmholtz (KH) instabilities can be excited in the large rotation shear regime. The scaling power laws of the linear growth rate for each harmonic mode in different rotation shear regimes are verified by the previous relevant theoretical results based on the non-constant-{psi} and constant-{psi} behavior categories in tearing modes. During the nonlinear evolution, the m/n=2/2 mode dominated phase first appears and then is followed by the m/n=1/1 mode dominated nonlinear phase instead. Afterward, some smaller sub-islands due to the high-order harmonics are produced in the large irregular m=1 crescent-shaped island, and then a coalescence process of turbulent island chains occurs before the decay phase.

  5. Width dependent transition of quantized spin-wave modes in Ni{sub 80}Fe{sub 20} square nanorings

    SciTech Connect (OSTI)

    Banerjee, Chandrima; Saha, Susmita; Barman, Saswati; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Rousseau, Olivier [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Otani, YoshiChika [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

    2014-10-28

    We investigated optically induced ultrafast magnetization dynamics in square shaped Ni{sub 80}Fe{sub 20} nanorings with varying ring width. Rich spin-wave spectra are observed whose frequencies showed a strong dependence on the ring width. Micromagnetic simulations showed different types of spin-wave modes, which are quantized upto very high quantization number. In the case of widest ring, the spin-wave mode spectrum shows quantized modes along the applied field direction, which is similar to the mode spectrum of an antidot array. As the ring width decreases, additional quantization in the azimuthal direction appears causing mixed modes. In the narrowest ring, the spin-waves exhibit quantization solely in azimuthal direction. The different quantization is attributed to the variation in the internal field distribution for different ring width as obtained from micromagnetic analysis and supported by magnetic force microscopy.

  6. Q-switched and mode-locked Er{sup 3+}-doped fibre laser using a single-multi-single fibre filter and piezoelectric

    SciTech Connect (OSTI)

    Ji Wang; Yunjun Zhang; Aotuo Dong; Xiaoxin Xu; Youlun Ju; Baoquan Yao

    2014-04-28

    The active Q-switched and passive mode-locked Er{sup 3+}-doped all-fibre laser is presented. The fibre laser centre wavelength is located at 1563 nm and determined by the homemade singlemulti- single (SMS) in-line fibre filter. The laser spectrum width is nearly 0.1 nm. The active Q-switched mechanism relies on the polarisation state control using a piezoelectric to press a segment of passive fibre on the circular cavity. The nonlinear polarisation rotation technology is used to realise the passive self-started modelocked operation. In the passive mode-locked regimes, the output average power is 2.1 mW, repetition frequency is 11.96 MHz, and single pulse energy is 0.18 nJ. With the 100-Hz Q-switched regimes running, the output average power is 1.5 mW. The total Q-switched pulse width is 15 μs, and every Q-switched pulse is made up by several tens of mode-locked peak pulses. The calculated output pulse energy of the Q-switched fibre laser is about 15 μJ, and the energy of every mode-locked pulse is about 64–68 nJ during a Q-switched pulse taking into account the power fraction propagating between pulses. (lasers)

  7. Current distribution measurements inside an electromagnetic plasma gun operated in a gas-puff mode

    SciTech Connect (OSTI)

    Poehlmann, Flavio R.; Cappelli, Mark A.; Rieker, Gregory B.

    2010-12-15

    Measurements are presented of the time-dependent current distribution inside a coaxial electromagnetic plasma gun. The measurements are carried out using an array of six axially distributed dual-Rogowski coils in a balanced circuit configuration. The radial current distributions indicate that operation in the gas-puff mode, i.e., the mode in which the electrode voltage is applied before injection of the gas, results in a stationary ionization front consistent with the presence of a plasma deflagration. The effects of varying the bank capacitance, transmission line inductance, and applied electrode voltage were studied over the range from 14 to 112 {mu}F, 50 to 200 nH, and 1 to 3 kV, respectively.

  8. Impact of inward turbulence spreading on energy loss of edge-localized modes

    SciTech Connect (OSTI)

    Ma, C. H.; Xi, P. W.; Xu, X. Q.; Xia, T. Y.; Snyder, P. B.; Kim, S. S.

    2015-05-15

    Nonlinear two-fluid and gyrofluid simulations show that an edge localized modes (ELM) crash has two phases: fast initial crash of ion temperature perturbation on the Alfvén time scale and slow turbulence spreading. The turbulence transport phase is a slow encroachment of electron temperature perturbation due to the ELM event into pedestal region. Because of the inward turbulence spreading effect, the energy loss of an ELM decreases when density pedestal height increases. The Landau resonance yields the different cross phase-shift of ions and electrons. A 3 + 1 gyro-Landau-fluid model is implemented in BOUT++ framework. The gyrofluid simulations show that the kinetic effects have stabilizing effects on the ideal ballooning mode and the energy loss increases with the pedestal height.

  9. phi-meson photoproduction on Hydrogen in the neutral decay mode

    SciTech Connect (OSTI)

    Seraydaryan, Helena; Amaryan, Moscov J.; Gavalian, Gagik; Baghdasaryan, Hovhannes A.; Weinstein, Larry

    2014-05-01

    We report the first measurement of the photoproduction cross section of the $\\phi$ meson in its neutral decay mode in the reaction $\\gamma p \\to p\\phi(K_SK_L)$. The experiment was performed with a tagged photon beam of energy $1.6 \\le E_\\gamma \\le 3.6$ GeV incident on a liquid hydrogen target of the CLAS spectrometer at the Thomas Jefferson National Accelerator Facility. The $p \\phi$ final state is identified via reconstruction of $K_S$ in the invariant mass of two oppositely charged pions and by requiring the missing particle in the reaction $\\gamma p \\to p K_S X$ to be $K_L$. The presented results significantly enlarge the existing data on $\\phi$-photoproduction. These data, combined with the data from the charged decay mode, will help to constrain different mechanisms of $\\phi$ photoproduction.

  10. Numerical study on the influence of electron cyclotron current drive on tearing mode

    SciTech Connect (OSTI)

    Chen, Long; Liu, Jinyuan; Mao, Aohua; Sun, Jizhong, E-mail: jsun@dlut.edu.cn [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Duan, Ping [Department of Physics, Dalian Maritime University, Dalian 116026 (China)

    2014-10-15

    Controlling tearing modes by localized current drive is explored by using numerical simulation with a set of compressible magnetohydrodynamics equations. By examining the effects of different characteristics of driven current, such as density distribution, duration time, and deposition location, it is found that a driven current with larger magnitude and more focused deposition region shows a better suppression effect on the tearing modes. Meanwhile destabilizing effects are also observed when a driven current over a certain magnitude is applied continuously. In comparison with those on the X-point of the magnetic island, the results are better when the current deposition is targeted on the O-point. In addition, the timing control of the current deposition will be also addressed.

  11. Acoustic wave device using plate modes with surface-parallel displacement

    DOE Patents [OSTI]

    Martin, S.J.; Ricco, A.J.

    1988-04-29

    Solid-state acoustic sensors for monitoring conditions at a surface immersed in a liquid and for monitoring concentrations of species in a liquid and for monitoring electrical properties of a liquid are formed by placing interdigital input and output transducers on a piezoelectric substrate and propagating acoustic plate modes therebetween. The deposition or removal of material on or from, respectively, a thin film in contact with the surface, or changes in the mechanical properties of a thin film in contact with the surface, or changes in the electrical characteristics of the solution, create perturbations in the velocity and attenuation of the acoustic plate modes as a function of these properties or changes in them. 6 figs.

  12. Finite ballooning angle effects on ion temperature gradient driven mode in gyrokinetic flux tube simulations

    SciTech Connect (OSTI)

    Singh, Rameswar, E-mail: rameswar.singh@lpp.polytechnique.fr [Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 (India) [Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 (India); Laboratoire de Physique des Plasmas, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Brunner, S. [CRPP, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland)] [CRPP, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Ganesh, R. [Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 (India)] [Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 (India); Jenko, F. [Max-Planck-Institut fur Plasmaphysik, EURATOM Association, D-85748 Garching (Germany)] [Max-Planck-Institut fur Plasmaphysik, EURATOM Association, D-85748 Garching (Germany)

    2014-03-15

    This paper presents effects of finite ballooning angles on linear ion temperature gradient (ITG) driven mode and associated heat and momentum flux in Gyrokinetic flux tube simulation GENE. It is found that zero ballooning angle is not always the one at which the linear growth rate is maximum. The ITG mode acquires a short wavelength (SW) branch (k{sub ?}?{sub i}?>?1) when growth rates maximized over all ballooning angles are considered. However, the SW branch disappears on reducing temperature gradient showing characteristics of zero ballooning angle SWITG in case of extremely high temperature gradient. Associated heat flux is even with respect to ballooning angle and maximizes at nonzero ballooning angle while the parallel momentum flux is odd with respect to the ballooning angle.

  13. Method and apparatus for acoustic plate mode liquid-solid phase transition detection

    DOE Patents [OSTI]

    Blair, Dianna S.; Freye, Gregory C.; Hughes, Robert C.; Martin, Stephen J.; Ricco, Antonio J.

    1993-01-01

    A method and apparatus for sensing a liquid-solid phase transition event is provided which comprises an acoustic plate mode detecting element placed in contact with a liquid or solid material which generates a high-frequency acoustic wave that is attenuated to an extent based on the physical state of the material is contact with the detecting element. The attenuation caused by the material in contact with the acoustic plate mode detecting element is used to determine the physical state of the material being detected. The method and device are particularly suited for detecting conditions such as the icing and deicing of wings of an aircraft. In another aspect of the present invention, a method is provided wherein the adhesion of a solid material to the detecting element can be measured using the apparatus of the invention.

  14. Acoustic wave device using plate modes with surface-parallel displacement

    DOE Patents [OSTI]

    Martin, Stephen J.; Ricco, Antonio J.

    1992-01-01

    Solid-state acoustic sensors for monitoring conditions at a surface immersed in a liquid and for monitoring concentrations of species in a liquid and for monitoring electrical properties of a liquid are formed by placing interdigital input and output transducers on a piezoelectric substrate and propagating acoustic plate modes therebetween. The deposition or removal of material on or from, respectively, a thin film in contact with the surface, or changes in the mechanical properties of a thin film in contact with the surface, or changes in the electrical characteristics of the solution, create perturbations in the velocity and attenuation of the acoustic plate modes as a function of these properties or changes in them.

  15. Acoustic wave device using plate modes with surface-parallel displacement

    DOE Patents [OSTI]

    Martin, S.J.; Ricco, A.J.

    1992-05-26

    Solid-state acoustic sensors for monitoring conditions at a surface immersed in a liquid and for monitoring concentrations of species in a liquid and for monitoring electrical properties of a liquid are formed by placing interdigital input and output transducers on a piezoelectric substrate and propagating acoustic plate modes there between. The deposition or removal of material on or from, respectively, a thin film in contact with the surface, or changes in the mechanical properties of a thin film in contact with the surface, or changes in the electrical characteristics of the solution, create perturbations in the velocity and attenuation of the acoustic plate modes as a function of these properties or changes in them. 6 figs.

  16. Microelectromechanical filter formed from parallel-connected lattice networks of contour-mode resonators

    DOE Patents [OSTI]

    Wojciechowski, Kenneth E; Olsson, III, Roy H; Ziaei-Moayyed, Maryam

    2013-07-30

    A microelectromechanical (MEM) filter is disclosed which has a plurality of lattice networks formed on a substrate and electrically connected together in parallel. Each lattice network has a series resonant frequency and a shunt resonant frequency provided by one or more contour-mode resonators in the lattice network. Different types of contour-mode resonators including single input, single output resonators, differential resonators, balun resonators, and ring resonators can be used in MEM filter. The MEM filter can have a center frequency in the range of 10 MHz-10 GHz, with a filter bandwidth of up to about 1% when all of the lattice networks have the same series resonant frequency and the same shunt resonant frequency. The filter bandwidth can be increased up to about 5% by using unique series and shunt resonant frequencies for the lattice networks.

  17. Intermediate energy electron impact excitation of composite vibrational modes in phenol

    SciTech Connect (OSTI)

    Neves, R. F. C.; Jones, D. B.; Lopes, M. C. A.; Nixon, K. L.; Oliveira, E. M. de; Lima, M. A. P.; Costa, R. F. da; Varella, M. T. do N.; Bettega, M. H. F.; Silva, G. B. da; Brunger, M. J.

    2015-05-21

    We report differential cross section results from an experimental investigation into the electron impact excitation of a number of the low-lying composite (unresolved) vibrational modes in phenol (C{sub 6}H{sub 5}OH). The measurements were carried out at incident electron energies in the range 15–40 eV and for scattered-electron angles in the range 10–90°. The energy resolution of those measurements was typically ∼80 meV. Calculations, using the GAMESS code, were also undertaken with a B3LYP/aug-cc-pVDZ level model chemistry, in order to enable us to assign vibrational modes to the features observed in our energy loss spectra. To the best of our knowledge, the present cross sections are the first to be reported for vibrational excitation of the C{sub 6}H{sub 5}OH molecule by electron impact.

  18. Suppression criteria of parasitic mode oscillations in a gyrotron beam tunnel

    SciTech Connect (OSTI)

    Kumar, Nitin; Singh, Udaybir; Sinha, A. K.; Singh, T. P.

    2011-02-15

    This paper presents the design criteria of the parasitic mode oscillations suppression for a periodic, ceramic, and copper loaded gyrotron beam tunnel. In such a type of beam tunnel, the suppression of parasitic mode oscillations is an important design problem. A method of beam-wave coupling coefficient and its mathematical formulation are presented. The developed design criteria are used in the beam tunnel design of a 42 GHz gyrotron to be developed for the Indian TOKAMAK system. The role of the thickness and the radius of the beam tunnel copper rings to obtain the developed design criteria are also discussed. The commercially available electromagnetic code CST and the electron trajectory code EGUN are used for the simulations.

  19. Double Quarter Wave Crab Cavity Field Profile Analysis and Higher Order Mode Characterization

    SciTech Connect (OSTI)

    Marques, Carlos; Xiao, B. P.; Belomestnykh, S.

    2014-06-01

    The Large Hadron Collider (LHC) is underway for a major upgrade to increase its luminosity by an order of magnitude beyond its original design specifications. This novel machine configuration known as the High Luminosity LHC (HL-LHC) will rely on various innovative technologies including very compact and ultra-precise superconducting crab cavities for beam rotation. A double quarter wave crab cavity (DQWCC) has been designed at Brookhaven National Laboratory for the HL-LHC. This cavity as well as the structural support components were fabricated and assembled at Niowave. The field profile of the crabbing mode for the DQWCC was investigated using a phase shift bead pulling technique and compared with simulated results to ensure proper operation or discover discrepancies from modeled results and/or variation in fabrication tolerances. Higher-Order Mode (HOM) characterization was also performed and correlated with simulations.

