Sample records for high gradient wakefield

  1. A THz Coaxial Two-Channel Dielectric Wakefield Structure for High Gradient Acceleration

    SciTech Connect (OSTI)

    Marshall, T. C. [Columbia University, New York, NY (United States); Omega-P, Inc., New Haven, CT (United States); Sotnikov, G. V. [Omega-P, Inc., New Haven, CT (United States); NSC Kharkov Institute of Physics and Technology, Kharkov (Ukraine); Hirshfield, J. L. [Omega-P, Inc., New Haven, CT (United States); Yale University, New Haven, CT (United States)

    2010-11-04T23:59:59.000Z

    A coaxial two-channel dielectric wakefield structure is examined for use as a high gradient accelerator. A THz design, having radius {approx}1 mm, is shown to provide GeV/m--level acceleration gradient, high transformer ratio, and stable accelerated bunch motion when excited by a stable-moving 5-GeV 6-nC annular drive bunch.

  2. High Transformer ratios in collinear wakefield accelerators.

    SciTech Connect (OSTI)

    Power, J. G.; Conde, M.; Yusof, Z.; Gai, W.; Jing, C.; Kanreykin, A.; Schoessow, P.; High Energy Physics; Euclid Techlabs, LLC

    2008-01-01T23:59:59.000Z

    Based on our previous experiment that successfully demonstrated wakefield transformer ratio enhancement in a 13.625 GHz dielectric-loaded collinear wakefield accelerator using the ramped bunch train technique, we present here a redesigned experimental scheme for even higher enhancement of the efficiency of this accelerator. Design of a collinear wakefield device with a transformer ratio R2, is presented. Using a ramped bunch train (RBT) rather than a single drive bunch, the enhanced transformer ratio (ETR) technique is able to increase the transformer ratio R above the ordinary limit of 2. To match the wavelength of the fundamental mode of the wakefield with the bunch length (sigmaz=2 mm) of the new Argonne wakefield accelerator (AWA) drive gun (where the experiment will be performed), a 26.625 GHz dielectric based accelerating structure is required. This transformer ratio enhancement technique based on our dielectric-loaded waveguide design will result in a compact, high efficiency accelerating structures for future wakefield accelerators.

  3. Correlation of Beam Parameters to Decelerating Gradient in the E-167 Plasma Wakefield Acceleration Experiment

    SciTech Connect (OSTI)

    Blumenfeld, I.; Berry, M.; Decker, F.-J.; Hogan, M.J.; Ischebeck, R.; Iverson, R.; Kirby, N.; Siemann, R.; Walz, D.; /SLAC; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; /UCLA; Katsouleas, T.C.; Muggli, P.; Oz, E.; /Southern California U.

    2007-06-27T23:59:59.000Z

    Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas [1,2]. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch length and beam waist location were varied systematically at constant charge. Here we investigate the correlation of peak beam current to the decelerating gradient. Limits on the transformer ratio will also be discussed. The results are compared to simulation.

  4. Application of High-performance Visual Analysis Methods to Laser Wakefield Particle Acceleration Data

    E-Print Network [OSTI]

    Application of High-performance Visual Analysis Methods to Laser Wakefield Particle Acceleration, time- varying laser wakefield particle accelerator simulation data. We ex- tend histogramBit, a state-of-the-art index/query technology, to acceler- ate data mining and multi-dimensional histogram

  5. Laser Guiding at Relativistic Intensities and Wakefield Particle Acceleration

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    Laser Guiding at Relativistic Intensities and Wakefield Particle Acceleration in Plasma Channels C for the first time in a high gradient laser wakefield accelerator by guiding the drive laser pulse. Channels formed by hydrodynamic shock were used to guide acceleration relevant laser intensities of at least 1E18

  6. Experimental Plans to Explore Dielectric Wakefield Acceleration in the THZ Regime

    SciTech Connect (OSTI)

    Lemery, F.; Mihalcea, D.; /Northern Illinois U.; Piot, P.; /Fermilab; Behrens, C.; Elsen, E.; Flottmann, K.; Gerth, C.; Kube, G.; Schmidt, B.; /DESY; Osterhoff, J.; /Hamburg U., Inst. Theor. Phys. II; Stoltz, P.

    2011-09-07T23:59:59.000Z

    Dielectric wakefield accelerators have shown great promise toward high-gradient acceleration. We investigate the performances of a possible experiment under consideration at the FLASH facility in DESY to explore wakefield acceleration with an enhanced transformer ratio. The experiment capitalizes on a unique pulse shaping capability recently demonstrated at this facility. In addition, the facility incorporates a superconducting linear accelerator that could generate bunch trains with closely spaced bunches thereby opening the exploration of potential dynamical effects in dielectric wakefield accelerators.

  7. HIGH GRADIENT INDUCTION ACCELERATOR

    SciTech Connect (OSTI)

    Caporaso, G J; Sampayan, S; Chen, Y; Blackfield, D; Harris, J; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Nunnally, W; Paul, A; Poole, B; Rhodes, M; Sanders, D; Selenes, K; Sullivan, J; Wang, L; Watson, J

    2007-06-21T23:59:59.000Z

    A new type of compact induction accelerator is under development at the Lawrence Livermore National Laboratory that promises to increase the average accelerating gradient by at least an order of magnitude over that of existing induction machines. The machine is based on the use of high gradient vacuum insulators, advanced dielectric materials and switches and is stimulated by the desire for compact flash x-ray radiography sources. Research describing an extreme variant of this technology aimed at proton therapy for cancer will be described. Progress in applying this technology to several applications will be reviewed.

  8. High transformer ratio drive beams for wakefield accelerator studies

    SciTech Connect (OSTI)

    England, R. J.; Ng, C.-K.; Frederico, J.; Hogan, M. J.; Litos, M.; Muggli, P.; Joshi, C.; An, W.; Andonian, G.; Mori, W.; Lu, W. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Max Planck Institute for Physics, 80805 Munich (Germany); University of California Los Angeles, Los Angeles, CA 90095 (United States); Tsinghua University, Beijing (China)

    2012-12-21T23:59:59.000Z

    For wakefield based acceleration schemes, use of an asymmetric (or linearly ramped) drive bunch current profile has been predicted to enhance the transformer ratio and generate large accelerating wakes. We discuss plans and initial results for producing such bunches using the 20 to 23 GeV electron beam at the FACET facility at SLAC National Accelerator Laboratory and sending them through plasmas and dielectric tubes to generate transformer ratios greater than 2 (the limit for symmetric bunches). The scheme proposed utilizes the final FACET chicane compressor and transverse collimation to shape the longitudinal phase space of the beam.

  9. High field gradient particle accelerator

    DOE Patents [OSTI]

    Nation, J.A.; Greenwald, S.

    1989-05-30T23:59:59.000Z

    A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications is disclosed. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle. 10 figs.

  10. High field gradient particle accelerator

    DOE Patents [OSTI]

    Nation, John A. (Ithaca, NY); Greenwald, Shlomo (Haifa, IL)

    1989-01-01T23:59:59.000Z

    A high electric field gradient electron accelerator utilizing short duration, microwave radiation, and capable of operating at high field gradients for high energy physics applications or at reduced electric field gradients for high average current intermediate energy accelerator applications. Particles are accelerated in a smooth bore, periodic undulating waveguide, wherein the period is so selected that the particles slip an integral number of cycles of the r.f. wave every period of the structure. This phase step of the particles produces substantially continuous acceleration in a traveling wave without transverse magnetic or other guide means for the particle.

  11. A proposal for a 1 GeV plasma-wakefield acceleration experiment at SLAC

    SciTech Connect (OSTI)

    Katsouleas, T.; Lee, S. [Univ. of Southern California, Los Angeles, CA (United States); Assmann, R. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)] [and others

    1997-07-01T23:59:59.000Z

    A plasma-based wakefield acceleration (PWFA) experiment is proposed that will accelerate parts of an SLC bunch by up to 1 GeV/m over a length of 1 m. A single SLC bunch is used to both induce wakefields in the one meter long plasma and to witness the resulting beam acceleration. The proposed experiment will explore and further develop the techniques that are needed to apply high-gradient plasma wakefield acceleration to large scale accelerators. The one meter length of the experiment is about two orders of magnitude larger than other high-gradient PWFA experiments and the 1 GeV/m accelerating gradient is roughly ten times larger than that achieved with conventional metallic structures. Using existing SLAC facilities, the proposed experiment will allow the study of high-gradient acceleration at the forefront of advanced accelerator research.

  12. Application of High-performance Visual Analysis Methods to Laser Wakefield Particle Acceleration Data

    SciTech Connect (OSTI)

    Rubel, Oliver; Prabhat, Mr.; Wu, Kesheng; Childs, Hank; Meredith, Jeremy; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Ahern, Sean; Weber, Gunther H.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes

    2008-08-28T23:59:59.000Z

    Our work combines and extends techniques from high-performance scientific data management and visualization to enable scientific researchers to gain insight from extremely large, complex, time-varying laser wakefield particle accelerator simulation data. We extend histogram-based parallel coordinates for use in visual information display as well as an interface for guiding and performing data mining operations, which are based upon multi-dimensional and temporal thresholding and data subsetting operations. To achieve very high performance on parallel computing platforms, we leverage FastBit, a state-of-the-art index/query technology, to accelerate data mining and multi-dimensional histogram computation. We show how these techniques are used in practice by scientific researchers to identify, visualize and analyze a particle beam in a large, time-varying dataset.

  13. Plasma Wakefield Experiments at FACET

    SciTech Connect (OSTI)

    Hogan, M.J.; England, R.J.; Frederico, J.; Hast, C.; Li, S.Z.; Litos, M.; Walz, D.; /SLAC; An, W.; Clayton, C.E.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Tochitsky, S.; /UCLA; Muggli, P.; Pinkerton, S.; Shi, Y.; /Southern California U.

    2011-08-19T23:59:59.000Z

    FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23GeV, 3nC electron bunches compressed to {approx}20{micro}m long and focused to {approx}10{micro}m wide. The intense fields of the FACET bunches will be used to field ionize neutral lithium or cesium vapor produced in a heat pipe oven. Previous experiments at the SLAC FFTB facility demonstrated 50GeV/m gradients in an 85cm field ionized lithium plasma where the interaction distance was limited by head erosion. Simulations indicate the lower ionization potential of cesium will decrease the rate of head erosion and increase single stage performance. The initial experimental program will compare the performance of lithium and cesium plasma sources with single and double bunches. Later experiments will investigate improved performance with a pre-ionized cesium plasma. The status of the experiments and expected performance are reviewed. The FACET Facility is being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The facility will begin commissioning in summer 2011 and conduct an experimental program over the coming five years to study electron and positron beam driven plasma acceleration with strong wake loading in the non-linear regime. The FACET experiments aim to demonstrate high-gradient acceleration of electron and positron beams with high efficiency and negligible emittance growth.

  14. Results from Plasma Wakefield Experiments at FACET

    SciTech Connect (OSTI)

    Li, S.Z.; Clarke, C.I.; England, R.J.; Frederico, J.; Gessner, S.J.; Hogan, M.J.; Jobe, R.K.; Litos, M.D.; Walz, D.R.; /SLAC; Muggli, P.; /Munich, Max Planck Inst.; An, W.; Clayton, C.E.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.; Tochitsky, S.; /UCLA; Adli, E.; /U. Oslo

    2011-12-13T23:59:59.000Z

    We report initial results of the Plasma Wakefield Acceleration (PWFA) Experiments performed at FACET - Facility for Advanced aCcelertor Experimental Tests at SLAC National Accelerator Laboratory. At FACET a 23 GeV electron beam with 1.8 x 10{sup 10} electrons is compressed to 20 {mu}m longitudinally and focused down to 10 {mu}m x 10 {mu}m transverse spot size for user driven experiments. Construction of the FACET facility completed in May 2011 with a first run of user assisted commissioning throughout the summer. The first PWFA experiments will use single electron bunches combined with a high density lithium plasma to produce accelerating gradients > 10 GeV/m benchmarking the FACET beam and the newly installed experimental hardware. Future plans for further study of plasma wakefield acceleration will be reviewed. The experimental hardware and operation of the plasma heat-pipe oven have been successfully commissioned. Plasma wakefield acceleration was not observed because the electron bunch density was insufficient to ionize the lithium vapor. The remaining commissioning time in summer 2011 will be dedicated to delivering the FACET design parameters for the experimental programs which will begin in early 2012. PWFA experiments require the shorter bunches and smaller transverse sizes to create the plasma and drive large amplitude wakefields. Low emittance and high energy will minimize head erosion which was found to be a limiting factor in acceleration distance and energy gain. We will run the PWFA experiments with the design single bunch conditions in early 2012. Future PWFA experiments at FACET are discussed in [5][6] and include drive and witness bunch production for high energy beam manipulation, ramped bunch to optimize tranformer ratio, field-ionized cesium plasma, preionized plasmas, positron acceleration, etc.. We will install a notch collimator for two-bunch operation as well as new beam diagnostics such as the X-band TCAV [7] to resolve the two bunches. With these new instruments and desired beam parameters in place next year, we will be able to complete the studies of plasma wakefield acceleration in the next few years.

  15. High Gradient Two-Beam Electron Accelerator

    SciTech Connect (OSTI)

    Jiang, Y. [Beam Physics Laboratory, Yale University, 272 Whitney Ave., New Haven, CT 06511 (United States); Kazakov, S. Yu. [Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Kuzikov, S. V. [Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Institute of Applied Physics, Nizhny Novgorod, 603600 (Russian Federation); Hirshfield, J. L. [Beam Physics Laboratory, Yale University, 272 Whitney Ave., New Haven, CT 06511 (United States); Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States)

    2010-11-04T23:59:59.000Z

    A high-gradient two-beam electron accelerator structure using detuned cavities is described. A self-consistent theory based on a circuit model is presented to calculate idealized acceleration gradient, transformer ratio, and efficiency for energy transfer from the drive beam to the accelerated beam. Experimental efforts are being carried out to demonstrate this acceleration concept.

  16. Dielectric Wakefield Accelerator to drive the future FEL Light Source.

    SciTech Connect (OSTI)

    Jing, C.; Power, J.; Zholents, A. (Accelerator Systems Division (APS)); ( HEP); (LLC)

    2011-04-20T23:59:59.000Z

    X-ray free-electron lasers (FELs) are expensive instruments and a large part of the cost of the entire facility is driven by the accelerator. Using a high-energy gain dielectric wake-field accelerator (DWA) instead of the conventional accelerator may provide a significant cost saving and reduction of the facility size. In this article, we investigate using a collinear dielectric wakefield accelerator to provide a high repetition rate, high current, high energy beam to drive a future FEL x-ray light source. As an initial case study, a {approx}100 MV/m loaded gradient, 850 GHz quartz dielectric based 2-stage, wakefield accelerator is proposed to generate a main electron beam of 8 GeV, 50 pC/bunch, {approx}1.2 kA of peak current, 10 x 10 kHz (10 beamlines) in just 100 meters with the fill factor and beam loading considered. This scheme provides 10 parallel main beams with one 100 kHz drive beam. A drive-to-main beam efficiency {approx}38.5% can be achieved with an advanced transformer ratio enhancement technique. rf power dissipation in the structure is only 5 W/cm{sup 2} in the high repetition rate, high gradient operation mode, which is in the range of advanced water cooling capability. Details of study presented in the article include the overall layout, the transform ratio enhancement scheme used to increase the drive to main beam efficiency, main wakefield linac design, cooling of the structure, etc.

  17. Plasma Wakefield Acceleration for Ultrahigh Energy Cosmic Rays

    E-Print Network [OSTI]

    Pisin Chen; Toshiki Tajima; Yoshiyuki Takahashi

    2002-05-21T23:59:59.000Z

    A cosmic acceleration mechanism is introduced which is based on the wakefields excited by the Alfven shocks in a relativistically flowing plasma, where the energy gain per distance of a test particle is Lorentz invariant. We show that there exists a threshold condition for transparency below which the accelerating particle is collision-free and suffers little energy loss in the plasma medium. The stochastic encounters of the random accelerating-decelerating phases results in a power-law energy spectrum: f(e) 1/e^2. The environment suitable for such plasma wakefield acceleration can be cosmically abundant. As an example, we discuss the possible production of super-GZK ultra high energy cosmic rays (UHECR) through this mechanism in the atmosphere of gamma ray bursts. We show that the acceleration gradient can be as high as G ~ 10^16 eV/cm. The estimated event rate in our model agrees with that from UHECR observations.

  18. Developing new high energy gradient concentration cathode material...

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

    new high energy gradient concentration cathode material Developing new high energy gradient concentration cathode material 2009 DOE Hydrogen Program and Vehicle Technologies...

  19. High-pressure liquid chromatographic gradient mixer

    DOE Patents [OSTI]

    Daughton, C.G.; Sakaji, R.H.

    1982-09-08T23:59:59.000Z

    A gradient mixer effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum band-broadening.

  20. High pressure liquid chromatographic gradient mixer

    DOE Patents [OSTI]

    Daughton, Christian G. (San Pablo, CA); Sakaji, Richard H. (El Cerrito, CA)

    1985-01-01T23:59:59.000Z

    A gradient mixer which effects the continuous mixing of any two miscible solvents without excessive decay or dispersion of the resultant isocratic effluent or of a linear or exponential gradient. The two solvents are fed under low or high pressure by means of two high performance liquid chromatographic pumps. The mixer comprises a series of ultra-low dead volume stainless steel tubes and low dead volume chambers. The two solvent streams impinge head-on at high fluxes. This initial nonhomogeneous mixture is then passed through a chamber packed with spirally-wound wires which cause turbulent mixing thereby homogenizing the mixture with minimum "band-broadening".

  1. Plasma wakefields driven by an incoherent combination of laser pulses: a path towards high-average power laser-plasma accelerators

    SciTech Connect (OSTI)

    Benedetti, C.; Schroeder, C.B.; Esarey, E.; Leemans, W.P.

    2014-05-01T23:59:59.000Z

    he wakefield generated in a plasma by incoherently combining a large number of low energy laser pulses (i.e.,without constraining the pulse phases) is studied analytically and by means of fully-self-consistent particle-in-cell simulations. The structure of the wakefield has been characterized and its amplitude compared with the amplitude of the wake generated by a single (coherent) laser pulse. We show that, in spite of the incoherent nature of the wakefield within the volume occupied by the laser pulses, behind this region the structure of the wakefield can be regular with an amplitude comparable or equal to that obtained from a single pulse with the same energy. Wake generation requires that the incoherent structure in the laser energy density produced by the combined pulses exists on a time scale short compared to the plasma period. Incoherent combination of multiple laser pulses may enable a technologically simpler path to high-repetition rate, high-average power laser-plasma accelerators and associated applications.

  2. HIGH-GRADIENT, HIGH-TRANSFORMER-RATIO, DIELECTRIC WAKE FIELD ACCELERATOR

    SciTech Connect (OSTI)

    Jay L. Hirshfield

    2012-04-12T23:59:59.000Z

    The Phase I work reported here responds to DoE'ss stated need "...to develop improved accelerator designs that can provide very high gradient (>200 MV/m for electrons...) acceleration of intense bunches of particles." Omega-P'�s approach to this goal is through use of a ramped train of annular electron bunches to drive a coaxial dielectric wakefield accelerator (CDWA) structure. This approach is a direct extension of the CDWA concept from acceleration in wake fields caused by a single drive bunch, to the more efficient acceleration that we predict can be realized from a tailored (or ramped) train of several drive bunches. This is possible because of a much higher transformer ratio for the latter. The CDWA structure itself has a number of unique features, including: a high accelerating gradient G, potentially with G > 1 GeV/m; continuous energy coupling from drive to test bunches without transfer structures; inherent transverse focusing forces for particles in the accelerated bunch; highly stable motion of high charge annular drive bunches; acceptable alignment tolerances for a multi-section system. What is new in the present approach is that the coaxial dielectric structure is now to be energized by-not one-�but by a short train of ramped annular-shaped drive bunches moving in the outer coaxial channel of the structure. We have shown that this allows acceleration of an electron bunch traveling along the axis in the inner channel with a markedly higher transformer ratio T than for a single drive bunch. As described in this report, the structure will be a GHz-scale prototype with cm-scale transverse dimensions that is expected to confirm principles that can be applied to the design of a future THz-scale high gradient (> 500 MV/m) accelerator with mm-scale transverse dimensions. We show here a new means to significantly increase the transformer ratio T of the device, and thereby to significantly improve its suitability as a flexible and effective component in a future high energy, high gradient accelerator facility. We predict that the T of a high gradient CDWA can be increased by a substantial factor; this enhancement is dramatically greater than what has been demonstrated heretofore. This large enhancement in T that we predict arises from using a train of three or four drive bunches in which the spacing of the bunches and their respective charges are selected according to a simple principle that requires each bunch lose energy to the wakefields at the same rate, so as not to sacrifice drive beam efficiency�¢����as would be the case if one bunch exhausted its available energy while others had not. It is anticipated that results from the study proposed here can have a direct impact on design of the dielectric accelerator in a TeV-scale collider concept, and in the accelerator for an x-ray FEL.

  3. Exploration of very high gradient cavities

    SciTech Connect (OSTI)

    Grigory Eremeev

    2011-07-01T23:59:59.000Z

    Several of the 9-cell ILC cavities processed at Jlab within ongoing ILC R&D program have shown interesting behavior at high fields, such as mode mixing and sudden field emission turn-on during quench. Equipped with thermometry and oscillating superleak transducer (OST) system for quench detection, we couple our RF measurements with local dissipation measurements. In this contribution we report on our findings with high gradient SRF cavities.

  4. Development of high gradient laser wakefield accelerators towards nuclear detection applications at LBNL

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    at LBNL Cameron G.R. Geddes1 , David L. Bruhwiler2 , John R. Cary2,3 , Eric H. Esarey1,4 , Anthony J Program, LBNL, 1 Cyclotron Rd MS 71-259, Berkeley CA 94720, United States 2 Tech-X Corp., 5621 Arapahoe experiments at LBNL demonstrated narrow energy spread beams, now with energies of up to 1 GeV in 3 cm using

  5. Development of high gradient laser wakefield accelerators towards nuclear detection applications at LBNL

    E-Print Network [OSTI]

    Geddes, Cameron GR

    2010-01-01T23:59:59.000Z

    detection applications at LBNL Cameron G.R. Geddes 1 , DavidLeemans 1,4 LOASIS Program, LBNL, 1 Cyclotron Rd MS 71-259,accelerator experiments at LBNL demonstrated narrow energy

  6. Proton-driven plasma wakefield acceleration: a path to the future of high-energy particle physics

    E-Print Network [OSTI]

    Assmann, R; Bohl, T; Bracco, C; Buttenschon, B; Butterworth, A; Caldwell, A; Chattopadhyay, S; Cipiccia, S; Feldbaumer, E; Fonseca, R A; Goddard, B; Gross, M; Grulke, O; Gschwendtner, E; Holloway, J; Huang, C; Jaroszynski, D; Jolly, S; Kempkes, P; Lopes, N; Lotov, K; Machacek, J; Mandry, S R; McKenzie, J W; Meddahi, M; Militsyn, B L; Moschuering, N; Muggli, P; Najmudin, Z; Noakes, T C Q; Norreys, P A; Oz, E; Pardons, A; Petrenko, A; Pukhov, A; Rieger, K; Reimann, O; Ruhl, H; Shaposhnikova, E; Silva, L O; Sosedkin, A; Tarkeshian, R; Trines, R M G N; Tuckmantel, T; Vieira, J; Vincke, H; Wing, M; Xia, G

    2014-01-01T23:59:59.000Z

    New acceleration technology is mandatory for the future elucidation of fundamental particles and their interactions. A promising approach is to exploit the properties of plasmas. Past research has focused on creating large-amplitude plasma waves by injecting an intense laser pulse or an electron bunch into the plasma. However, the maximum energy gain of electrons accelerated in a single plasma stage is limited by the energy of the driver. Proton bunches are the most promising drivers of wakefields to accelerate electrons to the TeV energy scale in a single stage. An experimental program at CERN -- the AWAKE experiment -- has been launched to study in detail the important physical processes and to demonstrate the power of proton-driven plasma wakefield acceleration. Here we review the physical principles and some experimental considerations for a future proton-driven plasma wakefield accelerator.

  7. Proton-driven plasma wakefield acceleration: a path to the future of high-energy particle physics

    E-Print Network [OSTI]

    Assmann, R; Bohl, T; Bracco, C; Buttenschon, B; Butterworth, A; Caldwell, A; Chattopadhyay, S; Cipiccia, S; Feldbaumer, E; Fonseca, R A; Goddard, B; Gross, M; Grulke, O; Gschwendtner, E; Holloway, J; Huang, C; Jaroszynski, D; Jolly, S; Kempkes, P; Lopes, N; Lotov, K; Machacek, J; Mandry, S R; McKenzie, J W; Meddahi, M; Militsyn, B L; Moschuering, N; Muggli, P; Najmudin, Z; Noakes, T C Q; Norreys, P A; Oz, E; Pardons, A; Petrenko, A; Pukhov, A; Rieger, K; Reimann, O; Ruhl, H; Shaposhnikova, E; Silva, L O; Sosedkin, A; Tarkeshian, R; Trines, R M G N; Tuckmantel, T; Vieira, J; Vincke, H; Wing, M; Xia G , G

    2014-01-01T23:59:59.000Z

    New acceleration technology is mandatory for the future elucidation of fundamental particles and their interactions. A promising approach is to exploit the properties of plasmas. Past research has focused on creating large-amplitude plasma waves by injecting an intense laser pulse or an electron bunch into the plasma. However, the maximum energy gain of electrons accelerated in a single plasma stage is limited by the energy of the driver. Proton bunches are the most promising drivers of wakefields to accelerate electrons to the TeV energy scale in a single stage. An experimental program at CERN { the AWAKE experiment { has been launched to study in detail the important physical processes and to demonstrate the power of proton-driven plasma wakefield acceleration. Here we review the physical principles and some experimental considerations for a future proton-driven plasma wakefield accelerator.

  8. High gradient lens for charged particle beam

    DOE Patents [OSTI]

    Chen, Yu-Jiuan

    2014-04-29T23:59:59.000Z

    Methods and devices enable shaping of a charged particle beam. A dynamically adjustable electric lens includes a series of alternating a series of alternating layers of insulators and conductors with a hollow center. The series of alternating layers when stacked together form a high gradient insulator (HGI) tube to allow propagation of the charged particle beam through the hollow center of the HGI tube. A plurality of transmission lines are connected to a plurality of sections of the HGI tube, and one or more voltage sources are provided to supply an adjustable voltage value to each transmission line of the plurality of transmission lines. By changing the voltage values supplied to each section of the HGI tube, any desired electric field can be established across the HGI tube. This way various functionalities including focusing, defocusing, acceleration, deceleration, intensity modulation and others can be effectuated on a time varying basis.

  9. Proof-of-principle experiments of laser Wakefield acceleration

    SciTech Connect (OSTI)

    Nakajima, K.; Kawakubo, T.; Nakanishi, H. [National Lab. for Higher Energy Physics, Ibaraki (Japan)] [and others

    1994-04-01T23:59:59.000Z

    Recently there has been a great interest in laser-plasma accelerators as possible next-generation particle accelerators because of their potential for ultra high accelerating gradients and compact size compared with conventional accelerators. It is known that the laser pulse is capable of exciting a plasma wave propagating at a phase velocity close to the velocity of light by means of beating two-frequency lasers or an ultra short laser pulse. These schemes came to be known as the Beat Wave Accelerator (BWA) for beating lasers or as the Laser Wakefield Accelerator (LWFA) for a short pulse laser. In this paper, the principle of laser wakefield particle acceleration has been tested by the Nd:glass laser system providing a short pulse with a power of 10 TW and a duration of 1 ps. Electrons accelerated up to 18 MeV/c have been observed by injecting 1 MeV/c electrons emitted from a solid target by an intense laser impact. The accelerating field gradient of 30 GeV/m is inferred.

  10. GeV electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

    E-Print Network [OSTI]

    P. E. Masson-Laborde; M. Z. Mo; A. Ali; S. Fourmaux; P. Lassonde; J. C. Kieffer; W. Rozmus; D. Teychenne; R. Fedosejevs

    2014-08-06T23:59:59.000Z

    We show through experiments that a transition from laser wakefield acceleration (LWFA) regime to a plasma wakefield acceleration (PWFA) regime can drive electrons up to energies close to the GeV level. Initially, the acceleration mechanism is dominated by the bubble created by the laser in the nonlinear regime of LWFA, leading to an injection of a large number of electrons. After propagation beyond the depletion length, leading to a depletion of the laser pulse, whose transverse ponderomotive force is not able to sustain the bubble anymore, the high energy dense bunch of electrons propagating inside bubble will drive its own wakefield by a PWFA regime. This wakefield will be able to trap and accelerate a population of electrons up to the GeV level during this second stage. Three dimensional (3D) particle-in-cell (PIC) simulations support this analysis, and confirm the scenario.

  11. High-gradient compact linear accelerator

    DOE Patents [OSTI]

    Carder, B.M.

    1998-05-26T23:59:59.000Z

    A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter. 10 figs.

  12. High Gradient Inverse Free Electron Laser (IFEL) Accelerator

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

    Gradient High energy gain Inverse Free Electron Laser P. Musumeci UCLA Department of Physics and Astronomy On Behalf of the RUBICON collaboration ATF user meeting, BNL, October 6...

  13. Microsoft PowerPoint - High Gradient Inverse Free Electron Laser...

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

    Hi h G di t Hi h i High Gradient High energy gain Inverse Free Electron Laser at BNL P. Musumeci UCLA Department of Physics and Astronomy ATF user meeting April 2-3 2009 Outline...

  14. HTS High Gradient Magnetic Separation system

    SciTech Connect (OSTI)

    Daugherty, M.A.; Coulter, J.Y.; Hults, W.L. [and others

    1996-09-01T23:59:59.000Z

    We report on the assembly, characterization and operation of a high temperature superconducting (HTS) magnetic separator. The magnet is made of 624 m of Silver/BSCCO superconducting wire and has overall dimensions of 18 cm OD, 15.5 cm height and 5 cm ID. The HTS current leads are designed to operate with the warm end at 75 K and the cold end cooled by a two stage Gifford-McMahon cryocooler. The upper stage of the cryocooler cools the thermal shield and two heat pipe thermal intercepts. The lower stage of the cryocooler cools the HTS magnet and the bottom end of the HTS current leads. The HTS magnet was initially characterized in liquid cryogens. We report on the current- voltage (I-V) characteristics of the HTS magnet at temperatures ranging from 15 to 40 K. At 40 K the magnet can generate a central field of 2.0 T at a current of 120 A.

  15. High and ulta-high gradient quadrupole magnets

    SciTech Connect (OSTI)

    Brunk, W.O.; Walz, D.R.

    1985-05-01T23:59:59.000Z

    Small bore conventional dc quadrupoles with apertures from 1 to 2.578cm were designed and prototypes built and measured. New fabrication techniques including the use of wire electric discharge milling (EDM) to economically generate the pole tip contours and aperture tolerances are described. Magnetic measurement data from a prototype of a 1cm aperture quadrupole with possible use in future e/sup +//e/sup -/ super colliders are presented. At a current of 400A, the lens achieved a gradient of 2.475 T/cm, and had an efficiency of 76.6%.

  16. Fabrication of high gradient insulators by stack compression

    DOE Patents [OSTI]

    Harris, John Richardson; Sanders, Dave; Hawkins, Steven Anthony; Norona, Marcelo

    2014-04-29T23:59:59.000Z

    Individual layers of a high gradient insulator (HGI) are first pre-cut to their final dimensions. The pre-cut layers are then stacked to form an assembly that is subsequently pressed into an HGI unit with the desired dimension. The individual layers are stacked, and alignment is maintained, using a sacrificial alignment tube that is removed after the stack is hot pressed. The HGI's are used as high voltage vacuum insulators in energy storage and transmission structures or devices, e.g. in particle accelerators and pulsed power systems.

  17. Operational experience with CW high gradient and high QL cryomodules

    SciTech Connect (OSTI)

    Hovater, J. Curt [JLAB; Allison, Trent L. [JLAB; Bachimanchi, Ramakrishna [JLAB; Daly, Edward F. [JLAB; Drury, Michael A. [JLAB; Lahti, George E. [JLAB; Mounts, Clyde I. [JLAB; Nelson, Richard M. [JLAB; Plawski, Tomasz E. [JLAB

    2014-12-01T23:59:59.000Z

    The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of ten new 100 MV cryomodules (80 cavities). The superconducting RF cavities are designed to operate CW at an accelerating gradient of 19.3 MV/m with a QL of 3×107. The RF system employs single cavity control using new digital LLRF controls and 13 kW klystrons. Recently, all of the new cryomodules and associated RF hardware and software have been commissioned and operated in the CEBAF accelerator. Electrons at linac currents up to 10 ?A have been successfully accelerated and used for nuclear physics experiments. This paper reports on the commissioning and operation of the cryomodules and RF system.

  18. SLIM, Short-pulse Technology for High Gradient Induction Accelerators

    SciTech Connect (OSTI)

    Arntz, Floyd; /Diversified Tech., Bedford; Kardo-Sysoev, A.; /Ioffe Phys. Tech. Inst.; Krasnykh, A.; /SLAC

    2008-12-16T23:59:59.000Z

    A novel short-pulse concept (SLIM) suited to a new generation of a high gradient induction particle accelerators is described herein. It applies advanced solid state semiconductor technology and modern microfabrication techniques to a coreless induction method of charged particle acceleration first proven on a macro scale in the 1960's. Because this approach avoids use of magnetic materials there is the prospect of such an accelerator working efficiently with accelerating pulses in the nanosecond range and, potentially, at megahertz pulse rates. The principal accelerator section is envisioned as a stack of coreless induction cells, the only active element within each being a single, extremely fast (subnanosecond) solid state opening switch: a Drift Step Recovery Diode (DSRD). Each coreless induction cell incorporates an electromagnetic pulse compressor in which inductive energy developed within a transmission-line feed structure over a period of tens of nanoseconds is diverted to the acceleration of the passing charge packet for a few nanoseconds by the abrupt opening of the DSRD switch. The duration of this accelerating output pulse--typically two-to-four nanoseconds--is precisely determined by a microfabricated pulse forming line connected to the cell. Because the accelerating pulse is only nanoseconds in duration, longitudinal accelerating gradients approaching 100 MeV per meter are believed to be achievable without inciting breakdown. Further benefits of this approach are that, (1) only a low voltage power supply is required to produce the high accelerating gradient, and, (2) since the DSRD switch is normally closed, voltage stress is limited to a few nanoseconds per period, hence the susceptibility to hostile environment conditions such as ionizing radiation, mismatch (e.g. in medical applications the peak beam current may be low), strong electromagnetic noise levels, etc is expected to be minimal. Finally, we observe the SLIM concept is not limited to linac applications; for instance, it could be employed to both accelerate the beam and to stabilize the superbunch mode of operation in circular track machines.