  20. Survey on Failure Modes and Failure Mechanisms in Digital Components and Systems

    SciTech Connect (OSTI)

    Cetiner, Mustafa Sacit; Korsah, Kofi; Muhlheim, Michael David

    2009-01-01

    This paper presents the preliminary results of a survey on the operating experience of a broad range of digital components and systems deployed in various industries. The primary objective of this survey is to identify principal modes and mechanisms of failure in field-deployed digital systems. Earlier works have sought to determine the failure rates of various classes of digital devices with the intent to integrate this information into the risk analysis calculations though still immature for such systems. Failure rates of individual components or systems are not taken into account in this evaluation; only failure modes and their respective probabilistic distribution are considered. Preliminary results from two data sources, SPIDR and FARADIP, are presented.

  1. Quasiperiodicity, mode-locking, and universal scaling in Rayleigh-Benard convection

    SciTech Connect (OSTI)

    Ecke, R.E.

    1990-01-01

    This major review paper describes research on a model nonlinear dynamical system of small-aspect-ratio Rayleigh-Benard convection in {sup 3}He {minus} {sup 4}He mixtures. The nonlinear effects of mode locking and quasiperiodic behavior are described. Analysis techniques for characterizing the state of the dynamical system include Fourier transforms, Poincare sections, phase differences, transients, multifractal f({proportional to}) spectra and scaling function dynamics. Theoretical results such as the fractal staircase of mode-locked intervals and the Arnold tongues are reproduced in experimental data. New techniques for analyzing scaling dynamics are developed and discussed. This is a tutorial article that introduces the major important concepts in nonlinear dynamics and focuses on experimental problems and techniques. 77 refs.

  2. Role of fourth-order phase-space moments in collective modes of trapped Fermi gases

    SciTech Connect (OSTI)

    Chiacchiera, Silvia; Lepers, Thomas; Davesne, Dany; Urban, Michael

    2011-10-15

    We study the transition from hydrodynamic to collisionless behavior in collective modes of ultracold trapped Fermi gases. To that end, we solve the Boltzmann equation for the trapped Fermi gas via the moments method. We showed previously that it is necessary to go beyond second-order moments if one wants to reproduce the results of a numerical solution of the Boltzmann equation. Here, we will give the detailed description of the method including fourth-order moments. We apply this method to the case of realistic parameters, and compare the results for the radial quadrupole and scissors modes at unitarity to experimental data obtained by the Innsbruck group. It turns out that the inclusion of fourth-order moments clearly improves the agreement with the experimental data. In particular, the fourth-order moments reduce the effect of collisions and therefore partially compensate the effect of the enhanced in-medium cross section at low temperatures.

  3. Quasinormal modes, scattering, and Hawking radiation of Kerr-Newman black holes in a magnetic field

    SciTech Connect (OSTI)

    Kokkotas, K. D.; Konoplya, R. A.; Zhidenko, A.

    2011-01-15

    We perform a comprehensive analysis of the spectrum of proper oscillations (quasinormal modes), transmission/reflection coefficients, and Hawking radiation for a massive charged scalar field in the background of the Kerr-Newman black hole immersed in an asymptotically homogeneous magnetic field. There are two main effects: the Zeeman shift of the particle energy in the magnetic field and the difference of values of an electromagnetic potential between the horizon and infinity, i.e. the Faraday induction. We have shown that 'turning on' the magnetic field induces a stronger energy-emission rate and leads to 'recharging' of the black hole. Thus, a black hole immersed in a magnetic field evaporates much quicker, achieving thereby an extremal state in a shorter period of time. Quasinormal modes are moderately affected by the presence of a magnetic field which is assumed to be relatively small compared to the gravitational field of the black hole.

  4. Bulk viscosity in a hyperonic star and r-mode instability

    SciTech Connect (OSTI)

    Jha, T. K.; Mishra, H.; Sreekanth, V.

    2010-08-15

    We consider a rotating neutron star with the presence of hyperons in its core. We use an equation of state in an effective chiral model within the relativistic mean-field approximation. We calculate the hyperonic bulk viscosity coefficient caused by nonleptonic weak interactions. By estimating the damping time scales of the dissipative processes, we investigate its role in the suppression of gravitationally driven instabilities in the r mode. We observe that r-mode instability remains very significant for hyperon core temperatures of around 10{sup 8} K, which results in a comparatively larger instability window. We find that such instability can reduce the angular velocity of the rapidly rotating star considerably up to {approx}0.04{Omega}{sub K}, with {Omega}{sub K} as the Keplerian angular velocity.

  5. Scissors Mode of 162 Dy Studied from Resonance Neutron Capture

    SciTech Connect (OSTI)

    Baramsai, B.; Be?v?, F.; Bredeweg, T. A.; Haight, R. C.; Jandel, M.; Kroll, J.; Krti?ka, M.; Mitchell, G. E.; ODonnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Valenta, S.; Wilhelmy, J. B.

    2015-05-28

    Multi-step cascade ?-ray spectra from the neutron capture at isolated resonances of 161Dy nucleus were measured at the LANSCE/DANCE time-of-flight facility in Los Alamos National Laboratory. The objectives of this experiment were to confirm and possibly extend the spin assignment of s-wave neutron resonances and get new information on photon strength functions with emphasis on the role of the M1 scissors mode vibration. The preliminary results show that the scissors mode plays a significant role in all transitions between accessible states of the studied nucleus. The photon strength functions describing well our data are compared to results from 3He-induced reactions, (n,?) experiments on Gd isotopes, and (?,?) reactions.

  6. Effect of noise on the power spectrum of passively mode-locked lasers

    SciTech Connect (OSTI)

    Eliyahu, D.; Salvatore, R.A.; Yariv, A.

    1997-01-01

    We analyze the effects of noise on the power spectrum of pulse trains generated by a continuously operating passively mode-locked laser. The shape of the different harmonics of the power spectrum is calculated in the presence of correlated timing fluctuations between neighboring pulses and in the presence of amplitude fluctuations. The spectra at the different harmonics are influenced mainly by the nonstationary timing-jitter fluctuations; amplitude fluctuations slightly modify the spectral tails. Estimation of the coupling term between the longitudinal cavity modes or the effective saturable absorber coefficient is made from the timing-jitter correlation time. Experimental results from an external cavity two-section semiconductor laser are given. The results show timing-jitter fluctuations having a relaxation time much longer than the repetition period. {copyright} 1997 Optical Society of America.

  7. Estimation and validation of mode distances for the 1993 Commodity Flow Survey

    SciTech Connect (OSTI)

    Middendorf, D.P.; Bronzini, M. S.; Peterson, B.; Liu, Cheng; Chin, Shih-Miao

    1995-09-01

    The 1993 Commodity Flow Survey (CFS) collected shipment data from a sample of approximately 200,000 domestic business establishments. Each selected establishment provided information on origin, destination, commodity, shipment weight and value, and modes of transport for a sample of its outbound shipments. One data item not reported by CFS participants was shipment distance. This important piece of information was estimated by simulating probable routes using computer models of the highway, rail, air, waterway, and pipeline networks and their interconnections. This paper describes the nature of the shipment distance estimation problem, the procedures used to estimate mode-specific distances between origin and destination ZIP codes, and the techniques used to validate the results.

  8. The instability condition of the aperiodic ordinary mode for new scalings of the counterstreaming parameters

    SciTech Connect (OSTI)

    Vafin, S.; Schlickeiser, R.; Lazar, M.

    2015-02-15

    The aperiodic ordinary (O-) mode instability in homogeneous and collisionless plasmas with kinetic anisotropies has recently received renewed attention due to its potential application in the solar wind, as well as for equal-mass plasmas. The present paper revisits the marginal instability condition of the O-mode derived from the electromagnetic linear dispersion equation for waves propagating perpendicular to the background magnetic field. For a counterstreaming bi-Maxwellian plasma system, this condition is found to be significantly affected by the streaming parameters. New functional dependencies (not studied before) of the counterstreaming parameters on the magnetic field and the other plasma parameters lead to new conditions of this instability for the both equal mass and electron-proton plasmas.

  9. A new reversal mode in exchange coupled antiferromagnetic/ferromagnetic disks: distorted viscous vortex

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

    Gilbert, Dustin A.; Ye, Li; Varea, Aïda; Agramunt-Puig, Sebastià; del Valle, Nuria; Navau, Carles; López-Barbera, José Francisco; Buchanan, Kristen S.; Hoffmann, Axel; Sánchez, Alvar; et al

    2015-04-28

    Magnetic vortices have generated intense interest in recent years due to their unique reversal mechanisms, fascinating topological properties, and exciting potential applications. In addition, the exchange coupling of magnetic vortices to antiferromagnets has also been shown to lead to a range of novel phenomena and functionalities. Here we report a new magnetization reversal mode of magnetic vortices in exchange coupled Ir20Mn80/Fe20Ni80 microdots: distorted viscous vortex reversal. In contrast to the previously known or proposed reversal modes, the vortex is distorted close to the interface and viscously dragged due to the uncompensated spins of a thin antiferromagnet, which leads to unexpectedmore » asymmetries in the annihilation and nucleation fields. These results provide a deeper understanding of the physics of exchange coupled vortices and may also have important implications for applications involving exchange coupled nanostructures.« less

  10. Mode-mismatched confocal thermal-lens microscope with collimated probe beam

    SciTech Connect (OSTI)

    Cabrera, Humberto; Korte, Dorota; Franko, Mladen

    2015-05-15

    We report a thermal lens microscope (TLM) based on an optimized mode-mismatched configuration. It takes advantage of the coaxial counter propagating tightly focused excitation and collimated probe beams, instead of both focused at the sample, as it is in currently known TLM setups. A simple mathematical model that takes into account the main features of the instrument is presented. The confocal detection scheme and the introduction of highly collimated probe beam allow enhancing the versatility, limit of detection (LOD), and sensitivity of the instrument. The theory is experimentally verified measuring ethanols absorption coefficient at 532.8 nm. Additionally, the presented technique is applied for detection of ultra-trace amounts of Cr(III) in liquid solution. The achieved LOD is 1.3 ppb, which represents 20-fold enhancement compared to transmission mode spectrometric techniques and a 7.5-fold improvement compared to previously reported methods for Cr(III) based on thermal lens effect.

  11. Comment on "Mode Conversion of Waves In The Ion-Cyclotron Frequency Range in Magnetospheric Plasmas"

    SciTech Connect (OSTI)

    Kim, Eun

    2014-02-28

    Recently, Kazakov and Fulop [1] studied mode conversion (MC) at the ion-ion hybrid (IIH) resonance in planetary magnetospheric plasmas by simplifying the dispersion relation of the fast wave (FW) modes to describe a cutoff-resonance (CR) pair near the IIH resonance, which can be reduced to a Budden problem. They suggested that when the IIH resonance frequency (?S) approaches the crossover frequency (?cr), and the parallel wavenumber (k?) is close to the critical wavenumber k? ?(?S = ?cr), MC can be efficient for arbitrary heavy ion density ratios. In this Comment, we argue that (a) the FW dispersion relation cannot be simplified to the CR pair especially near ?cr because in many parameter regimes there is a cutoff-resonance-cutoff (CRC) triplet that completely changes the wave absorption; and (b) the maximum MC efficiency does not always occur near k? ?#25; k???.

  12. Cryogenic Test of a Coaxial Coupling Scheme for Fundamental and Higher Order Modes in Superconducting Cavities

    SciTech Connect (OSTI)

    J.K. Sekutowicz, P. Kneisel

    2009-05-01

    A coaxial coupling device located in the beam pipe of the TESLA type superconducting cavities provides for better propagation of Higher Order Modes (HOMs) and their strong damping in appropriate HOM couplers. Additionally, it also provides efficient coupling for fundamental mode RF power into the superconducting cavity. The whole coupling device can be designed as a detachable system. If appropriately dimensioned, the magnetic field can be minimized to a negligible level at the flange position. This scheme, presented previously*, provides for several advantages: strong HOM damping, flangeable solution, exchangeability of the HOM damping device on a cavity, less complexity of the superconducting cavity, possible cost advantages. This contribution will describe the results of the first cryogenic test.

  13. Effect of electron flow on the ordinary-extraordinary mode conversion

    SciTech Connect (OSTI)

    Jia Guozhang; Gao Zhe

    2011-10-15

    Ordinary-extraordinary mode conversion in the electron cyclotron frequency range is revisited in the presence of a flowing electron component. The analytical expressions of optimal parallel refraction index and conversion efficiency are obtained from a one-dimensional cold plasma model. The presence of flowing electrons leads to an outward shift of the conversion layer and therefore increases the optimal value of parallel refraction index. If this effect is not considered, the efficiency of mode conversion degenerates. In typical tokamak plasmas, this degeneration is about a few percentages, which may induce the reflection of several tens of kilowatts of power from the cutoff layer when injecting megawatts of ECRF power into fusion plasma.

  14. A new reversal mode in exchange coupled antiferromagnetic/ferromagnetic disks: distorted viscous vortex

    SciTech Connect (OSTI)

    Gilbert, Dustin A.; Ye, Li; Varea, Aïda; Agramunt-Puig, Sebastià; del Valle, Nuria; Navau, Carles; López-Barbera, José Francisco; Buchanan, Kristen S.; Hoffmann, Axel; Sánchez, Alvar; Sort, Jordi; Liu, Kai; Nogués, Josep

    2015-04-28

    Magnetic vortices have generated intense interest in recent years due to their unique reversal mechanisms, fascinating topological properties, and exciting potential applications. In addition, the exchange coupling of magnetic vortices to antiferromagnets has also been shown to lead to a range of novel phenomena and functionalities. Here we report a new magnetization reversal mode of magnetic vortices in exchange coupled Ir20Mn80/Fe20Ni80 microdots: distorted viscous vortex reversal. In contrast to the previously known or proposed reversal modes, the vortex is distorted close to the interface and viscously dragged due to the uncompensated spins of a thin antiferromagnet, which leads to unexpected asymmetries in the annihilation and nucleation fields. These results provide a deeper understanding of the physics of exchange coupled vortices and may also have important implications for applications involving exchange coupled nanostructures.

  15. Gaussian geometric discord of two-mode systems in a thermal environment

    SciTech Connect (OSTI)

    Suciu, Serban Isar, Aurelian

    2014-11-24

    In the framework of the theory of open systems based on completely positive quantum dynamical semigroups, we give a description of the Gaussian geometric discord for a system consisting of two non-interacting non-resonant bosonic modes embedded in a thermal environment. We take as initial state of the system a two-mode squeezed thermal state and describe the time evolution of the Gaussian geometric discord under the influence of the thermal bath. By tracing the distance between the state of the considered subsystem and the closest classical-quantum Gaussian state we evaluate the Gaussian geometric discord for all times and temperatures. The geometric discord has finite values between 0 and 1 and decreases asymptotically to zero at large times and temperatures with oscillations on the time axis.

  16. Engineering tasl plan for the development, fabrication and installation of rotary mode core sample truck bellows

    SciTech Connect (OSTI)

    BOGER, R.M.

    1999-06-24

    The Rotary Mode Core Sampling Trucks (RMSCTs) currently use a multi-sectioned bellows between the grapple box and the quill rod to compensate for drill head motion and to provide a path for purge gas. The current bellows, which is detailed on drawing H-2-690059, is expensive to procure, has a lengthy procurement cycle, and is prone to failure. Therefore, a task has been identified to design, fabricate, and install a replacement bellows. This Engineering Task Plan (ETP) is the management plan document for accomplishing the identified tasks. Any changes in scope of the ETP shall require formal direction by the Characterization Engineering manager. This document shall also be considered the work planning document for developmental control per Development Control Requirements (HNF 1999a). This Engineering Task Plan (ETP) is the management plan document for accomplishing the design, fabrication, and installation of a replacement bellows assembly for the Rotary Mode Core Sampling Trucks 3 and 4 (RMCST).

  17. Marginal instability threshold condition of the aperiodic ordinary mode in equal-mass plasmas

    SciTech Connect (OSTI)

    Vafin, S.; Schlickeiser, R.; Yoon, P. H.

    2014-10-15

    The purely growing ordinary (O) mode instability for counter-streaming bi-Maxwellian plasma particle distribution functions has recently received renewed attention due to its importance for the solar wind plasma. Here, the analytical marginal instability condition is derived for magnetized plasmas consisting of equal-mass charged particles, distributed in counter-streams with equal temperatures. The equal-mass composition assumption enormously facilitates the theoretical analysis due to the equality of the values of the electron and positron (positive and negative ion) plasma and gyrofrequencies. The existence of a new instability domain of the O-mode at small plasma beta values is confirmed, when the parallel counter-stream free energy exceeds the perpendicular bi-Maxwellian free energy.

  18. Evidence of resonant mode coupling and the relationship between low and high frequencies in a rapidly rotating a star

    SciTech Connect (OSTI)

    Breger, M.; Montgomery, M. H.

    2014-03-10

    In the theory of resonant mode coupling, the parent and child modes are directly related in frequency and phase. The oscillations present in the fast rotating δ Sct star KIC 8054146 allow us to test the most general and generic aspects of such a theory. The only direct way to separate the parent and coupled (child) modes is to examine the correlations in amplitude variability between the different frequencies. For the dominant family of related frequencies, only a single mode and a triplet are the origins of nine dominant frequency peaks ranging from 2.93 to 66.30 cycles day{sup –1} (as well as dozens of small-amplitude combination modes and a predicted and detected third high-frequency triplet). The mode-coupling model correctly predicts the large amplitude variations of the coupled modes as a product of the amplitudes of the parent modes, while the phase changes are also correctly modeled. This differs from the behavior of 'normal' combination frequencies in that the amplitudes are three orders of magnitude larger and may exceed even the amplitudes of the parent modes. We show that two dominant low frequencies at 5.86 and 2.93 cycles day{sup –1} in the gravity-mode region are not harmonics of each other, and their properties follow those of the almost equidistant high-frequency triplet. We note that the previously puzzling situation of finding two strong peaks in the low-frequency region related by nearly a factor of two in frequency has been seen in other δ Sct stars as well.

  19. Temperature-package power correlations for open-mode geologic disposal concepts.

    SciTech Connect (OSTI)

    Hardin, Ernest L.

    2013-02-01

    Logistical simulation of spent nuclear fuel (SNF) management in the U.S. combines storage, transportation and disposal elements to evaluate schedule, cost and other resources needed for all major operations leading to final geologic disposal. Geologic repository reference options are associated with limits on waste package thermal power output at emplacement, in order to meet limits on peak temperature for certain key engineered and natural barriers. These package power limits are used in logistical simulation software such as CALVIN, as threshold requirements that must be met by means of decay storage or SNF blending in waste packages, before emplacement in a repository. Geologic repository reference options include enclosed modes developed for crystalline rock, clay or shale, and salt. In addition, a further need has been addressed for open modes in which SNF can be emplaced in a repository, then ventilated for decades or longer to remove heat, prior to permanent repository closure. For each open mode disposal concept there are specified durations for surface decay storage (prior to emplacement), repository ventilation, and repository closure operations. This study simulates those steps for several timing cases, and for SNF with three fuel-burnup characteristics, to develop package power limits at which waste packages can be emplaced without exceeding specified temperature limits many years later after permanent closure. The results are presented in the form of correlations that span a range of package power and peak postclosure temperature, for each open-mode disposal concept, and for each timing case. Given a particular temperature limit value, the corresponding package power limit for each case can be selected for use in CALVIN and similar tools.

  20. The influence of ice nucleation mode and ice vapor growth on simulation of

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

    arctic mixed-phase clouds The influence of ice nucleation mode and ice vapor growth on simulation of arctic mixed-phase clouds Avramov, Alexander The Pennsylvania State University Category: Modeling Mixed-phase arctic stratus clouds are the predominant cloud type in the Arctic . Perhaps one of the most intriguing of their features is that they tend to have liquid tops that precipitate ice. Despite the fact that this situation is colloidally unstable, these cloud systems are quite long lived

  1. Preliminary Failure Modes and Effects Analysis of the US DCLL Test Blanket Module

    SciTech Connect (OSTI)

    Lee C. Cadwallader

    2010-06-01

    This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a small tritium-breeding test blanket module design for the International Thermonuclear Experimental Reactor. The FMEA was quantified with “generic” component failure rate data, and the failure events are binned into postulated initiating event families and frequency categories for safety assessment. An appendix to this report contains repair time data to support an occupational radiation exposure assessment for test blanket module maintenance.

  2. DELPHI expert panel evaluation of Hanford high level waste tank failure modes and release quantities

    SciTech Connect (OSTI)

    Dunford, G.L.; Han, F.C.

    1996-09-30

    The Failure Modes and Release Quantities of the Hanford High Level Waste Tanks due to postulated accident loads were established by a DELPHI Expert Panel consisting of both on-site and off-site experts in the field of Structure and Release. The Report presents the evaluation process, accident loads, tank structural failure conclusion reached by the panel during the two-day meeting.

  3. Eigenmode characteristics of the double tearing mode in the presence of shear flows

    SciTech Connect (OSTI)

    Mao Aohua [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan); Li Jiquan; Kishimoto, Y. [Graduate School of Energy Science, Kyoto University, Uji, Kyoto 6110011 (Japan); Liu Jinyuan [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)

    2013-02-15

    The double tearing mode (DTM) is characterized by two eigen states with antisymmetric or symmetric magnetic island structure, referred to as the even or odd DTM. In this work, we systematically revisit the DTM instabilities in the presence of an antisymmetric shear flow with a focus on eigenmode characteristics as well as the stabilization or destabilization mechanism in a wide parameter region. Both initial value simulation and eigenvalue analysis are performed based on reduced resistive MHD model in slab geometry. A degenerated eigen state is found at a critical flow amplitude v{sub c}. The even (or odd) DTM is stabilized (or destabilized) by weak shear flow below v{sub c} through the distortion of magnetic islands mainly due to the global effect of shear flow rather than the local flow shear. The distortion can be quantified by the phase angles of the perturbed flux, showing a perfect correspondence to the growth rates. As the shear flow increases above v{sub c}, the degenerated eigen state bifurcates into two eigen modes with the same growth rate but opposite propagating direction, resulting in an oscillatory growth of fluctuation energy. It is identified that two eigen modes show the single tearing mode structure due to the Alfven resonance (AR) occurring on one current sheet. Most importantly, the AR can destabilize the DTMs through enhancing the plasma flow exerting on the remaining island. Meanwhile, the local flow shear plays a remarkable stabilizing role in this region. In addition, the eigenmode characteristic of the electromagnetic Kelvin-Helmholtz instability is also discussed.

  4. Mode specificity in the HF + OH → F + H{sub 2}O reaction

    SciTech Connect (OSTI)

    Song, Hongwei; Li, Jun; Guo, Hua

    2014-10-28

    Full-dimensional quantum dynamics and quasi-classical trajectory calculations are reported for the title reaction on a recently constructed ab initio based global potential energy surface. Strong mode specificity was found, consistent with the prediction of the sudden vector projection model. Specifically, the HF vibration strongly promotes the reaction while the OH vibration has little effect. Rotational excitations of both reactants slightly enhance the reaction.

  5. Impacts of urban transportation mode split on CO{sub 2} emissions in Jinan, China.

    SciTech Connect (OSTI)

    He, D.; Meng, F.; Wang, M.; He, K.

    2011-04-01

    As the world's largest developing country, China currently is undergoing rapid urbanization and motorization, which will result in far-reaching impacts on energy and the environment. According to estimates, energy use and carbon emissions in the transportation sector will comprise roughly 30% of total emissions by 2030. Since the late 1990s, transportation-related issues such as energy, consumption, and carbon emissions have become a policy focus in China. To date, most research and policies have centered on vehicle technologies that promote vehicle efficiency and reduced emissions. Limited research exists on the control of greenhouse gases through mode shifts in urban transportation - in particular, through the promotion of public transit. The purpose of this study is to establish a methodology to analyze carbon emissions from the urban transportation sector at the Chinese city level. By using Jinan, the capital of China's Shandong Province, as an example, we have developed an analytical model to simulate energy consumption and carbon emissions based on the number of trips, the transportation mode split, and the trip distance. This model has enabled us to assess the impacts of the transportation mode split on energy consumption and carbon emissions. Furthermore, this paper reviews a set of methods for data collection, estimation, and processing for situations where statistical data are scarce in China. This paper also describes the simulation of three transportation system development scenarios. The results of this study illustrate that if no policy intervention is implemented for the transportation mode split (the business-as-usual (BAU) case), then emissions from Chinese urban transportation systems will quadruple by 2030. However, a dense, mixed land-use pattern, as well as transportation policies that encourage public transportation, would result in the elimination of 1.93 million tons of carbon emissions - approximately 50% of the BAU scenario emissions.

  6. Sandia Demonstrated First-Time, Single-Mode Lasing in Gallium-Nitride

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

    Nanowire Lasers Demonstrated First-Time, Single-Mode Lasing in Gallium-Nitride Nanowire Lasers - 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

  7. Entangling optical and microwave cavity modes by means of a nanomechanical resonator

    SciTech Connect (OSTI)

    Barzanjeh, Sh.; Vitali, D.; Tombesi, P.; Milburn, G. J.

    2011-10-15

    We propose a scheme that is able to generate stationary continuous-variable entanglement between an optical and a microwave cavity mode by means of their common interaction with a nanomechanical resonator. We show that when both cavities are intensely driven, one can generate bipartite entanglement between any pair of the tripartite system, and that, due to entanglement sharing, optical-microwave entanglement is efficiently generated at the expense of microwave-mechanical and optomechanical entanglement.

  8. Collisionless damping of geodesic acoustic mode in plasma with nonextensive distribution

    SciTech Connect (OSTI)

    Qiu, Hui-Bin; Song, Hai-Ying; Liu, Shi-Bing

    2014-06-15

    Geodesic acoustic mode (GAM) in collisionless toroidal plasmas with a constant electrostatic potential around a magnetic surface is investigated based on the linear gyrokinetic theory in context of nonextensive statistics mechanics. The damping rate of GAM is shown to be dependent on the nonextensive parameters of ions, and in the extensive limit, the result in Maxwellian distribution plasma is recovered. The damping rate is found to be enhanced as the nonextensive parameter of ion decreases.

  9. Microsoft PowerPoint - ARM_STM_2007_Neggers.ppt [Compatibility Mode]

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

    ARM data in improving the ECMWF boundary layer scheme Roel Neggers Sylvain Cheinet Martin Köhler Anton Beljaars Contents Various ways to evaluate an operational forecast model Issues concerning the model physics A new boundary layer scheme Improvements Outlook How to evaluate an operational forecast model? GCM: resolved & unresolved (sub-grid) scales Physical process evaluation can be done in two modes: 3D Forecasts and climate runs Process is interactive with the larger scales (dynamics)

  10. Preliminary Failure Modes and Effects Analysis of the US Massive Gas Injection Disruption Mitigation System Design

    SciTech Connect (OSTI)

    Lee C. Cadwallader

    2013-10-01

    This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a candidate design for the ITER Disruption Mitigation System. This candidate is the Massive Gas Injection System that provides machine protection in a plasma disruption event. The FMEA was quantified with “generic” component failure rate data as well as some data calculated from operating facilities, and the failure events were ranked for their criticality to system operation.

  11. MAGNETOHYDRODYNAMIC SEISMOLOGY OF A CORONAL LOOP SYSTEM BY THE FIRST TWO MODES OF STANDING KINK WAVES

    SciTech Connect (OSTI)

    Guo, Y.; Hao, Q.; Cheng, X.; Chen, P. F.; Ding, M. D.; Erdélyi, R.; Srivastava, A. K.; Dwivedi, B. N.

    2015-02-01

    We report the observation of the first two harmonics of the horizontally polarized kink waves excited in a coronal loop system lying southeast of AR 11719 on 2013 April 11. The detected periods of the fundamental mode (P {sub 1}), its first overtone (P {sub 2}) in the northern half, and that in the southern one are 530.2 ± 13.3, 300.4 ± 27.7, and 334.7 ± 22.1 s, respectively. The periods of the first overtone in the two halves are the same considering uncertainties in the measurement. We estimate the average electron density, temperature, and length of the loop system as (5.1 ± 0.8) × 10{sup 8} cm{sup –3}, 0.65 ± 0.06 MK, and 203.8 ± 13.8 Mm, respectively. As a zeroth-order estimation, the magnetic field strength, B = 8.2 ± 1.0 G, derived by the coronal seismology using the fundamental kink mode matches with that derived by a potential field model. The extrapolation model also shows the asymmetric and nonuniform distribution of the magnetic field along the coronal loop. Using the amplitude profile distributions of both the fundamental mode and its first overtone, we observe that the antinode positions of both the fundamental mode and its first overtone shift toward the weak field region along the coronal loop. The results indicate that the density stratification and the temperature difference effects are larger than the magnetic field variation effect on the period ratio. On the other hand, the magnetic field variation has a greater effect on the eigenfunction of the first overtone than the density stratification does for this case.