  19. Dielectric-Lined High-Gradient Accelerator Structure

    SciTech Connect (OSTI)

    Jay L. Hirshfield

    2012-04-24T23:59:59.000Z

    Rectangular particle accelerator structures with internal planar dielectric elements have been studied, with a view towards devising structures with lower surface fields for a given accelerating field, as compared with structures without dielectrics. Success with this concept is expected to allow operation at higher accelerating gradients than otherwise on account of reduced breakdown probabilities. The project involves studies of RF breakdown on amorphous dielectrics in test cavities that could enable high-gradient structures to be built for a future multi-TeV collider. The aim is to determine what the limits are for RF fields at the surfaces of selected dielectrics, and the resulting acceleration gradient that could be achieved in a working structure. The dielectric of principal interest in this study is artificial CVD diamond, on account of its advertised high breakdown field ({approx}2 GV/m for dc), low loss tangent, and high thermal conductivity. Experimental studies at mm-wavelengths on materials and structures for achieving high acceleration gradient were based on the availability of the 34.3 GHz third-harmonic magnicon amplifier developed by Omega-P, and installed at the Yale University Beam Physics Laboratory. Peak power from the magnicon was measured to be about 20 MW in 0.5 {micro}s pulses, with a gain of 54 dB. Experiments for studying RF high-field effects on CVD diamond samples failed to show any evidence after more than 10{sup 5} RF pulses of RF breakdown up to a tangential surface field strength of 153 MV/m; studies at higher fields were not possible due to a degradation in magnicon performance. A rebuild of the tube is underway at this writing. Computed performance for a dielectric-loaded rectangular accelerator structure (DLA) shows highly competitive properties, as compared with an existing all-metal structure. For example, comparisons were made of a DLA structure having two planar CVD diamond elements with a all-metal CERN structure HDS operating at 30 GHz. It was shown that the ratio of maximum surface electric field to accelerating field at the metal wall is only 0.35-0.4 for DLA, much smaller than the value 2.2 for HDS; and the ratio of surface magnetic field to accelerating field is 3.0 mA/V for DLA, compared with 3.45 mA/V for HDS. These values bode well for DLA in helping to avoid breakdown and to reducing pulsed surface heating and fatigue. The shunt impedance is found to be 160-175 M{Omega}/m for DLA, as compared to 99 M{Omega}/m for HDS. Conclusions are reached from this project that CVD diamond appears promising as a dielectric with a high threshold for RF breakdown, and that rectangular accelerator structures can be devised using planar CVD diamond elements that could be operated at higher acceleration gradients with low probability of RF breakdown, as compared with corresponding all-metallic structures.

  20. SLIM, Short-pulse Technology for High Gradient Induction Accelerators

    SciTech Connect (OSTI)

    Krasnykh, A.; /SLAC; Kardo-Sysoev, A.; /Ioffe Phys. Tech. Inst.; Arntz, F.; /Diversified Tech., Bedford

    2009-12-09T23:59:59.000Z

    The conclusions of this paper are: (1) The gradient of the SLIM-based technology is believed to be achievable in the same range as it is for the gradient of a modern rf-linac technology ({approx}100 MeV per meter). (2) The SLIM concept is based on the nsec TEM pulse mode operation with no laser or rf systems. (3) Main components of SLIM are not stressed while the energy is pumped into the induction system. Components can accept the hard environment conditions such as a radiation dose, mismatch, hard electromagnetic nose level, etc. Only for several nanoseconds the switch is OFF and produces a stress in the induction system. At that time, the delivery of energy to the beam takes place. (4) The energy in the induction system initially is storied in the magnetic field when the switch is ON. That fact makes another benefit: a low voltage power supplies can be used. The reliability of a lower voltage power supply is higher and they are cheaper. (5) The coreless SLIM concept offers to work in the MHz range of repetition rate. The induction system has the high electric efficiency (much higher than the DWA). (6) The array of lined up and activated SLIM cells is believed to be a solid state structure of novel accelerating technology. The electron-hole plasma in the high power solid state structure is precisely controlled by the electromagnetic process of a pulsed power supply.

  1. Automatic beam path analysis of laser wakefield particle acceleration data

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    Automatic beam path analysis of laser wakefield particle acceleration data Oliver Rübel1 particle accelerators play a key role in the understanding of the complex acceleration process in a pipeline fashion to automatically locate and analyze high-energy particle bunches undergoing acceleration

  2. Automatic Beam Path Analysis of Laser Wakefield Particle Acceleration Data

    E-Print Network [OSTI]

    Knowles, David William

    Automatic Beam Path Analysis of Laser Wakefield Particle Acceleration Data Oliver R¨ubel1 particle accelerators play a key role in the understanding of the complex acceleration process in a pipeline fashion to automatically locate and analyze high energy particle bunches undergoing acceleration

  3. Analysis Code for High Gradient Dielectric Insulator Surface Breakdown

    SciTech Connect (OSTI)

    Ives, Robert Lawrence [Calabazas Creek Research, Inc.; Verboncoeur, John [University of California - Berkeley; Aldan, Manuel [University of California, Berkeley

    2010-05-30T23:59:59.000Z

    High voltage (HV) insulators are critical components in high-energy, accelerator and pulsed power systems that drive diverse applications in the national security, nuclear weapons science, defense and industrial arenas. In these systems, the insulator may separate vacuum/non-vacuum regions or conductors with high electrical field gradients. These insulators will often fail at electric fields over an order of magnitude lower than their intrinsic dielectric strength due to flashover at the dielectric interface. Decades of studies have produced a wealth of information on fundamental processes and mechanisms important for flashover initiation, but only for relatively simple insulator configurations in controlled environments. Accelerator and pulsed power system designers are faced with applying the fundamental knowledge to complex, operational devices with escalating HV requirements. Designers are forced to rely on “best practices” and expensive prototype testing, providing boundaries for successful operation. However, the safety margin is difficult to estimate, and system design must be very conservative for situations where testing is not practicable, or replacement of failed parts is disruptive or expensive. The Phase I program demonstrated the feasibility of developing an advanced code for modeling insulator breakdown. Such a code would be of great interest for a number of applications, including high energy physics, microwave source development, fusion sciences, and other research and industrial applications using high voltage devices.

  4. Modified Magnicon for High-Gradient Accelerator R&D

    SciTech Connect (OSTI)

    Jay L. Hirshfield

    2011-12-19T23:59:59.000Z

    Analysis, and low-power cold tests are described on a modified design intended for the Ka-band pulsed magnicon now in use for high-gradient accelerator R and D and rare elementary particle searches at the Yale University Beam Physics Laboratory. The modification is mainly to the output cavity of the magnicon, which presently operates in the TM310 mode. It is proposed to substitute for this a dual-chamber TE311 cavity structure. The first chamber is to extract about 40% of the beam power (about 25 MW) at 34.272 GHz, while the second chamber is to convey the power to four WR-28 output waveguides. Minor design changes are also proposed for the penultimate 11.424 GHz cavity and the beam collector. The intention of these design changes is to allow the magnicon to operate reliably 24/7, with minor sensitivity to operating parameters.

  5. Tomography of a laser wakefield accelerator Tomography of a laser wakefield accelerator

    E-Print Network [OSTI]

    history of laser-plasma accelerators is reviewed. The excitation of plasma waves by ultra-short laser Tomography of a laser wakefield accelerator Tomography of a laser wakefield accelerator 692220024 #12; Tomography of a laser wakefield accelerator i #12; Tomography of a laser

  6. Comparative Wakefield Analysis of a First Prototype of a DDS Structure for CLIC Main Linac

    E-Print Network [OSTI]

    D'Elia, A; Khan, V F; Grudiev, A; Wuensch, W

    2011-01-01T23:59:59.000Z

    A Damped Detuned Structure (DDS) for CLIC main linac has been proposed as an alternative to the present baseline design which is based on heavy damping. A first prototype, CLIC_DDS_A, for high power tests has been already designed and is under construction. It is also foreseen to design a further prototype, CLIC_DDS_B, to test both the wakefield suppression and high power performances. Wakefield calculations for DDS are, in the early design stage, based on single infinitely periodic cells. Though cell-to-cell interaction is taken into account to calculate the wakefields, it is important to study full structure properties using computational tools. In particular this is fundamental for defining the input parameters for the HOM coupler that is crucial for the performances of DDS. In the following a full analysis of wakefields and impedances based on simulations conducted with finite difference based electromagnetic computer code GdfidL will be presented.

  7. Beam dynamics and wakefield suppression in interleaved damped and detuned structures for CLIC

    E-Print Network [OSTI]

    D'Elia, A; Khan, V F; Jones, R M; Latina, A; Nesmiyan, I; Riddone, G

    2013-01-01T23:59:59.000Z

    Acceleration of multiple bunches of charged particles in the main linacs of the Compact Linear Collider (CLIC) with high accelerating fields provides two major challenges: firstly, to ensure the surface electromagnetic fields do not cause electrical breakdown and subsequent surface damage, and secondly, to ensure the beam-excited wakefields are sufficiently suppressed to avoid appreciable emittance dilution. In the baseline design for CLIC, heavy wakefield suppression is used (Q ~ 10) [1] and this ensures the beam quality is well-preserved [2]. Here we discuss an alternative means to suppress the wakefield which relies on strong detuning of the cell dipole frequencies, together with moderate damping, effected by manifolds which are slot-coupled to each accelerating cell. This damped and detuned wakefield suppression scheme is based on the methodology developed for the Japanese Linear Collider/Next Linear Collider (JLC/NLC) [3]. Here we track the multi-bunch beam down the complete collider, u...

  8. A HIGH GRADIENT QUADRUPOLE MAGNET FOR THE SSC

    E-Print Network [OSTI]

    Taylor, C.

    2010-01-01T23:59:59.000Z

    on gradient and qu;;lity, if the buss grooves are located atto accommodate the m;;! in current buss, the lowp.r ']roovewIring and corrector buss, and thp. symmetrically-placed

  9. Development of Ultra High Gradient and High Q{sub 0} Superconducting Radio Frequency Cavities

    SciTech Connect (OSTI)

    Geng, Rongli [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Clemens, William A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Follkie, James E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Harris, Teena M. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Kushnick, Peter W. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Machie, Danny [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Martin, Robert E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Palczewski, Ari D. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Perry, Era A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Slack, Gary L. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Williams, R. S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Adolphsen, C. [SLAC, Menlo Park, California, (United States); Li, Z. [SLAC, Menlo Park, California, (United States); Hao, J. K. [Peking University, Beijing (China); Li, Y. M. [Peking University, Beijing (China); Liu, K. X. [Peking University, Beijing (China)

    2013-06-01T23:59:59.000Z

    We report on the recent progress at Jefferson Lab in developing ultra high gradient and high Q{sub 0} superconducting radio frequency (SRF) cavities for future SRF based machines. A new 1300 MHz 9-cell prototype cavity is being fabricated. This cavity has an optimized shape in terms of the ratio of the peak surface field (both magnetic and electric) to the acceleration gradient, hence the name low surface field (LSF) shape. The goal of the effort is to demonstrate an acceleration gradient of 50 MV/m with Q{sub 0} of 10{sup 10} at 2 K in a 9-cell SRF cavity. Fine-grain niobium material is used. Conventional forming, machining and electron beam welding method are used for cavity fabrication. New techniques are adopted to ensure repeatable, accurate and inexpensive fabrication of components and the full assembly. The completed cavity is to be first mechanically polished to a mirror-finish, a newly acquired in-house capability at JLab, followed by the proven ILC-style processing recipe established already at JLab. In parallel, new single-cell cavities made from large-grain niobium material are made to further advance the cavity treatment and processing procedures, aiming for the demonstration of an acceleration gradient of 50 MV/m with Q{sub 0} of 2?10{sup 10} at 2K.

  10. Ultra-High Gradient Compact S-Band Linac for Laboratory and Industrial Applications

    SciTech Connect (OSTI)

    Faillace, Luigi; /RadiaBeam Tech.; Agustsson, Ronald; /RadiaBeam Tech.; Frigola, Pedro; /RadiaBeam Tech.; Murokh, Alex; /RadiaBeam Tech.; Dolgashev, Valery; /SLAC; Rosenzweig, James; /UCLA

    2012-07-03T23:59:59.000Z

    There is growing demand from the industrial and research communities for high gradient, compact RF accelerating structures. The commonly used S-band SLAC-type structure has an operating gradient of only about 20 MV/m; while much higher operating gradients (up to 70 MV/m) have been recently achieved in X-band, as a consequence of the substantial efforts by the Next Linear Collider (NLC) collaboration to push the performance envelope of RF structures towards higher accelerating gradients. Currently however, high power X-band RF sources are not readily available for industrial applications. Therefore, RadiaBeam Technologies is developing a short, standing wave S-band structure which uses frequency scaled NLC design concepts to achieve up to a 50 MV/m operating gradient at 2856 MHz. The design and prototype commissioning plans are presented.

  11. Observation of Wakefields and Resonances in Coherent Synchrotron Radiation

    E-Print Network [OSTI]

    Billinghurst, B E; Baribeau, C; Batten, T; Dallin, L; May, T E; Vogt, J M; Wurtz, W A; Warnock, R; Bizzizero, D A; Kramer, S

    2015-01-01T23:59:59.000Z

    We report on high resolution measurements of resonances in the spectrum of coherent synchrotron radiation (CSR) at the Canadian Light Source (CLS). The resonances permeate the spectrum at wavenumber intervals of $0.074 ~\\textrm{cm}^{-1}$, and are highly stable under changes in the machine setup (energy, bucket filling pattern, CSR in bursting or continuous mode). Analogous resonances were predicted long ago in an idealized theory as eigenmodes of a smooth toroidal vacuum chamber driven by a bunched beam moving on a circular orbit. A corollary of peaks in the spectrum is the presence of pulses in the wakefield of the bunch at well defined spatial intervals. Through experiments and further calculations we elucidate the resonance and wakefield mechanisms in the CLS vacuum chamber, which has a fluted form much different from a smooth torus. The wakefield is observed directly in the 30-110 GHz range by RF diodes, and indirectly by an interferometer in the THz range. The wake pulse sequence found by diodes is less ...

  12. High gradient magnetic separation of iron oxide minerals from soil clays

    E-Print Network [OSTI]

    Schulze, Darrell Gene

    1977-01-01T23:59:59.000Z

    HIGH GRADIENT MAGNETIC SEPARATION OF IRON OXIDE MINERALS FROM SOIL CLAYS A Thesis by DARRELL GENE SCHULZE Submitted to the Graduate College of Texas AIM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE... December 1977 Major Subject: Soil Science HIGH GRADIENT MAGNETIC SEPARATION OF IRON OXIDE MINERALS FROM SOIL CLAYS A Thesis DARRELL GENE SCHULZE Approved as to style and content by: (Chairman of C ittee) epartm t) j (Member) (Membe December 1977...

  13. Start-to-end beam dynamics simulation of double triangular current profile generation in Argonne Wakefield Accelerator

    SciTech Connect (OSTI)

    Ha, G.; Power, J.; Kim, S. H.; Gai, W.; Kim, K.-J.; Cho, M. H.; Namkung, W. [POSTECH, Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); POSTECH, Pohang, Gyeongbuk, 790-784 (Korea, Republic of) and Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); POSTECH, Pohang, Gyeongbuk, 790-784 (Korea, Republic of) and Pohang Accelerator Laboratory, Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Pohang Accelerator Laboratory, Pohang, Gyeongbuk, 790-784 (Korea, Republic of)

    2012-12-21T23:59:59.000Z

    Double triangular current profile (DT) gives a high transformer ratio which is the determining factor of the performance of collinear wakefield accelerator. This current profile can be generated using the emittance exchange (EEX) beam line. Argonne Wakefield Accelerator (AWA) facility plans to generate DT using the EEX beam line. We conducted start-to-end simulation for the AWA beam line using PARMELA code. Also, we discuss requirements of beam parameters for the generation of DT.

  14. High-Gradient Tests of the Single-Cell SC Cavity with a Feedback Waveguide

    SciTech Connect (OSTI)

    Yakovlev, V.; Solyak, N.; Wu, G.; Ge, M.; Gonin, I.; Khabiboulline, T.; Ozelis, J.; Rowe, A. [Fermilab, Batavia, IL 60510 (United States); Avrakhov, P.; Kanareykin, A. [Euclid TechLabs, LLC, Solon, Ohio 44139 (United States); Rathke, J. [AES, Medford, NY 11763 (United States)

    2010-11-04T23:59:59.000Z

    Use of a superconducting (SC) traveling-wave accelerating (STWA) structure with a small phase advance per cell, rather than a standing-wave structure, may provide a significant increase in the accelerating gradient in the ILC linac [1]. For the same surface electric and magnetic fields, the STWA achieves an accelerating gradient 1.2 larger than TESLA-like standing-wave cavities. In addition, the STWA allows longer acceleration cavities, reducing the number of gaps between them. However, the STWA structure requires a SC feedback waveguide to return the few hundreds of MW of circulating RF power from the structure output to the structure input. A test single-cell cavity with feedback was designed and manufactured to demonstrate the possibility of proper processing to achieve a high accelerating gradient. The first results of high-gradient tests of a prototype 1.3 GHz single-cell cavity with feedback waveguide will be presented.

  15. Generation of electron beams from a laser wakefield acceleration in pure neon gas

    SciTech Connect (OSTI)

    Li, Song; Hafz, Nasr A. M., E-mail: nasr@sjtu.edu.cn; Mirzaie, Mohammad; Elsied, Ahmed M. M.; Ge, Xulei; Liu, Feng; Sokollik, Thomas; Chen, Min; Sheng, Zhengming; Zhang, Jie, E-mail: jzhang1@sjtu.edu.cn [Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Tao, Mengze; Chen, Liming [Bejing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-08-15T23:59:59.000Z

    We report on the generation of quasimonoenergetic electron beams by the laser wakefield acceleration of 17–50 TW, 30 fs laser pulses in pure neon gas jet. The generated beams have energies in the range 40–120?MeV and up to ?430 pC of charge. At a relatively high density, we observed multiple electron beamlets which has been interpreted by simulations to be the result of breakup of the laser pulse into multiple filaments in the plasma. Each filament drives its own wakefield and generates its own electron beamlet.

  16. Non-Fickian ionic diffusion across high-concentration gradients

    SciTech Connect (OSTI)

    Carey, A.E.; Wheatcraft, S.W. [Univ. of Nevada, Reno, NV (United States)] [Univ. of Nevada, Reno, NV (United States); Glass, R.J. [Sandia National Laboratory, Albuquerque, NM (United States)] [and others] [Sandia National Laboratory, Albuquerque, NM (United States); and others

    1995-09-01T23:59:59.000Z

    A non-Fickian physico-chemical model for electrolyte transport in high-ionic strength systems is developed and tested with laboratory experiments with copper sulfate as an example electrolyte. The new model is based on irreversible thermodynamics and uses measured mutual diffusion coefficients, varying with concentration. Compared to a traditional Fickian model, the new model predicts less diffusion and asymmetric diffusion profiles. Laboratory experiments show diffusion rates even smaller than those predicted by our non-Fickian model, suggesting that there are additional, unaccounted for processes retarding diffusion. Ionic diffusion rates maybe a limiting factor in transporting salts whose effect on fluid density will in turn significantly affect the flow regime. These findings have important implications for understanding and predicting solute transport in geologic settings where dense, saline solutions occur. 30 refs., 5 figs.

  17. Material Selection and Characterization for High Gradient RF Applications

    E-Print Network [OSTI]

    Arnau-Izquierdo, G; Heikkinen, S; Ramsvik, T; Sgobba, Stefano; Taborelli, M; Wuensch, W

    2007-01-01T23:59:59.000Z

    The selection of candidate materials for the accelerating cavities of the Compact Linear Collider (CLIC) is carried out in parallel with high power RF testing. The maximum DC breakdown field of copper, copper alloys, refractory metals, aluminium and titanium have been measured with a dedicated setup. Higher maximum fields are obtained for refractory metals and for titanium, which exhibits, however, important damages after conditioning. Fatigue behaviour of copper alloys has been studied for surface and bulk by pulsed laser irradiation and ultrasonic excitation, respectively. The selected copper alloys show consistently higher fatigue resistance than copper in both experiments. In order to obtain the best local properties in the device a possible solution is a bi-metallic assembly. Junctions of molybdenum and copper-zirconium UNS C15000 alloy, achieved by HIP (Hot Isostatic Pressing) diffusion bonding or explosion bonding were evaluated for their mechanical strength. The reliability of the results obtained wit...

  18. Current Filamentation Instability in Laser Wakefield Accelerators

    SciTech Connect (OSTI)

    Huntington, C. M.; Drake, R. P. [Atmospheric, Oceanic and Space Science, University of Michigan, Ann Arbor, Michigan, 48103 (United States); Thomas, A. G. R.; McGuffey, C.; Matsuoka, T.; Chvykov, V.; Kalintchenko, G.; Yanovsky, V.; Maksimchuk, A.; Krushelnick, K. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Kneip, S.; Najmudin, Z.; Palmer, C. [Blackett Laboratory, Imperial College London, London, SW7 2BZ (United Kingdom); Katsouleas, T. [Platt School of Engineering, Duke University, Durham, North Carolina, 27708 (United States)

    2011-03-11T23:59:59.000Z

    Experiments using an electron beam produced by laser-wakefield acceleration have shown that varying the overall beam-plasma interaction length results in current filamentation at lengths that exceed the laser depletion length in the plasma. Three-dimensional simulations show this to be a combination of hosing, beam erosion, and filamentation of the decelerated beam. This work suggests the ability to perform scaled experiments of astrophysical instabilities. Additionally, understanding the processes involved with electron beam propagation is essential to the development of wakefield accelerator applications.

  19. Development of High-Gradient Dielectric Laser-Driven Particle Accelerator Structures

    SciTech Connect (OSTI)

    Byer, Robert L.

    2013-11-07T23:59:59.000Z

    The thrust of Stanford's program is to conduct research on high-gradient dielectric accelerator structures driven with high repetition-rate, tabletop infrared lasers. The close collaboration between Stanford and SLAC (Stanford Linear Accelerator Center) is critical to the success of this project, because it provides a unique environment where prototype dielectric accelerator structures can be rapidly fabricated and tested with a relativistic electron beam.

  20. Role of stochastic heating in wakefield acceleration when optical injection is used

    SciTech Connect (OSTI)

    Rassou, S.; Bourdier, A.; Drouin, M. [CEA, DAM, DIF, 91297 Arpajon (France)

    2014-08-15T23:59:59.000Z

    The dynamics of an electron in two counterpropagating waves is investigated. Conditions for stochastic acceleration are derived. The possibility of stochastic heating is confirmed when two waves interact with low density plasma by performing PIC (Particle In Cell) code simulations. It is shown that stochastic heating can play an important role in laser wakefield acceleration. When considering low density plasma interacting with a high intensity wave perturbed by a low intensity counterpropagating wave, stochastic heating can provide electrons with the right momentum for trapping in the wakefield. The influence of stochastic acceleration on the trapping of electrons is compared to the one of the beatwave force which is responsible for cold injection. To do so, several polarizations for the colliding pulses are considered. For some value of the plasma density and pulse duration, a transition from an injection due to stochastic acceleration to a cold injection dominated regime—regarding the trapped charge—has been observed from 2D and 3D PIC code simulations. This transition is ruled by the ratio of the interaction length of the pulses to the longitudinal size of the bubble. When the interaction length of the laser pulses reaches the radius of the accelerating cavity stochastic heating becomes dominant, and might be necessary to get electrons trapped into the wakefield, when wakefield inhibition grows with plasma density.

  1. Increasing the transformer ratio at the Argonne wakefield accelerator.

    SciTech Connect (OSTI)

    Power, J.G.; Conde, M.; Liu, W.; Yusof, Z.; Gai, W.; Jing, C.; Kanareykin, A. (High Energy Physics); (Euclid Techlabs, LLC)

    2011-01-01T23:59:59.000Z

    The transformer ratio is defined as the ratio of the maximum energy gain of the witness bunch to the maximum energy loss experienced by the drive bunch (or a bunch within a multidrive bunch train). This plays an important role in the collinear wakefield acceleration scheme. A high transformer ratio is desirable since it leads to a higher overall efficiency under similar conditions (e.g. the same beam loading, the same structure, etc.). One technique to enhance the transformer ratio beyond the ordinary limit of 2 is to use a ramped bunch train. The first experimental demonstration observed a transformer ratio only marginally above 2 due to the mismatch between the drive microbunch length and the frequency of the accelerating structure [C. Jing, A. Kanareykin, J. Power, M. Conde, Z. Yusof, P. Schoessow, and W. Gai, Phys. Rev. Lett. 98, 144801 (2007)]. Recently, we revisited this experiment with an optimized microbunch length using a UV laser stacking technique at the Argonne Wakefield Accelerator facility and measured a transformer ratio of 3.4. Measurements and data analysis from these experiments are presented in detail.

  2. Beam manipulation by self-wakefield at ATF

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

    Committee and the ATF Users' Meetings, April 26 - 27, 2012 Outline 1. Enhanced Transformer Ratio demonstration (wakefield mapping with the shaped beam) 2. Tunable beam energy...

  3. Wakefield Municipal Gas and Light Department- Residential Conservation Services Program

    Broader source: Energy.gov [DOE]

    The Wakefield Municipal Gas and Light Department (WMGLD), in cooperation with the Massachusetts Municipal Wholesale Electric Company (MMWEC), offers the "Incentive Rebate Program" to encourage...

  4. Visualizing Particle-in-Cell Simulation of Laser Wakefield Particle...

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

    of times greater than those obtained in conventional particle accelerators. LWFAs use the electric field of a plasma wave - the wakefield - driven by the radiation pressure of an...

  5. Observation of Enhanced Transformer Ratio in Collinear Wakefield Acceleration

    SciTech Connect (OSTI)

    Jing, C.; Kanareykin, A.; Schoessow, P. [Euclid Techlabs LLC, Solon, Ohio 44139 (United States); Power, J. G.; Conde, M.; Yusof, Z.; Gai, W. [High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois-60439 (United States)

    2007-04-06T23:59:59.000Z

    One approach to future high energy particle accelerators is based on the wakefield principle: a leading high-charge drive bunch is used to excite fields in an accelerating structure or plasma that in turn accelerates a trailing low-charge witness bunch. The transformer ratio R is defined as the ratio of the maximum energy gain of the witness bunch to the maximum energy loss of the drive bunch. In general, R<2 for this configuration. A number of techniques have been proposed to overcome the transformer ratio limitation. We report here the first experimental study of the ramped bunch train (RBT) technique in a dielectric based accelerating structure. A single drive bunch was replaced by two bunches with charge ratio of 1 ratio 2.5 and a separation of 10.5 wavelengths of the fundamental mode. An average measured transformer ratio enhancement by a factor of 1.31 over the single drive bunch case was obtained.

  6. Laser wakefield simulations towards development of compact particle accelerators

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    Laser wakefield simulations towards development of compact particle accelerators C.G.R. Geddes1, D understanding of accelerator physics to advance beam performance and stability, and particle simulations model, France; 9 Oxford University, UK E-mail: cgrgeddes@lbl.gov Abstract. Laser driven wakefield accelerators

  7. COLLECTION OF AIRBORNE PARTICLES BY A HIGH-GRADIENT PERMANENT MAGNETIC METHOD

    SciTech Connect (OSTI)

    Cheng, Mengdawn [ORNL; Allman, Steve L [ORNL; Ludtka, Gerard Michael [ORNL; Avens, Larry R [ORNL

    2014-01-01T23:59:59.000Z

    We report on the use of magnetic force in collection of airborne particles by a high- gradient permanent magnetic separation (HGPMS) device. Three aerosol particles of different magnetic susceptibility (NaCl, CuO, and Fe2O3) were generated in the electrical mobility size range of 10 to 200 nm and were used to study HGPMS collection. One HGPMS matrix element, made of stainless steel wool, was used in the device configuration. Three flow rates were selected to simulate the environmental wind speeds of interest to the study. Magnetic force was found to exhibit an insignificant effect on the separation of NaCl particles, even in the HGPMS configuration. Diffusion was a major mechanism in the removal of the diamagnetic particles; however, diffusion is insignificant under the influence of a high-gradient magnetic field for paramagnetic or ferromagnetic particles. The HGPMS showed high-performance collection (> 99%) of paramagnetic CuO and ferromagnetic Fe2O3 particles for particle sizes greater than or equal to 60 nm. As the wind speed increases, the influence of the magnetic force weakens, and the capability to remove particles from the gas stream diminishes. The results suggest that the HGPMS principle could be explored for development of an advanced miniaturized passive aerosol collector.

  8. Numerical Verification of the Power Transfer and Wakefield Coupling in the CLIC Two-Beam Accelerator

    E-Print Network [OSTI]

    Candel, Arno; NG, C; Rawat, V; Schussman, G; Ko, K; Syratchev, I; Grudiev, A; Wuensch, W

    2011-01-01T23:59:59.000Z

    The Compact Linear Collider (CLIC) provides a path to a multi-TeV accelerator to explore the energy frontier of High Energy Physics. Its two-beam accelerator (TBA) concept envisions complex 3D structures, which must be modeled to high accuracy so that simulation results can be directly used to prepare CAD drawings for machining. The required simulations include not only the fundamental mode properties of the accelerating structures but also the Power Extraction and Transfer Structure (PETS), as well as the coupling between the two systems. Time-domain simulations will be performed to understand pulse formation, wakefield damping, fundamental power transfer and wakefield coupling in these structures. Applying SLAC’s parallel finite element code suite, these large-scale problems will be solved on some of the largest supercomputers available. The results will help to identify potential issues and provide new insights on the design, leading to further improvements on the novel two-beam accelerator scheme.

  9. Overview of high gradient SRF R&D for ILC cavities at Jefferson Lab

    SciTech Connect (OSTI)

    Geng, Rongli [JLAB

    2009-11-01T23:59:59.000Z

    We report the progress on high gradient R&D of ILC cavities at Jefferson Lab (JLab) since the Beijing workshop. Routine 9-cell cavity electropolishing (EP) processing and RF testing has been enhanced with added surface mapping and T-mapping instrumentations. 12 new 9-cell cavities (10 of them are baseline fine-grain TESLA-shape cavities: 5 built by ACCEL/Research Instruments, 4 by AES and 1 by JLab; 2 of them are alternative cavities: 1 fine-grain ICHIRO-shape cavity built by KEK/Japan industry and 1 large-grain TESLA-shape cavity built by JLab) are EP processed and tested. 76 EP cycles are accumulated, corresponding to more than 200 hours of active EP time. Field emission (FE) and quench behaviors of electropolished 9-cell cavities are studied. EP process continues to be optimized, resulting in advanced procedures and hence improved cavity performance. Several 9-cell cavities reached 35 MV/m after the first light EP processing. FE-free performance has been demonstrated in 9-cell cavities in 35-40 MV/m range. 1-cell cavity studies explore new techniques for defect removal as well as advanced integrated cavity processing. Surface studies of niobium samples electropolished together with real cavities provide new insight into the nature of field emitters. Close cooperation with the US cavity fabrication industry has been undertaking with the successful achievement of 41 MV/m for the first time in a 9-cell ILC cavity built by AES. As the size of the data set grows, it is now possible to construct gradient yield curves, from which one can see that significant progress has been made in raising the high gradient yield.

  10. Wakefield acceleration in atmospheric plasmas: a possible source of MeV electrons

    E-Print Network [OSTI]

    Arrayás, M; Seviour, R; Trueba, J L

    2015-01-01T23:59:59.000Z

    Intense electromagnetic pulses interacting with a plasma can create a wake of plasma oscillations. Electrons trapped in such oscillations can be accelerated under certain conditions to very high energies. We study the conditions for the wakefield acceleration to produce MeV electrons in atmospheric plasmas. This mechanism may explain the origin of MeV or runaway electrons needed in the current theories for the production of Terrestrial Gamma ray Flashes.

  11. Dense Plasma Focus Z-pinches for High Gradient Particle Acceleration

    SciTech Connect (OSTI)

    Tang, V; Adams, M L; Rusnak, B

    2009-07-24T23:59:59.000Z

    The final Z-pinch stage of a Dense Plasma Focus (DPF) could be used as a simple, compact, and potentially rugged plasma-based high-gradient accelerator with fields at the 100 MV/m level. In this paper we review previously published experimental beam data that indicate the feasibility of such an DPF-based accelerator, qualitatively discuss the physical acceleration processes in terms of the induced voltages, and as a starting point examine the DPF acceleration potential by numerically applying a self-consistent DPF system model that includes the induced voltage from both macroscopic and instability driven plasma dynamics. Applications to the remote detection of high explosives and a multi-staged acceleration concept are briefly discussed.

  12. Experimental demonstration of wakefield effects in a THz planar...

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

    Change in D-W spacing energy gainloss of a witness Wakefield structure c b (c) * Polycrystalline diamond, 75um thick * 250 GHz slab-symmetrical structure Why Diamond...

  13. A comparison of NEXRAD WSR-88D rain estimates with gauge measurements for high and low reflectivity gradient precipitation events.

    SciTech Connect (OSTI)

    Jendrowski, P.; Kelly, D. S.; Klazura, G. E.; Thomale, J. M.

    1999-04-14T23:59:59.000Z

    Rain gauge measurements were compared with radar-estimated storm total precipitation for 43 rain events that occurred at ten locations. Gauge-to-radar ratios (G/R) were computed for each case. The G/R ratio is strongly related to precipitation type, with the mean G/R slightly less than 1.00 for high-reflectivity gradient cases and greater than 2.00 (factor of 2 radar underestimation) for low-reflectivity gradient cases. both precipitation types indicated radar underestimate at the nearest ranges. However, the high-reflectivity gradient cases indicated radar overestimation at further ranges, while the low-reflectivity gradient cases indicated significant radar underestimation at all ranges. Occurrences of radar overestimates may have been related to high reflectivity returns from melting ice, bright-band effects in stratiform systems and hail from convective systems. Bright-band effects probably were responsible for improving the radar underestimates in the second range interval (50-99.9 km) for the low-reflectivity gradient cases. Other possibilities for radar overestimates are anomalous propagation (AP) of the radar beam. Smith, et al. (1996) concluded that bright band and AP lead to systematic overestimate of rainfall at intermediate ranges.

  14. Evidence of Magnetic Breakdown on the Defects With Thermally Suppressed Critical Field in High Gradient SRF Cavities

    SciTech Connect (OSTI)

    Eremeev, Grigory [JLAB; Palczewski, Ari [JLAB

    2013-09-01T23:59:59.000Z

    At SRF 2011 we presented the study of quenches in high gradient SRF cavities with dual mode excitation technique. The data differed from measurements done in 80's that indicated thermal breakdown nature of quenches in SRF cavities. In this contribution we present analysis of the data that indicates that our recent data for high gradient quenches is consistent with the magnetic breakdown on the defects with thermally suppressed critical field. From the parametric fits derived within the model we estimate the critical breakdown fields.

  15. AUGMENTING COMPUTER MUSIC WITH JUST-IN-TIME COMPILATION Wesley Smith, Graham Wakefield

    E-Print Network [OSTI]

    California at Santa Barbara, University of

    AUGMENTING COMPUTER MUSIC WITH JUST-IN-TIME COMPILATION Wesley Smith, Graham Wakefield University of California Santa Barbara Media Arts and Technology whsmith|wakefield@mat.ucsb.edu ABSTRACT We discuss

  16. Automated analysis for detecting beams in laser wakefield simulations

    SciTech Connect (OSTI)

    Ushizima, Daniela M.; Rubel, Oliver; Prabhat, Mr.; Weber, Gunther H.; Bethel, E. Wes; Aragon, Cecilia R.; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Hamann, Bernd; Messmer, Peter; Hagen, Hans

    2008-07-03T23:59:59.000Z

    Laser wakefield particle accelerators have shown the potential to generate electric fields thousands of times higher than those of conventional accelerators. The resulting extremely short particle acceleration distance could yield a potential new compact source of energetic electrons and radiation, with wide applications from medicine to physics. Physicists investigate laser-plasma internal dynamics by running particle-in-cell simulations; however, this generates a large dataset that requires time-consuming, manual inspection by experts in order to detect key features such as beam formation. This paper describes a framework to automate the data analysis and classification of simulation data. First, we propose a new method to identify locations with high density of particles in the space-time domain, based on maximum extremum point detection on the particle distribution. We analyze high density electron regions using a lifetime diagram by organizing and pruning the maximum extrema as nodes in a minimum spanning tree. Second, we partition the multivariate data using fuzzy clustering to detect time steps in a experiment that may contain a high quality electron beam. Finally, we combine results from fuzzy clustering and bunch lifetime analysis to estimate spatially confined beams. We demonstrate our algorithms successfully on four different simulation datasets.

  17. Validation of classical density-dependent solute transport theory for stable, high-concentration-gradient brine displacements in

    E-Print Network [OSTI]

    Hassanizadeh, S. Majid

    -concentration-gradient brine displacements in coarse and medium sands S.J. Watson a,1 , D.A. Barry a,1 , R.J. Schotting b,*, S by a brine solution, under either constant head or constant volume flux conditions. The experimental data, significantly less ex- perimental research has been conducted to investigate high-concentration (e.g., brine

  18. Theory of factors limiting high gradient operation of warm accelerating structures

    SciTech Connect (OSTI)

    Nusinovich, Gregory S. [University of Maryland; Antonsen, Thomas M. [University of Maryland; Kishek, Rami [University of Maryland

    2014-07-25T23:59:59.000Z

    This final report summarizes the research performed during the time period from 8/1/2010 to 7/31/2013. It consists of two parts describing our studies in two directions: (a) analysis of factors limiting operation of dielectric-loaded accelerating (DLA) structures where the main problem is the occurrence of multipactor on dielectric surfaces, and (b) studies of effects associated with either RF magnetic or RF electric fields which may cause the RF breakdown in high-gradient metallic accelerating structures. In the studies of DLA structures, at least, two accomplishments should be mentioned: the development of a 3D non-stationary, self-consistent code describing the multipactor phenomena and yielding very good agreement with some experimental data obtained in joint ANL/NRL experiments. In the metallic structures, such phenomena as the heating and melting of micro-particles (metallic dust) by RF electric and magnetic fields in single-shot and rep-rate regimes is analyzed. Also, such processes in micro-protrusions on the structure surfaces as heating and melting due to the field emitted current and the Nottingham effect are thoroughly investigated with the account for space charge of emitted current on the field emission from the tip.

  19. A high-throughput microfluidic device to study neurite response to growth factor gradients

    E-Print Network [OSTI]

    Kothapalli, Chandrasekhar R.

    Studying neurite guidance by diffusible or substrate bound gradients is challenging with current techniques. In this study, we present the design, fabrication and utility of a microfluidic device to study neurite guidance ...

  20. Studies of the superconducting traveling wave cavity for high gradient LINAC

    E-Print Network [OSTI]

    Avrakhov, Pavel; Kanareykin, Alexei; Solyak, Nikolay; Yakovlev, Vyacheslav P

    2015-01-01T23:59:59.000Z

    Use of a traveling wave (TW) accelerating structure with a small phase advance per cell instead of standing wave may provide a significant increase of accelerating gradient in a superconducting linear accelerator. The TW section achieves an accelerating gradient 1.2-1.4 larger than TESLA-shaped standing wave cavities for the same surface electric and magnetic fields. Recent tests of an L-band single-cell cavity with a waveguide feedback demonstrated an accelerating gradient comparable to the gradient in a single-cell ILC-type cavity from the same manufacturer. This article presents the next stage of the 3- cell TW resonance ring development which will be tested in the traveling wave regime. The main simulation results of the microphonics and Lorentz Force Detuning (LFD) are also considered.

  1. Automatic Beam Path Analysis of Laser Wakefield Particle Acceleration Data

    SciTech Connect (OSTI)

    Rubel, Oliver; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Wu, Kesheng; Prabhat,; Weber, Gunther H.; Ushizima, Daniela M.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes

    2009-10-19T23:59:59.000Z

    Numerical simulations of laser wakefield particle accelerators play a key role in the understanding of the complex acceleration process and in the design of expensive experimental facilities. As the size and complexity of simulation output grows, an increasingly acute challenge is the practical need for computational techniques that aid in scientific knowledge discovery. To that end, we present a set of data-understanding algorithms that work in concert in a pipeline fashion to automatically locate and analyze high energy particle bunches undergoing acceleration in very large simulation datasets. These techniques work cooperatively by first identifying features of interest in individual timesteps, then integrating features across timesteps, and based on the information derived perform analysis of temporally dynamic features. This combination of techniques supports accurate detection of particle beams enabling a deeper level of scientific understanding of physical phenomena than hasbeen possible before. By combining efficient data analysis algorithms and state-of-the-art data management we enable high-performance analysis of extremely large particle datasets in 3D. We demonstrate the usefulness of our methods for a variety of 2D and 3D datasets and discuss the performance of our analysis pipeline.

  2. Effects of Temperature Gradients and Heat Fluxes on High-Temperature Oxidation

    SciTech Connect (OSTI)

    Holcomb, G.R.

    2008-04-01T23:59:59.000Z

    The effects of a temperature gradient and heat flux on point defect diffusion in protective oxide scales were examined. Irreversible thermodynamics were used to expand Fick’s first law of diffusion to include a heat-flux term—a Soret effect. Oxidation kinetics were developed for the oxidation of cobalt and of nickel doped with chromium. Research is described to verify the effects of a heat flux by oxidizing pure cobalt in a temperature gradient at 900 °C, and comparing the kinetics to isothermal oxidation. No evidence of a heat flux effect was found.

  3. USING LUA FOR AUDIOVISUAL COMPOSTION Graham Wakefield Wesley Smith

    E-Print Network [OSTI]

    California at Santa Barbara, University of

    USING LUA FOR AUDIOVISUAL COMPOSTION Graham Wakefield Wesley Smith University of California Santa Barbara Media Arts and Technology Program Santa Barbara, California, USA ABSTRACT In this paper, we/MSP/Jitter [27], PureData [19], etc.) are popular choices for composing interactive digital media works because

  4. Observation of Enhanced Transformer Ratio in Collinear Wakefield Acceleration

    SciTech Connect (OSTI)

    Jing, C.; Kanareykin, A. [Euclid Techlabs, LLC, Solon, OH-44139 (United States); Power, J.; Conde, M.; Yusof, Z.; Gai, W. [High Energy Physics Division, Argonne National Laboratory, Argonne, IL-60439 (United States)

    2006-11-27T23:59:59.000Z

    The transformer ratio R is a parameter that characterizes the efficiency of the energy transferred from the drive beam to the trailing witness beam passing through a wakefield accelerating structure (all metal or dielectric based) or a plasma chamber. Using a ramped bunch train (RBT) rather than a single drive bunch, the enhanced transformer ratio (ETR) technique is able to increase the transformer ratio R above the ordinary limit of 2 for a single bunch in a collinear wakefield accelerator. The RBT is a train of electron bunches separated by half integer multiples wavelength of the wakefield. The charge of the leading bunch is lowest and subsequent bunch charges are increased in such a way as to maximize R. In this article, an experimental study of this scheme is presented in which an RBT of 2 bunches with charge ratio of 1:2.5 and bunch length {sigma}z = 2 mm were used to enhance the transformer ratio. Measurement results and data analysis show good agreement with theoretical predictions. The ETR technique demonstrated here can be used in any collinear wakefield accelerator configuration, either structure- or plasma-based.

  5. Observation of enhanced transformer ratio in collinear Wakefield acceleration.

    SciTech Connect (OSTI)

    Power, J.; Conde, M.; Yusof, Z.; Gai, W.; Jing, C.; Kanareykin, A.; High Energy Physics; Euclid Techlabs, LLC

    2006-01-01T23:59:59.000Z

    The transformer ratio R is a parameter that characterizes the efficiency of the energy transferred from the drive beam to the trailing witness beam passing through a wakefield accelerating structure (all metal or dielectric based) or a plasma chamber. Using a ramped bunch train (RBT) rather than a single drive bunch, the enhanced transformer ratio (ETR) technique is able to increase the transformer ratio R above the ordinary limit of 2 for a single bunch in a collinear wakefield accelerator. The RBT is a train of electron bunches separated by half integer multiples wavelength of the wakefield. The charge of the leading bunch is lowest and subsequent bunch charges are increased in such a way as to maximize R. In this article, an experimental study of this scheme is presented in which an RBT of 2 bunches with charge ratio of 1:2.5 and bunch length {sigma}{sub z} = 2 mm were used to enhance the transformer ratio. Measurement results and data analysis show good agreement with theoretical predictions. The ETR technique demonstrated here can be used in any collinear wakefield accelerator configuration, either structure- or plasma-based.

  6. MuSiC: a Multibunch and multiparticle Simulation Code with an alternative approach to wakefield effects

    E-Print Network [OSTI]

    Migliorati, M

    2015-01-01T23:59:59.000Z

    The simulation of beam dynamics in presence of collective effects requires a strong computational effort to take into account, in a self consistent way, the wakefield acting on a given charge and produced by all the others. Generally this is done by means of a convolution integral or sum. Moreover, if the electromagnetic fields consist of resonant modes with high quality factors, responsible, for example, of coupled bunch instabilities, a charge is also affected by itself in previous turns, and a very long record of wakefield must be properly taken into account. In this paper we present a new simulation code for the longitudinal beam dynamics in a circular accelerator, which exploits an alternative approach to the currently used convolution sum, reducing the computing time and avoiding the issues related to the length of wakefield for coupled bunch instabilities. With this approach it is possible to simulate, without the need of a large computing power, simultaneously, the single and multi-bunch beam dynamics...

  7. Parameter sensitivity of plasma wakefields driven by self-modulating proton beams

    SciTech Connect (OSTI)

    Lotov, K. V.; Minakov, V. A.; Sosedkin, A. P. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk, Russia and Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2014-08-15T23:59:59.000Z

    The dependence of wakefield amplitude and phase on beam and plasma parameters is studied in the parameter area of interest for self-modulating proton beam-driven plasma wakefield acceleration. The wakefield phase is shown to be extremely sensitive to small variations of the plasma density, while sensitivity to small variations of other parameters is reasonably low. The study of large parameter variations clarifies the effects that limit the achievable accelerating field in different parts of the parameter space: nonlinear elongation of the wakefield period, insufficient charge of the drive beam, emittance-driven beam divergence, and motion of plasma ions.

  8. Optimization of the LCLS X-ray FEL output performance in the presence of strong undulator wakefields

    E-Print Network [OSTI]

    Reiche, S; Emma, P; Fawley, W M; Huang, Z; Nuhn, H D; Stupakov, G V

    2005-01-01T23:59:59.000Z

    Optimization of the LCLS X-ray FEL output performance in the presence of strong undulator wakefields

  9. Probing temperature gradients within the GaN buffer layer of AlGaN/GaN high electron mobility transistors with Raman thermography

    SciTech Connect (OSTI)

    Hodges, C., E-mail: chris.hodges@bristol.ac.uk; Pomeroy, J.; Kuball, M. [H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)

    2014-02-14T23:59:59.000Z

    We demonstrate the ability of confocal Raman thermography using a spatial filter and azimuthal polarization to probe vertical temperature gradients within the GaN buffer layer of operating AlGaN/GaN high electron mobility transistors. Temperature gradients in the GaN layer are measured by using offset focal planes to minimize the contribution from different regions of the GaN buffer. The measured temperature gradient is in good agreement with a thermal simulation treating the GaN thermal conductivity as homogeneous throughout the layer and including a low thermal conductivity nucleation layer to model the heat flow between the buffer and substrate.

  10. Wakefield effects of the bypass line in LCLS-II

    E-Print Network [OSTI]

    Bane, K

    2014-01-01T23:59:59.000Z

    In LCLS-II, after acceleration and compression and just before entering the undulator, the beam passes through 2.5 km of 24.5 mm (radius) stainless steel pipe. The bunch that passes through the pipe is extremely short---with an rms of 8 um for the nominal 100 pC case. Thus, even though the pipe has a large aperture, the wake that applies is the {\\it short-range} resistive wall wakefield. The bunch distribution is approximately uniform, and therefore the wake induced voltage is characterized by a rather linear voltage chirp. It turns out that the wake supplies needed dechirping to the LCLS-II beam before it enters the undulator. In this note we calculate the wake, discuss the confidence in the calculation, and investigate how to improve the induced chirp linearity and/or strength. Finally, we also study the strength and effects of the transverse (dipole) resistive wall wakefield.

  11. Recent Experiment on Wakefield Transformer Ratio Enhancement at AWA

    SciTech Connect (OSTI)

    Jing, C.; Kanareykin, A. [Euclid Techlabs, LLC, 5900 Harper Rd, Solon, OH 44139 (United States); High Energy Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Power, J. G.; Conde, M.; Liu, W.; Yusof, Z.; Gai, W. [High Energy Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2010-11-04T23:59:59.000Z

    One technique to enhance the transformer ratio beyond the ordinary limit of 2 in a collinear wakefield acceleration scheme is to use a ramped bunched train (RBT). The first experimental demonstration has been reported in [1]. However, due to the mismatch between the beam bunch length and frequency of the accelerating structure, the observed transformer ratio was only marginally above 2 in the earlier experiment. We recently revisited this experiment with an optimized bunch length using the laser stacking technique at Argonne Wakefield Accelerator (AWA) facility. A transformer ratio of 3.4 has been measured using two drive bunches. Attempting to use four drive bunches met with major challenges. In this article, measurement results and data analysis from these experiments are presented in detail.

  12. Wakefield measurements of SLAC linac structures at the Argonne AATF

    SciTech Connect (OSTI)

    Wang, J.W.; Loew, G.A. (Stanford Linear Accelerator Center, Menlo Park, CA (USA)); Simpson, J.; Chojnacki, E.; Gai, W.; Konecny, R.; Schoessow, P. (Argonne National Lab., IL (USA))

    1991-05-01T23:59:59.000Z

    Damped and detuned linac structures designed to minimize the effects of wakefields excited by e{sup {plus minus}} bunch trains in future linear colliders are presently under investigation at SLAC. This paper describes the results of measurements of both longitudinal and transverse wakefields performed at the ANL Advanced Accelerator Test Facility with two SLAC-built X-Band disk-loaded waveguides: a conventional 30-cavity long constant-impedance structure and a non-conventional 50-cavity long structure along which the iris and spacer diameters have been varied so as to stagger-tune the HEM{sub 11} mode frequency by 37%. The results are shown to be in excellent agreement with computations made by KN7C, TRANSVRS, TBCI, and LINACBBU. 8 refs., 5 figs.

  13. Stern-Gerlach surfing in laser wakefield accelerators

    E-Print Network [OSTI]

    Flood, Stephen P

    2015-01-01T23:59:59.000Z

    We investigate the effects of a Stern-Gerlach-type addition to the Lorentz force on electrons in a laser wakefield accelerator. The Stern-Gerlach-type terms are found to generate a family of trajectories describing electrons that surf along the plasma density wave driven by a laser pulse. Such trajectories could lead to an increase in the size of an electron bunch, which may have implications for attempts to exploit such bunches in future free electron lasers.

  14. Unphysical kinetic effects in particle-in-cell modeling of laser wakefield accelerators Estelle Cormier-Michel,1,2

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    Unphysical kinetic effects in particle-in-cell modeling of laser wakefield accelerators Estelle of laser wakefield accelerators using particle-in-cell codes are investigated. A dark current free laser wakefield accelerator stage, in which no trapping of background plasma electrons into the plasma wave should

  15. Experimental Study of the Effect of Beam Loading on RF Breakdown Rate in CLIC High-Gradient Accelerating Structures

    E-Print Network [OSTI]

    Tecker, F; Kelisani, M; Doebert, S; Grudiev, A; Quirante, J; Riddone, G; Syratchev, I; Wuensch, W; Kononenko, O; Solodko, A; Lebet, S

    2013-01-01T23:59:59.000Z

    RF breakdown is a key issue for the multi-TeV highluminosity e+e- Compact Linear Collider (CLIC). Breakdowns in the high-gradient accelerator structures can deflect the beam and decrease the desired luminosity. The limitations of the accelerating structures due to breakdowns have been studied so far without a beam present in the structure. The presence of the beam modifies the distribution of the electrical and magnetic field distributions, which determine the breakdown rate. Therefore an experiment has been designed for high power testing a CLIC prototype accelerating structure with a beam present in the CLIC Test Facility (CTF3). A special beam line allows extracting a beam with nominal CLIC beam current and duration from the CTF3 linac. The paper describes the beam optics design for this experimental beam line and the commissioning of the experiment with beam.

  16. Multimode Analysis of the Hollow Plasma Channel Wakefield Accelerator C. B. Schroeder,1

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    by resonant excitation [1]. In conventional accelerators, the size of these accel- erating fields is limited particle beam. For the laser wakefield accelerator one of the most se- vere limitations is the weakening- neous plasma. These properties make it well suited as a structure for both particle beam wakefield

  17. EXPERIMENTAL RESULTS OF A PLASMA WAKEFIELD ACCELERATOR USING MULTIPLE ELECTRON BUNCHES

    E-Print Network [OSTI]

    Brookhaven National Laboratory

    ) of the Brookhaven National Laboratory (BNL). We have observed increasing energy loss along the length of the beam preliminary experimental results of a plasma wakefield accelerator technique which utilizes multiple electron oscillations that can support electric fields (wakefields) that can be orders of magnitude higher than those

  18. RECENT PROGRESS AT LBNL ON CHARACTERIZATION OF LASER WAKEFIELD ACCELERATED ELECTRON BUNCHES USING

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    RECENT PROGRESS AT LBNL ON CHARACTERIZATION OF LASER WAKEFIELD ACCELERATED ELECTRON BUNCHES USING. Schroeder, J. van Tilborg, Cs. T´oth Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA 94720, USA Abstract At LBNL, laser wakefield accelerators (LWFA) can now produce ultra-short electron bunches

  19. Wakefield Induced Correlated Energy Spread and Emittance Growth at TTF FEL

    E-Print Network [OSTI]

    1 Wakefield Induced Correlated Energy Spread and Emittance Growth at TTF FEL Feng ZHOU DESY) at DESY. During FEL operations, the longitudinal and transverse wakefields which are generated by vacuum and emittance growth at the TTF FEL of phase I and II. 1 Introduction The Free Electron Laser at the TESLA Test

  20. Benchmarking the codes VORPAL, OSIRIS, and QuickPIC with Laser Wakefield Acceleration

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    with ultra-short Ti-Sapphire laser pulses propagating in hydrogen gas. Both first-order and secondBenchmarking the codes VORPAL, OSIRIS, and QuickPIC with Laser Wakefield Acceleration Simulations K Técnico, Lisboa, Portugal Abstract. Three-dimensional laser wakefield acceleration (LWFA) simulations have

  1. Properties of Trapped Electron Bunches in a Plasma Wakefield Accelerator

    SciTech Connect (OSTI)

    Kirby, Neil; /SLAC

    2009-10-30T23:59:59.000Z

    Plasma-based accelerators use the propagation of a drive bunch through plasma to create large electric fields. Recent plasma wakefield accelerator (PWFA) experiments, carried out at the Stanford Linear Accelerator Center (SLAC), successfully doubled the energy for some of the 42 GeV drive bunch electrons in less than a meter; this feat would have required 3 km in the SLAC linac. This dissertation covers one phenomenon associated with the PWFA, electron trapping. Recently it was shown that PWFAs, operated in the nonlinear bubble regime, can trap electrons that are released by ionization inside the plasma wake and accelerate them to high energies. These trapped electrons occupy and can degrade the accelerating portion of the plasma wake, so it is important to understand their origins and how to remove them. Here, the onset of electron trapping is connected to the drive bunch properties. Additionally, the trapped electron bunches are observed with normalized transverse emittance divided by peak current, {epsilon}{sub N,x}/I{sub t}, below the level of 0.2 {micro}m/kA. A theoretical model of the trapped electron emittance, developed here, indicates that the emittance scales inversely with the square root of the plasma density in the non-linear 'bubble' regime of the PWFA. This model and simulations indicate that the observed values of {epsilon}{sub N,x}/I{sub t} result from multi-GeV trapped electron bunches with emittances of a few {micro}m and multi-kA peak currents. These properties make the trapped electrons a possible particle source for next generation light sources. This dissertation is organized as follows. The first chapter is an overview of the PWFA, which includes a review of the accelerating and focusing fields and a survey of the remaining issues for a plasma-based particle collider. Then, the second chapter examines the physics of electron trapping in the PWFA. The third chapter uses theory and simulations to analyze the properties of the trapped electron bunches. Chapters four and five present the experimental diagnostics and measurements for the trapped electrons. Next, the sixth chapter introduces suggestions for future trapped electron experiments. Then, Chapter seven contains the conclusions. In addition, there is an appendix chapter that covers a topic which is extraneous to electron trapping, but relevant to the PWFA. This chapter explores the feasibility of one idea for the production of a hollow channel plasma, which if produced could solve some of the remaining issues for a plasma-based collider.

  2. FLOW OF A FLUID THROUGH A POROUS SOLID DUE TO HIGH PRESSURE GRADIENTS

    E-Print Network [OSTI]

    Bonito, Andrea

    or carbon diox- ide sequestration where very high pressure differentials are involved. Another important and geotechnical engineering, for example problems such as enhanced oil recovery and carbon di-oxide sequestration

  3. Plasma wakefields in the quasi-nonlinear regime: Experiments at ATF

    SciTech Connect (OSTI)

    Rosenzweig, J. B.; Andonian, G.; Barber, S.; Ferrario, M.; Muggli, P.; O'Shea, B.; Sakai, Y.; Valloni, A.; Williams, O.; Xi, Y.; Yakimenko, V. [UCLA Dept. of Physics and Astronomy, 405 Hilgard Ave. Los Angeles, CA, 90095 (United States); Accelerator Division, Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati , Via E. Fermi 40, Frascati (RM) 00044 (Italy); Max Planck Institute for Physics, Munich (Germany); UCLA Dept. of Physics and Astronomy, 405 Hilgard Ave. Los Angeles, CA, 90095 (United States); Brookhaven National Laboratory, Upton, NY, 11973 (United States)

    2012-12-21T23:59:59.000Z

    In this work we present details of planned experiments to investigate certain aspects of the quasi non linear regime (QNL) of plasma wakefield acceleration (PWFA). In the QNL regime it is, in principal, possible to combine the benefits of both nonlinear and linear PWFA. That is, beams of high quality can be maintained through acceleration due to the complete ejection of plasma electrons from beam occupied region, while large energy gains can be achieved through use of transformer ratio increasing schemes, such as ramped bunch trains. With the addition of an short focal length PMQ triplet capable of focusing beams to the few micron scale and the ability to generate tunable bunch trains, the Accelerator Test Facility (ATF) at Brookhaven National Lab offers the unique capabilities to probe these characteristics of the QNL regime.

  4. Single Bunch Wakefields in the CERN-PSI-ELETTRA X-band Linear Accelerator

    E-Print Network [OSTI]

    El-Ashmawy, Mostafa; Dehler, Micha; Raguin, Jean-Yves; Riddone, Germana; Zennaro, Riccardo

    2010-01-01T23:59:59.000Z

    FERMI@ELETTRA and PSI-XFEL are 4th Generation Light Sources that require high quality electron beam at the entrance of the undulator chains. In this context, a specially developed X-band structure with integrated alignment monitors will be used to mitigate the nonlinearities in the longitudinal phase space due to the second order RF time curvature and the second order momentum compaction term of chicane compressor. The knowledge of the transverse and longitudinal short range wakefields in the X-band structure is essential to evaluate the beam quality in terms of longitudinal energy spread and transverse kick spread. We have used the ABCI code to numerically evaluate the transverse and longitudinal wake potentials for short bunches in this structure

  5. Improvements to laser wakefield accelerated electron beam stability, divergence, and energy spread using three-dimensional printed two-stage gas cell targets

    SciTech Connect (OSTI)

    Vargas, M.; Schumaker, W.; He, Z.-H.; Zhao, Z.; Behm, K.; Chvykov, V.; Hou, B.; Krushelnick, K.; Maksimchuk, A.; Yanovsky, V.; Thomas, A. G. R., E-mail: agrt@umich.edu [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2014-04-28T23:59:59.000Z

    High intensity, short pulse lasers can be used to accelerate electrons to ultra-relativistic energies via laser wakefield acceleration (LWFA) [T. Tajima and J. M. Dawson, Phys. Rev. Lett. 43, 267 (1979)]. Recently, it was shown that separating the injection and acceleration processes into two distinct stages could prove beneficial in obtaining stable, high energy electron beams [Gonsalves et al., Nat. Phys. 7, 862 (2011); Liu et al., Phys. Rev. Lett. 107, 035001 (2011); Pollock et al., Phys. Rev. Lett. 107, 045001 (2011)]. Here, we use a stereolithography based 3D printer to produce two-stage gas targets for LWFA experiments on the HERCULES laser system at the University of Michigan. We demonstrate substantial improvements to the divergence, pointing stability, and energy spread of a laser wakefield accelerated electron beam compared with a single-stage gas cell or gas jet target.

  6. Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

    SciTech Connect (OSTI)

    He, Z.-H.; Thomas, A. G. R.; Nees, J. A.; Hou, B.; Krushelnick, K. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48106-2099 (United States)] [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48106-2099 (United States); Beaurepaire, B.; Malka, V.; Faure, J. [Laboratoire d'Optique Appliquee, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)] [Laboratoire d'Optique Appliquee, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)

    2013-02-11T23:59:59.000Z

    We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

  7. Sub-femtosecond electron bunches created by direct laser acceleration in a laser wakefield accelerator with ionization injection

    E-Print Network [OSTI]

    Lemos, N; Marsh, K A; Joshi, C

    2015-01-01T23:59:59.000Z

    In this work, we will show through three-dimensional particle-in-cell simulations that direct laser acceleration in laser a wakefield accelerator can generate sub-femtosecond electron bunches. Two simulations were done with two laser pulse durations, such that the shortest laser pulse occupies only a fraction of the first bubble, whereas the longer pulse fills the entire first bubble. In the latter case, as the trapped electrons moved forward and interacted with the high intensity region of the laser pulse, micro-bunching occurred naturally, producing 0.5 fs electron bunches. This is not observed in the short pulse simulation.

  8. Energy Doubling of 42 GeV Electrons in a Meter-scale Plasma Wakefield Accelerator

    SciTech Connect (OSTI)

    Blumenfeld, Ian; Clayton, Christopher E.; Decker, Franz-Josef; Hogan, Mark J.; Huang, Chengkun; Ischebeck, Rasmus; Iverson, Richard; Joshi, Chandrashekhar; Katsouleas,; Kirby, Neil; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; Muggli, Patric; Oz, Erdem; Siemann, Robert H.; Walz, Dieter; Zhou, Miaomiao; /SLAC /UCLA /Southern California U.

    2007-03-14T23:59:59.000Z

    The energy frontier of particle physics is several trillion electron volts, but colliders capable of reaching this regime (such as the Large Hadron Collider and the International Linear Collider) are costly and time-consuming to build; it is therefore important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators, a drive beam (either laser or particle) produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultrahigh accelerating fields over a substantial length to achieve a significant energy gain. Here we show that an energy gain of more than 42 GeV is achieved in a plasma wakefield accelerator of 85 cm length, driven by a 42 GeV electron beam at the Stanford Linear Accelerator Center (SLAC). The results are in excellent agreement with the predictions of three-dimensional particle-in-cell simulations. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of {approx} 52GV m{sup -1}. This effectively doubles their energy, producing the energy gain of the 3-km-long SLAC accelerator in less than a meter for a small fraction of the electrons in the injected bunch. This is an important step towards demonstrating the viability of plasma accelerators for high-energy physics applications.

  9. Wakefield Damping in a Pair of X-Band Accelerators for Linear Colliders

    SciTech Connect (OSTI)

    Jones, R.M.; Adolphsen, C.E.; Wang, J.W.; Li, Z.; /SLAC

    2006-12-18T23:59:59.000Z

    We consider means to damp the wake-field left behind ultra-relativistic charges. In particular, we focus on a pair of travelling wave accelerators operating at an X-band frequency of 11.424 GHz. In order to maximize the efficiency of acceleration, in the context of a linear collider, multiple bunches of charged particles are accelerated within a given pulse of the electromagnetic field. The wake-field left behind successive bunches, if left unchecked, can seriously disturb the progress of trailing bunches and can lead to an appreciable dilution in the emittance of the beam. We report on a method to minimize the influence of the wake-field on trailing bunches. This method entails detuning the characteristic mode frequencies which make-up the electromagnetic field, damping the wake-field, and interleaving the frequencies of adjacent accelerating structures. Theoretical predictions of the wake-field and modes, based on a circuit model, are compared with experimental measurements of the wake-field conducted within the ASSET facility at SLAC. Very good agreement is obtained between theory and experiment and this allows us to have some confidence in designing the damping of wake-fields in a future linear collider consisting of several thousand of these accelerating structures.

  10. Hybrid magnet devices for molecule manipulation and small scale high gradient-field applications

    DOE Patents [OSTI]

    Humphries, David E. (El Cerrito, CA); Hong, Seok-Cheol (Seoul, KR); Cozzarelli, legal representative, Linda A. (Berkeley, CA); Pollard, Martin J. (El Cerrito, CA); Cozzarelli, Nicholas R. (Berkeley, CA)

    2009-01-06T23:59:59.000Z

    The present disclosure provides a high performance hybrid magnetic structure made from a combination of permanent magnets and ferromagnetic pole materials which are assembled in a predetermined array. The hybrid magnetic structure provides means for separation and other biotechnology applications involving holding, manipulation, or separation of magnetizable molecular structures and targets. Also disclosed are hybrid magnetic tweezers able to exert approximately 1 nN of force to 4.5 .mu.m magnetic bead. The maximum force was experimentally measured to be .about.900 pN which is in good agreement with theoretical estimations and other measurements. In addition, a new analysis scheme that permits fast real-time position measurement in typical geometry of magnetic tweezers has been developed and described in detail.

  11. Generation of high order optical harmonics in steep plasma density gradients

    SciTech Connect (OSTI)

    Linde, D. von der [Institut fuer Laser- und Plasmaphysik, Universitaet Essen, D-45117 Essen (Germany)

    1998-02-20T23:59:59.000Z

    During the interaction of an intense ultrashort laser pulse with solid targets a thin layer of surface plasma is generated in which the density drops to the vacuum level in a distance much shorter than the wavelength. This sharp plasma-vacuum boundary performs an oscillatory motion in response to the electromagnetic forces of the intense laser light. It is shown that the generation of reflected harmonics can be interpreted as a phase modulation experienced by the light upon reflection from the oscillating boundary. The modulation sidebands of the reflected frequency spectrum correspond to odd and even harmonics of the laser frequency. Retardation effects lead to a strong anharmonicity for high velocities of the plasma-vacuum boundary. As a result, harmonic generation is strongly enhanced in the relativistic regime of laser intensities.

  12. Two Channel Dielectric-Lined Rectangular High Transformer Ratio Accelerator Structure Experiment

    SciTech Connect (OSTI)

    Shchelkunov, S. V.; LaPointe, M. A. [Beam Physics Laboratory, Yale University, 272 Whitney Avenue, New Haven, CT 06511 (United States); Hirshfield, J. L. [Beam Physics Laboratory, Yale University, 272 Whitney Avenue, New Haven, CT 06511 (United States); Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Marshall, T. C. [Columbia University, New York, NY 10027 (United States); Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Sotnikov, G. [NSC Kharkov Institute of Physics and Technology, Kharkov (Ukraine); Omega-P, Inc., 258 Bradley St., New Haven, CT 06510 (United States); Gai, Wei; Conde, M.; Power, J.; Mihalcea, D. [Argonne National Laboratory, Argonne, IL 60439 (United States)

    2010-11-04T23:59:59.000Z

    Current status of a two-channel cm-scale rectangular dielectric lined wakefield accelerator structure is described. This structure is installed at the Argonne Wakefield Accelerator facility (AWA), and is presently being evaluated. The device has a transformer ratio of {approx}12.5:1. When driven by a {approx}50 nC single drive bunch it is expected to obtain {approx}6 MV/m acceleration gradient. Related issues are discussed.

  13. Plasma Wakefield Acceleration: How it Works

    SciTech Connect (OSTI)

    None

    2014-11-05T23:59:59.000Z

    This animation explains how electrons can be efficiently accelerated to high energy using wakes created in a plasma.

  14. Wakefield generation by a relativistic ring beam in a coaxial two channel dielectric loaded structure.

    SciTech Connect (OSTI)

    Liu, W.; Gai, W. (High Energy Physics)

    2009-05-12T23:59:59.000Z

    In this paper, we give a complete analytical solution for wakefields generated by an azimuthally symmetric ring beam propagating in a coaxial two-channel dielectric structure. This wakefield can be used to accelerate a witness beam in the central channel. The ratio of the peak accelerating field in the center channel to the decelerating field in the ring channel (defined as transformer ratio R) is also derived. We find that, by appropriate choice of parameters, R can be much greater than 2, the limiting value for collinear wakefield accelerators.

  15. Measurement of wakefields generated in accelerator test structures using the SLC

    SciTech Connect (OSTI)

    Adolphsen, C.; Bane, K.; Loew, G.; Ruth, R.; Thompson, K.; Wang, J.

    1992-10-01T23:59:59.000Z

    Research is underway at SLAC to develop accelerator structures for the next generation linear collider. An important feature of the design is a detuning of the dipole modes of the cells to suppress the long-range transverse wakefield by two orders of magnitude. This paper describes a facility, called ASSET, that will be incorporated into the SLAC Linear Collider (SLC) to test the long-range wakefield suppression and also to measure the other components of the wakefields generated in accelerator test structures.