  12. The effect of periodic wavy profile on suppressing window multipactor under arbitrary electromagnetic mode

    SciTech Connect (OSTI)

    Chang, C.; Liu, Y. S.; Chen, C. H.; Guo, L. T.; Li, S.; Wu, X. L.; Verboncoeur, J.

    2015-01-05

    The three-dimensional periodic ripple profile with each unit of rotational symmetric surface is proposed to suppress multipactor for arbitrary electromagnetic mode with any polarization. The field distribution and multipactor electron dynamics on the wavy surface are studied to illustrate the multipactor inhibition mechanism. High power microwave experiment was conducted to demonstrate the effect of wavy surface on significantly improving the window power capacity.

  13. Multi-fluid transport code modeling of time-dependent recycling in ELMy H-mode

    SciTech Connect (OSTI)

    Pigarov, A. Yu.; Krasheninnikov, S. I.; Hollmann, E. M.; Rognlien, T. D.; Lasnier, C. J.; Unterberg, E.

    2014-06-15

    Simulations of a high-confinement-mode (H-mode) tokamak discharge with infrequent giant type-I ELMs are performed by the multi-fluid, multi-species, two-dimensional transport code UEDGE-MB, which incorporates the Macro-Blob approach for intermittent non-diffusive transport due to filamentary coherent structures observed during the Edge Localized Modes (ELMs) and simple time-dependent multi-parametric models for cross-field plasma transport coefficients and working gas inventory in material surfaces. Temporal evolutions of pedestal plasma profiles, divertor recycling, and wall inventory in a sequence of ELMs are studied and compared to the experimental time-dependent data. Short- and long-time-scale variations of the pedestal and divertor plasmas where the ELM is described as a sequence of macro-blobs are discussed. It is shown that the ELM recovery includes the phase of relatively dense and cold post-ELM divertor plasma evolving on a several ms scale, which is set by the transport properties of H-mode barrier. The global gas balance in the discharge is also analyzed. The calculated rates of working gas deposition during each ELM and wall outgassing between ELMs are compared to the ELM particle losses from the pedestal and neutral-beam-injection fueling rate, correspondingly. A sensitivity study of the pedestal and divertor plasmas to model assumptions for gas deposition and release on material surfaces is presented. The performed simulations show that the dynamics of pedestal particle inventory is dominated by the transient intense gas deposition into the wall during each ELM followed by continuous gas release between ELMs at roughly a constant rate.

  14. Constraints on standard and non-standard early universe models from CMB B-mode polarization

    SciTech Connect (OSTI)

    Ma, Yin-Zhe; Brown, Michael L.; Zhao, Wen E-mail: Wen.Zhao@astro.cf.ac.uk

    2010-10-01

    We investigate the observational signatures of three models of the early Universe in the B-mode polarization of the Cosmic Microwave Background (CMB) radiation. In addition to the standard single field inflationary model, we also consider the constraints obtainable on the loop quantum cosmology model (from Loop Quantum Gravity) and on cosmic strings, expected to be copiously produced during the latter stages of Brane inflation. We first examine the observational features of the three models, and then use current B-mode polarization data from the BICEP and QUaD experiments to constrain their parameters. We also examine the detectability of the primordial B-mode signal predicted by these models and forecast the parameter constraints achievable with future CMB polarization experiments. We find that: (a) since B-mode polarization measurements are mostly unaffected by parameter degeneracies, they provide the cleanest probe of these early Universe models; (b) using the BICEP and QUaD data we obtain the following parameter constraints: r = 0.02{sup +0.31}{sub −0.26} (1σ for the tensor-to-scalar ratio in the single field inflationary model); m < 1.36 × 10{sup −8}M{sub pl} and k{sub *} < 2.43 × 10{sup −4} Mpc{sup −1} (1σ for the mass and scale parameters in the loop quantum cosmology model); and Gμ < 5.77 × 10{sup −7} (1σ for the cosmic string tension); (c) future CMB observations (both satellite missions and forthcoming sub-orbital experiments) will provide much more rigorous tests of these early Universe models.

  15. Abrupt changes in alpha-decay systematics as a manifestation of collective nuclear modes

    SciTech Connect (OSTI)

    Qi, C.; Liotta, R. J.; Wyss, R. A.; Andreyev, A. N.; Huyse, M.; Van Duppen, P.

    2010-06-15

    An abrupt change in alpha-decay systematics around the N=126 neutron shell closure is discussed. It is explained as a sudden hindrance of the clustering of the nucleons that eventually form the alpha particle. This is because the clustering induced by the pairing mode acting upon the four nucleons is inhibited if the configuration space does not allow a proper manifestation of the pairing collectivity.

  16. Multi-fluid transport code modeling of time-dependent recycling in ELMy H-mode

    SciTech Connect (OSTI)

    Pigarov, A. Yu.; Krasheninnikov, S. I.; Rognlien, T. D.; Hollmann, E. M.; Lasnier, C. J.; Unterberg, Ezekial A

    2014-01-01

    Simulations of a high-confinement-mode (H-mode) tokamak discharge with infrequent giant type-I ELMs are performed by the multi-fluid, multi-species, two-dimensional transport code UEDGE-MB, which incorporates the Macro-Blob approach for intermittent non-diffusive transport due to filamentary coherent structures observed during the Edge Localized Modes (ELMs) and simple time-dependent multi-parametric models for cross-field plasma transport coefficients and working gas inventory in material surfaces. Temporal evolutions of pedestal plasma profiles, divertor recycling, and wall inventory in a sequence of ELMs are studied and compared to the experimental time-dependent data. Short- and long-time-scale variations of the pedestal and divertor plasmas where the ELM is described as a sequence of macro-blobs are discussed. It is shown that the ELM recovery includes the phase of relatively dense and cold post-ELM divertor plasma evolving on a several ms scale, which is set by the transport properties of H-mode barrier. The global gas balance in the discharge is also analyzed. The calculated rates of working gas deposition during each ELM and wall outgassing between ELMs are compared to the ELM particle losses from the pedestal and neutral-beam-injection fueling rate, correspondingly. A sensitivity study of the pedestal and divertor plasmas to model assumptions for gas deposition and release on material surfaces is presented. The performed simulations show that the dynamics of pedestal particle inventory is dominated by the transient intense gas deposition into the wall during each ELM followed by continuous gas release between ELMs at roughly a constant rate.

  17. Two modes of surface roughening during plasma etching of silicon: Role of ionized etch products

    SciTech Connect (OSTI)

    Nakazaki, Nobuya Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2014-12-14

    Atomic- or nanometer-scale surface roughening has been investigated during Si etching in inductively coupled Cl{sub 2} plasmas, as a function of rf bias power or ion incident energy E{sub i}, by varying feed gas flow rate, wafer stage temperature, and etching time. The experiments revealed two modes of surface roughening which occur depending on E{sub i}: one is the roughening mode at low E{sub i} < 200–300 eV, where the root-mean-square (rms) roughness of etched surfaces increases with increasing E{sub i}, exhibiting an almost linear increase with time during etching (t < 20 min). The other is the smoothing mode at higher E{sub i}, where the rms surface roughness decreases substantially with E{sub i} down to a low level < 0.4 nm, exhibiting a quasi-steady state after some increase at the initial stage (t < 1 min). Correspondingly, two different behaviors depending on E{sub i} were also observed in the etch rate versus √(E{sub i}) curve, and in the evolution of the power spectral density distribution of surfaces. Such changes from the roughening to smoothing modes with increasing E{sub i} were found to correspond to changes in the predominant ion flux from feed gas ions Cl{sub x}{sup +} to ionized etch products SiCl{sub x}{sup +} caused by the increased etch rates at increased E{sub i}, in view of the results of several plasma diagnostics. Possible mechanisms for the formation and evolution of surface roughness during plasma etching are discussed with the help of Monte Carlo simulations of the surface feature evolution and classical molecular dynamics simulations of etch fundamentals, including stochastic roughening and effects of ion reflection and etch inhibitors.

  18. High-speed adaptive contact-mode atomic force microscopy imaging with near-minimum-force

    SciTech Connect (OSTI)

    Ren, Juan; Zou, Qingze

    2014-07-15

    In this paper, an adaptive contact-mode imaging approach is proposed to replace the traditional contact-mode imaging by addressing the major concerns in both the speed and the force exerted to the sample. The speed of the traditional contact-mode imaging is largely limited by the need to maintain precision tracking of the sample topography over the entire imaged sample surface, while large image distortion and excessive probe-sample interaction force occur during high-speed imaging. In this work, first, the image distortion caused by the topography tracking error is accounted for in the topography quantification. Second, the quantified sample topography is utilized in a gradient-based optimization method to adjust the cantilever deflection set-point for each scanline closely around the minimal level needed for maintaining stable probe-sample contact, and a data-driven iterative feedforward control that utilizes a prediction of the next-line topography is integrated to the topography feeedback loop to enhance the sample topography tracking. The proposed approach is demonstrated and evaluated through imaging a calibration sample of square pitches at both high speeds (e.g., scan rate of 75 Hz and 130 Hz) and large sizes (e.g., scan size of 30 ?m and 80??m). The experimental results show that compared to the traditional constant-force contact-mode imaging, the imaging speed can be increased by over 30 folds (with the scanning speed at 13 mm/s), and the probe-sample interaction force can be reduced by more than 15% while maintaining the same image quality.

  19. Efficient Emissions Control for Multi-Mode Lean DI Engines | Department of

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

    Energy 11 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer Evaluation PDF icon ace031_parks_2011_o.pdf More Documents & Publications Hydrocarbon fouling of SCR during Premixed Charge Compression Ignition (PCCI) combustion High Efficiency Clean Combustion in Multi-Cylinder Light-Duty Engines Efficient Emissions Control for Multi-Mode Lean DI Engines

  20. Pygmy dipole mode in deformed neutron-rich Mg isotopes close to the drip line

    SciTech Connect (OSTI)

    Yoshida, Kenichi

    2009-10-15

    We investigate the microscopic structure of the low-lying isovector-dipole excitation mode in neutron-rich {sup 36,38,40}Mg close to the drip line by means of the deformed quasiparticle random-phase approximation employing the Skyrme and the local pairing energy-density functionals. It is found that the low-lying bump structure above the neutron emission-threshold energy develops when the drip line is approached, and that the isovector dipole strength at E{sub x}<10 MeV exhausts about 6.0% of the classical Thomas-Reiche-Kuhn dipole sum rule in {sup 40}Mg. We obtained the collective dipole modes at around 8-10 MeV in Mg isotopes, that consist of many two-quasiparticle excitations of the neutron. The transition density clearly shows an oscillation of the neutron skin against the isoscalar core. We found significant coupling effects between the dipole and octupole excitation modes due to the nuclear deformation. It is also found that the responses for the compressional dipole and isoscalar octupole excitations are much enhanced in the lower energy region.

  1. RECONNECTION OF QUASI-SINGULAR CURRENT SHEETS: THE ''IDEAL'' TEARING MODE

    SciTech Connect (OSTI)

    Pucci, Fulvia; Velli, Marco E-mail: mvelli@jpl.nasa.gov

    2014-01-10

    A strong indication that fast reconnection regimes exist within resistive magnetohydrodynamics was given by the proof that the Sweet-Parker current sheet, maintained by a flow field with an appropriate inflow-outflow structure, could be unstable to a reconnecting instability which grows without bound as the Lundquist number, S, tends to infinity. The requirement of a minimum value for S in order for the plasmoid instability to kick in does little to resolve the paradoxical nature of the result. Here we argue against the realizability of Sweet-Parker current sheets in astrophysical plasmas with very large S by showing that an ''ideal'' tearing mode takes over before current sheets reach such a thickness. While the Sweet-Parker current sheet thickness scales as ?S {sup 1/2}, the tearing mode becomes effectively ideal when a current sheet collapses to a thickness of the order of ?S {sup 1/3}, up to 100times thicker than S {sup 1/2}, when (as happens in many astrophysical environments) S is as large as 10{sup 12}. Such a sheet, while still diffusing over a very long time, is unstable to a tearing mode with multiple x-points: here we detail the characteristics of the instability and discuss how it may help solve the flare trigger problem and effectively initiate the turbulent disruption of the sheet.

  2. Tapered laser rods as a means of minimizing the path length of trapped barrel mode rays

    DOE Patents [OSTI]

    Beach, Raymond J.; Honea, Eric C.; Payne, Stephen A.; Mercer, Ian; Perry, Michael D.

    2005-08-30

    By tapering the diameter of a flanged barrel laser rod over its length, the maximum trapped path length of a barrel mode can be dramatically reduced, thereby reducing the ability of the trapped spontaneous emission to negatively impact laser performance through amplified spontaneous emission (ASE). Laser rods with polished barrels and flanged end caps have found increasing application in diode array end-pumped laser systems. The polished barrel of the rod serves to confine diode array pump light within the rod. In systems utilizing an end-pumping geometry and such polished barrel laser rods, the pump light that is introduced into one or both ends of the laser rod, is ducted down the length of the rod via the total internal reflections (TIRs) that occur when the light strikes the rod's barrel. A disadvantage of using polished barrel laser rods is that such rods are very susceptible to barrel mode paths that can trap spontaneous emission over long path lengths. This trapped spontaneous emission can then be amplified through stimulated emission resulting in a situation where the stored energy available to the desired lasing mode is effectively depleted, which then negatively impacts the laser's performance, a result that is effectively reduced by introducing a taper onto the laser rod.