  16. Beyond injection: Trojan horse underdense photocathode plasma wakefield acceleration

    SciTech Connect (OSTI)

    Hidding, B.; Rosenzweig, J. B.; Xi, Y.; O'Shea, B.; Andonian, G.; Schiller, D.; Barber, S.; Williams, O.; Pretzler, G.; Koenigstein, T.; Kleeschulte, F.; Hogan, M. J.; Litos, M.; Corde, S.; White, W. W.; Muggli, P.; Bruhwiler, D. L.; Lotov, K. [Institut fuer Laser- und Plasmaphysik, Heinrich-Heine-Universitaet Duesseldorf 40225 Duesseldorf (Germany) and Particle Beam Physics Laboratory, Department for Physics and Astronomy, UCLA (United States); Particle Beam Physics Laboratory, Department for Physics and Astronomy, UCLA (United States); Institut fuer Laser- und Plasmaphysik, Heinrich-Heine-Universitaet Duesseldorf 40225 Duesseldorf (Germany); Stanford Linear Accelerator Center (United States); Max-Planck-Institut fuer Physik, Muenchen (Germany); Tech-X Corporation, Boulder, Colorado (United States) and 1348 Redwood Ave., Boulder, Colorado 80304 (United States); Budker Institute of Nuclear Physics SB RAS, 630090, Novosibirsk (Russian Federation) and Novosibirsk State University, 630090, Novosibirsk (Russian Federation)

    2012-12-21T23:59:59.000Z

    An overview on the underlying principles of the hybrid plasma wakefield acceleration scheme dubbed 'Trojan Horse' acceleration is given. The concept is based on laser-controlled release of electrons directly into a particle-beam-driven plasma blowout, paving the way for controlled, shapeable electron bunches with ultralow emittance and ultrahigh brightness. Combining the virtues of a low-ionization-threshold underdense photocathode with the GV/m-scale electric fields of a practically dephasing-free beam-driven plasma blowout, this constitutes a 4th generation electron acceleration scheme. It is applicable as a beam brightness transformer for electron bunches from LWFA and PWFA systems alike. At FACET, the proof-of-concept experiment 'E-210: Trojan Horse Plasma Wakefield Acceleration' has recently been approved and is in preparation. At the same time, various LWFA facilities are currently considered to host experiments aiming at stabilizing and boosting the electron bunch output quality via a trojan horse afterburner stage. Since normalized emittance and brightness can be improved by many orders of magnitude, the scheme is an ideal candidate for light sources such as free-electron-lasers and those based on Thomson scattering and betatron radiation alike.

  17. Beam Head Erosion in Self-Ionized Plasma Wakefield Accelerators

    SciTech Connect (OSTI)

    Berry, M.K.; Blumenfeld, I.; Decker, F.J.; Hogan, M.J.; Ischebeck, R.; Iverson, R.H.; Kirby, N.A.; Siemann, Robert H.; Walz, D.R.; /SLAC; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; /UCLA; Katsouleas, T.C.; Muggli, P.; Oz, E.; /Southern California U.

    2008-01-28T23:59:59.000Z

    In the recent plasma wakefield accelerator experiments at SLAC, the energy of the particles in the tail of the 42 GeV electron beam were doubled in less than one meter [1]. Simulations suggest that the acceleration length was limited by a new phenomenon--beam head erosion in self-ionized plasmas. In vacuum, a particle beam expands transversely in a distance given by {beta}*. In the blowout regime of a plasma wakefield [2], the majority of the beam is focused by the ion channel, while the beam head slowly spreads since it takes a finite time for the ion channel to form. It is observed that in self-ionized plasmas, the head spreading is exacerbated compared to that in pre-ionized plasmas, causing the ionization front to move backward (erode). A simple theoretical model is used to estimate the upper limit of the erosion rate for a bi-gaussian beam by assuming free expansion of the beam head before the ionization front. Comparison with simulations suggests that half this maximum value can serve as an estimate for the erosion rate. Critical parameters to the erosion rate are discussed.

  18. Laser pulse propagation in inhomogeneous magnetoplasma channels and wakefield acceleration

    SciTech Connect (OSTI)

    Sharma, B. S., E-mail: bs-phy@yahoo.com; Jain, Archana [Government College Kota, Kota 324001 (India)] [Government College Kota, Kota 324001 (India); Jaiman, N. K. [Department of Pure and Applied Physics, University of Kota, Kota 324010 (India)] [Department of Pure and Applied Physics, University of Kota, Kota 324010 (India); Gupta, D. N. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)] [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Jang, D. G.; Suk, H. [Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)] [Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Kulagin, V. V. [Sternberg Astronomical Institute of Moscow State University, Moscow 119992 (Russian Federation)] [Sternberg Astronomical Institute of Moscow State University, Moscow 119992 (Russian Federation)

    2014-02-15T23:59:59.000Z

    Wakefield excitation in a preformed inhomogeneous parabolic plasma channel by an intense relativistic (?10{sup 19}?W/cm{sup 2}) circularly polarized Gaussian laser pulse is investigated analytically and numerically in the presence of an external longitudinal magnetic field. A three dimensional envelope equation for the evolution of the laser pulse is derived, which includes the effect of the nonparaxial and applied external magnetic field. A relation for the channel radius with the laser spot size is derived and examines numerically to see the external magnetic field effect. It is observed that the channel radius depends on the applied external magnetic field. An analytical expression for the wakefield is derived and validated with the help of a two dimensional particle in cell (2D PIC) simulation code. It is shown that the electromagnetic nature of the wakes in an inhomogeneous plasma channel makes their excitation nonlocal, which results in change of fields with time and external magnetic field due to phase mixing of the plasma oscillations with spatially varying frequencies. The magnetic field effect on perturbation of the plasma density and decreasing length is also analyzed numerically. In addition, it has been shown that the electron energy gain in the inhomogeneous parabolic magnetoplasma channel can be increased significantly compared with the homogeneous plasma channel.

  19. Collimator Wakefield Calculations for ILC-TRC Report(LCC-0101)

    SciTech Connect (OSTI)

    Tenenbaum, P

    2003-10-07T23:59:59.000Z

    We summarize the formalism of collimator wakefields and their effect on beams that are near the center of the collimator gap, and apply the formalism to the TESLA, NLC, and CLIC collimation systems.

  20. Calculation of wakefields in a 17 GHz beam-driven photonic band-gap accelerator structure

    E-Print Network [OSTI]

    Hu, Min

    We present the theoretical analysis and computer simulation of the wakefields in a 17 GHz photonic band-gap (PBG) structure for accelerator applications. Using the commercial code CST Particle Studio, the fundamental ...

  1. P. Muggli, ATF Users Meeting 07/05/07 Multi-bunch Plasma Wakefield

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

    Optronics, Inc., Bellevue, WA Presented by Patric Muggli, USC Work supported by US DoE 2 P. Muggli, ATF Users Meeting 070507 OUTLINE Introduction to the plasma wakefield...

  2. ACE3P Computations of Wakefield Coupling in the CLIC Two-Beam Accelerator

    SciTech Connect (OSTI)

    Candel, Arno; Li, Z.; Ng, C.; Rawat, V.; Schussman, G.; Ko, K.; /SLAC; Syratchev, I.; Grudiev, A.; Wuensch, W.; /CERN

    2010-10-27T23:59:59.000Z

    The Compact Linear Collider (CLIC) provides a path to a multi-TeV accelerator to explore the energy frontier of High Energy Physics. Its novel two-beam accelerator concept envisions rf power transfer to the accelerating structures from a separate high-current decelerator beam line consisting of power extraction and transfer structures (PETS). It is critical to numerically verify the fundamental and higher-order mode properties in and between the two beam lines with high accuracy and confidence. To solve these large-scale problems, SLAC's parallel finite element electromagnetic code suite ACE3P is employed. Using curvilinear conformal meshes and higher-order finite element vector basis functions, unprecedented accuracy and computational efficiency are achieved, enabling high-fidelity modeling of complex detuned structures such as the CLIC TD24 accelerating structure. In this paper, time-domain simulations of wakefield coupling effects in the combined system of PETS and the TD24 structures are presented. The results will help to identify potential issues and provide new insights on the design, leading to further improvements on the novel CLIC two-beam accelerator scheme.

  3. Meter scale plasma source for plasma wakefield experiments

    SciTech Connect (OSTI)

    Vafaei-Najafabadi, N.; Shaw, J. L.; Marsh, K. A.; Joshi, C.; Hogan, M. J. [Department of Electrical Engineering, University of California Los Angeles, Los Angeles, CA 90095 (United States); SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States)

    2012-12-21T23:59:59.000Z

    High accelerating gradients generated by a high density electron beam moving through plasma has been used to double the energy of the SLAC electron beam [1]. During that experiment, the electron current density was high enough to generate its own plasma without significant head erosion. In the newly commissioned FACET facility at SLAC, the peak current will be lower and without pre-ionization, head erosion will be a significant challenge for the planned experiments. In this work we report on our design of a meter scale plasma source for these experiments to effectively avoid the problem of head erosion. The plasma source is based on a homogeneous metal vapor gas column that is generated in a heat pipe oven [2]. A lithium oven over 30 cm long at densities over 10{sup 17} cm{sup -3} has been constructed and tested at UCLA. The plasma is then generated by coupling a 10 TW short pulse Ti:Sapphire laser into the gas column using an axicon lens setup. The Bessel profile of the axicon setup creates a region of high intensity that can stretch over the full length of the gas column with approximately constant diameter. In this region of high intensity, the alkali metal vapor is ionized through multi-photon ionization process. In this manner, a fully ionized meter scale plasma of uniform density can be formed. Methods for controlling the plasma diameter and length will also be discussed.

  4. Gradient elution in capillary electrochromatography

    SciTech Connect (OSTI)

    Anex, D.; Rakestraw, D.J. [Sandia National Labs., Livermore, CA (United States); Yan, Chao; Dadoo, R.; Zare, R.N. [Stanford Univ., CA (United States). Dept. of Chemistry

    1997-08-01T23:59:59.000Z

    In analogy to pressure-driven gradient techniques in high-performance liquid chromatography, a system has been developed for delivering electroosmotically-driven solvent gradients for capillary electrochromatography (CEC). Dynamic gradients with sub-mL/min flow rates are generated by merging two electroosmotic flows that are regulated by computer-controlled voltages. These flows are delivered by two fused-silica capillary arms attached to a T-connector, where they mix and then flow into a capillary column that has been electrokinetically packed with 3-mm reversed-phase particles. The inlet of one capillary arm is placed in a solution reservoir containing one mobile phase and the inlet of the other is placed in a second reservoir containing a second mobile phase. Two independent computer-controlled programmable high-voltage power supplies (0-50 kV)--one providing an increasing ramp and the other providing a decreasing ramp--are used to apply variable high-voltage potentials to the mobile phase reservoirs to regulate the electroosmotic flow in each arm. The ratio of the electroosmotic flow rates between the two arms is changed with time according to the computer-controlled voltages to deliver the required gradient profile to the separation column. Experiments were performed to confirm the composition of the mobile phase during a gradient run and to determine the change of the composition in response to the programmed voltage profile. To demonstrate the performance of electroosmotically-driven gradient elution in CEC, a mixture of 16 polycyclic aromatic hydrocarbons (PAHs) was separated in less than 90 minutes. This gradient technique is expected to be well-suited for generating not only solvent gradients in CEC, but also other types of gradients such as pH- and ionic-strength gradients in capillary electrokinetic separations and analyses.

  5. Wakefield and RF Kicks Due to Coupler Asymmetry in TESLA-Type Accelerating Cavities

    SciTech Connect (OSTI)

    Bane, K.L.F.; Adolphsen, C.; Li, Z.; /SLAC; Dohlus, M.; Zagorodnov, I.; /DESY; Gonin, I.; Lunin, A.; Solyak, N.; Yakovlev, V.; /Fermilab; Gjonaj, E.; Weiland, T.; /Darmstadt, Tech. Hochsch.

    2008-07-07T23:59:59.000Z

    In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate fields that will kick the beam transversely and degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental (FM) and higher mode (HM) couplers that are asymmetric and thus the source of such kicks. The kicks are of two types: one, due to (the asymmetry in) the fundamental RF fields and the other, due to transverse wakefields that are generated by the beam even when it is on axis. In this report we calculate the strength of these kicks and estimate their effect on the ILC beam. The TESLA cavity comprises nine cells, one HM coupler in the upstream end, and one (identical, though rotated) HM coupler and one FM coupler in the downstream end (for their shapes and location see Figs. 1, 2) [1]. The cavity is 1.1 m long, the iris radius 35 mm, and the coupler beam pipe radius 39 mm. Note that the couplers reach closer to the axis than the irises, down to a distance of 30 mm.

  6. Modeling Self-Ionized Plasma Wakefield Acceleration for Afterburner Parameters Using QuickPIC

    SciTech Connect (OSTI)

    Zhou, M.; Clayton, C.E.; Decyk, V.K.; Huang, C.; Johnson, D.K.; Joshi, C.; Lu, W.; Mori, W.B.; Tsung, F.S.; /UCLA; Deng, S.; Katsouleas, T.; Muggli, P.; Oz, E.; /Southern; Decker, F.-J.; Iverson, R.; O'Connel, C.; Walz, D.; /SLAC

    2006-01-25T23:59:59.000Z

    For the parameters envisaged in possible afterburner stages[1] of a plasma wakefield accelerator (PWFA), the self-fields of the particle beam can be intense enough to tunnel ionize some neutral gases. Tunnel ionization has been investigated as a way for the beam itself to create the plasma, and the wakes generated may differ from those generated in pre-ionized plasmas[2],[3]. However, it is not practical to model the whole stage of PWFA with afterburner parameters using the models described in [2] and [3]. Here we describe the addition of a tunnel ionization package using the ADK model into QuickPIC, a highly efficient quasi-static particle in cell (PIC) code which can model a PWFA with afterburner parameters. Comparison between results from OSIRIS (a full PIC code with ionization) and from QuickPIC with the ionization package shows good agreement. Preliminary results using parameters relevant to the E164X experiment and the upcoming E167 experiment at SLAC are shown.

  7. Quasimonoenergetic collimated electron beams from a laser wakefield acceleration in low density pure nitrogen

    SciTech Connect (OSTI)

    Tao, Mengze [Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Bejing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Hafz, Nasr A. M., E-mail: nasr@sjtu.edu.cn; Li, Song; Mirzaie, Mohammad; Elsied, Ahmed M. M.; Ge, Xulei; Liu, Feng; Sokollik, Thomas; Sheng, Zhengming; Zhang, Jie, E-mail: jzhang1@sjtu.edu.cn [Key Laboratory for Laser Plasmas (MOE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Chen, Liming [Bejing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-07-15T23:59:59.000Z

    A laser wakefield acceleration (LWFA) experiment is performed using 30 TW, 30 fs, and 800?nm laser pulses, focused onto pure nitrogen plasma having relatively low densities in the range of 0.8×10{sup 18}?cm{sup ?3} to 2.7×10{sup 18}?cm{sup ?3}. Electron beams having a low divergence of ?3??mrad (full-width at half-maximum) and quasi-monoenergetic peak energies of ?105??MeV are achieved over 4-mm interaction length. The total electron beam charge reached to 2 nC, however, only 1%–2% of this (tens of pC) had energies >35?MeV. We tried different conditions to optimize the electron beam acceleration; our experiment verifies that lower nitrogen plasma densities are generating electron beams with high quality in terms of divergence, charge, pointing stability, and maximum energy. In addition, if LWFA is to be widely used as a basis for compact particle accelerators in the future, therefore, from the economic and safety points of view we propose the use of nitrogen gas rather than helium or hydrogen.

  8. Using Surface Impedance for Calculating Wakefields in Flat Geometry

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

    Bane, Karl; Stupakov, Gennady

    2015-03-01T23:59:59.000Z

    Beginning with Maxwell's equations and assuming only that the wall interaction can be approximated by a surface impedance, we derive formulas for the generalized longitudinal and transverse impedance in flat geometry, from which the wakefields can also be obtained. From the generalized impedances, by taking the proper limits, we obtain the normal longitudinal, dipole, and quad impedances in flat geometry. These equations can be applied to any surface impedance, such as the known dc, ac, and anomalous skin models of wall resistance, a model of wall roughness, or one for a pipe with small, periodic corrugations. We show that, formore »the particular case of dc wall resistance, the longitudinal impedance obtained here agrees with a known result in the literature, a result that was derived from a very general formula by Henke and Napoly. As concrete example, we apply our results to representative beam and machine parameters in the undulator region of LCLS-II and estimate the impact of the transverse wakes on the machine performance.« less

  9. Using Surface Impedance for Calculating Wakefields in Flat Geometry

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

    Bane, Karl; Stupakov, Gennady

    2015-03-01T23:59:59.000Z

    Beginning with Maxwell's equations and assuming only that the wall interaction can be approximated by a surface impedance, we derive formulas for the generalized longitudinal and transverse impedance in flat geometry, from which the wakefields can also be obtained. From the generalized impedances, by taking the proper limits, we obtain the normal longitudinal, dipole, and quad impedances in flat geometry. These equations can be applied to any surface impedance, such as the known dc, ac, and anomalous skin models of wall resistance, a model of wall roughness, or one for a pipe with small, periodic corrugations. We show that, for the particular case of dc wall resistance, the longitudinal impedance obtained here agrees with a known result in the literature, a result that was derived from a very general formula by Henke and Napoly. As concrete example, we apply our results to representative beam and machine parameters in the undulator region of LCLS-II and estimate the impact of the transverse wakes on the machine performance.

  10. Scaling of the Longitudinal Electric Field and Transformer Ratio in a Nonlinear Plasma Wakefield Accelerator

    SciTech Connect (OSTI)

    Blumenfeld, I.; /SLAC; Clayton, C.E.; /UCLA; Decker, F.J.; Hogan, M.J.; /SLAC; Huang, C.; /UCLA; Ischebeck, R.; Iverson, R.H.; /SLAC; Joshi, C.; /UCLA; Katsouleas, T.; /Southern California U.; Kirby, N.; /SLAC; Lu, W.; Marsh, K.A.; Mori, W.B.; /UCLA; Muggli, P.; Oz, E.; /Southern California U.; Siemann, R.H.; Walz, D.R.; /SLAC; Zhou, M.; /UCLA

    2012-06-12T23:59:59.000Z

    The scaling of the two important figures of merit, the transformer ratio T and the longitudinal electric field E{sub z}, with the peak drive-bunch current I{sub p}, in a nonlinear plasma wakefield accelerator is presented for the first time. The longitudinal field scales as I{sub P}{sup 0.623{+-}0.007}, in good agreement with nonlinear wakefield theory ({approx}I{sub P}{sup 0.5}), while the unloaded transformer ratio is shown to be greater than unity and scales weakly with the bunch current. The effect of bunch head erosion on both parameters is also discussed.

  11. Measurement of wakefield suppression in a detuned x-band accelerator structure

    SciTech Connect (OSTI)

    Adolphsen, C.; Bane, K.; Higo, T.; Kubo, K.; Miller, R.; Ruth, R.; Thompson, K.; Wang, J.

    1994-08-01T23:59:59.000Z

    Research is underway at SLAC to develop accelerator structures for a next generation linear collider. A full-scale prototype X-band structure has been built in which the dipole mode frequencies were detuned to suppress the long-range transverse wakefield by about two orders of magnitude. To verify that the detuning works as expected, a facility to measure the long-range wakefield, called the Accelerator Structure SETup, or ASSET, was constructed in the SLAC Linear Collider (SLC). This paper presents the results from the measurement of the prototype X-band structure with this facility.

  12. The development of a high-throughput gradient array apparatus for the study of porous polymer networks.

    SciTech Connect (OSTI)

    Majumdar, Partha (North Dakota State University, Fargo, ND); Lee, Elizabeth (North Dakota State University, Fargo, ND); Chisholm, Bret J. (North Dakota State University, Fargo, ND); Dirk, Shawn M.; Weisz, Michael (North Dakota State University, Fargo, ND); Bahr, James (North Dakota State University, Fargo, ND); Schiele, Kris (North Dakota State University, Fargo, ND)

    2010-01-01T23:59:59.000Z

    A gradient array apparatus was constructed for the study of porous polymers produced using the process of chemically-induced phase separation (CIPS). The apparatus consisted of a 60 element, two-dimensional array in which a temperature gradient was placed in the y-direction and composition was varied in the x-direction. The apparatus allowed for changes in opacity of blends to be monitored as a function of temperature and cure time by taking images of the array with time. The apparatus was validated by dispense a single blend composition into all 60 wells of the array and curing them for 24 hours and doing the experiment in triplicate. Variations in micron scale phase separation were readily observed as a function of both curing time and temperature and there was very good well-to-well consistency as well as trial-to-trial consistency. Poragen of samples varying with respect to cure temperature was removed and SEM images were obtained. The results obtained showed that cure temperature had a dramatic affect on sample morphology, and combining data obtained from visual observations made during the curing process with SEM data can enable a much better understanding of the CIPS process and provide predictive capability through the relatively facile generation of composition-process-morphology relationships. Data quality could be greatly enhanced by making further improvements in the apparatus. The primary improvements contemplated include the use of a more uniform light source, an optical table, and a CCD camera with data analysis software. These improvements would enable quantification of the amount of scattered light generated from individual elements as a function of cure time. In addition to the gradient array development, porous composites were produced by incorporating metal particles into a blend of poragen, epoxy resin, and crosslinker. The variables involved in the experiment were metal particle composition, primary metal particle size, metal concentration, and poragen composition. A total of 16 different porous composites were produced and characterized using SEM. In general, the results showed that pore morphology and the distribution of metal particles was dependent on multiple factors. For example, the use of silver nanoparticles did not significantly affect pore morphology for composites derived from decanol as the poragen, but exceptionally large pores were obtained with the use of decane as the poragen. With regard to the effect of metal particle size, silver nanoparticles were essentially exclusively dispered in the polymer matrix while silver microparticles were found in pores. For nickel particles, both nanoparticles and microparticles were largely dispersed in the polymer matrix and not in the pores.

  13. Introduction Conjugate Gradient Method

    E-Print Network [OSTI]

    Vuik, Kees

    Introduction Conjugate Gradient Method Deflation Domain Decomposition Research Master Thesis Presentation #12;Introduction Conjugate Gradient Method Deflation Domain Decomposition Research Plaxis Finite Kaliszka Master Thesis Literature Study Presentation #12;Introduction Conjugate Gradient Method Deflation

  14. Wakefield induced Losses in the Manual Valves of the TESLA Cryomodule

    E-Print Network [OSTI]

    1 Wakefield induced Losses in the Manual Valves of the TESLA Cryomodule M.Dohlus,H.-P.Wedekind,K.Zapfe DeutschesElektronenSynchrotron Notkestr.85,D-22603Hamburg,Germany Abstract The beam pipe of the TESLA valves with spring type rf-shield which are presently used in the linac of the TESLA Test Facility

  15. LuaAV: Extensibility and Heterogeneity for Audiovisual Graham WAKEFIELD and Wesley SMITH and Charles ROBERTS

    E-Print Network [OSTI]

    California at Santa Barbara, University of

    LuaAV: Extensibility and Heterogeneity for Audiovisual Computing Graham WAKEFIELD and Wesley SMITH and Charles ROBERTS Media Arts and Technology, University of California Santa Barbara Santa Barbara, CA 93110 providing the flexibility and temporal accuracy demanded by interactive audio-visual media. Code generation

  16. Extremely short relativistic-electron-bunch generation in the laser wakefield via novel bunch injection scheme

    E-Print Network [OSTI]

    Strathclyde, University of

    Extremely short relativistic-electron-bunch generation in the laser wakefield via novel bunch accelerator (LWFA) a short in- tense laser pulse, with a duration on the order of a plasma wave period July 2004; published 6 December 2004) Recently a new electron-bunch injection scheme for the laser

  17. EXPERIMENTAL DEMONSTRATION OF WAKEFIELD EFFECTS IN A 250 GHZ PLANAR DIAMOND ACCELERATING STRUCTURE*

    E-Print Network [OSTI]

    Brookhaven National Laboratory

    of a rectangular waveguide loaded with polycrystalline CVD diamond plates as an accelerating structure. It should polycrystalline diamond plates loaded in a 6 cm long waveguide (Fig. 2). The beam gap was 200 microns (Fig. TM11EXPERIMENTAL DEMONSTRATION OF WAKEFIELD EFFECTS IN A 250 GHZ PLANAR DIAMOND ACCELERATING STRUCTURE

  18. Visual Exploration of Turbulent Combustion and Laser-Wakefield Accelerator Simulations

    E-Print Network [OSTI]

    hydrogen flames under different levels of turbulence ­ Lean combustion reduces emissions Important hydrogen flames] #12;Visual Exploration of Turbulent Combustion and Laser-Wakefield Accelerator Simulations 12 Tracking Graph Extraction Pipeline 1. Concatenate to obtain 4D mesh 2. Extract isotherm in 4D 3

  19. An evaluation of the TSE MR sequence for time efficient data acquisition in polymer gel dosimetry of applications involving high doses and steep dose gradients

    SciTech Connect (OSTI)

    Baras, P.; Seimenis, I.; Sandilos, P.; Vlahos, L.; Bieganski, T.; Georgiou, E.; Pantelis, E.; Papagiannis, P.; Sakelliou, L. [Philips Hellas Medical Systems, 44 Kifissias Ave., Maroussi 151 25, Athens (Greece); Department of Radiology, Medical School, University of Athens, Areteion Hospital, 76 Vas. Sofias Ave., 115 28 Athens (Greece) and Medical Physics Department, Hygeia Hospital, Kiffisias Avenue, 24 Erythrou Stavrou, Marousi, 151 23, Athens (Greece); Department of Radiology, Mother's Memorial Hospital, Rzgowska 281/289, 93-388, Lodz (Poland); Medical Physics Department, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece); Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece)

    2005-11-15T23:59:59.000Z

    The use of magnetic resonance imaging as a readout method for polymer gel dosimetry commonly involves long imaging sessions, particularly when high spatial resolution is required in all three dimensions, for the investigation of dose distributions with steep dose gradients and stringent dose delivery specifications. In this work, a volume selective turbo spin echo (TSE) pulse sequence is compared to the established Carr-Purcell-Meiboom-Gill (CPMG) multiecho acquisition with regard to providing accurate dosimetric results in significantly reduced imaging times. Polyethylene glycol diacrylate based (PABIG) gels were irradiated and subsequently scanned to obtain R2 relaxation rate measurements, using a CPMG multiecho sequence and a dual echo TSE utilizing an acceleration (turbo) factor of 64. R2 values, plotted against corresponding Monte Carlo dose calculations, provided calibration data of PABIG gels dose response over a wide dose range. A linear R2 versus dose relationship was demonstrated for both sequences with TSE results presenting reduced dose sensitivity. Although TSE data were found to deviate from linearity at lower doses compared to CPMG data, a relatively wide dynamic dose range of response extending up to approximately 100 Gy was observed for both sequences. The TSE and CPMG sequences were evaluated with a brachytherapy irradiation using a high dose rate {sup 192}Ir source and a gamma knife stereotactic radiosurgery irradiation with a single 4 mm collimator helmet shot. Dosimetric results obtained with the TSE and CPMG are shown to compare equally well with the expected dose distributions for these irradiations. The 60-fold scan time reduction achieved with TSE implies that this sequence could prove to be a useful tool for the introduction of polymer gel dosimetry in clinical radiation therapy applications involving high doses and steep dose gradients.

  20. Wakefield Calculations for the LCLS in Multbunch Operation

    SciTech Connect (OSTI)

    Bane, K; /SLAC

    2011-10-17T23:59:59.000Z

    Normally the Linac Coherent Light Source (LCLS) operates in single-bunch mode, sending a bunch of up to 250 pC charge at 120 Hz through the linac and the undulator, and the resulting FEL radiation into one of the experimental hutches. With two bunches per rf pulse, each pulse could feed either two experiments or one experiment in a pump-probe type configuration. Two-bunch FEL operation has already been briefly tested at the LCLS, and works reasonably well, although not yet routinely. In this report we study the longitudinal and transverse long-range (bunch-to-bunch) wakefields of the linacs and their effects on LCLS performance in two-bunch mode, which is initially the most likely scenario. The longitudinal wake changes the average energy at the second bunch, and the transverse wake misaligns the second bunch (in transverse phase space) in the presence of e.g. transverse injection jitter or quad misalignments. Finally, we extend the study to consider the LCLS with trains of up to 20 bunches per rf pulse. In the LCLS the bunch is created in an rf gun, and then passes in sequence through Linac 0, Linac 1, Linac X, Bunch Compressor 1 (BC 1), Linac 2, BC 2, Linac 3, and finally the undulator. In the process the bunch energy reaches 13.5 GeV and peak current 3 kA. In Table 1 we present some machine and beam parameters in three of the linacs that we will use in the calculations: initial beam energy E{sub 0}, total accelerator length L, average beta function {beta}{sub y}, bunch peak current I, and rf phase (with respect to crest) {phi}; the final energy of a linac equals E{sub 0} of the following linac, and in Linac 3 is E{sub f} = 13.5 GeV. (The X-band linac, with L = 60 cm, has wake effects that are small compared to the other linacs, and will not be discussed.) In this report we limit our study to trains of equally populated, equally spaced bunches with a total length of less than 100 ns. The charge of each bunch is eN{sub b} = 250 pC.

  1. Injection and acceleration of electron bunch in a plasma wakefield produced by a chirped laser pulse

    SciTech Connect (OSTI)

    Afhami, Saeedeh; Eslami, Esmaeil, E-mail: eeslami@iust.ac.ir [Department of Physics, Iran University of Science and Technology (IUST), Narmak, Tehran 16846-13114 (Iran, Islamic Republic of)

    2014-06-15T23:59:59.000Z

    An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can trap and accelerate charged particles up to GeV. One-dimensional analysis of electron injection, trapping, and acceleration by different chirped pulses propagating in plasma is investigated numerically. In this paper, we inject electron bunches in front of the chirped pulses. It is indicated that periodical chirped laser pulse can trap electrons earlier than other pulses. It is shown that periodical chirped laser pulses lead to decrease the minimum momentum necessary to trap the electrons. This is due to the fact that periodical chirped laser pulses are globally much efficient than nonchirped pulses in the wakefield generation. It is found that chirped laser pulses could lead to much larger electron energy than that of nonchirped pulses. Relative energy spread has a lower value in the case of periodical chirped laser pulses.

  2. Emittance and Current of Electrons Trapped in a Plasma Wakefield Accelerator

    SciTech Connect (OSTI)

    Kirby, N; Blumenfeld, I; Clayton, C.E.; Decker, F.J.; Hogan, M.J.; Huang, C.; Ischebeck, R.; Iverson, R.H.; Joshi, C.; Katsouleas, T.; Lu, W.; Marsh, K.A.; Mori, W.B.; Muggli, P; Oz, E.; Siemann, R.H.; Walz, D.R.; Zhou, M.; /SLAC /UCLA /USC

    2008-09-24T23:59:59.000Z

    In recent experiments plasma electrons became trapped in a plasma wakefield accelerator (PWFA). The transverse size of these trapped electrons on a downstream diagnostic yields an upper limit measurement of transverse normalized emittance divided by peak current, {var_epsilon}{sub N,x}/I. The lowest upper limit for {var_epsilon}{sub N,x}/I measured in the experiment is 1.3 {center_dot} 10{sup -10} m/A.

  3. Plasma Wakefield Acceleration and FACET - Facilities for Accelerator Science and Experimental Test Beams at SLAC

    ScienceCinema (OSTI)

    Andrei Seryi

    2010-01-08T23:59:59.000Z

    Plasma wakefield acceleration is one of the most promising approaches to advancing accelerator technology. This approach offers a potential 1,000-fold or more increase in acceleration over a given distance, compared to existing accelerators.  FACET, enabled by the Recovery Act funds, will study plasma acceleration, using short, intense pulses of electrons and positrons. In this lecture, the physics of plasma acceleration and features of FACET will be presented.  

  4. Self-guided wakefield experiments driven by petawatt class ultra-short laser pulses

    E-Print Network [OSTI]

    Mangles, S P D; Bellei, C; Dangor, A E; Kamperidis, C; Kneip, S; Nagel, S R; Willingale, L; Najmudin, Z

    2007-01-01T23:59:59.000Z

    We investigate the extension of self-injecting laser wakefield experiments to the regime that will be accessible with the next generation of petawatt class ultra-short pulse laser systems. Using linear scalings, current experimental trends and numerical simulations we determine the optimal laser and target parameters, i.e. focusing geometry, plasma density and target length, that are required to increase the electron beam energy (to > 1 GeV) without the use of external guiding structures.

  5. X-ray phase contrast imaging of biological specimens with femtosecond pulses of betatron radiation from a compact laser plasma wakefield accelerator

    SciTech Connect (OSTI)

    Kneip, S. [Blackett Laboratory, Imperial College London, London SW7 2AZ (United Kingdom); Center for Ultrafast Optical Science, University of Michigan, Ann Arbor 48109 (United States); McGuffey, C.; Dollar, F.; Chvykov, V.; Kalintchenko, G.; Krushelnick, K.; Maksimchuk, A.; Mangles, S. P. D.; Matsuoka, T.; Schumaker, W.; Thomas, A. G. R.; Yanovsky, V. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor 48109 (United States); Bloom, M. S.; Najmudin, Z.; Palmer, C. A. J.; Schreiber, J. [Blackett Laboratory, Imperial College London, London SW7 2AZ (United Kingdom)

    2011-08-29T23:59:59.000Z

    We show that x-rays from a recently demonstrated table top source of bright, ultrafast, coherent synchrotron radiation [Kneip et al., Nat. Phys. 6, 980 (2010)] can be applied to phase contrast imaging of biological specimens. Our scheme is based on focusing a high power short pulse laser in a tenuous gas jet, setting up a plasma wakefield accelerator that accelerates and wiggles electrons analogously to a conventional synchrotron, but on the centimeter rather than tens of meter scale. We use the scheme to record absorption and phase contrast images of a tetra fish, damselfly and yellow jacket, in particular highlighting the contrast enhancement achievable with the simple propagation technique of phase contrast imaging. Coherence and ultrafast pulse duration will allow for the study of various aspects of biomechanics.

  6. Converting Level Set Gradients to Shape Gradients

    E-Print Network [OSTI]

    Radke, Rich

    distance function (SDF) associated with a shape, and differentiate these energies with respect to the SDF to the SDF. We discuss some problematic gradients from the literature, show how they can easily be fixed function (SDF) of , i.e. the function that associates any point x with the signed distance (x) = ±d

  7. Exploiting Matrix Symmetry to Improve FPGA-Accelerated Conjugate Gradient

    E-Print Network [OSTI]

    Bakos, Jason D.

    the Conjugate Gradient (CG) method using an FPGA co-processor. As in previous approaches, our coExploiting Matrix Symmetry to Improve FPGA- Accelerated Conjugate Gradient Jason D. Bakos, Krishna, high- performance computing, sparse matrix vector multiply, conjugate gradient I. INTRODUCTION Linear

  8. UNDULATOR-BASED LASER WAKEFIELD ACCELERATOR ELECTRON BEAM DIAGNOSTIC

    E-Print Network [OSTI]

    Bakeman, M.S.

    2010-01-01T23:59:59.000Z

    ultra-short, high-peak- current, electron beams are ideal for driving a compact XUV free electron laser (

  9. Tomorrow's cities -the lamp-posts watching every move1 by Jane Wakefield for BBC News2

    E-Print Network [OSTI]

    South Bohemia, University of

    the city council is looking to upgrade its23 streetlights to more energy-efficient LED lights - likely in the area. The pilot project will be integrated with the newly built City Operations Centre, where CCTVTomorrow's cities - the lamp-posts watching every move1 by Jane Wakefield for BBC News2 3 Imagine

  10. Detailed dynamics of electron beams self-trapped and accelerated in a self-modulated laser wakefield

    E-Print Network [OSTI]

    Umstadter, Donald

    . These features are explained by analysis and test particle simulations of electron dynamics during acceleration wave,1 such as the plasma wakefield accel- erator, the plasma beat-wave accelerator, the Laser Wake the linear dephasing limit, and explained it, using Particle-In-Cell PIC simulations, as a result

  11. Numerical modeling of multi-GeV laser wakefield electron acceleration inside a dielectric capillary tube

    SciTech Connect (OSTI)

    Paradkar, B. S.; Cros, B.; Maynard, G. [Laboratoire de Physique des Gaz et des Plasmas, University Paris Sud 11-CNRS, Orsay (France)] [Laboratoire de Physique des Gaz et des Plasmas, University Paris Sud 11-CNRS, Orsay (France); Mora, P. [Centre de Physique Theorique, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France)] [Centre de Physique Theorique, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France)

    2013-08-15T23:59:59.000Z

    Numerical modeling of laser wakefield electron acceleration inside a gas filled dielectric capillary tube is presented. Guiding of a short pulse laser inside a dielectric capillary tube over a long distance (?1 m) and acceleration of an externally injected electron bunch to ultra-relativistic energies (?5-10 GeV) are demonstrated in the quasi-linear regime of laser wakefield acceleration. Two dimensional axisymmetric simulations were performed with the code WAKE-EP (Extended Performances), which allows computationally efficient simulations of such long scale plasma. The code is an upgrade of the quasi-static particle code, WAKE [P. Mora and T. M. Antonsen, Jr., Phys. Plasmas 4, 217 (1997)], to simulate the acceleration of an externally injected electron bunch (including beam loading effect) and propagation of the laser beam inside a dielectric capillary. The influence of the transverse electric field of the plasma wake on the radial loss of the accelerated electrons to the dielectric wall is investigated. The stable acceleration of electrons to multi-GeV energy with a non-resonant laser pulse with a large spot-size is demonstrated.

  12. Shape reconstruction from gradient data

    SciTech Connect (OSTI)

    Ettl, Svenja; Kaminski, Juergen; Knauer, Markus C.; Haeusler, Gerd

    2008-04-20T23:59:59.000Z

    We present a generalized method for reconstructing the shape of an object from measured gradient data. A certain class of optical sensors does not measure the shape of an object but rather its local slope. These sensors display several advantages, including high information efficiency, sensitivity, and robustness. For many applications, however, it is necessary to acquire the shape, which must be calculated from the slopes by numerical integration. Existing integration techniques show drawbacks that render them unusable in many cases. Our method is based on an approximation employing radial basis functions. It can be applied to irregularly sampled, noisy, and incomplete data, and it reconstructs surfaces both locally and globally with high accuracy.

  13. Conjugate Gradient Method Numerisches Rechnen

    E-Print Network [OSTI]

    Conjugate Gradient Method Numerisches Rechnen (für Informatiker) M. Grepl J. Berger & J.T. Frings Numerisches Rechnen #12;Conjugate Gradient Method The Quadratic Form Steepest Descent Conjugate Directions/Gradients IGPM, RWTH Aachen Numerisches Rechnen #12;Conjugate Gradient Method The Quadratic Form Steepest Descent

  14. Enhanced betatron X-rays from axially modulated plasma wakefields

    E-Print Network [OSTI]

    Palastro, J P; Gordon, D

    2015-01-01T23:59:59.000Z

    In the cavitation regime of plasma-based accelerators, a population of high-energy electrons tailing the driver can undergo betatron motion. The motion results in X-ray emission, but the brilliance and photon energy are limited by the electrons' initial transverse coordinate. To overcome this, we exploit parametrically unstable betatron motion in a cavitated, axially modulated plasma. Theory and simulations are presented showing that the unstable oscillations increase both the total X-ray energy and average photon energy.

  15. Hot Pot Contoured Temperature Gradient Map

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

    Lane, Michael

    Temperature gradient contours derived from Oski temperature gradient hole program and from earlier published information.

  16. Hot Pot Contoured Temperature Gradient Map

    SciTech Connect (OSTI)

    Lane, Michael

    2013-06-28T23:59:59.000Z

    Temperature gradient contours derived from Oski temperature gradient hole program and from earlier published information.

  17. An ultrashort pulse ultra-violet radiation undulator source driven by a laser plasma wakefield accelerator

    SciTech Connect (OSTI)

    Anania, M. P. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); INFN, Laboratori Nazionali di Frascati, I-00044 Frascati (Italy); Brunetti, E.; Wiggins, S. M.; Grant, D. W.; Welsh, G. H.; Issac, R. C.; Cipiccia, S.; Shanks, R. P.; Manahan, G. G.; Aniculaesei, C.; Jaroszynski, D. A., E-mail: d.a.jaroszynski@strath.ac.uk [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Geer, S. B. van der; Loos, M. J. de [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands); Poole, M. W.; Shepherd, B. J. A.; Clarke, J. A. [ASTeC, STFC, Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Gillespie, W. A. [SUPA, School of Engineering, Physics and Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom); MacLeod, A. M. [School of Computing and Creative Technologies, University of Abertay Dundee, Dundee DD1 1HG (United Kingdom)

    2014-06-30T23:59:59.000Z

    Narrow band undulator radiation tuneable over the wavelength range of 150–260?nm has been produced by short electron bunches from a 2?mm long laser plasma wakefield accelerator based on a 20?TW femtosecond laser system. The number of photons measured is up to 9?×?10{sup 6} per shot for a 100 period undulator, with a mean peak brilliance of 1?×?10{sup 18} photons/s/mrad{sup 2}/mm{sup 2}/0.1% bandwidth. Simulations estimate that the driving electron bunch r.m.s. duration is as short as 3 fs when the electron beam has energy of 120–130?MeV with the radiation pulse duration in the range of 50–100 fs.

  18. Measurements of the critical power for self-injection of electrons in a laser wakefield accelerator

    SciTech Connect (OSTI)

    Froula, D H; Clayton, C E; Doppner, T; Fonseca, R A; Marsh, K A; Barty, C J; Divol, L; Glenzer, S H; Joshi, C; Lu, W; Martins, S F; Michel, P; Mori, W; Palastro, J P; Pollock, B B; Pak, A; Ralph, J E; Ross, J S; Siders, C; Silva, L O; Wang, T

    2009-06-02T23:59:59.000Z

    A laser wakefield acceleration study has been performed in the matched, self-guided, blow-out regime where a 10 J, 60 fs laser produced 720 {+-} 50 MeV quasi-monoenergetic electrons with a divergence of {Delta}{theta} = 2.85 {+-} 0.15 mRad. While maintaining a nearly constant plasma density (3 x 10{sup 18} cm{sup -3}), a linear electron energy gain was measured from 100 MeV to 700 MeV when the plasma length was scaled from 3 mm to 8 mm. Absolute charge measurements indicate that self-injection occurs when P/P{sub cr} > 4 and saturates around 100 pC for P/P{sub cr} > 12. The results are compared with both analytical scalings and full 3D particle-in-cell simulations.

  19. Optimization of Drive-Bunch Current Profile for Enhanced Transformer Ratio in Beam-Driven Acceleration Techniques

    SciTech Connect (OSTI)

    Lemery, F.; Mihalcea, D.; Prokop, C.R.; /Northern Illinois U.; Piot, P.; /Northern Illinois U. /Fermilab

    2012-07-08T23:59:59.000Z

    In recent years, wakefield acceleration has gained attention due to its high acceleration gradients and cost effectiveness. In beam-driven wakefield acceleration, a critical parameter to optimize is the transformer ratio. It has been shown that current shaping of electron beams allows for enhanced (> 2) transformer ratios. In this paper we present the optimization of the pulse shape of the drive bunch for dielectric-wakefield acceleration.

  20. Laser Wakefield Acceleration: Structural and Dynamic Studies. Final Technical Report ER40954

    SciTech Connect (OSTI)

    Downer, Michael C.

    2014-12-19T23:59:59.000Z

    Particle accelerators enable scientists to study the fundamental structure of the universe, but have become the largest and most expensive of scientific instruments. In this project, we advanced the science and technology of laser-plasma accelerators, which are thousands of times smaller and less expensive than their conventional counterparts. In a laser-plasma accelerator, a powerful laser pulse exerts light pressure on an ionized gas, or plasma, thereby driving an electron density wave, which resembles the wake behind a boat. Electrostatic fields within this plasma wake reach tens of billions of volts per meter, fields far stronger than ordinary non-plasma matter (such as the matter that a conventional accelerator is made of) can withstand. Under the right conditions, stray electrons from the surrounding plasma become trapped within these “wake-fields”, surf them, and acquire energy much faster than is possible in a conventional accelerator. Laser-plasma accelerators thus might herald a new generation of compact, low-cost accelerators for future particle physics, x-ray and medical research. In this project, we made two major advances in the science of laser-plasma accelerators. The first of these was to accelerate electrons beyond 1 gigaelectronvolt (1 GeV) for the first time. In experimental results reported in Nature Communications in 2013, about 1 billion electrons were captured from a tenuous plasma (about 1/100 of atmosphere density) and accelerated to 2 GeV within about one inch, while maintaining less than 5% energy spread, and spreading out less than ½ milliradian (i.e. ½ millimeter per meter of travel). Low energy spread and high beam collimation are important for applications of accelerators as coherent x-ray sources or particle colliders. This advance was made possible by exploiting unique properties of the Texas Petawatt Laser, a powerful laser at the University of Texas at Austin that produces pulses of 150 femtoseconds (1 femtosecond is 10-15 seconds) in duration and 150 Joules in energy (equivalent to the muzzle energy of a small pistol bullet). This duration was well matched to the natural electron density oscillation period of plasma of 1/100 atmospheric density, enabling efficient excitation of a plasma wake, while this energy was sufficient to drive a high-amplitude wake of the right shape to produce an energetic, collimated electron beam. Continuing research is aimed at increasing electron energy even further, increasing the number of electrons captured and accelerated, and developing applications of the compact, multi-GeV accelerator as a coherent, hard x-ray source for materials science, biomedical imaging and homeland security applications. The second major advance under this project was to develop new methods of visualizing the laser-driven plasma wake structures that underlie laser-plasma accelerators. Visualizing these structures is essential to understanding, optimizing and scaling laser-plasma accelerators. Yet prior to work under this project, computer simulations based on estimated initial conditions were the sole source of detailed knowledge of the complex, evolving internal structure of laser-driven plasma wakes. In this project we developed and demonstrated a suite of optical visualization methods based on well-known methods such as holography, streak cameras, and coherence tomography, but adapted to the ultrafast, light-speed, microscopic world of laser-driven plasma wakes. Our methods output images of laser-driven plasma structures in a single laser shot. We first reported snapshots of low-amplitude laser wakes in Nature Physics in 2006. We subsequently reported images of high-amplitude laser-driven plasma “bubbles”, which are important for producing electron beams with low energy spread, in Physical Review Letters in 2010. More recently, we have figured out how to image laser-driven structures that change shape while propagating in a single laser shot. The latter techniques, which use the methods of computerized tomography, were demonstrated on test objects – e.g. laser-d

  1. Conjugate Gradient Methods in Confirmatory Factor Analysis

    E-Print Network [OSTI]

    Jamshardian, Mortaza; Jennrich, Robert

    1993-01-01T23:59:59.000Z

    R. I. (1988), "Conjugate Gradient Methods in Confirmatoryapply generalized conjugate gradient methods in an attemptby used. The conjugate gradient method, which is simple and

  2. Conjugate Gradient Acceleration of the EM Algorithm

    E-Print Network [OSTI]

    Mortaza Jamshidian; Robert Jennrich

    2011-01-01T23:59:59.000Z

    R. I. (1988), "Conjugate Gradient Methods in Confirmatoryapply generalized conjugate gradient methods in an attemptby used. The conjugate gradient method, which is simple and

  3. VOLUME 82, NUMBER 6 P H Y S I C A L R E V I E W L E T T E R S 8 FEBRUARY 1999 Multimode Analysis of the Hollow Plasma Channel Wakefield Accelerator

    E-Print Network [OSTI]

    Wurtele, Jonathan

    ]. In conventional accelerators, the size of these accel- erating fields is limited by breakdown. For two decades wakefield accelerator, the plasma wave is excited by the self-fields of an intense relativistic particle- neous plasma. These properties make it well suited as a structure for both particle beam wakefield

  4. Fourier Accelerated Conjugate Gradient Lattice Gauge Fixing

    E-Print Network [OSTI]

    R. J. Hudspith

    2014-05-22T23:59:59.000Z

    We provide details of the first implementation of a non-linear conjugate gradient method for Landau and Coulomb gauge fixing with Fourier acceleration. We find clear improvement over the Fourier accelerated steepest descent method, with the average time taken for the algorithm to converge to a fixed, high accuracy, being reduced by a factor of 2 to 4.

  5. Short wavelength ion temperature gradient turbulence

    SciTech Connect (OSTI)

    Chowdhury, J.; Ganesh, R. [Institute for Plasma Research, Bhat, Gandhinagar (India); Brunner, S.; Lapillonne, X.; Villard, L. [CRPP, Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland); Jenko, F. [Max-Planck-Institut fuer Plasmaphysik Boltzmannstr. 2, D-85748 Garching (Germany)

    2012-10-15T23:59:59.000Z

    The ion temperature gradient (ITG) mode in the high wavenumber regime (k{sub y}{rho}{sub s}>1), referred to as short wavelength ion temperature gradient mode (SWITG) is studied using the nonlinear gyrokinetic electromagnetic code GENE. It is shown that, although the SWITG mode may be linearly more unstable than the standard long wavelength (k{sub y}{rho}{sub s}<1) ITG mode, nonlinearly its contribution to the total thermal ion heat transport is found to be low. We interpret this as resulting from an increased zonal flow shearing effect on the SWITG mode suppression.

  6. Experimental determination of the radial dose distribution in high gradient regions around {sup 192}Ir wires: Comparison of electron paramagnetic resonance imaging, films, and Monte Carlo simulations

    SciTech Connect (OSTI)

    Kolbun, N.; Leveque, Ph.; Abboud, F.; Bol, A.; Vynckier, S.; Gallez, B. [Biomedical Magnetic Resonance Unit, Louvain Drug Research Institute, Universite catholique de Louvain, Avenue Mounier 73.40, B-1200 Brussels (Belgium); Molecular Imaging and Experimental Radiotherapy Unit, Institute of Experimental and Clinical Research, Universite catholique de Louvain, Avenue Hippocrate 55, B-1200 Brussels (Belgium); Biomedical Magnetic Resonance Unit, Louvain Drug Research Institute, Universite catholique de Louvain, Avenue Mounier 73.40, B-1200 Brussels (Belgium)

    2010-10-15T23:59:59.000Z

    Purpose: The experimental determination of doses at proximal distances from radioactive sources is difficult because of the steepness of the dose gradient. The goal of this study was to determine the relative radial dose distribution for a low dose rate {sup 192}Ir wire source using electron paramagnetic resonance imaging (EPRI) and to compare the results to those obtained using Gafchromic EBT film dosimetry and Monte Carlo (MC) simulations. Methods: Lithium formate and ammonium formate were chosen as the EPR dosimetric materials and were used to form cylindrical phantoms. The dose distribution of the stable radiation-induced free radicals in the lithium formate and ammonium formate phantoms was assessed by EPRI. EBT films were also inserted inside in ammonium formate phantoms for comparison. MC simulation was performed using the MCNP4C2 software code. Results: The radical signal in irradiated ammonium formate is contained in a single narrow EPR line, with an EPR peak-to-peak linewidth narrower than that of lithium formate ({approx}0.64 and 1.4 mT, respectively). The spatial resolution of EPR images was enhanced by a factor of 2.3 using ammonium formate compared to lithium formate because its linewidth is about 0.75 mT narrower than that of lithium formate. The EPRI results were consistent to within 1% with those of Gafchromic EBT films and MC simulations at distances from 1.0 to 2.9 mm. The radial dose values obtained by EPRI were about 4% lower at distances from 2.9 to 4.0 mm than those determined by MC simulation and EBT film dosimetry. Conclusions: Ammonium formate is a suitable material under certain conditions for use in brachytherapy dosimetry using EPRI. In this study, the authors demonstrated that the EPRI technique allows the estimation of the relative radial dose distribution at short distances for a {sup 192}Ir wire source.

  7. Energy in density gradient

    E-Print Network [OSTI]

    Vranjes, J

    2015-01-01T23:59:59.000Z

    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindric configuration. This is of practical importance for drift wave instability in various plasmas, and in particular in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit ...

  8. Some wakefield effects in the superconducting RF cavities of LCLS-II

    E-Print Network [OSTI]

    Bane, K; Yakovlev, V

    2014-01-01T23:59:59.000Z

    For LCLS-II we estimate the power of radiated wakefields generated in the SRF cavities (including the 3rd harmonic cavities) and in the end transitions. Much of this power will pass through and reflect in the strings of cryomodules that comprise linacs L1, L2, or L3. Presumably, some of it will be absorbed by the higher order mode (HOM) couplers, or by the absorbers at warmer temperatures situated between the cryomodules. We investigate where such power gets generated, but not where it ends up. As such the results can serve as a pessimistic calculation of the extra power that needs to be removed by the cryosystem. Finally, we also estimate---under the assumption that all the wake power ends up in the SRF walls---the wall heating and the extent of Cooper pair breaking in L3, where the bunch is most intense. Note that all calculations here are of single bunch effects; thus resonant interactions are not included.

  9. Application of High-performance Visual Analysis Methods to Laser Wakefield Particle Acceleration Data

    E-Print Network [OSTI]

    Rubel, Oliver

    2008-01-01T23:59:59.000Z

    index/query system for data extraction and subsetting. It implements the fastest-known bitmap compression

  10. Modelling Flow through Porous Media under Large Pressure Gradients

    E-Print Network [OSTI]

    Srinivasan, Shriram

    2013-11-01T23:59:59.000Z

    The most interesting and technologically important problems in the study of flow through porous media involve very high pressures and pressure gradients in the flow do- main such as enhanced oil recovery and carbon dioxide sequestration. The popular...

  11. alternating gradient synchrotron: Topics by E-print Network

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

    sources also have the advantage of a time structure with a high peak neutron flux. The basic requirement is for a... Bryant, P J 1995-01-01 36 Gradient House. Open...

  12. Rapid Migration of Radionuclides Leaked from High-Level Water Tanks; A Study of Salinity Gradients, Wetted Path Geometry and Water Vapor Transport

    SciTech Connect (OSTI)

    Anderson l. Ward; Glendon W. Gee; John S. Selker; Clay Cooper

    2002-04-24T23:59:59.000Z

    The basis of this study was the hypothesis that the physical and chemical properties of hypersaline tank waste could lead to wetting from instability and fingered flow following a tank leak. Thus, the goal of this project was to develop an understanding of the impacts of the properties of hypersaline fluids on transport through the unsaturated zone beneath Hanford's Tank Farms. There were three specific objectives (i) to develop an improved conceptualization of hypersaline fluid transport in laboratory (ii) to identify the degree to which field conditions mimic the flow processes observed in the laboratory and (iii) to provide a validation data set to establish the degree to which the conceptual models, embodied in a numerical simulator, could explain the observed field behavior. As hypothesized, high ionic strength solutions entering homogeneous pre-wetted porous media formed unstable wetting fronts atypical of low ionic strength infiltration. In the field, this mechanism could for ce flow in vertical flow paths, 5-15 cm in width, bypassing much of the media and leading to waste penetration to greater depths than would be predicted by current conceptual models. Preferential flow may lead to highly accelerated transport through large homogeneous units, and must be included in any conservative analysis of tank waste losses through coarse-textured units. However, numerical description of fingered flow using current techniques has been unreliable, thereby precluding tank-scale 3-D simulation of these processes. A new approach based on nonzero, hysteretic contract angles and fluid-dependent liquid entry has been developed for the continuum scale modeling of fingered flow. This approach has been coupled with and adaptive-grid finite-difference solver to permit the prediction of finger formation and persistence form sub centimeter scales to the filed scale using both scalar and vector processors. Although laboratory experiments demonstrated that elevated surface tens ion of imbibing solutions can enhance vertical fingered flow, this phenomenon was not observed in the field. Field tests showed that the fingered flow behavior was overwhelmed by the variability in texture resulting from differences in the depositional environment. Field plumes were characterized by lateral spreading with an average width to depth aspect ratio of 4. For both vertical fingers and lateral flow, the high ionic strength contributed to the vapor phase dilution of the waste, which increased waste volume and pushed the wetting from well beyond what would have occurred if the volume of material had remained unchanged from that initially released into the system. It was also observed that following significant vapor-phase dilution of this waste simulants that streams of colloids were ejected from the sediment surfaces. It was shown that due to the high-sodium content of the tank wastes the colloids were deflocculated below a critical salt concentration in Hanford sediments. Th e released colloids, which at the site would be expected to carry the bulk of the sorbed heavy metals and radioisotopes, were mobile though coarse Hanford sediments, but clogged finer layers. The developments resulting from this study are already being applied at Hanford in the nonisothermal prediction of the hypersaline, high pH waste migration in tank farms and in the development of inverse methods for history matching under DOE's Groundwater/Vadose Zone Integration Project at Hanford.

  13. Rapid Migration of Radionuclides Leaked from High-Level Water Tanks: A Study of Salinity Gradients, Wetted Path Geometry and Water Vapor Transport

    SciTech Connect (OSTI)

    Anderson L. Ward; Glendon W. Gee; John S. Selker; Caly Cooper

    2002-04-24T23:59:59.000Z

    The basis of this study was the hypothesis that the physical and chemical properties of hypersaline tank waste could lead to wetting from instability and fingered flow following a tank leak. Thus, the goal of this project was to develop an understanding of the impacts of the properties of hypersaline fluids on transport through the unsaturated zone beneath Hanford's Tank Farms. There were three specific objectives (i) to develop an improved conceptualization of hypersaline fluid transport in laboratory (ii) to identify the degree to which field conditions mimic the flow processes observed in the laboratory and (iii) to provide a validation data set to establish the degree to which the conceptual models, embodied in a numerical simulator, could explain the observed field behavior. As hypothesized, high ionic strength solutions entering homogeneous pre-wetted porous media formed unstable wetting fronts a typical of low ionic strength infiltration. In the field, this mechanism could force flow in vertical flow paths, 5-15 cm in width, bypassing much of the media and leading to waste penetration to greater depths than would be predicted by current conceptual models. Preferential flow may lead to highly accelerated transport through large homogeneous units, and must be included in any conservative analysis of tank waste losses through coarse-textured units. However, numerical description of fingered flow using current techniques has been unreliable, thereby precluding tank-scale 3-D simulation of these processes. A new approach based on nonzero, hysteretic contact angles and fluid-dependent liquid entry has been developed for the continuum scale modeling of fingered flow. This approach has been coupled with and adaptive-grid finite-difference solver to permit the prediction of finger formation and persistence form sub centimeter scales to the filed scale using both scalar and vector processors. Although laboratory experiments demonstrated that elevated surface tension of imbibing solutions can enhance vertical fingered flow, this phenomenon was not observed in the field. Field tests of showed that the fingered flow behavior was overwhelmed by the variability in texture resulting from differences in the depositional environment. Field plumes were characterized by lateral spreading with an average width to depth aspect ratio of 4. For both vertical fingers and lateral flow, the high ionic strength contributed to the vapor phase dilution of the waste, which increased waste volume and pushed the wetting from well beyond what would have occurred if the volume of material had remained unchanged from that initially released into the system. It was also observed that following significant vapor-phase dilution of the waste simulants that streams of colloids were ejected from the sediment surfaces. It was shown that due to the high-sodium content of the tank wastes the colloids were deflocculated below a critical salt concentration in Hanford sediment s. The released colloids, which at the site would be expected to carry the bulk of the sorbed heavy metals and radioisotopes, were mobile though coarse Hanford sediments, but clogged finer layers. The developments resulting from this study are already being applied at Hanford in the nonisothermal prediction of the hypersaline, high pH waste migration in tank farms and in the development of inverse methods for history matching under DOE's Groundwater/Vadose Zone Integration Project at Hanford.

  14. PNL-SA-22914 Presented at the 48th Meeting of the Mechanical Failures Prevention Group (MFPG 48) 19-21 April 1994 in Wakefield, MA

    E-Print Network [OSTI]

    -21 April 1994 in Wakefield, MA AN ARTIFICIAL NEURAL NETWORK SYSTEM FOR DIAGNOSING GAS TURBINE ENGINE FUEL until it produces an accurate diagnosis. For example, troubleshooting the AGT-1500 gas turbine engine Laboratory are developing a turbine engine diagnostic system for the M1A1 Abrams tank. This system employs

  15. Shielding effect and wakefield pattern of a moving test charge in a non-Maxwellian dusty plasma

    SciTech Connect (OSTI)

    Ali, S. [National Centre for Physics (NCP), Quaid-e-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan)] [National Centre for Physics (NCP), Quaid-e-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Khan, S. [National Centre for Physics (NCP), Quaid-e-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan) [National Centre for Physics (NCP), Quaid-e-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Department of Physics, Gomal University, Dera Ismail Khan 29050 (Pakistan)

    2013-07-15T23:59:59.000Z

    By using the Vlasov-Poisson equations, we calculate an expression for the electrostatic potential caused by a test charge in an unmagnetized non-Maxwellian dusty plasma, whose constituents are the superthermal hot-electrons, the mobile cold-electrons with a neutralizing background of cold ions, and charge fluctuating isolated dust grains. The superthermality effects due to hot electrons not only modify the dielectric constant of the electron-acoustic waves but also significantly affect the electrostatic potential. The latter can be decomposed into the Debye-Hückel and oscillatory wake potentials. Analytical and numerical results reveal that the Debye-Hückel and wakefield potentials converge to the Maxwellian case for large values of superthermality parameter. Furthermore, the plasma parameters play a vital role in the formation of shielding and wakefield pattern in a two-electron temperature plasma. The present results should be important for laboratory and space dusty plasmas, where hot-electrons can be assumed to follow the non-Maxwellian distribution function.

  16. Block-conjugate-gradient method

    SciTech Connect (OSTI)

    McCarthy, J.F. (Department of Physics, Indiana University, Bloomington, Indiana 47405 (US))

    1989-09-15T23:59:59.000Z

    It is shown that by using the block-conjugate-gradient method several, say {ital s}, columns of the inverse Kogut-Susskind fermion matrix can be found simultaneously, in less time than it would take to run the standard conjugate-gradient algorithm {ital s} times. The method improves in efficiency relative to the standard conjugate-gradient algorithm as the fermion mass is decreased and as the value of the coupling is pushed to its limit before the finite-size effects become important. Thus it is potentially useful for measuring propagators in large lattice-gauge-theory calculations of the particle spectrum.

  17. CONJUGATE GRADIENT WITH SUBSPACE OPTIMIZATION 1 ...

    E-Print Network [OSTI]

    2011-12-25T23:59:59.000Z

    last update. Unlike some other conjugate gradient methods, our algorithm attains a theoretical ... The method of conjugate gradients (CG) was introduced by.

  18. Multi-GeV Energy Gain in a Plasma-Wakefield Accelerator M. J. Hogan,1

    E-Print Network [OSTI]

    Jalali. Bahram

    m at the entrance of a 10 cm long column of lithium vapor with density 2:8 1017 atoms=cm3. The electron bunch fully ionizes the lithium vapor to create a plasma and then expels the plasma electrons-plasma interactions have demonstrated focusing gradients of MT=m [1] while laser plasma interactions have demonstrated

  19. Plasma density from Cerenkov radiation, betatron oscillations, and beam steering in a plasma wakefield experiment at 30 GeV

    SciTech Connect (OSTI)

    Catravas, P.; Chattopadhyay, S.; Esarey, E.; Leemans, W.P.; Assmann, R.; Decker, F.-J.; Hogan, M.J.; Iverson, R.; Siemann, R.H.; Walz, D.; Whittum, D.; Blue, B.; Clayton, C.; Joshi, C.; Marsh, K.; Mori, W.B.; Wang, S.; Katsouleas, T.; Lee, S.; Muggli, P.

    2001-01-01T23:59:59.000Z

    A method for using Cerenkov radiation near atomic spectral lines to measure plasma source properties for plasma wakefield applications has been discussed and experimentally verified. Because the radiation co-propagates with the electron beam, the radiation samples the source properties exactly along the path of interest with perfect temporal synchronization. Observation wavelengths were chosen with respect to the atomic resonances of the plasma source, where the relative change in the index of refraction strongly affects the Cerenkov cone angle, and permits flexible diagnostic design. The Cerenkov spatial profiles were systematically studied for a Lithium heat pipe oven as a function of oven temperature and observation wavelength. Neutral densities and plasma densities were extracted from the measurements.

  20. Gas Exchange, Partial Pressure Gradients,

    E-Print Network [OSTI]

    Riba Sagarra, Jaume

    Gas Exchange, Partial Pressure Gradients, and the Oxygen Window Johnny E. Brian, Jr., M of circulatory and gas transport physiology, and the best place to start is with normobaric physiology. LIFE affect the precise gas exchange occurring in individual areas of the lungs and body tissues. To make

  1. Variable metric conjugate gradient methods

    SciTech Connect (OSTI)

    Barth, T.; Manteuffel, T.

    1994-07-01T23:59:59.000Z

    1.1 Motivation. In this paper we present a framework that includes many well known iterative methods for the solution of nonsymmetric linear systems of equations, Ax = b. Section 2 begins with a brief review of the conjugate gradient method. Next, we describe a broader class of methods, known as projection methods, to which the conjugate gradient (CG) method and most conjugate gradient-like methods belong. The concept of a method having either a fixed or a variable metric is introduced. Methods that have a metric are referred to as either fixed or variable metric methods. Some relationships between projection methods and fixed (variable) metric methods are discussed. The main emphasis of the remainder of this paper is on variable metric methods. In Section 3 we show how the biconjugate gradient (BCG), and the quasi-minimal residual (QMR) methods fit into this framework as variable metric methods. By modifying the underlying Lanczos biorthogonalization process used in the implementation of BCG and QMR, we obtain other variable metric methods. These, we refer to as generalizations of BCG and QMR.

  2. Geosynthetics in a salinity-gradient solar pond environment

    SciTech Connect (OSTI)

    Lichwardt, M.A.; Comer, A.I.

    1997-11-01T23:59:59.000Z

    This paper describes the latest in salinity-gradient solar pond lining systems. The high-temperature, high-salinity environment unique to a salinity-gradient solar pond resulted in failure of the geomembrane liner at the El Paso Solar Pond Test Facility after only eight years of operation. Research involved in pond reconstruction led to the selection of a lining system consisting of a flexible polypropylene (PP) geomembrane for the sidewalls and a specially formulated geosynthetic clay liner (GCL) on the bottom of the pond. The two liners have been installed and a comprehensive test program is being conducted to measure their performance. The environment encountered in a salinity-gradient solar pond will be discussed as well as material selection criteria and the design of the two liners. Preliminary results of the GCL performance monitoring will also be presented.

  3. Conjugate Gradient Algorithms Using Multiple Recursions

    E-Print Network [OSTI]

    of Colorado Much is already known about when a conjugate gradient method can be implemented with short and sufficient conditions on the iteration matrix A, in order for a conjugate gradient method to be implemented that the conjugate gradient method for unitary and shifted unitary matrices can be implemented using a single short

  4. An Introduction to the Conjugate Gradient Method

    E-Print Network [OSTI]

    Zhang, Yi

    An Introduction to the Conjugate Gradient Method Without the Agonizing Pain Edition 11 4 Jonathan Abstract The Conjugate Gradient Method is the most prominent iterative method for solving sparse systems, the Conjugate Gradient Method is a composite of simple, elegant ideas that almost anyone can understand

  5. An Introduction to the Conjugate Gradient Method

    E-Print Network [OSTI]

    Shewchuk, Jonathan

    An Introduction to the Conjugate Gradient Method Without the Agonizing Pain Edition 1 1 4 Jonathan Abstract The Conjugate Gradient Method is the most prominent iterative method for solving sparse systems, the Conjugate Gradient Method is a composite of simple, elegant ideas that almost anyone can understand

  6. Porting the NAS-NPB Conjugate Gradient

    E-Print Network [OSTI]

    Crawford, T. Daniel

    .kr/Center_for_Manycore_Programming/SNU_NPB_Suite.html NPB Benchmarks #12;! "A conjugate gradient method is used to compute an approximation to the smallestPorting the NAS-NPB Conjugate Gradient Benchmark to CUDA NVIDIA Corporation #12;Outline ! Overview coding methodologies and architectures. ! Suite of benchmarks: ! Integer Sort ! Conjugate Gradient ! CFD

  7. Accurate conjugate gradient methods for shifted systems

    E-Print Network [OSTI]

    Sleijpen, Gerard

    Accurate conjugate gradient methods for shifted systems by Jasper van den Eshof and Gerard L. G CONJUGATE GRADIENT METHODS FOR SHIFTED SYSTEMS JASPER VAN DEN ESHOF AND GERARD L. G. SLEIJPEN Abstract We present an efficient and accurate variant of the conjugate gradient method for solving families of shifted

  8. A parallel scaled conjugate-gradient

    E-Print Network [OSTI]

    Aykanat, Cevdet

    . The scaled conjugate- gradient method is a powerful technique for solving large sparse linear systems for form-factor computation. Key words: Gathering radiosity -- Scaled conjugate-gradient method -- Parallel, the Gauss--Jacobi (GJ) method is used in the solution phase. The scaled conjugate-gradient (SCG) method

  9. An Introduction to the Conjugate Gradient Method

    E-Print Network [OSTI]

    An Introduction to the Conjugate Gradient Method Without the Agonizing Pain Jonathan Richard 15213 Abstract The Conjugate Gradient Method is the most prominent iterative method for solving sparse the mumblings of their forebears. Nevertheless, the Conjugate Gradient Method is a composite of simple, elegant

  10. Accurate conjugate gradient methods for shifted systems

    E-Print Network [OSTI]

    Sleijpen, Gerard

    Accurate conjugate gradient methods for shifted systems by Jasper van den Eshof and Gerard L. G CONJUGATE GRADIENT METHODS FOR SHIFTED SYSTEMS JASPER VAN DEN ESHOF # AND GERARD L. G. SLEIJPEN # Abstract We present an e#cient and accurate variant of the conjugate gradient method for solving families

  11. Bayesian Policy Gradient and Actor-Critic Algorithms Bayesian Policy Gradient and Actor-Critic Algorithms

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Bayesian Policy Gradient and Actor-Critic Algorithms Bayesian Policy Gradient and Actor Yaakov Engel yakiengel@gmail.com Editor: Abstract Policy gradient methods are reinforcement learning algorithms that adapt a param- eterized policy by following a performance gradient estimate. Many

  12. Gradient Navigation Model for Pedestrian Dynamics

    E-Print Network [OSTI]

    Felix Dietrich; Gerta Köster

    2014-05-14T23:59:59.000Z

    We present a new microscopic ODE-based model for pedestrian dynamics: the Gradient Navigation Model. The model uses a superposition of gradients of distance functions to directly change the direction of the velocity vector. The velocity is then integrated to obtain the location. The approach differs fundamentally from force based models needing only three equations to derive the ODE system, as opposed to four in, e.g., the Social Force Model. Also, as a result, pedestrians are no longer subject to inertia. Several other advantages ensue: Model induced oscillations are avoided completely since no actual forces are present. The derivatives in the equations of motion are smooth and therefore allow the use of fast and accurate high order numerical integrators. At the same time, existence and uniqueness of the solution to the ODE system follow almost directly from the smoothness properties. In addition, we introduce a method to calibrate parameters by theoretical arguments based on empirically validated assumptions rather than by numerical tests. These parameters, combined with the accurate integration, yield simulation results with no collisions of pedestrians. Several empirically observed system phenomena emerge without the need to recalibrate the parameter set for each scenario: obstacle avoidance, lane formation, stop-and-go waves and congestion at bottlenecks. The density evolution in the latter is shown to be quantitatively close to controlled experiments. Likewise, we observe a dependence of the crowd velocity on the local density that compares well with benchmark fundamental diagrams.