  3. Linear stability and nonlinear dynamics of the fishbone mode in spherical tokamaks

    SciTech Connect (OSTI)

    Wang, Feng; Liu, J. Y. [School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024 (China); Fu, G. Y.; Breslau, J. A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2013-10-15

    Extensive linear and nonlinear simulations have been carried out to investigate the energetic particle-driven fishbone instability in spherical tokamak plasmas with weakly reversed q profile and the q{sub min} slightly above unity. The global kinetic-MHD hybrid code M3D-K is used. Numerical results show that a fishbone instability is excited by energetic beam ions preferentially at higher q{sub min} values, consistent with the observed appearance of the fishbone before the long-lived mode in MAST and NSTX experiments. In contrast, at lower q{sub min} values, the fishbone tends to be stable. In this case, the beam ion effects are strongly stabilizing for the non-resonant kink mode. Nonlinear simulations show that the fishbone saturates with strong downward frequency chirping as well as radial flattening of the beam ion distribution. An (m, n) = (2, 1) magnetic island is found to be driven nonlinearly by the fishbone instability, which could provide a trigger for the (2, 1) neoclassical tearing mode sometimes observed after the fishbone instability in NSTX.

  4. Continuous Variable Cluster State Generation over the Optical Spatial Mode Comb

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

    Pooser, Raphael C.; Jing, Jietai

    2014-10-20

    One way quantum computing uses single qubit projective measurements performed on a cluster state (a highly entangled state of multiple qubits) in order to enact quantum gates. The model is promising due to its potential scalability; the cluster state may be produced at the beginning of the computation and operated on over time. Continuous variables (CV) offer another potential benefit in the form of deterministic entanglement generation. This determinism can lead to robust cluster states and scalable quantum computation. Recent demonstrations of CV cluster states have made great strides on the path to scalability utilizing either time or frequency multiplexingmore » in optical parametric oscillators (OPO) both above and below threshold. The techniques relied on a combination of entangling operators and beam splitter transformations. Here we show that an analogous transformation exists for amplifiers with Gaussian inputs states operating on multiple spatial modes. By judicious selection of local oscillators (LOs), the spatial mode distribution is analogous to the optical frequency comb consisting of axial modes in an OPO cavity. We outline an experimental system that generates cluster states across the spatial frequency comb which can also scale the amount of quantum noise reduction to potentially larger than in other systems.« less

  5. Continuous Variable Cluster State Generation over the Optical Spatial Mode Comb

    SciTech Connect (OSTI)

    Pooser, Raphael C.; Jing, Jietai

    2014-10-20

    One way quantum computing uses single qubit projective measurements performed on a cluster state (a highly entangled state of multiple qubits) in order to enact quantum gates. The model is promising due to its potential scalability; the cluster state may be produced at the beginning of the computation and operated on over time. Continuous variables (CV) offer another potential benefit in the form of deterministic entanglement generation. This determinism can lead to robust cluster states and scalable quantum computation. Recent demonstrations of CV cluster states have made great strides on the path to scalability utilizing either time or frequency multiplexing in optical parametric oscillators (OPO) both above and below threshold. The techniques relied on a combination of entangling operators and beam splitter transformations. Here we show that an analogous transformation exists for amplifiers with Gaussian inputs states operating on multiple spatial modes. By judicious selection of local oscillators (LOs), the spatial mode distribution is analogous to the optical frequency comb consisting of axial modes in an OPO cavity. We outline an experimental system that generates cluster states across the spatial frequency comb which can also scale the amount of quantum noise reduction to potentially larger than in other systems.

  6. A theorem for the existence of Majorana fermion modes in spin-orbit-coupled semiconductors

    SciTech Connect (OSTI)

    Tewari, Sumanta Sau, Jay D.; Das Sarma, S.

    2010-01-15

    We prove an index theorem for the existence of Majorana zero modes in a semiconducting thin film with a sizable spin-orbit coupling when it is adjacent to an s-wave superconductor. The theorem, which is analogous to the Jackiw-Rebbi index theorem for the zero modes in mass domain walls in one-dimensional Dirac theory, applies to vortices with odd flux-quantum in a semiconducting film in which s-wave superconductivity and a Zeeman splitting are induced by proximity effect. The momentum space construction of the zero-mode solution presented here is complementary to the approximate real space solution of the Bogoliubov-de Gennes equations at a vortex core (Sau et al., arXiv:0907.2239), proving the existence of non-degenerate zero-energy Majorana excitations and the resultant non-Abelian topological order in the semiconductor heterostructure. With increasing magnitude of the proximity-induced pairing potential, the non-Abelian superconducting state makes a topological quantum phase transition to an ordinary s-wave superconducting state which no topological order.

  7. Abbreviated epitaxial growth mode (AGM) method for reducing cost and improving quality of LEDs and lasers

    DOE Patents [OSTI]

    Tansu, Nelson; Chan, Helen M; Vinci, Richard P; Ee, Yik-Khoon; Biser, Jeffrey

    2013-09-24

    The use of an abbreviated GaN growth mode on nano-patterned AGOG sapphire substrates, which utilizes a process of using 15 nm low temperature GaN buffer and bypassing etch-back and recovery processes during epitaxy, enables the growth of high-quality GaN template on nano-patterned AGOG sapphire. The GaN template grown on nano-patterned AGOG sapphire by employing abbreviated growth mode has two orders of magnitude lower threading dislocation density than that of conventional GaN template grown on planar sapphire. The use of abbreviated growth mode also leads to significant reduction in cost of the epitaxy. The growths and characteristics of InGaN quantum wells (QWs) light emitting diodes (LEDs) on both templates were compared. The InGaN QWs LEDs grown on the nano-patterned AGOG sapphire demonstrated at least a 24% enhancement of output power enhancement over that of LEDs grown on conventional GaN templates.

  8. Pressure and arc voltage coupling in dc plasma torches: Identification and extraction of oscillation modes

    SciTech Connect (OSTI)

    Rat, V.; Coudert, J. F.

    2010-08-15

    This work is devoted to the instabilities occurring in a plasma torch, such as those found in plasma spraying. These instabilities are responsible for a lack of reproducibility of coatings properties, especially in the case of suspension plasma spraying that is an innovative way to obtain thin coatings of submicron-sized particles. Strong Helmholtz oscillations are highlighted in the plasma flow and it is demonstrated that they overlap with different acoustic modes in addition with the more commonly admitted ''restrike'' mode, the later being due to rearcing events in the arc region. The instabilities occur in the arc voltage but it is experimentally shown in this paper that the pressure within the torch body presents the same kind of instabilities. Besides, a numerical filtering technique has been adapted to isolate the different instability components. The operating parameters of the plasma torch were varied in order to highlight their influence on the amplitude of the different modes, both for the arc voltage and the pressure.

  9. Epsilon-near-zero modes for tailored light-matter interaction

    SciTech Connect (OSTI)

    Campione, Salvatore; Liu, Sheng; Benz, Alexander; Klem, John F.; Sinclair, Michael B.; Brener, Igal

    2015-10-20

    Epsilon-near-zero (ENZ) modes arising from condensed-matter excitations such as phonons and plasmons are a new path for tailoring light-matter interactions at the nanoscale. Complex spectral shaping can be achieved by creating such modes in nanoscale semiconductor layers and controlling their interaction with multiple, distinct, dipole resonant systems. Examples of this behavior are presented at midinfrared frequencies for ENZ modes that are strongly coupled to metamaterial resonators and simultaneously strongly coupled to semiconductor phonons or quantum-well intersubband transitions (ISTs), resulting in double- and triple-polariton branches in transmission spectra. For the double-polariton branch case, we find that the best strategy to maximize the Rabi splitting is to use a combination of a doped layer supporting an ENZ feature and a layer supporting ISTs, with overlapping ENZ and IST frequencies. As a result, this design flexibility renders this platform attractive for low-voltage tunable filters, light-emitting diodes, and efficient nonlinear composite materials.

  10. Nonlinear excitation of low-n harmonics in reduced magnetohydrodynamic simulations of edge-localized modes

    SciTech Connect (OSTI)

    Krebs, I.; Hölzl, M.; Lackner, K.; Günter, S.

    2013-08-15

    Nonlinear simulations of the early edge-localized mode (ELM) phase based on a typical type-I ELMy ASDEX Upgrade discharge have been carried out using the reduced MHD code JOREK. The analysis is focused on the evolution of the toroidal Fourier spectrum. It is found that during the nonlinear evolution, linearly subdominant low-n Fourier components, in particular the n = 1, grow to energies comparable with linearly dominant harmonics. A simple model is developed, based on the idea that energy is transferred among the toroidal harmonics via second order nonlinear interaction. The simple model reproduces and explains very well the early nonlinear evolution of the toroidal spectrum in the JOREK simulations. Furthermore, it is shown for the n = 1 harmonic, that its spatial structure changes significantly during the transition from linear to nonlinearly driven growth. The rigidly growing structure of the linearly barely unstable n = 1 reaches far into the plasma core. In contrast, the nonlinearly driven n= 1 has a rigidly growing structure localized at the plasma edge, where the dominant toroidal harmonics driving the n = 1 are maximal and in phase. The presented quadratic coupling model might explain the recent experimental observation of strong low-n components in magnetic measurements [Wenninger et al., “Non-linear magnetic perturbations during edge localized modes in TCV dominated by low n mode components,” Nucl. Fusion (submitted)].

  11. Epsilon-near-zero modes for tailored light-matter interaction

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

    Campione, Salvatore; Liu, Sheng; Benz, Alexander; Klem, John F.; Sinclair, Michael B.; Brener, Igal

    2015-10-20

    Epsilon-near-zero (ENZ) modes arising from condensed-matter excitations such as phonons and plasmons are a new path for tailoring light-matter interactions at the nanoscale. Complex spectral shaping can be achieved by creating such modes in nanoscale semiconductor layers and controlling their interaction with multiple, distinct, dipole resonant systems. Examples of this behavior are presented at midinfrared frequencies for ENZ modes that are strongly coupled to metamaterial resonators and simultaneously strongly coupled to semiconductor phonons or quantum-well intersubband transitions (ISTs), resulting in double- and triple-polariton branches in transmission spectra. For the double-polariton branch case, we find that the best strategy to maximizemore » the Rabi splitting is to use a combination of a doped layer supporting an ENZ feature and a layer supporting ISTs, with overlapping ENZ and IST frequencies. As a result, this design flexibility renders this platform attractive for low-voltage tunable filters, light-emitting diodes, and efficient nonlinear composite materials.« less

  12. Bi-harmonic cantilever design for improved measurement sensitivity in tapping-mode atomic force microscopy

    SciTech Connect (OSTI)

    Loganathan, Muthukumaran; Bristow, Douglas A.

    2014-04-15

    This paper presents a method and cantilever design for improving the mechanical measurement sensitivity in the atomic force microscopy (AFM) tapping mode. The method uses two harmonics in the drive signal to generate a bi-harmonic tapping trajectory. Mathematical analysis demonstrates that the wide-valley bi-harmonic tapping trajectory is as much as 70% more sensitive to changes in the sample topography than the standard single-harmonic trajectory typically used. Although standard AFM cantilevers can be driven in the bi-harmonic tapping trajectory, they require large forcing at the second harmonic. A design is presented for a bi-harmonic cantilever that has a second resonant mode at twice its first resonant mode, thereby capable of generating bi-harmonic trajectories with small forcing signals. Bi-harmonic cantilevers are fabricated by milling a small cantilever on the interior of a standard cantilever probe using a focused ion beam. Bi-harmonic drive signals are derived for standard cantilevers and bi-harmonic cantilevers. Experimental results demonstrate better than 30% improvement in measurement sensitivity using the bi-harmonic cantilever. Images obtained through bi-harmonic tapping exhibit improved sharpness and surface tracking, especially at high scan speeds and low force fields.

  13. A millimeter wave relativistic backward wave oscillator operating in TM{sub 03} mode with low guiding magnetic field

    SciTech Connect (OSTI)

    Ye, Hu; Wu, Ping; Teng, Yan; Chen, Changhua; Ning, Hui; Song, Zhimin; Cao, Yibing

    2015-06-15

    A V-band overmoded relativistic backward wave oscillator (RBWO) guided by low magnetic field and operating on a TM{sub 03} mode is presented to increase both the power handling capacity and the wave-beam interaction conversion efficiency. Trapezoidal slow wave structures (SWSs) with shallow corrugations and long periods are adopted to make the group velocity of TM{sub 03} mode at the intersection point close to zero. The coupling impedance and diffraction Q-factor of the RBWO increase, while the starting current decreases owing to the reduction of the group velocity of TM{sub 03} mode. In addition, the TM{sub 03} mode dominates over the other modes in the startup of the oscillation. Via numerical simulation, the generation of the microwave pulse with an output power of 425?MW and a conversion efficiency of 32% are achieved at 60.5?GHz with an external magnetic field of 1.25?T. This RBWO can provide greater power handling capacity when operating on the TM{sub 03} mode than on the TM{sub 01} mode.

  14. Enhancement of surface phonon modes in the Raman spectrum of ZnSe nanoparticles on adsorption of 4-mercaptopyridine

    SciTech Connect (OSTI)

    Islam, Syed K.; Lombardi, John R.

    2014-02-21

    By chemically etching a thin film of crystalline ZnSe with acid, we observe a strong Raman enhancement of the surface phonon modes of ZnSe on adsorption of a molecule (4-mercaptopyridine). The surface is composed of oblate hemi-ellipsoids, which has a large surface-to-bulk ratio. The assignment of the observed modes (at 248 and 492 cm{sup ?1}) to a fundamental and first overtone of the surface optical mode is consistent with observations from high-resolution electron energy loss spectroscopy as well as calculations.

  15. Note: Matching index technique for avoiding higher order mode resonance in accelerators: INDUS-2 accelerator as a case study

    SciTech Connect (OSTI)

    Jain, V.; Joshi, S. C.; Bhandarkar, U. V.; Krishnagopal, S.; Centre for Excellence in Basic Sciences, Mumbai 400098

    2013-08-15

    Resonance between circulating beam frequencies and RF cavity Higher Order Modes (HOMs) of accelerators can lead to coupled-bunch instabilities. Shifting these HOMs to avoid the resonance is a topic of active interest. A study has been carried out for the accelerating cavities of the INDUS-2. For quantitative measure of deciding which modes have to be moved and by how much, we introduce a new index called the matching index (I{sub M}), as a measure of how close a HOM is to the nearest beam mode. Depending on the value of I{sub M}, the operating scenarios are classified as safe and unsafe.

  16. Development of ITER 15 MA ELMy H-mode Inductive Scenario

    SciTech Connect (OSTI)

    Kessel, C. E.; Campbell, D.; Gribov, Y.; Saibene, G.; Ambrosino, G.; Casper, T.; Cavinato, M.; Fujieda, H.; Hawryluk, R.; Horton, L. D.; Kavin, A.; Kharyrutdinov, R.; Koechl, F.; Leuer, J.; Loarte, A.; Lomas, P. J.; Luce, T.; Lukash, V.; Mattei, M.; Nunes, I.; Parail, V.; Polevoi, A.; Portone, A.; Sartori, R.; Sips, A. C.C.; Thomas, P. R.; Welander, A.; Wesley, J.