  13. Pumpernickel Valley Geothermal Project Thermal Gradient Wells

    SciTech Connect (OSTI)

    Z. Adam Szybinski

    2006-01-01T23:59:59.000Z

    The Pumpernickel Valley geothermal project area is located near the eastern edge of the Sonoma Range and is positioned within the structurally complex Winnemucca fold and thrust belt of north-central Nevada. A series of approximately north-northeast-striking faults related to the Basin and Range tectonics are superimposed on the earlier structures within the project area, and are responsible for the final overall geometry and distribution of the pre-existing structural features on the property. Two of these faults, the Pumpernickel Valley fault and Edna Mountain fault, are range-bounding and display numerous characteristics typical of strike-slip fault systems. These characteristics, when combined with geophysical data from Shore (2005), indicate the presence of a pull-apart basin, formed within the releasing bend of the Pumpernickel Valley – Edna Mountain fault system. A substantial body of evidence exists, in the form of available geothermal, geological and geophysical information, to suggest that the property and the pull-apart basin host a structurally controlled, extensive geothermal field. The most evident manifestations of the geothermal activity in the valley are two areas with hot springs, seepages, and wet ground/vegetation anomalies near the Pumpernickel Valley fault, which indicate that the fault focuses the fluid up-flow. There has not been any geothermal production from the Pumpernickel Valley area, but it was the focus of a limited exploration effort by Magma Power Company. In 1974, the company drilled one exploration/temperature gradient borehole east of the Pumpernickel Valley fault and recorded a thermal gradient of 160oC/km. The 1982 temperature data from five unrelated mineral exploration holes to the north of the Magma well indicated geothermal gradients in a range from 66 to 249oC/km for wells west of the fault, and ~283oC/km in a well next to the fault. In 2005, Nevada Geothermal Power Company drilled four geothermal gradient wells, PVTG-1, -2, -3, and -4, and all four encountered geothermal fluids. The holes provided valuable water geochemistry, supporting the geothermometry results obtained from the hot springs and Magma well. The temperature data gathered from all the wells clearly indicates the presence of a major plume of thermal water centered on the Pumpernickel Valley fault, and suggests that the main plume is controlled, at least in part, by flow from this fault system. The temperature data also defines the geothermal resource with gradients >100oC/km, which covers an area a minimum of 8 km2. Structural blocks, down dropped with respect to the Pumpernickel Valley fault, may define an immediate reservoir. The geothermal system almost certainly continues beyond the recently drilled holes and might be open to the east and south, whereas the heat source responsible for the temperatures associated with this plume has not been intersected and must be at a depth greater than 920 meters (depth of the deepest well – Magma well). The geological and structural setting and other characteristics of the Pumpernickel Valley geothermal project area are markedly similar to the portions of the nearby Dixie Valley geothermal field. These similarities include, among others, the numerous, unexposed en echelon faults and large-scale pull-apart structure, which in Dixie Valley may host part of the geothermal field. The Pumpernickel Valley project area, for the majority of which Nevada Geothermal Power Company has geothermal rights, represents a geothermal site with a potential for the discovery of a relatively high temperature reservoir suitable for electric power production. Among locations not previously identified as having high geothermal potential, Pumpernickel Valley has been ranked as one of four sites with the highest potential for electrical power production in Nevada (Shevenell and Garside, 2003). Richards and Blackwell (2002) estimated the total heat loss and the preliminary production capacity for the entire Pumpernickel Valley geothermal system to be at 35MW. A more conservative estimate, for

  14. Gradient limits and SCRF performance.

    SciTech Connect (OSTI)

    Norem, J.; Pellin, M.

    2007-01-01T23:59:59.000Z

    Superconducting rf gradients are limited by a number of mechanisms, among them are field emission, multipactor, Lorentz detuning, global and local heating, quench fields, Q-Slope, assembly defects, and overall power use. We describe how each of these mechanisms interacts with the cavity fields and show how significant improvements may be possible assuming improvements in control over the cavity surface. New techniques such as Atomic Layer Deposition (ALD), the use of layered composites, Gas Cluster Ion Beam (GCIB) smoothing and Dry Ice Cleaning (DIC) have been proposed as ways to control the surface.

  15. Gradient Resources | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are8COaBulkTransmissionSitingProcess.pdfGetec AG Contracting JumpGove County, Kansas: EnergyGradient Resources Jump to:

  16. Preparation of Genomic DNA from Hawaiian Bobtail Squid (Euprymna scolopes) Tissue by Cesium Chloride Gradient

    E-Print Network [OSTI]

    Ruby, Edward G.

    by Cesium Chloride Gradient Centrifugation Patricia N. Lee1,2 , Margaret J. McFall-Ngai3 , Patrick Callaerts from adult bobtail squid (Euprymna scolopes) tissues by cesium chloride (CsCl) gradient centrifugation modifications of nucleic acids are inhibited by these contaminants. The method described here yields high

  17. Seasonal Changes in Bacterial and Archaeal Gene Expression Patterns across Salinity Gradients in the

    E-Print Network [OSTI]

    their metabolic activities, microbial populations mediate the impact of high gradient regions on ecologicalSeasonal Changes in Bacterial and Archaeal Gene Expression Patterns across Salinity Gradients in nitrogen and carbon metabolism in the CRCM. Initial experiments with the environmental microarrays were

  18. Gradient instabilities of electromagnetic waves in Hall thruster plasma

    SciTech Connect (OSTI)

    Tomilin, Dmitry [Department of Electrophysics, Keldysh Research Centre, Moscow 125438 (Russian Federation)

    2013-04-15T23:59:59.000Z

    This paper presents a linear analysis of gradient plasma instabilities in Hall thrusters. The study obtains and analyzes the dispersion equation of high-frequency electromagnetic waves based on the two-fluid model of a cold plasma. The regions of parameters corresponding to unstable high frequency modes are determined and the dependence of the increments and intrinsic frequencies on plasma parameters is obtained. The obtained results agree with those of previously published studies.

  19. Optimization Online - Using Simplex Gradients of Nonsmooth ...

    E-Print Network [OSTI]

    A. L. Custódio

    2006-10-27T23:59:59.000Z

    Oct 27, 2006 ... Using Simplex Gradients of Nonsmooth Functions in Direct Search Methods. A. L. Custódio (alcustodio ***at*** fct.unl.pt) J. E. Dennis (dennis ...

  20. Optimization Online - A Nonlinear Conjugate Gradient Algorithm ...

    E-Print Network [OSTI]

    Yu-Hong Dai

    2011-06-28T23:59:59.000Z

    Jun 28, 2011 ... Abstract: In this paper, we seek the conjugate gradient direction closest to the direction of the scaled memoryless BFGS method and propose a ...

  1. A GLOBALLY CONVERGENT MODIFIED CONJUGATE-GRADIENT ...

    E-Print Network [OSTI]

    2009-10-01T23:59:59.000Z

    gradient algorithms which implements this strategy in a robust and efficient way. ... Both begin with a second-order Taylor expansion modeling changes in f(xk) ...

  2. Optimization of synchronization in gradient clustered networks

    E-Print Network [OSTI]

    Xingang Wang; Liang Huang; Ying-Cheng Lai; Choy Heng Lai

    2007-11-23T23:59:59.000Z

    We consider complex clustered networks with a gradient structure, where sizes of the clusters are distributed unevenly. Such networks describe more closely actual networks in biophysical systems and in technological applications than previous models. Theoretical analysis predicts that the network synchronizability can be optimized by the strength of the gradient field but only when the gradient field points from large to small clusters. A remarkable finding is that, if the gradient field is sufficiently strong, synchronizability of the network is mainly determined by the properties of the subnetworks in the two largest clusters. These results are verified by numerical eigenvalue analysis and by direct simulation of synchronization dynamics on coupled-oscillator networks.

  3. LCLS X-Ray FEL Output Performance in the Presence of Highly Time-Dependent Undulator Wakefields

    E-Print Network [OSTI]

    Bane, Karl L.F.; Emma, Paul; Huang, Heinz-Dieter Nuhn; Stupakov, Gennady; Fawley, William M.; Reiche, Sven

    2005-01-01T23:59:59.000Z

    resistive-wall wake for a 1-nC LCLS bunch charge propagatingST Accel. Beams, 8, [3] LCLS CDR, SLAC Rpt. SLAC-R-593 (al. , “Optimization of the LCLS X-RAY FEL Performance in the

  4. LCLS X-Ray FEL Output Performance in the Presence of Highly Time-Dependent Undulator Wakefields

    E-Print Network [OSTI]

    Bane, Karl L.F.; Emma, Paul; Huang, Heinz-Dieter Nuhn; Stupakov, Gennady; Fawley, William M.; Reiche, Sven

    2005-01-01T23:59:59.000Z

    al. , “Optimization of the LCLS X-RAY FEL Performance in theLCLS X-Ray FEL Output Performance in the Presence of Highlyeld strength, can degrade the FEL process by detun- ing the

  5. Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic

    E-Print Network [OSTI]

    Bakeman, M.S.

    2011-01-01T23:59:59.000Z

    ultra-short, high- peak-current, electron beams are ideal for driving a compact X U V free electron laser (

  6. Approximate error conjugation gradient minimization methods

    DOE Patents [OSTI]

    Kallman, Jeffrey S

    2013-05-21T23:59:59.000Z

    In one embodiment, a method includes selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, calculating an approximate error using the subset of rays, and calculating a minimum in a conjugate gradient direction based on the approximate error. In another embodiment, a system includes a processor for executing logic, logic for selecting a subset of rays from a set of all rays to use in an error calculation for a constrained conjugate gradient minimization problem, logic for calculating an approximate error using the subset of rays, and logic for calculating a minimum in a conjugate gradient direction based on the approximate error. In other embodiments, computer program products, methods, and systems are described capable of using approximate error in constrained conjugate gradient minimization problems.

  7. Gradient Improvement by Removal of Identified Local Defects

    SciTech Connect (OSTI)

    R.L. Geng, W.A. Clemens, C.A. Cooper, H. Hayano, K. Watanabe

    2011-07-01T23:59:59.000Z

    Recent experience of ILC cavity processing and testing at Jefferson Lab has shown that some 9-cell cavities are quench limited at a gradient in the range of 15-25 MV/m. Further studies reveal that these quench limits are often correlated with sub-mm sized and highly localized geometrical defects at or near the equator weld. There are increasing evidence to show that these genetic defects have their origin in the material or in the electron beam welding process (for example due to weld irregularities or splatters on the RF surface and welding porosity underneath the surface). A local defect removal method has been proposed at Jefferson Lab by locally re-melting the niobium material. Several 1-cell cavities with known local defects have been treated by using the JLab local e-beam re-melting method, resulting in gradient and Q0 improvement. We also sent 9-cell cavities with known gradient limiting local defects to KEK for local grinding and to FNAL for global mechanical polishing. We report on the results of gradient improvements by removal of local defects in these cavities.

  8. Results of temperature gradient and heat flow in Santiam Pass Area, Oregon, Volume 1

    SciTech Connect (OSTI)

    Cox, B.L.; Gardner, M.C.; Koenig, J.B.

    1981-08-01T23:59:59.000Z

    The conclusions of this report are: (1) There is a weakly defined thermal anomaly within the area examined by temperature-gradient holes in the Santiam Pass area. This is a relict anomaly showing differences in permeability between the High Cascades and Western Cascades areas, more than a fundamental difference in shallow crustal temperatures. (2) The anomaly as defined by the 60 F isotherms at 400 feet follows a north-south trend immediately westward of the Cascade axis in the boundary region. It is clear that all holes spudded into High Cascades rocks result in isothermal and reversal gradients. Holes spudded in Western Cascades rocks result in positive gradients. (3) Cold groundwater flow influences and masks temperature gradients in the High Cascades to a depth of at least 700 feet, especially eastward from the major north-south trending faults. Pleistocene and Holocene rocks are very permeable aquifers. (4) Shallow gradient drilling in the lowlands westward of the faults provides more interpretable information than shallow drilling in the cold-water recharge zones. Topographic and climatological effects can be filtered out of the temperature gradient results. (5) The thermal anomaly seems to have 2 centers: one in the Belknap-Foley area, and one northward in the Sand Mountain area. The anomalies may or may not be connected along a north-south trend. (6) A geothermal effect is seen in holes downslope of the Western-High Cascade boundary. Mixing with cold waters is a powerful influence on temperature gradient data. (7) The temperature-gradient program has not yet examined and defined the geothermal resources potential of the area eastward of the Western Cascades-High Cascades boundary. Holes to 1500-2000 feet in depth are required to penetrate the high permeability-cold groundwater regime. (8) Drilling conditions are unfavorable. There are very few accessible level drill sites. Seasonal access problems and environmental restrictions together with frequent lost circulation results in very high costs per foot drilled.

  9. Measurement of thermodynamics using gradient flow

    E-Print Network [OSTI]

    Masakiyo Kitazawa; Masayuki Asakawa; Tetsuo Hatsuda; Takumi Iritani; Etsuko Itou; Hiroshi Suzuki

    2014-12-15T23:59:59.000Z

    We analyze bulk thermodynamics and correlation functions of the energy-momentum tensor in pure Yang-Mills gauge theory using the energy-momentum tensor defined by the gradient flow and small flow time expansion. Our results on thermodynamic observables are consistent with those obtained by the conventional integral method. The analysis of the correlation function of total energy supports the energy conservation. It is also addressed that these analyses with gradient flow require less statistics compared with the previous methods. All these results suggest that the energy-momentum tensor can be successfully defined and observed on the lattice with moderate numerical costs with the gradient flow.

  10. Time changes in gradient and observed winds 

    E-Print Network [OSTI]

    Carlson, Ronald Dale

    1972-01-01T23:59:59.000Z

    TIME CHANGES IN GRADIENT AND OBSERVED WINDS A Thesis by RONALD DALE CARLSON Submitted to the Graduate College of Texas A&M University in partial fulfillm=n of the requirement for the degree of MASTER OF SCIENCE MAY 1972 Major Subject...: Meteorology TIME CHANGES IN GRADIENT AND OBSERVED WINDS A Thesis by RONALD D. CARLSON Approved as to style and content by: (Chairman of Co , ee) (Member) (Member) May 1972 ABSTRACT Time Changes in Gradient and Observed Winds. (May 1972) Ronald Dale...

  11. The ISO Galactic Metallicity Gradient Revisited

    E-Print Network [OSTI]

    Uriel Giveon; Christophe Morisset; Amiel Sternberg

    2002-07-22T23:59:59.000Z

    Two independent groups (Giveon et al. 2002; Martin-Hernandez et al. 2002) have recently investigated the Galactic metallicity gradient as probed by ISO observations of mid-infrared emission lines from HII regions. We show that the different gradients inferred by the two groups are due to differing source selection and differing extinction corrections. We show that both data sets in fact provide consistent results if identical assumptions are made in the analysis. We present a consistent set of gradients in which we account for extinction and variation in electron temperature across the disk.

  12. Drive Beam Shaping and Witness Bunch Generation for the Plasma Wakefield Accelerator

    SciTech Connect (OSTI)

    England, R. J.; Frederico, J.; Hogan, M. J. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Muggli, P. [University of Southern California, Los Angeles, CA 90089 (United States); Joshi, C. [University of California Los Angeles, Los Angeles, CA 90024 (United States)

    2010-11-04T23:59:59.000Z

    High transformer ratio operation of the plasma wake field accelerator requires a tailored drive beam current profile followed by a short witness bunch. We discuss techniques for generating the requisite dual bunches and for obtaining the desired drive beam profile, with emphasis on the FACET experiment at SLAC National Accelerator Laboratory.

  13. THE MULTIGRID PRECONDITIONED CONJUGATE GRADIENT METHOD Osamu Tatebe

    E-Print Network [OSTI]

    THE MULTIGRID PRECONDITIONED CONJUGATE GRADIENT METHOD Osamu Tatebe Department of Information Science University of Tokyo Tokyo, JAPAN SUMMARY A multigrid preconditioned conjugate gradient method iterations and the multigrid preconditioner is a desirable preconditioner of the conjugate gradient method. 1

  14. Program predicts two-phase pressure gradients

    SciTech Connect (OSTI)

    Jacks, D.C.; Hill, A.D.

    1983-11-18T23:59:59.000Z

    The calculator program discussed, ORK, was designed for the HP-41CV hand-held calculator and uses the Orkiszewski correlation for predicting 2-phase pressure gradients in vertical tubulars. Accurate predictions of pressure gradients in flowing and gas lift wells over a wide range of well conditions can be obtained with this method, which was developed based on data from 148 wells. The correlation is one of the best generalized 2-phase pressure gradient prediction methods developed to date for vertical flow. It is unique in that hold-up is derived from observed physical phenomena, and the pressure gradient is related to the geometrical distribution of the liquid and gas phase (flow regime).

  15. A globally convergent modified conjugate-gradient line-search ...

    E-Print Network [OSTI]

    Wenwen Zhou

    2009-09-23T23:59:59.000Z

    Sep 23, 2009 ... Further, we provide a new variant of modified conjugate gradient algorithms ... optimization, trust region methods, conjugate gradient method.

  16. An inexact accelerated proximal gradient method for large scale ...

    E-Print Network [OSTI]

    2011-09-09T23:59:59.000Z

    projected gradient method, and usually has good practical performance on .... conditioned, the conjugate gradient (CG) method would have great difficulty in ...

  17. On the regularizing behavior of recent gradient methods in the ...

    E-Print Network [OSTI]

    Roberta De Asmundis

    2014-06-14T23:59:59.000Z

    Jun 14, 2014 ... On the regularizing behavior of recent gradient methods in the ... can be competitive with the Conjugate Gradient (CG) method, since they are ...

  18. a perry descent conjugate gradient method with restricted spectrum ...

    E-Print Network [OSTI]

    2011-05-09T23:59:59.000Z

    A new nonlinear conjugate gradient method, based on Perry's ... Key words and phrases. large scale optimization, conjugate gradient method, descent property ...

  19. Comparative systems biology across an evolutionary gradient within...

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

    systems biology across an evolutionary gradient within the Shewanella genus . Comparative systems biology across an evolutionary gradient within the Shewanella genus . Abstract: To...

  20. Fabrication process for a gradient index x-ray lens

    DOE Patents [OSTI]

    Bionta, Richard M. (Livermore, CA); Makowiecki, Daniel M. (Livermore, CA); Skulina, Kenneth M. (Livermore, CA)

    1995-01-01T23:59:59.000Z

    A process for fabricating high efficiency x-ray lenses that operate in the 0.5-4.0 keV region suitable for use in biological imaging, surface science, and x-ray lithography of integrated circuits. The gradient index x-ray optics fabrication process broadly involves co-sputtering multi-layers of film on a wire, followed by slicing and mounting on block, and then ion beam thinning to a thickness determined by periodic testing for efficiency. The process enables the fabrication of transmissive gradient index x-ray optics for the 0.5-4.0 keV energy range. This process allows the fabrication of optical elements for the next generation of imaging and x-ray lithography instruments m the soft x-ray region.

  1. Fabrication process for a gradient index x-ray lens

    DOE Patents [OSTI]

    Bionta, R.M.; Makowiecki, D.M.; Skulina, K.M.

    1995-01-17T23:59:59.000Z

    A process is disclosed for fabricating high efficiency x-ray lenses that operate in the 0.5-4.0 keV region suitable for use in biological imaging, surface science, and x-ray lithography of integrated circuits. The gradient index x-ray optics fabrication process broadly involves co-sputtering multi-layers of film on a wire, followed by slicing and mounting on block, and then ion beam thinning to a thickness determined by periodic testing for efficiency. The process enables the fabrication of transmissive gradient index x-ray optics for the 0.5-4.0 keV energy range. This process allows the fabrication of optical elements for the next generation of imaging and x-ray lithography instruments in the soft x-ray region. 13 figures.

  2. Robust relativistic electron mirrors in laser wakefields for enhanced Thomson backscattering

    SciTech Connect (OSTI)

    Mu, Jie; Li, Fei-Yu; Zeng, Ming; Chen, Min [Key Laboratory for Laser Plasmas (MoE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China)] [Key Laboratory for Laser Plasmas (MoE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Sheng, Zheng-Ming [Key Laboratory for Laser Plasmas (MoE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China) [Key Laboratory for Laser Plasmas (MoE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Zhang, Jie [Key Laboratory for Laser Plasmas (MoE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China) [Key Laboratory for Laser Plasmas (MoE) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190 (China)

    2013-12-23T23:59:59.000Z

    By adopting an up-ramp density profile, we propose to generate relativistic electron mirrors from laser-driven underdense plasma waves, which are insensitive to finite thermal temperature within a certain range. Along the density ramp, premature wavebreaking due to thermal effects is shown to be well mitigated. Under sufficiently high amplitudes of wake excitation, overcritical dense electron mirrors can pile up when approaching the end of the up-ramp. The consequent mirror speed can be stably driven to the group velocity of the laser propagating in a corresponding uniform plasma. Compared with using purely uniform but thermal plasmas, the present thermal-insensitive mirrors can provide enhanced scattering efficiency and spectral upshift for a counter-propagating probe pulse. These observations are confirmed by multi-dimensional particle-in-cell simulations.

  3. Transverse self-modulation of ultra-relativistic lepton beams in the plasma wakefield accelerator

    E-Print Network [OSTI]

    Vieira, J; Mori, W B; Silva, L O; Muggli, P

    2015-01-01T23:59:59.000Z

    The transverse self-modulation of ultra-relativistic, long lepton bunches in high-density plasmas is explored through full-scale particle-in-cell simulations. We demonstrate that long SLAC-type electron and positron bunches can become strongly self-modulated over centimeter distances, leading to wake excitation in the blowout regime with accelerating fields in excess of 20 GV/m. We show that particles energy variations exceeding 10 GeV can occur in meter-long plasmas. We find that the self-modulation of positively and negatively charged bunches differ when the blowout is reached. Seeding the self-modulation instability suppresses the competing hosing instability. This work reveals that a proof-of-principle experiment to test the physics of bunch self-modulation can be performed with available lepton bunches and with existing experimental apparatus and diagnostics.

  4. Non-linear Ion-wake Excitation by Ultra-relativistic Electron Wakefields

    E-Print Network [OSTI]

    Sahai, Aakash A

    2015-01-01T23:59:59.000Z

    The excitation of a non-linear ion-wake by a train of ultra-relativistic plasmons is modeled and its use for a novel regime of positron acceleration is explored. Its channel-like structure is independent of the energy-source driving the bubble-shaped slowly-propagating high phase-velocity electron density waves. The back of the bubble electron compression sucks-in the ions and the space-charge within the bubble expels them, forming a near-void channel with on-axis and bubble-edge density-spikes. The channel-edge density-spike is driven radially outwards as a non-linear ion acoustic-wave by the wake electron thermal pressure. OSIRIS PIC simulations are used to study the ion-wake structure, its evolution and its use for positron acceleration.

  5. TOWARDS STOCHASTIC CONJUGATE GRADIENT METHODS Nicol N. Schraudolph Thore Graepel

    E-Print Network [OSTI]

    Schraudolph, Nicol N.

    TOWARDS STOCHASTIC CONJUGATE GRADIENT METHODS Nicol N. Schraudolph Thore Graepel schraudo of conjugate gradients provides a very effective way to optimize large, deterministic systems by gradient de. Here we explore a number of ways to adopt ideas from conjugate gradient in the stochastic setting

  6. Relationship between gradient and EM steps in latent variable models.

    E-Print Network [OSTI]

    Roweis, Sam

    includes random search, standard gradient­based algorithms, line search methods such as conjugate gradient to to first order method operat­ ing on the gradient of a locally reshaped likelihood function. DirectRelationship between gradient and EM steps in latent variable models. Ruslan Salakhutdinov Sam

  7. 11 SOME PROPERTIES OF A NEW CONJUGATE GRADIENT METHOD

    E-Print Network [OSTI]

    Yuan, Ya-xiang

    11 SOME PROPERTIES OF A NEW CONJUGATE GRADIENT METHOD Y. H. Dai and Y. Yuan State Key Laboratory@cc.ac.cn Abstract: It is proved that the new conjugate gradient method proposed by Dai and Yuan 5] produces problem minf(x) x 2 Rn (1.1) where f is smooth and its gradient g is available. Conjugate gradient methods

  8. Relationship between gradient and EM steps in latent variable models.

    E-Print Network [OSTI]

    Roweis, Sam

    includes random search, standard gradient-based algorithms, line search methods such as conjugate gradient to to first order method operat- ing on the gradient of a locally reshaped likelihood function. DirectRelationship between gradient and EM steps in latent variable models. Ruslan Salakhutdinov Sam

  9. Critical gradient formula for toroidal electron temperature gradient modes F. Jenko, W. Dorland,a)

    E-Print Network [OSTI]

    Hammett, Greg

    Critical gradient formula for toroidal electron temperature gradient modes F. Jenko, W. Dorland and edge plasmas are presented. An algebraic formula for the threshold of the linear instability is derived formula. We discuss the results with respect to previous analytical results and to experimental

  10. Electric field gradient, generalized Sternheimer shieldings and electric field gradient polarizabilities by multiconfigurational SCF response

    E-Print Network [OSTI]

    Helgaker, Trygve

    Electric field gradient, generalized Sternheimer shieldings and electric field gradient at the nuclei, the generalized Sternheimer shielding constants and the EFG electric dipole polarizabilities discussed by Egstro¨m and co-workers4 and recently in a more general way by Fowler and co-workers.5

  11. Conjugate gradient algorithms using multiple recursions

    SciTech Connect (OSTI)

    Barth, T.; Manteuffel, T.

    1996-12-31T23:59:59.000Z

    Much is already known about when a conjugate gradient method can be implemented with short recursions for the direction vectors. The work done in 1984 by Faber and Manteuffel gave necessary and sufficient conditions on the iteration matrix A, in order for a conjugate gradient method to be implemented with a single recursion of a certain form. However, this form does not take into account all possible recursions. This became evident when Jagels and Reichel used an algorithm of Gragg for unitary matrices to demonstrate that the class of matrices for which a practical conjugate gradient algorithm exists can be extended to include unitary and shifted unitary matrices. The implementation uses short double recursions for the direction vectors. This motivates the study of multiple recursion algorithms.

  12. Time changes in gradient and observed winds

    E-Print Network [OSTI]

    Carlson, Ronald Dale

    1972-01-01T23:59:59.000Z

    - cal purposes, represents the changes in the components of the gradient wind speed, as calculated from Eqs. (9) and (10). Equations (9) and (10) were solved by the use of finite dif- ference methods. Due to the long incremental time steps, 3 to 12... hours, the changes in the components of the gradient wind speed obtained numerically from Eqs. (9) and (10) may differ slightly from the changes observed due to the numerical techniques employed. How- ever, the patterns obtained by the two methods...

  13. The gradient flow running coupling with twisted boundary conditions

    E-Print Network [OSTI]

    A. Ramos

    2014-09-04T23:59:59.000Z

    We study the gradient flow for Yang-Mills theories with twisted boundary conditions. The perturbative behavior of the energy density $\\langle E(t)\\rangle$ is used to define a running coupling at a scale given by the linear size of the finite volume box. We compute the non-perturbative running of the pure gauge $SU(2)$ coupling constant and conclude that the technique is well suited for further applications due to the relatively mild cutoff effects of the step scaling function and the high numerical precision that can be achieved in lattice simulations. We also comment on the inclusion of matter fields.

  14. Efficient Gradient Computation for Dynamical B. Sengupta

    E-Print Network [OSTI]

    Penny, Will

    descriptive length, variational free energy, etc. Generally, optimisation rests on evaluating the localEfficient Gradient Computation for Dynamical Models B. Sengupta , K.J. Friston and W.D. Penny of thousands of neurons using fMRI. Data assimilation involves inverting a generative model that can not only

  15. Multi-gradient drilling method and system

    DOE Patents [OSTI]

    Maurer, William C. (Houston, TX); Medley, Jr., George H. (Spring, TX); McDonald, William J. (Houston, TX)

    2003-01-01T23:59:59.000Z

    A multi-gradient system for drilling a well bore from a surface location into a seabed includes an injector for injecting buoyant substantially incompressible articles into a column of drilling fluid associated with the well bore. Preferably, the substantially incompressible articles comprises hollow substantially spherical bodies.

  16. Application of Gradient Expansion to Inflationary Universe

    E-Print Network [OSTI]

    Yasusada Nambu; Atsushi Taruya

    1994-11-03T23:59:59.000Z

    Using the long wave perturbation scheme(gradient expansion), the effect of inhomogeneity on the inflationary phase is investigated. We solved the perturbation equation of which source term comes from inhomogeneity of a scalar field and a seed metric. The result indicates that sub-horizon scale inhomogeneity strongly affects the onset of inflation.

  17. Gradient Clock Synchronization in Wireless Sensor Networks

    E-Print Network [OSTI]

    Gradient Clock Synchronization in Wireless Sensor Networks Philipp Sommer Computer Engineering- olution. Without doubt, time is a first-class citizen in wireless sensor networks. Without accurate time if the nodes in the wireless sensor network manage to have an adequate agreement of time. Indeed

  18. Universal Microfluidic Gradient Generator Daniel Irimia1

    E-Print Network [OSTI]

    Geba, Dan-Andrei

    Universal Microfluidic Gradient Generator Daniel Irimia1 , Dan A Geba2 , Mehmet Toner1 1 Bio, Building 114, 16th St, Charlestown, MA 02129. Email: mtoner@hms.harvard.edu Keywords: microfluidics cells in vitro. While microfluidic devices have shown unmatched capability in generating linear stable

  19. Gradient zone-boundary control in salt-gradient solar ponds

    DOE Patents [OSTI]

    Hull, J.R.

    1982-09-29T23:59:59.000Z

    A method and apparatus for suppressing zone boundary migration in a salt gradient solar pond includes extending perforated membranes across the pond at the boundaries, between the convective and non-convective zones, the perforations being small enough in size to prevent individual turbulence disturbances from penetrating the hole, but being large enough to allow easy molecular diffusion of salt thereby preventing the formation of convective zones in the gradient layer. The total area of the perforations is a sizeable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

  20. Low Impedance Bellows for High-current Beam Operations

    SciTech Connect (OSTI)

    Wu, G; Nassiri, A; Waldschmidt, G J; Yang, Y; Feingold, J J; Mammosser, J D; Rimmer, R A; Wang, H; Jang, J

    2012-07-01T23:59:59.000Z

    In particle accelerators, bellows are commonly used to connect beamline components. Such bellows are traditionally shielded to lower the beam impedance. Excessive beam impedance can cause overheating in the bellows, especially in high beam current operation. For an SRF-based accelerator, the bellows must also be particulate free. Many designs of shielded bellows incorporate rf slides or fingers that prevent convolutions from being exposed to wakefields. Unfortunately these mechanical structures tend to generate particulates that, if left in the SRF accelerator, can migrate into superconducting cavities, the accelerator's critical components. In this paper, we describe a prototype unshielded bellows that has low beam impedance and no risk of particulate generation.

  1. Stellar Population Gradients in Bulges along the Hubble Sequence: II. Relations with Galaxy Properties

    E-Print Network [OSTI]

    P. Jablonka; J. Gorgas; P. Goudfrooij

    2007-07-04T23:59:59.000Z

    We present the analysis of the radial gradients of stellar absorption lines in a sample of 32 bulges of edge-on spiral galaxies, spanning nearly the full Hubble sequence (from S0 to Sc types), and a large range of velocity dispersion (from about 60 to 300 km/s). Different diagnostics such as index-index, gradient-gradient diagrams, and simple stellar population models are used to tackle the origin of the variation of the bulge stellar population. We find that the vast majority of bulges show older age, lower metallicity and higher [alpha/Fe] in their outer regions than in their central parts. The radial gradients in [Fe/H] are 2 to 3 times larger than in Log(age). The relation between gradient and bulge velocity dispersion is interpreted as a gradual build up of the gradient mean values and their dispersions from high to low velocity dispersion, rather than a pure correlation. The bulge effective radii and the Hubble type of the parent galaxies seem to play a more minor role in causing the observed spatial distributions. At a given velocity dispersion, bulges and ellipticals share common properties.

  2. Geothermal potential of West-Central New Mexico from geochemical and thermal gradient data

    SciTech Connect (OSTI)

    Levitte, D.; Gambill, D.T.

    1980-11-01T23:59:59.000Z

    To study the low temperature and Hot Dry Rock (HDR) geothermal potential of west-central New Mexico, 46 water samples were collected and geothermal gradient measurements were made in 29 wells. Water chemistry data indicate that all the samples collected are meteoric waters. High temperatures of samples taken from wells between Gallup and Tohatchi indicate these wells may derive water from a warm aquifer below the depth of the wells. The chemistries of the samples farther south on the Zuni Indian reservation suggest these waters are not circulating below 600 m of the surface. Geothermometry calculations support the conclusion that the waters sampled are meteoric. The geothermometry also indicates that the deep reservoir between Gallup and Tohatchi may be greater than 60/sup 0/C. Thermal gradient data indicate an area of high gradient on the Zuni Indian Reservation with a measured maximum of 67/sup 0/C/km between 181 m and 284 m. This high probably is not hydrologically controlled. The maximum gradients in the study area are 76/sup 0/C/km and 138/sup 0/C/km, measured just east of Springerville, Arizona. These gradients are undoubtedly controlled by circulating water, possibly heated by a magmatic source at depth and circulating back to the surface.

  3. FIRST MEASUREMENT OF PRESSURE GRADIENT-DRIVEN CURRENTS IN TOKAMAK EDGE PLASMAS

    SciTech Connect (OSTI)

    THOMAS DM; LEONARD AW; LAO LL; OSBORNE TH; MUELLER HW; FINKENTHAL DK

    2003-11-01T23:59:59.000Z

    Localized currents driven by pressure gradients play a pivotal role in the magnetohydrodynamic stability of toroidal plasma confinement devices. We have measured the currents generated in the edge of L- (low) and H- (high confinement) mode discharges on the DIII-D tokamak, utilizing the Zeeman effect in an injected lithium beam to obtain high resolution profiles of the poloidal magnetic field. We find current densities in excess of 1 MA/m{sup 2} in a 1 to 2 cm region near the peak of the edge pressure gradient. These values are sufficient to challenge edge stability theories based on specific current formation models.

  4. Fast quantum algorithm for numerical gradient estimation

    E-Print Network [OSTI]

    Stephen P. Jordan

    2005-01-02T23:59:59.000Z

    Given a blackbox for f, a smooth real scalar function of d real variables, one wants to estimate the gradient of f at a given point with n bits of precision. On a classical computer this requires a minimum of d+1 blackbox queries, whereas on a quantum computer it requires only one query regardless of d. The number of bits of precision to which f must be evaluated matches the classical requirement in the limit of large n.

  5. A Preconditioner for a Primal-Dual Newton Conjugate Gradients ...

    E-Print Network [OSTI]

    Kimon Fountoulakis

    2014-12-30T23:59:59.000Z

    Dec 30, 2014 ... A Preconditioner for a Primal-Dual Newton Conjugate Gradients Method for Compressed Sensing Problems.

  6. Optimization Online - Conjugate gradient methods based on secant ...

    E-Print Network [OSTI]

    Y Narushima

    2011-09-28T23:59:59.000Z

    Sep 28, 2011 ... Conjugate gradient methods based on secant conditions that generate descent search directions for unconstrained optimization.

  7. A three-term conjugate gradient method with sufficient descent ...

    E-Print Network [OSTI]

    2009-11-02T23:59:59.000Z

    Finally, some numerical results of the proposed method are given. keyword; Unconstrained optimization, three-term conjugate gradient method, sufficient.

  8. BASIC GEOPHYSICAL FLUID Lecture 3: Gradient winds, pressure

    E-Print Network [OSTI]

    Read, Peter L.

    cyclostrophic balance. 2 #12;Example of gradient-wind balance: Hurricane Andrew 3 #12;Examples of cyclostrophic

  9. Energy Gradient Theory of Hydrodynamic Instability

    E-Print Network [OSTI]

    Hua-Shu Dou

    2005-01-29T23:59:59.000Z

    A new universal theory for flow instability and turbulent transition is proposed in this study. Flow instability and turbulence transition have been challenging subjects for fluid dynamics for a century. The critical condition of turbulent transition from theory and experiments differs largely from each other for Poiseuille flows. In this paper, a new mechanism of flow instability and turbulence transition is presented for parallel shear flows and the energy gradient theory of hydrodynamic instability is proposed. It is stated that the total energy gradient in the transverse direction and that in the streamwise direction of the main flow dominate the disturbance amplification or decay. A new dimensionless parameter K for characterizing flow instability is proposed for wall bounded shear flows, which is expressed as the ratio of the energy gradients in the two directions. It is thought that flow instability should first occur at the position of Kmax which may be the most dangerous position. This speculation is confirmed by Nishioka et al's experimental data. Comparison with experimental data for plane Poiseuille flow and pipe Poiseuille flow indicates that the proposed idea is really valid. It is found that the turbulence transition takes place at a critical value of Kmax of about 385 for both plane Poiseuille flow and pipe Poiseuille flow, below which no turbulence will occur regardless the disturbance. More studies show that the theory is also valid for plane Couette flows and Taylor-Couette flows between concentric rotating cylinders.

  10. Evaluation of liquid lift approach to dual gradient

    E-Print Network [OSTI]

    Okafor, Ugochukwu Nnamdi

    2009-05-15T23:59:59.000Z

    ............................................... 4 2.2 Dual Gradient Drilling Method.............................................. 5 2.3 Methods of Achieving Dual Gradient Drilling ...................... 9 2.3.1 Subsea Mudlift Drilling... ................................................... 9 2.5 Schematic diagram of a modified subsea mudlift system .......................... 11 2.6 Hollow glass-spheres dual gradient drilling system................................... 13 2.7 A typical offshore drilling rig modified...

  11. Evaluation of liquid lift approach to dual gradient drilling

    E-Print Network [OSTI]

    Okafor, Ugochukwu Nnamdi

    2008-10-10T23:59:59.000Z

    ............................................... 4 2.2 Dual Gradient Drilling Method.............................................. 5 2.3 Methods of Achieving Dual Gradient Drilling ...................... 9 2.3.1 Subsea Mudlift Drilling... ................................................... 9 2.5 Schematic diagram of a modified subsea mudlift system .......................... 11 2.6 Hollow glass-spheres dual gradient drilling system................................... 13 2.7 A typical offshore drilling rig modified...

  12. USING SIMPLEX GRADIENTS OF NONSMOOTH FUNCTIONS IN DIRECT SEARCH METHODS

    E-Print Network [OSTI]

    Vicente, Luís Nunes

    USING SIMPLEX GRADIENTS OF NONSMOOTH FUNCTIONS IN DIRECT SEARCH METHODS A. L. CUST´ODIO , J. E by reordering the poll directions according to descent indicators built from simplex gradients. The purpose of this paper is twofold. First, we analyze the properties of simplex gradients of nonsmooth functions

  13. AN EXTENDED CLASS OF NONLINEAR CONJUGATE GRADIENT METHODS \\Lambda

    E-Print Network [OSTI]

    Yuan, Ya-xiang

    AN EXTENDED CLASS OF NONLINEAR CONJUGATE GRADIENT METHODS \\Lambda Y. H. Dai and Y. Yuan State Key 100080, P. R. China. Email: dyh,yyx@lsec.cc.ac.cn Abstract Conjugate gradient methods are very important be analyzed uniformly, conjugate gradient methods are often analyzed individually. Recently, Dai and Yuan

  14. AN AUGMENTED CONJUGATE GRADIENT METHOD FOR SOLVING CONSECUTIVE

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    AN AUGMENTED CONJUGATE GRADIENT METHOD FOR SOLVING CONSECUTIVE SYMMETRIC POSITIVE DEFINITE LINEAR definite matrix A. The conjugate gradient method applied to the first system generates a Krylov subspace conjugate gradient method is then applied with a specific initial guess and initial descent direction

  15. CONVERGENCE PROPERTIES OF NONLINEAR CONJUGATE GRADIENT METHODS1

    E-Print Network [OSTI]

    Yuan, Ya-xiang

    CONVERGENCE PROPERTIES OF NONLINEAR CONJUGATE GRADIENT METHODS1 Yuhong Dai2 , Jiye Han3 , Guanghui contributions on convergence studies of conjugate gradient methods have been made by Gilbert and Nocedal [6 for ensuring the global convergence of conjugate gradient methods. This paper shows that the sufficient descent

  16. ON THE CONNECTION BETWEEN THE CONJUGATE GRADIENT METHOD AND

    E-Print Network [OSTI]

    Forsgren, Anders

    ON THE CONNECTION BETWEEN THE CONJUGATE GRADIENT METHOD AND QUASI-NEWTON METHODS ON QUADRATIC Royal Institute of Technology February 2013 Abstract It is well known that the conjugate gradient method gradient method. In the framework based on a sufficient condition to obtain mutually conjugate search

  17. Preconditioned Conjugate Gradient Methods for Three Dimensional Linear Elasticity

    E-Print Network [OSTI]

    Waterloo, University of

    Preconditioned Conjugate Gradient Methods for Three Dimensional Linear Elasticity by John Kenneth. A brief review is also made of stopping criteria for conjugate gradient solvers. One method based and tested with poor results. iv #12;Contents 1 Introduction 1 1.1 Preconditioned Conjugate Gradient Methods

  18. CG DESCENT, A CONJUGATE GRADIENT METHOD WITH GUARANTEED DESCENT

    E-Print Network [OSTI]

    Zhang, Hongchao

    CG DESCENT, A CONJUGATE GRADIENT METHOD WITH GUARANTEED DESCENT #3; WILLIAM W. HAGER y AND HONGCHAO are given. Key words. Conjugate gradient method, unconstrained optimization, convergence, line search, Wolfe nonlinear conjugate gradient method for solving an unconstrained optimization problem min ff(x) : x 2

  19. A conjugate gradient learning algorithm for recurrent neural networks

    E-Print Network [OSTI]

    Mak, Man-Wai

    ]. In particular, the conjugate gradient method is commonly used in training BP networks due to its speed1 A conjugate gradient learning algorithm for recurrent neural networks (Revised Version) Wing algorithm by incorporating conjugate gradient computation into its learning procedure. The resulting

  20. APPROXIMATE INVERSE PRECONDITIONING FOR THE CONJUGATE GRADIENT METHOD

    E-Print Network [OSTI]

    Tùma, Miroslav

    APPROXIMATE INVERSE PRECONDITIONING FOR THE CONJUGATE GRADIENT METHOD ON A VECTOR COMPUTER Michele definite matrix, by the preconditioned conjugate gradient method (PCG) (see, e.g., [4]). It is well of the conjugate gradient method reduces to computing a matrix­ vector product with G, an operation which offers

  1. Ducted kinetic Alfven waves in plasma with steep density gradients

    SciTech Connect (OSTI)

    Houshmandyar, Saeid [Solar Observatory Department, Prairie View A and M University, Prairie View, Texas 77446 (United States); Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States); Scime, Earl E. [Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)

    2011-11-15T23:59:59.000Z

    Given their high plasma density (n {approx} 10{sup 13} cm{sup -3}), it is theoretically possible to excite Alfven waves in a conventional, moderate length (L {approx} 2 m) helicon plasma source. However, helicon plasmas are decidedly inhomogeneous, having a steep radial density gradient, and typically have a significant background neutral pressure. The inhomogeneity introduces regions of kinetic and inertial Alfven wave propagation. Ion-neutral and electron-neutral collisions alter the Alfven wave dispersion characteristics. Here, we present the measurements of propagating kinetic Alfven waves in helium helicon plasma. The measured wave dispersion is well fit with a kinetic model that includes the effects of ion-neutral damping and that assumes the high density plasma core defines the radial extent of the wave propagation region. The measured wave amplitude versus plasma radius is consistent with the pile up of wave magnetic energy at the boundary between the kinetic and inertial regime regions.

  2. Illinois: High-Energy, Concentration-Gradient Cathode Material...

    Office of Environmental Management (EM)

    Project Overview Positive Impact Batteries for electric drive vehicles and renewable energy storage will reduce petroleum usage, improving energy security and reducing harmful...

  3. Fast global convergence of gradient methods for high-dimensional ...

    E-Print Network [OSTI]

    2012-08-24T23:59:59.000Z

    of the optimization error, measured in terms of the Euclidean norm ?t ? ?? between the current iterate ?t ...... [4] S. Becker, J. Bobin, and E. J. Candes. Nesta: a ...

  4. Developing new high energy gradient concentration cathode material |

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't Your Destiny:Revised Finding of No53197E T A * S H I E LGeothermalEnergy Aa newState

  5. New High Energy Gradient Concentration Cathode Material | Department of

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn'tOrigin of Contamination in Many DevilsForum |EnergyNewEnergy Services

  6. New High Energy Gradient Concentration Cathode Material | Department of

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn'tOrigin of Contamination in Many DevilsForum |EnergyNewEnergy ServicesEnergy 1 DOE

  7. New High Energy Gradient Concentration Cathode Material | Department of

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn'tOrigin of Contamination in Many DevilsForum |EnergyNewEnergy ServicesEnergy 1

  8. 9519 biotite granodiorite reacted in a temperature gradient

    SciTech Connect (OSTI)

    Charles, R.W.; Bayhurst, G.K.

    1980-10-01T23:59:59.000Z

    A biotite granodiorite from the Fenton Hill Hot Dry Rock (HDR) geothermal system was reacted in a controlled temperature gradient with initially distilled water for 60d. Polished rock prisms were located in the gradient at 72, 119, 161, 209, 270, and 310/sup 0/C. Scanning electron microscope and microprobe analyses show the appearance of secondary phases: Ca-montmorillonite at 72/sup 0/C and 119/sup 0/C; zeolite, either stilbite or heulandite, at 161/sup 0/C; and another zeolite, thomsonite, at higher temperatures. Solution analyses show a steady state equilibrium exists between solution and overgrowths after about 2 weeks of reaction. The chemographic relations for the system are explored in some detail indicating the divariant assemblages may be placed in a reasonable sequence in intensive variable space. These relations predict high and low temperature effects not directly observed experimentally as well as relevant univariant equilibria. Solution chemistry indicates the Na-Ca-K geothermometer more adequately predicts temperature in this system than does the silica geothermometer.

  9. Capacitive mixing power production from salinity gradient energy enhanced through exoelectrogen-

    E-Print Network [OSTI]

    thermolytic solutions that can be used to capture waste heat energy as salinity gradient energy. Forced our expanding water and energy infrastructures across the globe, the development of sustainable dual energy generation and water treatment process is highly desirable. A combined capacitive mixing

  10. Adjustable, rapidly switching microfluidic gradient generation using focused travelling surface acoustic waves

    SciTech Connect (OSTI)

    Destgeer, Ghulam; Im, Sunghyuk; Hang Ha, Byung; Ho Jung, Jin; Ahmad Ansari, Mubashshir; Jin Sung, Hyung, E-mail: hjsung@kaist.ac.kr [Department of Mechanical Engineering, KAIST, 291 Daejak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2014-01-13T23:59:59.000Z

    We demonstrate a simple device to generate chemical concentration gradients in a microfluidic channel using focused travelling surface acoustic waves (F-TSAW). A pair of curved interdigitated metal electrodes deposited on the surface of a piezoelectric (LiNbO{sub 3}) substrate disseminate high frequency sound waves when actuated by an alternating current source. The F-TSAW produces chaotic acoustic streaming flow upon its interaction with the fluid inside a microfluidic channel, which mixes confluent streams of chemicals in a controlled fashion for an adjustable and rapidly switching gradient generation.

  11. The gradient flow running coupling scheme

    E-Print Network [OSTI]

    Zoltan Fodor; Kieran Holland; Julius Kuti; Daniel Nogradi; Chik Him Wong

    2012-11-14T23:59:59.000Z

    The Yang-Mills gradient flow in finite volume is used to define a running coupling scheme. As our main result the discrete beta-function, or step scaling function, is calculated for scale change s=3/2 at several lattice spacings for SU(3) gauge theory coupled to N_f = 4 fundamental massless fermions. The continuum extrapolation is performed and agreement is found with the continuum perturbative results for small renormalized coupling. The case of SU(2) gauge group is briefly commented on.

  12. Steep Gradient Flume | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov YouKizildere IRaghuraji Agro Industries Pvt LtdShawangunk,SoutheastSt.Steep Gradient Flume Jump to: navigation, search

  13. Electron transport and frozen concentration gradients in a mixed valent viologen molten salt

    SciTech Connect (OSTI)

    Terrill, R.H.; Hatazawa, Tsuyonobu; Murray, R.W. [Univ. of North Carolina, Chapel Hill, NC (United States)

    1995-11-09T23:59:59.000Z

    This paper shows that electrolytically generated crossed concentration gradients of viologen (2+) and viologen (1+) in films of its mixed valent molten salt on interdigitated array electrodes can be thermally and stably frozen in place in the interelectrode gaps. A study is presented of properties of the gradient-containing films, as compared to films that are non-mixed valent (V{sup 2+}) or that are mixed valent but lack concentration gradients. Comparisons of charge transport measurements show that the 2-5 {mu}m wide concentration gradients are persistent in the molten salt at lowered temperatures, where ionic motions are quenched relative to electron hopping as shown by differences in conductivity between mixed valent and non-mixed valent films as the temperature is lowered from +50 to -70{degree}C. Differences in the magnitude and shape of high-field current-voltage curves taken from mixed valent nongradient and V{sup 2+}/V{sup +} gradient-containing samples are interpreted with an electron-hopping model that includes a parameter for kinetic dispersity. Differences between the capacitance of the mixed valent and non-mixed valent phase of the viologen molten salt are consistent with the formation of an electronic space charge at the metal/redox conductor interface. 18 refs., 8 figs., 1 tab.

  14. Integrating 3D seismic curvature and curvature gradient attributes for fracture characterization: Methodologies and interpretational implications

    SciTech Connect (OSTI)

    Gao, Dengliang

    2013-03-01T23:59:59.000Z

    In 3D seismic interpretation, curvature is a popular attribute that depicts the geometry of seismic reflectors and has been widely used to detect faults in the subsurface; however, it provides only part of the solutions to subsurface structure analysis. This study extends the curvature algorithm to a new curvature gradient algorithm, and integrates both algorithms for fracture detection using a 3D seismic test data set over Teapot Dome (Wyoming). In fractured reservoirs at Teapot Dome known to be formed by tectonic folding and faulting, curvature helps define the crestal portion of the reservoirs that is associated with strong seismic amplitude and high oil productivity. In contrast, curvature gradient helps better define the regional northwest-trending and the cross-regional northeast-trending lineaments that are associated with weak seismic amplitude and low oil productivity. In concert with previous reports from image logs, cores, and outcrops, the current study based on an integrated seismic curvature and curvature gradient analysis suggests that curvature might help define areas of enhanced potential to form tensile fractures, whereas curvature gradient might help define zones of enhanced potential to develop shear fractures. In certain fractured reservoirs such as at Teapot Dome where faulting and fault-related folding contribute dominantly to the formation and evolution of fractures, curvature and curvature gradient attributes can be potentially applied to differentiate fracture mode, to predict fracture intensity and orientation, to detect fracture volume and connectivity, and to model fracture networks.

  15. Photon storage in Lambda-type optically dense atomic media. IV. Optimal control using gradient ascent

    E-Print Network [OSTI]

    Alexey V. Gorshkov; Tommaso Calarco; Mikhail D. Lukin; Anders S. Sorensen

    2008-04-07T23:59:59.000Z

    We use the numerical gradient ascent method from optimal control theory to extend efficient photon storage in Lambda-type media to previously inaccessible regimes and to provide simple intuitive explanations for our optimization techniques. In particular, by using gradient ascent to shape classical control pulses used to mediate photon storage, we open up the possibility of high efficiency photon storage in the non-adiabatic limit, in which analytical solutions to the equations of motion do not exist. This control shaping technique enables an order-of-magnitude increase in the bandwidth of the memory. We also demonstrate that the often discussed connection between time reversal and optimality in photon storage follows naturally from gradient ascent. Finally, we discuss the optimization of controlled reversible inhomogeneous broadening.

  16. 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)

    2014-03-15T23:59:59.000Z

    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.

  17. Millisecond ordering of block-copolymer films via photo-thermal gradients

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

    Majewski, Pawel W.; Yager, Kevin G.

    2015-04-28T23:59:59.000Z

    For the promise of self-assembly to be realized, processing techniques must be developed that simultaneously enable control of the nanoscale morphology, rapid assembly, and, ideally, the ability to pattern the nanostructure. Here, we demonstrate how photo-thermal gradients can be used to control the ordering of block-copolymer thin films. Highly localized laser heating leads to intense thermal gradients, which induce a thermophoretic force on morphological defects. This increases the ordering kinetics by at least 3 orders-of-magnitude, compared to conventional oven annealing. By simultaneously exploiting the thermal gradients to induce shear fields, we demonstrate uniaxial alignment of a block-copolymer film in lessmore »than a second. Finally, we provide examples of how control of the incident light-field can be used to generate prescribed configurations of block-copolymer nanoscale patterns.« less

  18. METALLICITY GRADIENTS IN THE MILKY WAY DISK AS OBSERVED BY THE SEGUE SURVEY

    SciTech Connect (OSTI)

    Cheng, Judy Y. [Department of Astronomy and Astrophysics, University of California Santa Cruz, Santa Cruz, CA 95064 (United States); Rockosi, Constance M. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Morrison, Heather L. [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States); Schoenrich, Ralph A. [Max-Planck-Institute fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Lee, Young Sun; Beers, Timothy C. [Department of Physics and Astronomy and JINA (Joint Institute for Nuclear Astrophysics), Michigan State University, East Lansing, MI 48824 (United States); Bizyaev, Dmitry; Pan, Kaike [Apache Point Observatory, Sunspot, NM 88349 (United States); Schneider, Donald P., E-mail: jyc@ucolick.org [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)

    2012-02-20T23:59:59.000Z

    The observed radial and vertical metallicity distribution of old stars in the Milky Way disk provides a powerful constraint on the chemical enrichment and dynamical history of the disk system. We present the radial metallicity gradient, {Delta}[Fe/H]/{Delta}R, as a function of height above the plane, |Z|, using 7010 main-sequence turnoff stars observed by the Sloan Extension for Galactic Understanding and Exploration survey. The sample consists of mostly old thin and thick disk stars, with a minimal contribution from the stellar halo, in the region 6 kpc < R < 16 kpc, 0.15 kpc < |Z| < 1.5 kpc. The data reveal that the radial metallicity gradient becomes flat at heights |Z| > 1 kpc. The median metallicity at large |Z| is consistent with the metallicities seen in outer disk open clusters, which exhibit a flat radial gradient at [Fe/H] {approx}-0.5. We note that the outer disk clusters are also located at large |Z|; because the flat gradient extends to small R for our sample, there is some ambiguity in whether the observed trends for clusters are due to a change in R or |Z|. We therefore stress the importance of considering both the radial and vertical directions when measuring spatial abundance trends in the disk. The flattening of the gradient at high |Z| also has implications on thick disk formation scenarios, which predict different metallicity patterns in the thick disk. A flat gradient, such as we observe, is predicted by a turbulent disk at high redshift, but may also be consistent with radial migration, as long as mixing is strong. We test our analysis methods using a mock catalog based on the model of Schoenrich and Binney, and we estimate our distance errors to be {approx}25%. We also show that we can properly correct for selection biases by assigning weights to our targets.

  19. Study of thermal-gradient-induced migration of brine inclusions in salt. Final report

    SciTech Connect (OSTI)

    Olander, D.R.

    1984-08-01T23:59:59.000Z

    Natural salt deposits, which are being considered for high-level waste disposal, contain a small volume fraction of water in the form of brine inclusions distributed throughout the salt. Radioactive decay heating of the nuclear wastes will impose a temperature gradient on the surrounding salt which mobilizes the brine inclusions. Inclusions filled completely with brine (the all-liquid inclusions) migrate up the temperature gradient and eventually accumulate brine near the buried waste forms. The brine may slowly corrode or degrade the waste forms, which is undesirable. Therefore it is important to consider the migration of brine inclusions in salt under imposed temperature gradients to properly evaluate the performance of a future salt repository for nuclear wastes. The migration velocities of the inclusions were found to be dependent on temperature, temperature gradient, and inclusion shape and size. The velocities were also dictated by the interfacial mass transfer resistance at brine/solid interface. This interfacial resistance depends on the dislocation density in the crystal, which in turn, depends on the axial compressive loading of the crystal. At low axial loads, the dependence between the velocity and temperature gradient is nonlinear. At high axial loads, the interfacial resistance is reduced and the migration velocity depends linearly on the temperature gradient. All-liquid inclusions filled with mixed brines were also studied. For gas-liquid inclusions, helium, air and argon were compared. Migration studies were also conducted on single crystallites of natural salt as well as in polycrystalline natural salt samples. The behavior of the inclusions at large-ange grain boundaries was observed.

  20. Sources of stress gradients in electrodeposited Ni MEMS.

    SciTech Connect (OSTI)

    Hearne, Sean Joseph; Floro, Jerrold Anthony; Dyck, Christopher William

    2004-06-01T23:59:59.000Z

    The ability of future integrated metal-semiconductor micro-systems such as RF MEMS to perform highly complex functions will depend on developing freestanding metal structures that offer improved conductivity and reflectivity over polysilicon structures. For example, metal-based RF MEMS technology could replace the bulky RF system presently used in communications, navigation, and avionics systems. However, stress gradients that induce warpage of active components have prevented the implementation of this technology. Figure 1, is an interference micrograph image of a series of cantilever beams fabricated from electrodeposited Ni. The curvature in the beams was the result of stress gradients intrinsic to the electrodeposition process. To study the sources of the stress in electrodeposition of Ni we have incorporated a wafer curvature based stress sensor, the multibeam optical stress sensor, into an electrodeposition cell. We have determined that there are two regions of stress induced by electrodepositing Ni from a sulfamate-based bath (Fig 2). The stress evolution during the first region, 0-1000{angstrom}, was determined to be dependent only on the substrate material (Au vs. Cu), whereas the stress evolution during the second region, >1000{angstrom}, was highly dependent on the deposition conditions. In this region, the stress varied from +0.5 GPa to -0.5GPa, depending solely on the deposition rate. We examined four likely sources for the compressive intrinsic stress, i.e. reduction in tensile stress, and determined that only the adatom diffusion into grain boundaries model of Sheldon, et al. could account for the observed compressive stress. In the presentation, we shall discuss the compressive stress generation mechanisms considered and the ramifications of these results on fabrication of electrodeposited Ni for MEMS applications.

  1. Constant field gradient planar coupled cavity structure

    DOE Patents [OSTI]

    Kang, Y.W.; Kustom, R.L.

    1999-07-27T23:59:59.000Z

    A cavity structure is disclosed having at least two opposing planar housing members spaced apart to accommodate the passage of a particle beam through the structure between the members. Each of the housing members have a plurality of serially aligned hollows defined therein, and also passages, formed in the members, which interconnect serially adjacent hollows to provide communication between the hollows. The opposing planar housing members are spaced and aligned such that the hollows in one member cooperate with corresponding hollows in the other member to form a plurality of resonant cavities aligned along the particle beam within the cavity structure. To facilitate the obtaining of a constant field gradient within the cavity structure, the passages are configured so as to be incrementally narrower in the direction of travel of the particle beam. In addition, the spacing distance between the opposing housing members is configured to be incrementally smaller in the direction of travel of the beam. 16 figs.

  2. Thermal Gradient Holes At Waunita Hot Springs Geothermal Area...

    Open Energy Info (EERE)

    Zacharakis, 1981) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Waunita Hot Springs Geothermal Area (Zacharakis,...

  3. Gradient methods for convex minimization: better rates under ...

    E-Print Network [OSTI]

    Hui Zhang

    2013-03-20T23:59:59.000Z

    Mar 20, 2013 ... Gradient methods for convex minimization: better rates under weaker conditions. Hui Zhang(hhuuii.zhang ***at*** gmail.com)

  4. Geology and Temperature Gradient Surveys Blue Mountain Geothermal...

    Open Energy Info (EERE)

    Gradient Surveys Blue Mountain Geothermal Discovery, Humboldt County, Nevada Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: Geology and...

  5. Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank...

    Open Energy Info (EERE)

    search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank & Ross, 1999) Exploration Activity Details Location...

  6. Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank...

    Open Energy Info (EERE)

    Blue Mountain Geothermal Area (Fairbank & Niggemann, 2004) Exploration Activity Details Location Blue Mountain Geothermal Area Exploration Technique Thermal Gradient Holes Activity...

  7. Spatiotemporal Gradient Modeling with Applications Harrison S. Quick1

    E-Print Network [OSTI]

    Carlin, Bradley P.

    , and geospatial information storage, analysis, and distribution systems have led to a burgeoning of spatial 2.3 Gradient analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.5 Data analysis

  8. On the application of the spectral projected gradient method in ...

    E-Print Network [OSTI]

    2015-02-17T23:59:59.000Z

    On the application of the spectral projected gradient method in image segmentation. 7. (a) cameraman – 204 × 204. (b) carplate – 285 × 224. (c) granite – 225 × ...

  9. second-order convex splitting schemes for gradient flows with ...

    E-Print Network [OSTI]

    2011-11-08T23:59:59.000Z

    Abstract. We construct unconditionally stable, unconditionally uniquely solvable, and second-order accurate (in time) schemes for gradient flows with energy of ...

  10. Existence and uniqueness of global classical solutions of a gradient ...

    E-Print Network [OSTI]

    2015-01-22T23:59:59.000Z

    This gradient flow is generated by the Laudau-de Gennes energy functional that ... feature of this evolution problem is that it is generated by an energy functional ...

  11. Optimization Online - A three-term conjugate gradient method with ...

    E-Print Network [OSTI]

    Y Narushima

    2009-12-03T23:59:59.000Z

    Dec 3, 2009 ... A three-term conjugate gradient method with sufficient descent property for unconstrained optimization. Y Narushima(narusima ***at*** ...

  12. Optimization Online - Linearizing the Method of Conjugate Gradients

    E-Print Network [OSTI]

    Serge Gratton

    2012-09-09T23:59:59.000Z

    Sep 9, 2012 ... Abstract: The method of conjugate gradients (CG) is widely used for the iterative solution of large sparse systems of equations $Ax=b$, where ...

  13. A Perry Descent Conjugate Gradient Method with Restricted Spectrum

    E-Print Network [OSTI]

    Dongyi Liu

    2011-03-07T23:59:59.000Z

    Mar 7, 2011 ... Abstract: A new nonlinear conjugate gradient method, based on Perry's idea, is presented. And it is shown that its sufficient descent property is ...

  14. On the connection between the conjugate gradient method and ...

    E-Print Network [OSTI]

    Anders Forsgren

    2013-02-09T23:59:59.000Z

    Feb 9, 2013 ... Abstract: It is well known that the conjugate gradient method and a quasi-Newton method, using any well-defined update matrix from the ...

  15. A Nonmonotone Approach without Differentiability Test for Gradient ...

    E-Print Network [OSTI]

    Elias S. Helou

    2015-03-18T23:59:59.000Z

    Mar 18, 2015 ... A Nonmonotone Approach without Differentiability Test for Gradient Sampling Methods. Elias S. Helou(elias ***at*** icmc.usp.br) Sandra A.

  16. Concentration Gradient and Information Energy for Decentralized UAV Control1

    E-Print Network [OSTI]

    Mohseni, Kamran

    spills, industrial release accidents, or chemical/biological/nuclear terrorist attacks. DependingConcentration Gradient and Information Energy for Decentralized UAV Control1 William J. Pisano2

  17. Thermal Gradient Holes At Long Valley Caldera Geothermal Area...

    Open Energy Info (EERE)

    Geothermal Area (Farrar, Et Al., 2003) Exploration Activity Details Location Long Valley Caldera Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1998 -...

  18. alpine elevation gradient: Topics by E-print Network

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

    Niche expansion leads to small-scale adaptive divergence along an elevation gradient in a medium of the Environment, University of California, Los Angeles, CA 90095, USA Niche...

  19. An accelerated proximal gradient algorithm for nuclear norm ...

    E-Print Network [OSTI]

    Kim-Chuan Toh

    2009-03-27T23:59:59.000Z

    Mar 27, 2009 ... An accelerated proximal gradient algorithm for nuclear norm regularized least squares problems. Kim-Chuan Toh (mattohkc ***at*** nus.edu.sg)

  20. Thermal Gradient Holes At Long Valley Caldera Geothermal Area...

    Open Energy Info (EERE)

    Activity Details Location Long Valley Caldera Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1991 - 1991 Usefulness not useful DOE-funding Unknown...

  1. Thermal Gradient Holes At Long Valley Caldera Geothermal Area...

    Open Energy Info (EERE)

    Activity Details Location Long Valley Caldera Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1978 - 1985 Usefulness useful DOE-funding Unknown...

  2. Thermal Gradient Holes At North Brawley Geothermal Area (Edmunds...

    Open Energy Info (EERE)

    of the North Brawley, Heber, East Mesa, and Salton Sea Geothermal Areas. Notes Well logs, thermal gradient data, and magnetic data were correlated to form a better geologic...

  3. Thermal Gradient Holes At Lightning Dock Geothermal Area (Cunniff...

    Open Energy Info (EERE)

    Thermal Gradient Holes At Lightning Dock Geothermal Area (Cunniff & Bowers, 2005) Exploration Activity Details Location Lightning Dock Geothermal Area Exploration Technique Thermal...

  4. Thermal Gradient Holes At North Brawley Geothermal Area (Matlick...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At North Brawley Geothermal Area (Matlick & Jayne, 2008) Exploration...

  5. SampleRank: Training Factor Graphs with Atomic Gradients

    E-Print Network [OSTI]

    McCallum, Andrew

    a user-provided loss function to distribute stochastic gradients across an MCMC chain. As a result, parameter updates can be computed between arbitrary MCMC states. Sam- pleRank is not only faster than CD- expensive gradients between the ground-truth and samples along an MCMC chain yielding a stochastic

  6. The Simplex Gradient and Noisy Optimization Problems \\Lambda

    E-Print Network [OSTI]

    The Simplex Gradient and Noisy Optimization Problems \\Lambda D. M. Bortz C. T. Kelley North the simplex gradient from [14], the first order estimates it satisfies, and its application to the Nelder/or exploit parallelism. The algorithms we discuss in this paper all examine a simplex of points in R N

  7. Dynamics of the Dorsal morphogen gradient Jitendra S. Kanodiaa

    E-Print Network [OSTI]

    Shvartsman, Stanislav "Stas"

    Dynamics of the Dorsal morphogen gradient Jitendra S. Kanodiaa , Richa Rikhyb , Yoosik Kima Road, Princeton, NJ 08544; bCell Biology and Metabolism Branch, NIH, Building 32, 18 Library Drive localization gradient of Dorsal (Dl), a protein related to the mammalian NF- B transcription factors. Current

  8. Enhancing Optical Gradient Forces with Metamaterials Vincent Ginis,1

    E-Print Network [OSTI]

    Enhancing Optical Gradient Forces with Metamaterials Vincent Ginis,1 Philippe Tassin,2,* Costas M demonstrate how the optical gradient force between two waveguides can be enhanced using transformation optics perceived by light, resulting in a more than tenfold enhancement of the optical force. This process

  9. Combining Conjugate Direction Methods with Stochastic Approximation of Gradients

    E-Print Network [OSTI]

    Schraudolph, Nicol N.