    2008-10-16

    The poloidal field (PF) coil system on ITER, which provides both feedforward and feedback control of plasma position, shape, and current, is a critical element for achieving mission performance. Analysis of PF capabilities has focused on the 15 MA Q = 10 scenario with a 300-500 s flattop burn phase. The operating space available for the 15 MA ELMy H-mode plasma discharges in ITER and upgrades to the PF coils or associated systems to establish confidence that ITER mission objectives can be reached have been identified. Time dependent self-consistent free-boundary calculations were performed to examine the impact of plasma variability, discharge programming, and plasma disturbances. Based on these calculations a new reference scenario was developed based upon a large bore initial plasma, early divertor transition, low level heating in L-mode, and a late H-mode onset. Equilibrium analyses for this scenario indicate that the original PF coil limitations do not allow low li (<0.8) operation or lower flux states, and the flattop burn durations were predicted to be less than the desired 400 s. This finding motivates the expansion of the operating space, considering several upgrade options to the PF coils. Analysis was also carried out to examine the feedback current reserve required in the CS and PF coils during a series of disturbances and a feasibility assessment of the 17 MA scenario was undertaken. Results of the studies show that the new scenario and modified PF system will allow a wide range of 15 MA 300-500 s operation and more limited but finite 17 MA operation.

  17. Magnetohydrodynamic modes analysis and control of Fusion Advanced Studies Torus high-current scenarios

    SciTech Connect (OSTI)

    Villone, F.; Mastrostefano, S.; Calabrò, G.; Vlad, G.; Crisanti, F.; Fusco, V.; Marchiori, G.; Bolzonella, T.; Marrelli, L.; Martin, P.; Liu, Y. Q.

    2014-08-15

    One of the main FAST (Fusion Advanced Studies Torus) goals is to have a flexible experiment capable to test tools and scenarios for safe and reliable tokamak operation, in order to support ITER and help the final DEMO design. In particular, in this paper, we focus on operation close to a possible border of stability related to low-q operation. To this purpose, a new FAST scenario has then been designed at I{sub p} = 10 MA, B{sub T} = 8.5 T, q{sub 95} ≈ 2.3. Transport simulations, carried out by using the code JETTO and the first principle transport model GLF23, indicate that, under these conditions, FAST could achieve an equivalent Q ≈ 3.5. FAST will be equipped with a set of internal active coils for feedback control, which will produce magnetic perturbation with toroidal number n = 1 or n = 2. Magnetohydrodynamic (MHD) mode analysis and feedback control simulations performed with the codes MARS, MARS-F, CarMa (both assuming the presence of a perfect conductive wall and using the exact 3D resistive wall structure) show the possibility of the FAST conductive structures to stabilize n = 1 ideal modes. This leaves therefore room for active mitigation of the resistive mode (down to a characteristic time of 1 ms) for safety purposes, i.e., to avoid dangerous MHD-driven plasma disruption, when working close to the machine limits and magnetic and kinetic energy density not far from reactor values.

  18. Design of a spin-wave majority gate employing mode selection

    SciTech Connect (OSTI)

    Klingler, S. Pirro, P.; Brcher, T.; Leven, B.; Hillebrands, B.; Chumak, A. V.

    2014-10-13

    The design of a microstructured, fully functional spin-wave majority gate is presented and studied using micromagnetic simulations. This all-magnon logic gate consists of three-input waveguides, a spin-wave combiner, and an output waveguide. In order to ensure the functionality of the device, the output waveguide is designed to perform spin-wave mode selection. We demonstrate that the gate evaluates the majority of the input signals coded into the spin-wave phase. Moreover, the all-magnon data processing device is used to perform logic AND-, OR-, NAND-, and NOR- operations.

  19. Optical apparatus for conversion of whispering-gallery modes into a free space gaussian like beam

    DOE Patents [OSTI]

    Stallard, Barry W.; Makowski, Michael A.; Byers, Jack A.

    1992-01-01

    An optical converter for efficient conversion of millimeter wavelength whispering-gallery gyrotron output into a linearly polarized, free-space Gaussian-like beam. The converter uses a mode-converting taper and three mirror optics. The first mirror has an azimuthal tilt to eliminate the k.sub..phi. component of the propagation vector of the gyrotron output beam. The second mirror has a twist reflector to linearly polarize the beam. The third mirror has a constant phase surface so the converter output is in phase.

  20. Mode Coupling and the Pygmy Dipole Resonance in a Relativistic Two-Phonon Model

    SciTech Connect (OSTI)

    Litvinova, Elena; Ring, Peter; Tselyaev, Victor

    2010-07-09

    A new class of many-body models, based on covariant density functional theory for excited states, is presented. It allows a parameter free description of the fragmentation of nuclear states induced by mode coupling of two-quasiparticle and two-phonon configurations. As compared to earlier methods it provides a consistent and parameter free theory of the fine structure of nuclear resonances. The method is applied very successfully to investigate the newly discovered low-lying dipole excitations in Sn and Ni isotopes with large neutron excess.

  1. Selection of stirling engine parameter and modes of joint operation with the Topaz II

    SciTech Connect (OSTI)

    Kirillov, E.Y.; Ogloblin, B.G.; Shalaev, A.I.

    1996-03-01

    In addition to a high-temperature thermionic conversion cycle, application of a low-temperature machine cycle, such as the Stirling engine, is being considered. To select the optimum mode for joint operation of the Topaz II system and Stirling engine, output electric parameters are obtained as a function of thermal power released in the TFE fuel cores. The hydraulic diagram used for joint operation of the Topaz II and the Stirling engine is considered. Requirements to hydraulic characteristics of the Stirling engine heat exchanges are formulated. Scope of necessary modifications to mount the Stirling Engine on the Topaz II is estimated. {copyright} {ital 1996 American Institute of Physics.}

  2. Optimizing and calibrating a mode-mismatched thermal lens experiment for low absorption measurement

    SciTech Connect (OSTI)

    Marcano, Aristides; Cabrera, Humberto; Guerra, Mayamaru; Cruz, Renato A.; Jacinto, Carlos; Catunda, Tomaz

    2006-07-15

    We describe a calibrated two-beam mode-mismatched thermal lens experiment aimed at determination of the absorption coefficient and the photothermal parameters of a nearly transparent material. The use of a collimated probe beam in the presence of a focused excitation beam optimizes the thermal lens experiment. The signal becomes independent from the Rayleigh parameters and waist positions of the beams. We apply this method to determine the absolute value of the thermal diffusivity and absorption coefficient of distilled water at 533 nm.

  3. Method of pedestal and common-mode noise correction for switched-capacitor analog memories

    DOE Patents [OSTI]

    Britton, Charles L.

    1996-01-01

    A method and apparatus for correcting common-mode noise and pedestal noise in a multichannel array of switched-capacitor analog memories wherein each analog memory is connected to an associated analog-to-digital converter. The apparatus comprises a single differential element in two different embodiments. In a first embodiment, the differential element is a reference analog memory connected to a buffer. In the second embodiment, the differential element is a reference analog memory connected to a reference analog-to-digital connected to an array of digital summing circuits.

  4. Ultrasensitive mode-localized mass sensor with electrically tunable parametric sensitivity

    SciTech Connect (OSTI)

    Thiruvenkatanathan, P.; Yan, J.; Seshia, A. A. [Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Nanoscience Centre, University of Cambridge, 11 JJ Thomson Avenue, Cambridge CB3 0FF (United Kingdom); Woodhouse, J. [Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ (United Kingdom); Aziz, A. [Nanoscience Centre, University of Cambridge, 11 JJ Thomson Avenue, Cambridge CB3 0FF (United Kingdom)

    2010-02-22

    We use the phenomena of mode localization and vibration confinement in pairs of weakly coupled, nearly identical microelectromechanical (MEMS) resonators as an ultrasensitive technique of detecting added mass on the resonator. The variations in the eigenstates for induced mass additions are studied and compared with corresponding resonant frequency shifts in pairs of MEMS resonators that are coupled electrostatically. We demonstrate that the relative shifts in the eigenstates can be over three orders of magnitude greater than those in resonant frequency for the same addition of mass. We also investigate the effects of voltage controlled electrical spring tuning on the parametric sensitivity of such sensors and demonstrate sensitivities tunable by over 400%.

  5. Radial transport of energetic ions in the presence of trapped electron mode turbulence

    SciTech Connect (OSTI)

    Chowdhury, J.; Wang, W.; Ethier, S.; Manickam, J. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Ganesh, R. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

    2011-11-15

    The nature of transport of hot ions is studied in the presence of microturbulence generated by the trapped electron mode in a Tokamak using massively parallel, first principle based global nonlinear gyrokinetic simulation, and with the help of a passive tracer method. Passing and trapped hot ions are observed to exhibit inverse and inverse square scaling with energy, while those with isotropic pitch distribution are found to exhibit inverse dependence on energy. For all types of hot ions, namely, isotropic, passing, and trapped, the radial transport appears to be subdiffusive for the parameters considered.

  6. Method of pedestal and common-mode noise correction for switched-capacitor analog memories

    DOE Patents [OSTI]

    Britton, C.L.

    1996-12-31

    A method and apparatus are disclosed for correcting common-mode noise and pedestal noise in a multichannel array of switched-capacitor analog memories wherein each analog memory is connected to an associated analog-to-digital converter. The apparatus comprises a single differential element in two different embodiments. In a first embodiment, the differential element is a reference analog memory connected to a buffer. In the second embodiment, the differential element is a reference analog memory connected to a reference analog-to-digital connected to an array of digital summing circuits. 4 figs.

  7. Method of pedestal and common-mode noise correction for switched-capacitor analog memories

    DOE Patents [OSTI]

    Britton, C.L.

    1997-09-23

    A method and apparatus are disclosed for correcting common-mode noise and pedestal noise in a multichannel array of switched-capacitor analog memories wherein each analog memory is connected to an associated analog-to-digital converter. The apparatus comprises a single differential element in two different embodiments. In a first embodiment, the differential element is a reference analog memory connected to a buffer. In the second embodiment, the differential dement is a reference analog memory connected to a reference analog-to-digital connected to an array of digital summing circuits. 4 figs.

  8. Method of pedestal and common-mode noise correction for switched-capacitor analog memories

    DOE Patents [OSTI]

    Britton, Charles L.

    1997-01-01

    A method and apparatus for correcting common-mode noise and pedestal noise in a multichannel array of switched-capacitor analog memories wherein each analog memory is connected to an associated analog-to-digital converter. The apparatus comprises a single differential element in two different embodiments. In a first embodiment, the differential element is a reference analog memory connected to a buffer. In the second embodiment, the differential dement is a reference analog memory connected to a reference analog-to-digital connected to an array of digital summing circuits.

  9. Conditional generation of arbitrary single-mode quantum states of light by repeated photon subtractions

    SciTech Connect (OSTI)

    Fiurasek, Jaromir; Garcia-Patron, Raul; Cerf, Nicolas J.

    2005-09-15

    We propose a scheme for the conditional generation of arbitrary finite superpositions of Fock states in a single mode of a traveling optical field. The setup requires a source of squeezed vacuum states, beam splitters, strong coherent beams, photodetectors with single-photon sensitivity, and a final squeezer. If we want to generate a squeezed superposition of Fock states, which is sufficient in several applications, then the last squeezer is not even needed. The thrust of this method is that it achieves a high fidelity without requiring photodetectors with a high efficiency or a single-photon resolution. The possibility to improve its scaling by using a quantum memory is also discussed.

  10. Spontaneous Fission Modes and Lifetimes of Superheavy Elements in the Nuclear Density Functional Theory

    SciTech Connect (OSTI)

    Staszczak, A,

    2013-01-01

    Background: The reactions with the neutron-rich 48Ca beam and actinide targets resulted in the detection of new superheavy (SH) nuclides with Z=104 118. The unambiguous identification of the new isotopes, however, still poses a problem because their -decay chains terminate by spontaneous fission (SF) before reaching the known region of the nuclear chart. The understanding of the competition between -decay and SF channels in SH nuclei is, therefore, of crucial importance for our ability to map the SH region and to assess its extent.

    Purpose: We perform self-consistent calculations of the competing decay modes of even-even SH isotopes with 108 Z 126 and 148 N 188.

    Methods: We use the state-of-the-art computational framework based on self-consistent symmetry-unrestricted nuclear density functional theory capable of describing the competition between nuclear attraction and electrostatic repulsion. We apply the SkM* Skyrme energy density functional. The collective mass tensor of the fissioning superfluid nucleus is computed by means of the cranking approximation to the adiabatic time-dependent Hartree-Fock-Bogoliubov (HFB) approach. This paper constitutes a systematic self-consistent study of spontaneous fission in the SH region, carried out at a full HFB level, that simultaneously takes into account both triaxiality and reflection asymmetry.

    Results: Breaking axial symmetry and parity turns out to be crucial for a realistic estimate of collective action; it results in lowering SF lifetimes by more than 7 orders of magnitude in some cases. We predict two competing SF modes: reflection symmetric modes and reflection asymmetric modes.

    Conclusions: The shortest-lived SH isotopes decay by SF; they are expected to lie in a narrow corridor formed by 280Hs, 284Fl, and 118284Uuo that separates the regions of SH nuclei synthesized in cold-fusion and hot-fusion reactions. The region of long-lived SH nuclei is expected to be centered on 294Ds with a total half-life of 1.5 days. Our survey provides a solid benchmark for the future improvements of self-consistent SF calculations in the region of SH nuclei.

  11. STOMP Sparse Vegetation Evapotranspiration Model for the Water-Air-Energy Operational Mode

    SciTech Connect (OSTI)

    Ward, Anderson L.; White, Mark D.; Freeman, Eugene J.; Zhang, Z. F.

    2005-09-15

    The Water-Air-Energy (WAE) Operational Mode of the Subsurface Transport Over Multiple Phases (STOMP) numerical simulator solves the coupled conservation equations for water mass, air mass, and thermal energy in multiple dimensions. This addendum describes the theory, input file formatting, and application of a soil-vegetation-atmosphere transfer (SVAT) scheme for STOMP that is based on a sparse vegetation evapotranspiration model. The SVAT scheme is implemented as a boundary condition on the upper surface of the computational domain and has capabilities for simulating evaporation from bare surfaces as well as evapotranspiration from sparsely vegetated surfaces populated with single or multiple plant species in response to meteorological forcings. With this extension, the model calculates water mass, air mass and thermal energy across a boundary surface in addition to root-water transport between the subsurface and atmosphere. This mode represents the barrier extension of the WAE mode and is designated as STOMP-WAE-B. Input for STOMP-WAE-B is specified via three input cards and include: atmospheric conditions through the Atmospheric Conditions Card; time-invariant plant species data through the Plant Properties Card; and time varying plant species data through the Boundary Conditions Card. Two optional cards, the Observed Data and UCODE Control Cards allow use of STOMP-WAE with UCODE in an inverse mode to estimate model parameters. STOMP-WAE was validated by solving a number of test problems from the literature that included experimental observations as well as analytical or numerical solutions. Several of the UNSAT-H verification problems are included along with a benchmark simulation derived from a recently published intercode comparison for barrier design tools. Results show that STOMP is able to meet, and in most cases, exceed performance of other commonly used simulation codes without having to resort to may of their simplifying assumptions. Use of the fully coupled STOMP simulator to guide barrier design will result in optimized designs with reduced construction costs; reduced environmental impacts at borrow sites; and minimized post-closure care and monitoring needs, while meeting regulatory requirements.

  12. Frequency splitter based on the directional emission from surface modes in dielectric photonic crystal structures

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

    Tasolamprou, Anna C.; Zhang, Lei; Kafesaki, Maria; Koschny, Thomas; Soukoulis, Costas M.

    2015-05-19

    We demonstrate the numerical design and the experimental validation of frequency dependent directional emission from a dielectric photonic crystal structure. The wave propagates through a photonic crystal line-defect waveguide, while a surface layer at the termination of the photonic crystal enables the excitation of surface modes and a subsequent grating layer transforms the surface energy into outgoing propagating waves of the form of a directional beam. The angle of the beam is controlled by the frequency and the structure operates as a frequency splitter in the intermediate and far field region.

  13. Spin zero Hawking radiation for non-zero-angular momentum mode

    SciTech Connect (OSTI)

    Ngampitipan, Tritos; Bonserm, Petarpa; Visser, Matt

    2015-05-15

    Black hole greybody factors carry some quantum black hole information. Studying greybody factors may lead to understanding the quantum nature of black holes. However, solving for exact greybody factors in many black hole systems is impossible. One way to deal with this problem is to place some rigorous analytic bounds on the greybody factors. In this paper, we calculate rigorous bounds on the greybody factors for spin zero hawking radiation for non-zero-angular momentum mode from the Kerr-Newman black holes.

  14. Tests of Four PT-415 Coolers Installed in the Drop-in Mode

    SciTech Connect (OSTI)

    Green, Michael A.; Wang, S.T.

    2008-07-08

    The superconducting magnets and absorbers for MICE will be cooled using PT415 pulse tube coolers. The cooler 2nd stage will be connected to magnets and the absorbers through a helium or hydrogen re-condensing system. It was proposed that the coolers be connected to the magnets in such a way that the cooler can be easily installed and removed, which permits the magnets to be shipped without the coolers. The drop-in mode requires that the cooler 1st stage be well connected to the magnet shields and leads through a low temperature drop demountable connection. The results of the PT415 drop-in cooler tests are presented.

  15. Telescope Guiding with a HyViSI H2RG Used in Guide Mode

    SciTech Connect (OSTI)

    Simms, Lance M.; Figerb, Donald F.; Hanold, Brandon J.; Kahn, Steven M.; Gilmore, D.Kirk

    2010-06-04

    We report on long exposure results obtained with a Teledyne HyViSI H2RG detector operating in guide mode. The sensor simultaneously obtained nearly seeing-limited data while also guiding the Kitt Peak 2.1 m telescope. Results from unguided and guided operation are presented and used to place lower limits on flux/fluence values for accurate centroid measurements. We also report on significant noise reduction obtained in recent laboratory measurements that should further improve guiding capability with higher magnitude stars.

  16. A transputer-based list mode parallel system for digital radiography with 2D silicon detectors

    SciTech Connect (OSTI)

    Conti, M.; Russo, P.; Scarlatella, A. . Dipt. di Scienze Fisiche and INFN); Del Guerra, A. . Dipt. di Fisica and INFN); Mazzeo, A.; Mazzocca, N.; Russo, S. . Dipt. di Informatica e Sistemistica)

    1993-08-01

    The authors believe that a dedicated parallel computer system can represent an effective and flexible approach to the problem of list mode acquisition and reconstruction of digital radiographic images obtained with a double-sided silicon microstrip detector. They present a Transputer-based implementation of a parallel system for the data acquisition and image reconstruction from a silicon crystal with 200[mu]m read-out pitch. They are currently developing a prototype of the system connected to a detector with a 10mm[sup 2] sensitive area.

  17. Unpaired Majorana modes in Josephson-Junction Arrays with gapless bulk excitations

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

    Pino, M.; Tsvelik, A.; Ioffe, L. B.

    2015-11-06

    In this study, the search for Majorana bound states in solid-state physics has been limited to materials that display a gap in their bulk spectrum. We show that such unpaired states appear in certain quasi-one-dimensional Josephson-junction arrays with gapless bulk excitations. The bulk modes mediate a coupling between Majorana bound states via the Ruderman-Kittel-Yosida-Kasuya mechanism. As a consequence, the lowest energy doublet acquires a finite energy difference. For a realistic set of parameters this energy splitting remains much smaller than the energy of the bulk eigenstates even for short chains of length L~10.

  18. Predicting the occurrence of mixed mode failure associated with hydraulic fracturing, part 2 water saturated tests

    SciTech Connect (OSTI)

    Bauer, Stephen J.; Broome, Scott Thomas; Choens, Charles; Barrow, Perry Carl

    2015-09-14

    Seven water-saturated triaxial extension experiments were conducted on four sedimentary rocks. This experimental condition was hypothesized more representative of that existing for downhole hydrofracture and thus it may improve our understanding of the phenomena. In all tests the pore pressure was 10 MPa and confirming pressure was adjusted to achieve tensile and transitional failure mode conditions. Using previous work in this LDRD for comparison, the law of effective stress is demonstrated in extension using this sample geometry. In three of the four lithologies, no apparent chemo-mechanical effect of water is apparent, and in the fourth lithology test results indicate some chemo-mechanical effect of water.

  19. Enhanced third harmonic generation from the epsilon-near-zero modes of ultrathin films

    SciTech Connect (OSTI)

    Luk, Ting S. Liu, Sheng; Campione, Salvatore; Ceglia, Domenico de; Vincenti, Maria A.; Keeler, Gordon A.; Sinclair, Michael B.; Prasankumar, Rohit P.; Scalora, Michael

    2015-04-13

    We experimentally demonstrate efficient third harmonic generation from an indium tin oxide nanofilm (λ/42 thick) on a glass substrate for a pump wavelength of 1.4 μm. A conversion efficiency of 3.3 × 10{sup −6} is achieved by exploiting the field enhancement properties of the epsilon-near-zero mode with an enhancement factor of 200. This nanoscale frequency conversion method is applicable to other plasmonic materials and reststrahlen materials in proximity of the longitudinal optical phonon frequencies.

  20. Enhanced third harmonic generation from the epsilon-near-zero modes of ultrathin films

    SciTech Connect (OSTI)

    Luk, Ting S.; De Ceglia, Domenico; Liu, Sheng; Keeler, Gordon Arthur; Prasankumar, Rohit; Los Alamos National Lab. , Los Alamos, NM ; Vincenti, Maria A; Scalora, Michael; Sinclair, Michael B.; campione, salvatore

    2015-04-13

    We demonstrate, through our experimentation, efficient third harmonic generation from an indium tin oxide nanofilm (λ/42 thick) on a glass substrate for a pump wavelength of 1.4 μm. A conversion efficiency of 3.3 × 10-6 is achieved by exploiting the field enhancement properties of the epsilon-near-zero mode with an enhancement factor of 200. Furthermore, this nanoscale frequency conversion method is applicable to other plasmonic materials and reststrahlen materials in proximity of the longitudinal optical phonon frequencies.

  1. Extremely high Q-factor mechanical modes in quartz bulk acoustic wave resonators at millikelvin temperature

    SciTech Connect (OSTI)

    Goryachev, M.; Creedon, D. L.; Ivanov, E. N.; Tobar, M. E.; Galliou, S.; Bourquin, R.

    2014-12-04

    We demonstrate that Bulk Acoustic Wave (BAW) quartz resonator cooled down to millikelvin temperatures are excellent building blocks for hybrid quantum systems with extremely long coherence times. Two overtones of the longitudinal mode at frequencies of 15.6 and 65.4 MHz demonstrate a maximum f.Q product of 7.810{sup 16} Hz. With this result, the Q-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained in other mechanical systems. Tested quartz resonators possess the ultra low acoustic losses crucial for electromagnetic cooling to the phonon ground state.

  2. Statistical comparison of ICRF and NBI heating performance in JET-ILW L-mode plasmas

    SciTech Connect (OSTI)

    Lerche, E.; Van Eester, D.; Jacquet, Ph.; Mayoral, M.-L.; Graham, M.; Matthews, G.; Monakhov, I.; Rimini, F.; Colas, L.; Czarnecka, A.; Vries, P. de; Collaboration: JET-EFDA Contributors

    2014-02-12

    After the change over from the C-wall to the ITER-like Be/W wall (ILW) in JET, the radiation losses during ICRF heating have increased and are now substantially larger than those observed with NBI at the same power levels, in spite of the similar global plasma energies reached with the two heating systems. A comparison of the NBI and ICRF performances in the JET-ILW experiments, based on a statistical analysis of ?3000 L-mode discharges, will be presented.

  3. Coupling radiative heat transfer in participating media with other heat transfer modes

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

    Tencer, John; Howell, John R.

    2015-09-28

    The common methods for finding the local radiative flux divergence in participating media through solution of the radiative transfer equation are outlined. The pros and cons of each method are discussed in terms of their speed, ability to handle spectral properties and scattering phenomena, as well as their accuracy in different ranges of media transport properties. The suitability of each method for inclusion in the energy equation to efficiently solve multi-mode thermal transfer problems is discussed. Lastly, remaining topics needing research are outlined.

  4. Dual-mode self-validating resistance/Johnson noise thermometer system

    DOE Patents [OSTI]

    Shepard, Robert L.; Blalock, Theron V.; Roberts, Michael J.

    1993-01-01

    A dual-mode Johnson noise and DC resistance thermometer capable of use in control systems where prompt indications of temperature changes and long term accuracy are needed. A resistance-inductance-capacitance (RLC) tuned circuit produces a continuous voltage signal for Johnson noise temperature measurement. The RLC circuit provides a mean-squared noise voltage that depends only on the capacitance used and the temperature of the sensor. The sensor has four leads for simultaneous coupling to a noise signal processor and to a DC resistance signal processor.

  5. Multi-Mode RCCI Has Great Potential to Improve Fuel Economy in Light-Duty Diesel Engines

    Broader source: Energy.gov [DOE]

    Multi-mode RCCI (Reactivity-Controlled Compression Ignition), a promising advanced combustion process, has the potential to improve fuel economy of passenger cars by at least 15%, according to a...

  6. SU-E-T-322: The Evaluation of the Gafchromic EBT3 Film in Low Dose 6 MV X-Ray Beams with Different Scanning Modes

    SciTech Connect (OSTI)

    Lee, H; Sung, J; Yoon, M; Kim, D; Chung, W

    2014-06-01

    Purpose: We have evaluated the response of the Gafchromic EBT3 film in low dose for 6 MV x-ray beams with two scanning modes, the reflection scanning mode and the transmission scanning mode. Methods: We irradiated the Gafcromic EBT3 film using a 60 degree enhanced dynamic wedge (EDW) with 6 MV x-ray beams from Clinac iX Linear accelerator (Varian Medical Systems, Palo Alto, CA). The irradiated Gafchromic EBT3 film was scanned with different scanning modes, the reflection scanning mode and the transmission scanning mode. The scanned Gafchromic EBT3 film was analyzed with MATLAB. Results: When 7.2 cGy was irradiated to the Gafchromic EBT3 film, the uncertainty was 0.54 cGy with reflection scanning mode and was 0.88 cGy with transmission scanning mode. When 24 cGy was irradiated to the Gafchromic EBT3 film, the uncertainty was similar to the case of 7.2 cGy irradiation showing 0.51 cGy of uncertainty with reflection scanning mode and 0.87 cGy of uncertainty with transmission scanning mode. The result suggests that the reflection mode should be used in Gafchromic EBT3 film for low irradiation. Conclusion: The result suggests that the reflection mode should be used in Gafchromic EBT3 film for low irradiation.

  7. Simulation of non-resonant internal kink mode with toroidal rotation in the National Spherical Torus Experiment

    SciTech Connect (OSTI)

    Wang, Feng; Liu, J. Y. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Fu, G. Y.; Breslau, J. A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Tritz, Kevin [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)] [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2013-07-15

    Plasmas in spherical and conventional tokamaks, with weakly reversed shear q profile and minimum q above but close to unity, are susceptible to an non-resonant (m,n) = (1,1) internal kink mode. This mode can saturate and persist and can induce a (2,1) seed island for Neoclassical Tearing Mode. [Breslau et al. Nucl. Fusion 51, 063027 (2011)]. The mode can also lead to large energetic particle transport and significant broadening of beam-driven current. Motivated by these important effects, we have carried out extensive nonlinear simulations of the mode with finite toroidal rotation using parameters and profiles of an NTSX plasma with a weakly reversed shear profile. The numerical results show that, at the experimental level, plasma rotation has little effect on either equilibrium or linear stability. However, rotation can significantly influence the nonlinear dynamics of the (1,1) mode and the induced (2,1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at finite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the effects of rotation are found to greatly suppress the (2,1) magnetic island even at a low level.

  8. Component mode synthesis methods applied to 3D heterogeneous core calculations, using the mixed dual finite element solver MINOS

    SciTech Connect (OSTI)

    Guerin, P.; Baudron, A. M.; Lautard, J. J.

    2006-07-01

    This paper describes a new technique for determining the pin power in heterogeneous core calculations. It is based on a domain decomposition with overlapping sub-domains and a component mode synthesis technique for the global flux determination. Local basis functions are used to span a discrete space that allows fundamental global mode approximation through a Galerkin technique. Two approaches are given to obtain these local basis functions: in the first one (Component Mode Synthesis method), the first few spatial eigenfunctions are computed on each sub-domain, using periodic boundary conditions. In the second one (Factorized Component Mode Synthesis method), only the fundamental mode is computed, and we use a factorization principle for the flux in order to replace the higher order Eigenmodes. These different local spatial functions are extended to the global domain by defining them as zero outside the sub-domain. These methods are well-fitted for heterogeneous core calculations because the spatial interface modes are taken into account in the domain decomposition. Although these methods could be applied to higher order angular approximations - particularly easily to a SPN approximation - the numerical results we provide are obtained using a diffusion model. We show the methods' accuracy for reactor cores loaded with UOX and MOX assemblies, for which standard reconstruction techniques are known to perform poorly. Furthermore, we show that our methods are highly and easily parallelizable. (authors)

  9. Influence of driving frequency on discharge modes in a dielectric-barrier discharge with multiple current pulses

    SciTech Connect (OSTI)

    Jiang, Weiman; Tang, Jie; Wang, Yishan; Zhao, Wei; Duan, Yixiang; Research Center of Analytical Instrumentation, Sichuan University, Chengdu 610064

    2013-07-15

    A one-dimensional self-consistent fluid model was employed to investigate the effect of the driving frequency on the discharge modes in atmospheric-pressure argon discharge with multiple current pulses. The discharge mode was discussed in detail not only at current peaks but also between two adjacent peaks. The simulation results show that different transitions between the Townsend and glow modes during the discharge take place with the driving frequency increased. A complicated transition from the Townsend mode, through glow, Townsend, and glow, and finally back to the Townsend one is found in the discharge with the driving frequency of 8 kHz. There is a tendency of transition from the Townsend to glow mode for the discharge both at the current peaks and troughs with the increasing frequency. The discharge in the half period can all along operate in the glow mode with the driving frequency high enough. This is resulted from the preservation of more electrons in the gas gap and acquisition of more electron energy from the swiftly varying electric field with the increase in driving frequency. Comparison of the spatial and temporal evolutions of the electron density at different driving frequencies indicates that the increment of the driving frequency allows the plasma chemistry to be enhanced. This electrical characteristic is important for the applications, such as surface treatment and biomedical sterilization.

  10. Experimental verification of a model describing the intensity distribution from a single mode optical fiber

    SciTech Connect (OSTI)

    Moro, Erik A; Puckett, Anthony D; Todd, Michael D

    2011-01-24

    The intensity distribution of a transmission from a single mode optical fiber is often approximated using a Gaussian-shaped curve. While this approximation is useful for some applications such as fiber alignment, it does not accurately describe transmission behavior off the axis of propagation. In this paper, another model is presented, which describes the intensity distribution of the transmission from a single mode optical fiber. A simple experimental setup is used to verify the model's accuracy, and agreement between model and experiment is established both on and off the axis of propagation. Displacement sensor designs based on the extrinsic optical lever architecture are presented. The behavior of the transmission off the axis of propagation dictates the performance of sensor architectures where large lateral offsets (25-1500 {micro}m) exist between transmitting and receiving fibers. The practical implications of modeling accuracy over this lateral offset region are discussed as they relate to the development of high-performance intensity modulated optical displacement sensors. In particular, the sensitivity, linearity, resolution, and displacement range of a sensor are functions of the relative positioning of the sensor's transmitting and receiving fibers. Sensor architectures with high combinations of sensitivity and displacement range are discussed. It is concluded that the utility of the accurate model is in its predicative capability and that this research could lead to an improved methodology for high-performance sensor design.

  11. Engineering task plan for rotary mode core sampling exhausters CAM high radiation interlock

    SciTech Connect (OSTI)

    BOGER, R.M.

    1999-05-19

    The Rotary Mode Core Sampling (RMCS) system is primarily made up of the Rotary Mode Core Sample Trucks (RMCST) and the RMCS Exhausters. During RMCS operations an Exhauster is connected to a tank riser and withdraws gases from the tank dome vapor space at approximately 200 Standard Cubic Feet per Minute (SCFM). The gases are passed through two High Efficiency Particulate Air (HEPA) filters before passing out the exhaust stack to the atmosphere. A Continuous Air Monitor (CAM) monitors the exhaust gases in the exhaust stack for beta particle and gamma radiation. The CAM has a high radiation alarm output and a detector fail alarm output. The CAM alarms are currently connected to the data logger only. The CAM alarms require operator response per procedure LMHC 1998 but no automatic functions are initiated by the CAM alarms. Currently, there are three events that can cause an automatic shut down of the Exhauster. These are, Low Tank Pressure, Highnow Stack Flow and High HEPA Filter Differential Pressure (DP).

  12. Parameter sensitivity analysis of nonlinear piezoelectric probe in tapping mode atomic force microscopy for measurement improvement

    SciTech Connect (OSTI)

    McCarty, Rachael; Nima Mahmoodi, S.

    2014-02-21

    The equations of motion for a piezoelectric microcantilever are derived for a nonlinear contact force. The analytical expressions for natural frequencies and mode shapes are obtained. Then, the method of multiple scales is used to analyze the analytical frequency response of the piezoelectric probe. The effects of nonlinear excitation force on the microcantilever beam's frequency and amplitude are analytically studied. The results show a frequency shift in the response resulting from the force nonlinearities. This frequency shift during contact mode is an important consideration in the modeling of AFM mechanics for generation of more accurate imaging. Also, a sensitivity analysis of the system parameters on the nonlinearity effect is performed. The results of a sensitivity analysis show that it is possible to choose parameters such that the frequency shift minimizes. Certain parameters such as tip radius, microcantilever beam dimensions, and modulus of elasticity have more influence on the nonlinearity of the system than other parameters. By changing only three parameters—tip radius, thickness, and modulus of elasticity of the microbeam—a more than 70% reduction in nonlinearity effect was achieved.

  13. Anderson Localization of Ballooning Modes, Quantum Chaos and the Stability of Compact Quasiaxially Symmetric Stellarators

    SciTech Connect (OSTI)

    M.H. Redi; J.L. Johnson; S. Klasky; J. Canik; R.L. Dewar; W.A. Cooper

    2001-10-31

    The radially local magnetohydrodynamic (MHD) ballooning stability of a compact, quasiaxially symmetric stellarator (QAS), is examined just above the ballooning beta limit with a method that can lead to estimates of global stability. Here MHD stability is analyzed through the calculation and examination of the ballooning mode eigenvalue isosurfaces in the 3-space [s, alpha, theta(subscript ''k'')]; s is the edge normalized toroidal flux, alpha is the field line variable, and q(subscript ''k'') is the perpendicular wave vector or ballooning parameter. Broken symmetry, i.e., deviations from axisymmetry, in the stellarator magnetic field geometry causes localization of the ballooning mode eigenfunction, and gives rise to new types of nonsymmetric eigenvalue isosurfaces in both the stable and unstable spectrum. For eigenvalues far above the marginal point, isosurfaces are topologically spherical, indicative of strong ''quantum chaos.'' The complexity of QAS marginal isosurfaces suggests that finite Larmor radius stabilization estimates will be difficult and that fully three-dimensional, high-n MHD computations are required to predict the beta limit.

  14. A flux-matched gyrokinetic analysis of DIII-D L-mode turbulence

    SciTech Connect (OSTI)

    Grler, T. Told, D.; White, A. E.; Jenko, F.; Holland, C.; Rhodes, T. L.

    2014-12-15

    Previous nonlinear gyrokinetic simulations of specific DIII-D L-mode cases have been found to significantly underpredict the ion heat transport and associated density and temperature fluctuation levels by up to almost one of order of magnitude in the outer-core domain, i.e., roughly in the last third of the minor radius. Since then, this so-called shortfall issue has been subject to various speculations on possible reasons and furthermore motivation for a number of dedicated comparisons for L-mode plasmas in comparable machines. However, only a rather limited number of simulations and gyrokinetic codes has been applied to the original scenario, thus calling for further dedicated investigations in order to broaden the scientific basis. The present work contributes along these lines by employing another well-established gyrokinetic code in a numerically and physically comprehensive manner. Contrary to the previous studies, only a mild underprediction is observed at the outer radial positions which can furthermore be overcome by varying the ion temperature gradient within the error bars associated with the experimental measurement. The significance and reliability of these simulations are demonstrated by benchmarks, numerical convergence tests, and furthermore by extensive validation studies. The latter involve cross-phase and cross-power spectra analyses of various fluctuating quantities and confirm a high degree of realism. The code discrepancies come as a surprise since the involved software packages had been benchmarked repeatedly and very successfully in the past. Further collaborative effort in identifying the underlying difference is hence required.

  15. A Ka-band TM{sub 02} mode relativistic backward wave oscillator with cascaded resonators

    SciTech Connect (OSTI)

    Teng, Yan; Cao, Yinbin; Song, Zhimin; Ye, Hu; Shi, Yanchao; Chen, Changhua; Sun, Jun

    2014-12-15

    By combining the Cerenkov-type generator with the cascaded resonators, this paper proposes a Ka-band relativistic backward wave oscillator operating under the guide magnetic field 1.0?T with high power handling capability and high conversion efficiency. It is found that TM{sub 02} can be selected as the operation mode in order to increase the power handling capability and provide sufficient coupling with the electron beam. In slow wave structure (SWS), ripples composed of semicircle on top of the rectangle enhance the wave-beam interaction and decrease the intensity of the electric field on the metallic surface. Taking advantage of the resonator cascades, the output power and the conversion efficiency are promoted greatly. The front cascaded resonators efficiently prevent the power generated in SWS from leaking into the diode region, and quicken the startup of the oscillation due to the premodulation of the beam. However, the post cascade slightly postpones the startup because of the further energy extraction from the electron beam. The numerical simulation shows that generation with power 514?MW and efficiency 41% is obtained under the diode voltage 520?kV and current 2.4?kA. And the microwave with the pure frequency spectrum of 29.35 GHz radiates in the pure TM{sub 01} mode.

  16. Reliability analysis and prediction of mixed mode load using Markov Chain Model

    SciTech Connect (OSTI)

    Nikabdullah, N.; Singh, S. S. K.; Alebrahim, R.; Azizi, M. A.; K, Elwaleed A.; Noorani, M. S. M.

    2014-06-19

    The aim of this paper is to present the reliability analysis and prediction of mixed mode loading by using a simple two state Markov Chain Model for an automotive crankshaft. The reliability analysis and prediction for any automotive component or structure is important for analyzing and measuring the failure to increase the design life, eliminate or reduce the likelihood of failures and safety risk. The mechanical failures of the crankshaft are due of high bending and torsion stress concentration from high cycle and low rotating bending and torsional stress. The Markov Chain was used to model the two states based on the probability of failure due to bending and torsion stress. In most investigations it revealed that bending stress is much serve than torsional stress, therefore the probability criteria for the bending state would be higher compared to the torsion state. A statistical comparison between the developed Markov Chain Model and field data was done to observe the percentage of error. The reliability analysis and prediction was derived and illustrated from the Markov Chain Model were shown in the Weibull probability and cumulative distribution function, hazard rate and reliability curve and the bathtub curve. It can be concluded that Markov Chain Model has the ability to generate near similar data with minimal percentage of error and for a practical application; the proposed model provides a good accuracy in determining the reliability for the crankshaft under mixed mode loading.

  17. A two-fluid study of oblique tearing modes in a force-free current sheet

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

    Akçay, Cihan; Daughton, William; Lukin, Vyacheslav S.; Liu, Yi-Hsin

    2016-01-01

    Kinetic simulations have demonstrated that three-dimensional reconnection in collisionless regimes proceeds through the formation and interaction of magnetic flux ropes, which are generated due to the growth of tearing instabilities at multiple resonance surfaces. Because kinetic simulations are intrinsically expensive, it is desirable to explore the feasibility of reduced two-fluid models to capture this complex evolution, particularly, in the strong guide field regime, where two-fluid models are better justified. With this goal in mind, this paper compares the evolution of the collisionless tearing instability in a force-free current sheet with a two-fluid model and fully kinetic simulations. Our results indicatemore » that the most unstable modes are oblique for guide fields larger than the reconnecting field, in agreement with the kinetic results. The standard two-fluid tearing theory is extended to address the tearing instability at oblique angles. As a results this theory yields a flat oblique spectrum and underestimates the growth of oblique modes in a similar manner to kinetic theory relative to kinetic simulations.« less

  18. Operability test procedure for rotary mode core sampling system {number_sign}4

    SciTech Connect (OSTI)

    Farris, T.R.; Jarecki, T.D.

    1995-04-26

    This document gives instructions for the Operability Testing of the Rotary Mode Core Sampling (RMCS) System No. 4. This document is based on the Operability Test Procedure for RMCS system No. 2 because the basic design is the same for all three systems. Modifications have been made from the original design only when exact duplication was not feasible or design improvements could be incorporated without affecting the operation of the system. Operability testing of the Rotary Mode Core Sampling System No. 4 will verify that functional and operational requirements have been met. Testing will be completed in two phases. The first phase of testing (section 7) will involve operating the truck equipment to demonstrate its capabilities. The second phase of testing (section 8) will take repeated samples in a simulated operation environment. These tests will be conducted at the ``Rock Slinger`` test site located just south of U-Plant in the 200 West Area. Tests will be done in a simulated tank farm environment. All testing will be non-radioactive and stand-in materials shall be used to simulate waste tank conditions. Systems will be assembled and arranged in a manner similar to that expected in the field.

  19. Operability test procedure for rotary mode core sampling system {number_sign}3

    SciTech Connect (OSTI)

    Farris, T.R.; Jarecki, T.D.

    1995-04-26

    This document gives instructions for the Operability Testing of the Rotary Mode Core Sampling (RMCS) System No. 3. This document is based on the Operability Test Procedure for RMCS system No. 2 because the basic design is the same for all three systems. Modifications have been made from the original design only when exact duplication was not feasible or design improvements could be incorporated without affecting the operation of the system. Operability testing of the Rotary Mode Core Sampling System No. 3, will verify that functional and operational requirements have been met. Testing will be completed in two phases. The first phase of testing (section 7) will involve operating the truck equipment to demonstrate its capabilities. The second phase of testing (section 8) will take repeated samples in a simulated operation environment. These tests will be conducted at the ``Rock Slinger`` test site located just south of U-Plant in the 200 West Area. Tests will be done in a simulated tank farm environment. All testing will be non-radioactive and stand-in materials shall be used to simulate waste tank conditions. Systems will be assembled and arranged in a manner similar to that expected in the field.

  20. 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.