    Combining Conjugate Direction Methods with Stochastic Approximation of Gradients #3; Nicol N-8092 Zurich, Switzerland http://www.icos.ethz.ch/ Abstract The method of conjugate directions provides from conjugate gra- dient in the stochastic (online) setting, us- ing fast Hessian-gradient products

  10. Combining Conjugate Direction Methods with Stochastic Approximation of Gradients

    E-Print Network [OSTI]

    Schraudolph, Nicol N.

    Combining Conjugate Direction Methods with Stochastic Approximation of Gradients Nicol N-8092 Z¨urich, Switzerland http://www.icos.ethz.ch/ Abstract The method of conjugate directions provides conjugate gra- dient in the stochastic (online) setting, us- ing fast Hessian-gradient products to set up

  11. Generalized Hooke's law for isotropic second gradient materials

    E-Print Network [OSTI]

    F. dell'Isola; G. Sciarra; S. Vidoli

    2010-08-17T23:59:59.000Z

    In the spirit of Germain the most general objective stored elastic energy for a second gradient material is deduced using a literature result of Fortun\\'e & Vall\\'ee. Linear isotropic constitutive relations for stress and hyperstress in terms of strain and strain-gradient are then obtained proving that these materials are characterized by seven elastic moduli and generalizing previous studies by Toupin, Mindlin and Sokolowski. Using a suitable decomposition of the strain-gradient, it is found a necessary and sufficient condition, to be verified by the elastic moduli, assuring positive definiteness of the stored elastic energy. The problem of warping in linear torsion of a prismatic second gradient cylinder is formulated, thus obtaining a possible measurement procedure for one of the second gradient elastic moduli.

  12. A complete implementation of the conjugate gradient algorithm on a reconfigurable supercomputer

    SciTech Connect (OSTI)

    Dubois, David H [Los Alamos National Laboratory; Dubois, Andrew J [Los Alamos National Laboratory; Connor, Carolyn M [Los Alamos National Laboratory; Boorman, Thomas M [Los Alamos National Laboratory; Poole, Stephen W [ORNL

    2008-01-01T23:59:59.000Z

    The conjugate gradient is a prominent iterative method for solving systems of sparse linear equations. Large-scale scientific applications often utilize a conjugate gradient solver at their computational core. In this paper we present a field programmable gate array (FPGA) based implementation of a double precision, non-preconditioned, conjugate gradient solver for fmite-element or finite-difference methods. OUf work utilizes the SRC Computers, Inc. MAPStation hardware platform along with the 'Carte' software programming environment to ease the programming workload when working with the hybrid (CPUIFPGA) environment. The implementation is designed to handle large sparse matrices of up to order N x N where N <= 116,394, with up to 7 non-zero, 64-bit elements per sparse row. This implementation utilizes an optimized sparse matrix-vector multiply operation which is critical for obtaining high performance. Direct parallel implementations of loop unrolling and loop fusion are utilized to extract performance from the various vector/matrix operations. Rather than utilize the FPGA devices as function off-load accelerators, our implementation uses the FPGAs to implement the core conjugate gradient algorithm. Measured run-time performance data is presented comparing the FPGA implementation to a software-only version showing that the FPGA can outperform processors running up to 30x the clock rate. In conclusion we take a look at the new SRC-7 system and estimate the performance of this algorithm on that architecture.

  13. Natural Conjugate Gradient on Complex Flag Manifolds for Complex Independent Subspace

    E-Print Network [OSTI]

    Plumbley, Mark

    conjugate gradient method yields better convergence compared to the natural gradient geodesic search method is the natural gradient geodesic search method (NGS), and the other is the natural conjugate gradient method (NCG the natural gradient or the Newton's method on complex manifolds, however, the behavior of the conjugate

  14. A conjugate Rosen's gradient projection method with global line search for piecewise linear optimization

    E-Print Network [OSTI]

    Beltran-Royo, Cesar

    A conjugate Rosen's gradient projection method with global line search for piecewise linear cutting plane method, simplex method, Rosen's gradient projection, conjugate gradient. 1 Introduction the zig-zagging of the gradient projection, we propose a conjugate gradient version of the face simplex

  15. Strict convexity of the free energy for non-convex gradient models at moderate $?$

    E-Print Network [OSTI]

    Codina Cotar; Jean-Dominique Deuschel; Stefan Müller

    2008-01-08T23:59:59.000Z

    We consider a gradient interface model on the lattice with interaction potential which is a non-convex perturbation of a convex potential. We show using a one-step multiple scale analysis the strict convexity of the surface tension at high temperature. This is an extension of Funaki and Spohn's result, where the strict convexity of potential was crucial in their proof that for every tilt there is a unique, shift invariant, ergodic Gibbs measure for the $\

  16. Efficient and robust gradient enhanced Kriging emulators.

    SciTech Connect (OSTI)

    Dalbey, Keith R.

    2013-08-01T23:59:59.000Z

    %E2%80%9CNaive%E2%80%9D or straight-forward Kriging implementations can often perform poorly in practice. The relevant features of the robustly accurate and efficient Kriging and Gradient Enhanced Kriging (GEK) implementations in the DAKOTA software package are detailed herein. The principal contribution is a novel, effective, and efficient approach to handle ill-conditioning of GEK's %E2%80%9Ccorrelation%E2%80%9D matrix, RN%CC%83, based on a pivoted Cholesky factorization of Kriging's (not GEK's) correlation matrix, R, which is a small sub-matrix within GEK's RN%CC%83 matrix. The approach discards sample points/equations that contribute the least %E2%80%9Cnew%E2%80%9D information to RN%CC%83. Since these points contain the least new information, they are the ones which when discarded are both the easiest to predict and provide maximum improvement of RN%CC%83's conditioning. Prior to this work, handling ill-conditioned correlation matrices was a major, perhaps the principal, unsolved challenge necessary for robust and efficient GEK emulators. Numerical results demonstrate that GEK predictions can be significantly more accurate when GEK is allowed to discard points by the presented method. Numerical results also indicate that GEK can be used to break the curse of dimensionality by exploiting inexpensive derivatives (such as those provided by automatic differentiation or adjoint techniques), smoothness in the response being modeled, and adaptive sampling. Development of a suitable adaptive sampling algorithm was beyond the scope of this work; instead adaptive sampling was approximated by omitting the cost of samples discarded by the presented pivoted Cholesky approach.

  17. Subwavelength silicon through-hole arrays as an all-dielectric broadband terahertz gradient index metamaterial

    SciTech Connect (OSTI)

    Park, Sang-Gil; Jeong, Ki-Hun, E-mail: kjeong@kaist.ac.kr [Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); KAIST Institute for Optical Science and Technology, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Lee, Kanghee; Han, Daehoon; Ahn, Jaewook [KAIST Institute for Optical Science and Technology, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2014-09-01T23:59:59.000Z

    Structuring at subwavelength scales brings out artificial media with anomalous optical features called metamaterials. All-dielectric metamaterials have high potential for practical applications over the whole electromagnetic spectrum owing to low loss and optical isotropy. Here, we report subwavelength silicon through-hole arrays as an all-dielectric gradient index metamaterial with broadband THz operation. The unit cell consists of a single subwavelength through-hole on highly resistive monocrystalline silicon. Depending on the fill-factor and period, the effective index was linearly modulated at 0.3–1.6 THz. The experimental results also demonstrate silicon gradient refractive index (Si-GRIN) lenses with parabolic index profiles through the spatial modification of a single unit cell along the radial direction. Si-GRIN lenses either focus 0.4–1.6 THz beam to the diffraction-limit or serve as a flat and thin solid immersion lens on the backside of THz photoconductive antenna for highly efficient pulse extraction. This all-dielectric gradient index metamaterial opens up opportunities for integrated THz GRIN optics.

  18. Investigation of Turbulent transition in plane Couette flows Using Energy Gradient Method

    E-Print Network [OSTI]

    Hua-Shu Dou; Boo Cheong Khoo

    2010-06-07T23:59:59.000Z

    The energy gradient method has been proposed with the aim of better understanding the mechanism of flow transition from laminar flow to turbulent flow. In this method, it is demonstrated that the transition to turbulence depends on the relative magnitudes of the transverse gradient of the total mechanical energy which amplifies the disturbance and the energy loss from viscous friction which damps the disturbance, for given imposed disturbance. For a given flow geometry and fluid properties, when the maximum of the function K (a function standing for the ratio of the gradient of total mechanical energy in the transverse direction to the rate of energy loss due to viscous friction in the streamwise direction) in the flow field is larger than a certain critical value, it is expected that instability would occur for some initial disturbances. In this paper, using the energy gradient analysis, the equation for calculating the energy gradient function K for plane Couette flow is derived. The result indicates that K reaches the maximum at the moving walls. Thus, the fluid layer near the moving wall is the most dangerous position to generate initial oscillation at sufficient high Re for given same level of normalized perturbation in the domain. The critical value of K at turbulent transition, which is observed from experiments, is about 370 for plane Couette flow when two walls move in opposite directions (anti-symmetry). This value is about the same as that for plane Poiseuille flow and pipe Poiseuille flow (385-389). Therefore, it is concluded that the critical value of K at turbulent transition is about 370-389 for wall-bounded parallel shear flows which include both pressure (symmetrical case) and shear driven flows (anti-symmetrical case).

  19. Algorithm PREQN: Fortran 77 Subroutines for Preconditioning the Conjugate Gradient Method

    E-Print Network [OSTI]

    Nocedal, Jorge

    Algorithm PREQN: Fortran 77 Subroutines for Preconditioning the Conjugate Gradient Method Jos subroutines for automatically generating pre­ conditioners for the conjugate gradient method. It is designed. Additional Key Words and Phrases: Preconditioning, conjugate gradient method, quasi­ Newton method, Hessian

  20. COMPARISON OF THE DEFLATED PRECONDITIONED CONJUGATE GRADIENT METHOD AND ALGEBRAIC MULTIGRID FOR COMPOSITE

    E-Print Network [OSTI]

    MacLachlan, Scott

    COMPARISON OF THE DEFLATED PRECONDITIONED CONJUGATE GRADIENT METHOD AND ALGEBRAIC MULTIGRID algorithms such as the Preconditioned Conjugate Gradient (PCG) method. This paper considers the Deflated Preconditioned Conjugate Gradient (DPCG) method in which the rigid body modes of sets of elements

  1. Characterization and Application of Hard X-Ray Betatron Radiation Generated by Relativistic Electrons from a Laser-Wakefield Accelerator

    E-Print Network [OSTI]

    Schnell, Michael; Uschmann, Ingo; Jansen, Oliver; Kaluza, Malte Christoph; Spielmann, Christian

    2015-01-01T23:59:59.000Z

    The necessity for compact table-top x-ray sources with higher brightness, shorter wavelength and shorter pulse duration has led to the development of complementary sources based on laser-plasma accelerators, in contrast to conventional accelerators. Relativistic interaction of short-pulse lasers with underdense plasmas results in acceleration of electrons and in consequence in the emission of spatially coherent radiation, which is known in the literature as betatron radiation. In this article we report on our recent results in the rapidly developing field of secondary x-ray radiation generated by high-energy electron pulses. The betatron radiation is characterized with a novel setup allowing to measure the energy, the spatial energy distribution in the far-field of the beam and the source size in a single laser shot. Furthermore, the polarization state is measured for each laser shot. In this way the emitted betatron x-rays can be used as a non-invasive diagnostic tool to retrieve very subtle information of t...

  2. Distributed Kalman filtering compared to Fourier domain preconditioned conjugate gradient

    E-Print Network [OSTI]

    Greer, Julia R.

    Distributed Kalman filtering compared to Fourier domain preconditioned conjugate gradient for laser of the tomography problem. The second algorithm is the distributed Kalman filter (DKF) developed by Massioni et al

  3. Colour Gradients in the Optical and Near-IR

    E-Print Network [OSTI]

    Roelof S. de Jong

    1995-09-01T23:59:59.000Z

    For many years broadband colours have been used to obtain insight into the contents of galaxies, in particular to estimate stellar and dust content. Broadband colours are easy to obtain for large samples of objects, making them ideal for statistical studies. In this paper I use the radial distribution of the colours in galaxies, which gives more insight into the local processes driving the global colour differences than integrated colours. Almost all galaxies in my sample of 86 face-on galaxies become systematically bluer with increasing radius. The radial photometry is compared to new dust extinction models and stellar population synthesis models. This comparison shows that the colour gradients in face-on galaxies are best explained by age and metallicity gradients in the stellar populations and that dust reddening plays a minor role. The colour gradients imply $M/L$ gradients, making the `missing light' problem as derived from rotation curve fitting even worse.

  4. Field Investigations And Temperature-Gradient Drilling At Marine...

    Open Energy Info (EERE)

    Investigations And Temperature-Gradient Drilling At Marine Corps Air-Ground Combat Center (Mcagcc), Twenty-Nine Palms, Ca Jump to: navigation, search OpenEI Reference LibraryAdd to...

  5. Optimization Online - A conjugate-gradient based approach for ...

    E-Print Network [OSTI]

    Fredrik Carlsson

    2008-02-29T23:59:59.000Z

    Feb 29, 2008 ... In particular, it is noted that with a bound on the two-norm of the columns, the method is equivalent to the conjugate-gradient method. Further ...

  6. Function of the anterior gradient protein family in cancer 

    E-Print Network [OSTI]

    Fourtouna, Argyro

    2009-01-01T23:59:59.000Z

    Proteomic technologies verified Anterior Gradient 2, AGR-2, as a protein over-expressed in human cancers, including breast, prostate and oesophagus cancers, with the ability to inhibit the tumour suppressor protein p53. AGR-2 gene is a hormone...

  7. Energy Flow in Extended Gradient Partial Differential Equations

    E-Print Network [OSTI]

    Energy Flow in Extended Gradient Partial Differential Equations Th. Gallay S. Slijepâ??atiment 425 BijeniŸcka 30 F­91405 Orsay, France 10000 Zagreb, Croatia Thierry.Gallay@math.u­psud.fr slijepce

  8. A Nonlinear Conjugate Gradient Algorithm with An Optimal Property ...

    E-Print Network [OSTI]

    2011-06-15T23:59:59.000Z

    State Key Laboratory of Scientific and Engineering Computing, ..... To establish a basic property for the family of conjugate gradient methods (1.3), (2.11) and ...... of Engineering Economic Systems, Stanford University, Stanford, Calif., 1972. 23

  9. Spatial gradient of protein phosphorylation underlies replicative bacterium

    E-Print Network [OSTI]

    Chen, Y. Erin

    Spatial asymmetry is crucial to development. One mechanism for generating asymmetry involves the localized synthesis of a key regulatory protein that diffuses away from its source, forming a spatial gradient. Although ...

  10. Thermal Gradient Holes At Lightning Dock Geothermal Area (Arnold...

    Open Energy Info (EERE)

    DOE-funding Unknown Exploration Basis Known shallow hot spot in Animas Valley Notes Four thermal gradient holes were authorized to be drilled by AMEX, but no results were...

  11. Accounting for the Change in the Gradient: Health Inequality among Infants

    E-Print Network [OSTI]

    Lin, Wanchuan

    2006-01-01T23:59:59.000Z

    R. 1985. “Social Class Inequality in Mortality from 1921 toin the Gradient: Health Inequality Among Infants Wanchuanin the Gradient: Health Inequality Among Infants * Wanchuan

  12. Measurements of aerosol thermophoretic deposition: Transition with temperature gradient

    SciTech Connect (OSTI)

    Varma, A.; Tompson, R.V.; Loyalka, S.K. [Univ. of Missouri, Columbia, MO (United States)

    1995-12-31T23:59:59.000Z

    Thermophoresis is the motion of aerosol particles due to a temperature gradient in the suspending gas. The thermophoretic velocity V{sub T} is expressed as: where a {alpha} = thermal diffusivity v = kinematic viscosity H= Pr K Pr = Prandtl number K = dimensionless coefficient that is a function of several parameters (particle radius, thermal conductivity, gas properties, gas surface interactions). This report describes measurements of the effects of temperature gradients on the deposition of polystyrene latex particles.

  13. A Spectral Conjugate Gradient Method for Unconstrained Optimization

    SciTech Connect (OSTI)

    Birgin, E. G. [Department of Computer Science, IME-USP, University of Sao Paulo, Rua do Matao, 1010 - Cidade Universitaria, 05508-900 Sao Paulo SP (Brazil)], E-mail: egbirgin@ime.usp.br; Martinez, J. M. [Department of Applied Mathematics, IMECC-UNICAMP, University of Campinas, CP 6065, 13081-970 Campinas SP (Brazil)], E-mail: martinez@ime.unicamp.br

    2001-07-01T23:59:59.000Z

    A family of scaled conjugate gradient algorithms for large-scale unconstrained minimization is defined. The Perry, the Polak-Ribiere and the Fletcher-Reeves formulae are compared using a spectral scaling derived from Raydan's spectral gradient optimization method. The best combination of formula, scaling and initial choice of step-length is compared against well known algorithms using a classical set of problems. An additional comparison involving an ill-conditioned estimation problem in Optics is presented.

  14. Reduction of particle deposition on substrates using temperature gradient control

    DOE Patents [OSTI]

    Rader, Daniel J. (Albuquerque, NM); Dykhuizen, Ronald C. (Albuquerque, NM); Geller, Anthony S. (Albuquerque, NM)

    2000-01-01T23:59:59.000Z

    A method of reducing particle deposition during the fabrication of microelectronic circuitry is presented. Reduction of particle deposition is accomplished by controlling the relative temperatures of various parts of the deposition system so that a large temperature gradient near the surface on which fabrication is taking place exists. This temperature gradient acts to repel particles from that surface, thereby producing cleaner surfaces, and thus obtaining higher yields from a given microelectronic fabrication process.

  15. Mass Function Gradients and the Need for Dark Matter

    E-Print Network [OSTI]

    Jason A. Taylor

    1998-03-05T23:59:59.000Z

    There is substantial evidence that the initial mass function (IMF) may be a function of the local star formation conditions. In particular, the IMF is predicted to flatten with increasing local luminosity density, with the formation of massive stars being preferentially enhanced in brighter regions. If IMF gradients are general features of galaxies, several previous astrophysical measurements, such as the surface mass densities of spirals (obtained assuming constant mass to light ratios), were plagued by substantial systematic errors. In this Letter, calculations which account for possible IMF gradients are presented of surface densities of spiral galaxies. Compared to previous estimates, the mass densities corrected for IMF gradients are higher in the outer regions of the disks. For a model based on the Milky Way but with an IMF scaled according to R136, the rotation curve without the traditional dark halo component falls with Galactocentric radius, though slower than it would without IMF gradients. For a second model of the Milky Way in which the IMF gradient is increased by 50%, the rotation curve is approximately flat in the outer disk, with a rotational velocity below ~220 km/s only before the traditional dark halo component is added. These results, if generalizable to other galaxies, not only call into question the assertion that dark matter halos are compatible with the flat rotation curves of spiral galaxies, but also may clarify our understanding of a wide variety of other astrophysical phenomena such as the G-dwarf problem, metallicity gradients, and the Tully-Fisher relation.

  16. Development of Ti/Ti{sub 3}Sn functionally gradient material produced by eutectic bonding method

    SciTech Connect (OSTI)

    Kirihara, S.; Takeda, M.; Tsujimoto, T. [Ibaraki Univ., Hitachi (Japan). Faculty of Engineering] [Ibaraki Univ., Hitachi (Japan). Faculty of Engineering

    1996-07-15T23:59:59.000Z

    Although many materials which have a single function have been developed, future needs are anticipated to include materials which have various functions. A functionally gradient material (FGM) which has characteristics of two different materials is a promising candidate for multi-functional material. The present methods for production of FGM, however, are very complicated and costly. In this study the authors answer the serious problem of high production cost by fabricating the FGM by a eutectic bonding method. This fabrication method includes structural control of FGM by changing the cooling process. They describe Ti/Ti{sub 3}Sn FGM obtained by the eutectic bonding method, and tell how the structure of its composition gradient part is changed by controlling the cooling process.

  17. Imaging diffusion with non-uniform B{sub 1} gradients.

    SciTech Connect (OSTI)

    Woelk, K.

    1998-01-30T23:59:59.000Z

    Rotating-frame imaging with the mathematically well-defined, non-constant magnetic field gradient of toroid cavity detectors represents a new technique to evaluate diffusion in solids, fluids or mixed-phase systems. While conventional NMR methods to measure diffusion utilize constant magnetic field gradients and, therefore, constant k-space wave numbers across the sample volume, the hyperbolic B{sub 1} fields of toroid cavity detectors exhibit large ranges of wave numbers radially distributed around the central conductor. As a consequence, signal amplitudes decay depending on the radial distance from the center axis of the torus. Applying a numerical finite-difference procedure to solve partial differential transport equations makes it possible not only to determine diffusion in toroid detectors to a high precision but also to include and accurately reproduce transport phenomena at or through singularities, such as phase transitions, membranes or impermeable boundaries.

  18. Study of Turbulent Fluctuations Driven by the Electron Temperature Gradient in the National Spherical Torus Experiment

    SciTech Connect (OSTI)

    Mazzucato, E.; Bell, R. E.; Ethier, S.; Hosea, J. C.; Kaye, S. M.; LeBlanc, B. P.; Lee, W. W.; Ryan, P. M.; Smith, D. R.; Wang, W. X.; Wilson, J. R.

    2009-03-26T23:59:59.000Z

    Various theories and numerical simulations support the conjecture that the ubiquitous problem of anomalous electron transport in tokamaks may arise from a short-scale turbulence driven by the electron temperature gradient. To check whether this turbulence is present in plasmas of the National Spherical Torus Experiment (NSTX), measurements of turbulent fluctuations were performed with coherent scattering of electromagnetic waves. Results from plasmas heated by high harmonic fast waves (HHFW) show the existence of density fluctuations in the range of wave numbers k??e=0.1-0.4, corresponding to a turbulence scale length of the order of the collisionless skin depth. Experimental observations and agreement with numerical results from the linear gyro-kinetic GS2 code indicate that the observed turbulence is driven by the electron temperature gradient. These turbulent fluctuations were not observed at the location of an internal transport barrier driven by a negative magnetic shear.

  19. Major transitions in evolution linked to thermal gradients above hydrothermal vents

    E-Print Network [OSTI]

    Anthonie W. J. Muller

    2012-12-03T23:59:59.000Z

    The emergence of the main divisions of today's life: (1) unicellular prokaryotes, (2) unicellular eukaryotes, (3) multicellular eukaryotes, and (4) metazoans, are examples of the--still unexplained--major transitions in evolution. Regarding the origin of life, I have proposed that primordial life functioned as heat engine (thermosynthesis) while thermally cycled in convecting volcanic hot springs. Here I argue for a role of thermal gradients above submarine hydrothermal vents (SHV) in several major transitions. The last decade has witnessed the emergence of phononics, a novel discipline in physics based on controlled heat transport in thermal gradients. It builds thermal analogs to electronic devices: the thermal diode, the thermal transistor, the thermal switch, the thermal amplifier, the thermal memory--the thermal computer has been proposed. Encouraged by (1) the many similarities between microtubules (MT) and carbon nanotubes, which have a very high thermal conductivity, and (2) the recent discovery of a silk protein which also has a very high thermal conductivity, I combine and extend the mentioned ideas, and propose the general conjecture that several major transitions of evolution were effected by thermal processes, with four additional partial conjectures: (1) The first organisms used heat engines during thermosynthesis in convection cells; (2) The first eukaryotic cells used MT during thermosynthesis in the thermal gradient above SHV; (3) The first metazoans used transport of water or in water during thermosynthesis above SHV under an ice-covered ocean during the Gaskiers Snowball Earth; and (4) The first mammalian brain used a thermal machinery based on thermal gradients in or across the cortex. When experimentally proven these conjectures, which are testable by the methods of synthetic biology, would significantly enhance our understanding of life.

  20. Environmental regulation of carbon isotope composition and crassulacean acid metabolism in three plant communities along a water availability gradient

    E-Print Network [OSTI]

    2010-01-01T23:59:59.000Z

    gradient Á Tissue acidity Á Yucatan Introduction Crassulacean acid metabolism (metabolism in three plant communities along a water availability gradient

  1. Scalar gradient behaviour in MILD combustion

    E-Print Network [OSTI]

    Minamoto, Y.; Swaminathan, N.

    2013-10-22T23:59:59.000Z

    the exhaust gas recircula- tion (EGR) techniques. The recirculation can be either internal or external to the combustor and external EGR is common in heavy duty diesel engines and internal recirculation is common in furnaces. At very high EGR rate, the oxygen...

  2. Evolutionary and Gradient-Based Algorithms for Lennard-Jones Cluster Optimization

    E-Print Network [OSTI]

    Schraudolph, Nicol N.

    gradient method, while Section 3 shows how the asynchronous conjugate gradient method compares and randomized gradient methods with respect to their global search behavior. The randomized gradient method.g., conjugate gra- dient method) is started. With the local minima in- formation, the search is continued

  3. The Solution of Systems of Linear Equations using the Conjugate Gradient Method

    E-Print Network [OSTI]

    Schneider, Jean-Guy

    The Solution of Systems of Linear Equations using the Conjugate Gradient Method on the Parallel gradient solver on the SPMD­programmable MUSIC­system. We outline the conjugate gradient method, give­associativity of the floating point addition. We investi­ gate the speed of convergence of the conjugate gradient method

  4. Newton-conjugate-gradient methods for solitary wave computations Jianke Yang

    E-Print Network [OSTI]

    Yang, Jianke

    Newton-conjugate-gradient methods for solitary wave computations Jianke Yang Department's method Conjugate-gradient methods a b s t r a c t In this paper, the Newton-conjugate-gradient methods the linearization operator is self-adjoint, the preconditioned conjugate-gradient method is pro- posed to solve

  5. A NONLINEAR CONJUGATE GRADIENT METHOD WITH A STRONG GLOBAL CONVERGENCE PROPERTY

    E-Print Network [OSTI]

    Yuan, Ya-xiang

    A NONLINEAR CONJUGATE GRADIENT METHOD WITH A STRONG GLOBAL CONVERGENCE PROPERTY Y. H. DAI AND Y­182 Abstract. Conjugate gradient methods are widely used for unconstrained optimization, especially large scale gradient methods. This paper presents a new version of the conjugate gradient method, which converges

  6. Algorithm 851: CG DESCENT, a Conjugate Gradient Method with Guaranteed Descent

    E-Print Network [OSTI]

    Zhang, Hongchao

    Algorithm 851: CG DESCENT, a Conjugate Gradient Method with Guaranteed Descent WILLIAM W. HAGER In Hager and Zhang [2005] we introduce a new nonlinear conjugate gradient method for solving con- jugate gradient research. The iterates xk, k 0, in conjugate gradient methods satisfy

  7. Efficient Computation of Entropy Gradient for Semi-Supervised Conditional Random Fields

    E-Print Network [OSTI]

    McCallum, Andrew

    gradient that is significantly more efficient--having the same asymptotic time complexity as su- pervised

  8. Quasi-linear gradients for capillary liquid chromatography with mass and tandem mass

    E-Print Network [OSTI]

    Dabiri, John O.

    Gradient elution, capillary liquid chromatography mass spectrometry was performed with linear, static the use of additional valves, mixers, pumps or software. It took less than 10 minutes to form a gradient-line as static gradients.12­14 The technique of forming static gradients was first proposed by Ishii and co

  9. X-band EPR imaging as a tool for gradient dose reconstruction in irradiated bones

    SciTech Connect (OSTI)

    Leveque, Philippe; Godechal, Quentin; Bol, Anne; Trompier, Francois; Gallez, Bernard [Biomedical Magnetic Resonance Unit, Universite catholique de Louvain, B-1200 Brussels (Belgium); Molecular Imaging and Experimental Radiotherapy Unit, Universite catholique de Louvain, B-1200 Brussels (Belgium); Institut de Surete Nucleaire et de Radioprotection, F-92262 Fontenay-aux-Roses (France); Biomedical Magnetic Resonance Unit, Universite catholique de Louvain, B-1200 Brussels (Belgium)

    2009-09-15T23:59:59.000Z

    Purpose: Various tools are currently available for dose reconstruction in individuals after accidental exposure to ionizing radiation. Among the available biological analyses, Monte Carlo simulations, and biophysical methods, such as electron paramagnetic resonance (EPR), the latter has proved its usefulness for retrospective dosimetry. Although EPR spectroscopy is probably the most sensitive technique, it does not provide spatial dosimetric data. This information is, however, highly desirable when steep dose gradient irradiations are involved. The purpose of this work was to explore the possibilities of EPR imaging (EPRI) for spatial dose reconstruction in irradiated biological material. Methods: X-band EPRI was used to reconstruct ex vivo the relative dose distribution in human bone samples and hydroxyapatite phantoms after irradiation with brachytherapy seeds or x rays. Three situations were investigated: Homogeneous, stepwise gradient, and continuous gradient irradiation. Results: EPRI gave a faithful relative spin density distribution in bone samples and in hydroxyapatite phantoms. Measured dose ratios were in close agreement with the actual delivered dose ratios. EPRI was able to distinguish the dose gradients induced by two different sources ({sup 125}I and {sup 192}Ir). However, the measured spatial resolution of the system was 1.9 mm and this appeared to be a limiting factor. The method could be improved by using new signal postprocessing strategies. Conclusions: This study demonstrates that EPRI can be used to assess the regional relative dose distribution in irradiated bone samples. The method is currently applicable to ex vivo measurements of small size samples with low variation in tissue density but is likely to be adapted for in vivo application using L-band EPRI.

  10. High Performance Multivariate Visual Data Exploration for Extremely Large Data

    SciTech Connect (OSTI)

    Rubel, Oliver; Wu, Kesheng; Childs, Hank; Meredith, Jeremy; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Ahern, Sean; Weber, Gunther H.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes; Prabhat,

    2008-08-22T23:59:59.000Z

    One of the central challenges in modern science is the need to quickly derive knowledge and understanding from large, complex collections of data. We present a new approach that deals with this challenge by combining and extending techniques from high performance visual data analysis and scientific data management. This approach is demonstrated within the context of gaining insight from complex, time-varying datasets produced by a laser wakefield accelerator simulation. Our approach leverages histogram-based parallel coordinates for both visual information display as well as a vehicle for guiding a data mining operation. Data extraction and subsetting are implemented with state-of-the-art index/query technology. This approach, while applied here to accelerator science, is generally applicable to a broad set of science applications, and is implemented in a production-quality visual data analysis infrastructure. We conduct a detailed performance analysis and demonstrate good scalability on a distributed memory Cray XT4 system.

  11. Resistive Wall Heating of the Undulator in High Repetition Rate

    SciTech Connect (OSTI)

    Qiang, J; Corlett, J; Emma, P; Wu, J

    2012-05-20T23:59:59.000Z

    In next generation high repetition rate FELs, beam energy loss due to resistive wall wakefields will produce significant amount of heat. The heat load for a superconducting undulator (operating at low temperature), must be removed and will be expensive to remove. In this paper, we study this effect in an undulator proposed for a Next Generation Light Source (NGLS) at LBNL. We benchmark our calculations with measurements at the LCLS and carry out detailed parameter studies using beam from a start-to-end simulation. Our preliminarym results suggest that the heat load in the undulator is about 2 W/m or lower with an aperture size of 6 mm for nominal NGLS preliminary design parameters.

  12. SOLPOND: a simulation program for salinity gradient solar ponds

    SciTech Connect (OSTI)

    Henderson, J.; Leboeuf, C.M.

    1980-01-01T23:59:59.000Z

    A computer simulation design tool was developed to simulate dynamic thermal performance for salinity gradient solar ponds. Dynamic programming techniques allow the user significant flexibility in analyzing pond performance under realistic load and weather conditions. Finite element techniques describe conduction heat transfer through the pond, earth, and edges. Results illustrate typical thermal performance of salinity gradient ponds. Sensitivity studies of salty pond thermal performance with respect to geometry, load, and optical transmission are included. Experimental validation of the program with an operating pond is also presented.

  13. Radial gradients and metallicities in the galactic disk

    E-Print Network [OSTI]

    W. J. Maciel

    2000-12-08T23:59:59.000Z

    Radial O/H abundance gradients derived from HII regions, hot stars and planetary nebulae are combined with [Fe/H] gradients from open cluster stars in order to derive an independent [O/Fe] x [Fe/H] relation for the galactic disk. A comparison of the obtained relation with recent observational data and theoretical models suggests that the [O/Fe] ratio is not higher than [O/Fe] ~ 0.4, at least within the metallicity range of the considered samples.

  14. Nonlinear elastic free energies and gradient Young-Gibbs measures

    E-Print Network [OSTI]

    Roman Kotecký; Stephan Luckhaus

    2012-06-26T23:59:59.000Z

    We investigate, in a fairly general setting, the limit of large volume equilibrium Gibbs measures for elasticity type Hamiltonians with clamped boundary conditions. The existence of a quasiconvex free energy, forming the large deviations rate functional, is shown using a new interpolation lemma for partition functions. The local behaviour of the Gibbs measures can be parametrized by Young measures on the space of gradient Gibbs measures. In view of unboundedness of the state space, the crucial tool here is an exponential tightness estimate that holds for a vast class of potentials and the construction of suitable compact sets of gradient Gibbs measures.

  15. On Higuchi Ghosts and Gradient Instabilities in Bimetric Gravity

    E-Print Network [OSTI]

    Könnig, Frank

    2015-01-01T23:59:59.000Z

    We discuss the conditions to satisfy the Higuchi bound and to avoid gradient instabilities in the scalar sector for cosmological solutions in singly coupled bimetric gravity theories. We find that in expanding universes the ratio of the scale factors of the reference and observable metric has to increase at all times. This automatically implies a ghost-free helicity-2 sector and enforces a phantom Dark Energy. Furthermore, the condition for the absence of gradient instabilities in the scalar sector will be analyzed. Finally, we discuss whether cosmological solutions, including exotic evolutions like bouncing cosmologies, can exist, in which both the Higuchi ghost and scalar instabilities are absent at all times.

  16. Gradient isolator for flow field of fuel cell assembly

    DOE Patents [OSTI]

    Ernst, William D. (Troy, NY)

    1999-01-01T23:59:59.000Z

    Isolator(s) include isolating material and optionally gasketing material strategically positioned within a fuel cell assembly. The isolating material is disposed between a solid electrolyte and a metal flow field plate. Reactant fluid carried by flow field plate channel(s) forms a generally transverse electrochemical gradient. The isolator(s) serve to isolate electrochemically a portion of the flow field plate, for example, transversely outward from the channel(s), from the electrochemical gradient. Further, the isolator(s) serve to protect a portion of the solid electrolyte from metallic ions.

  17. Velocity bunching in travelling wave accelerator with low acceleration gradient

    E-Print Network [OSTI]

    Huang, Rui-Xuan; Li, Wei-Wei; Jia, Qi-Ka

    2013-01-01T23:59:59.000Z

    We present the analytical and simulated results concerning the influences of the acceleration gradient in the velocity bunching process, which is a bunch compression scheme that uses a traveling wave accelerating structure as a compressor. Our study shows that the bunch compression application with low acceleration gradient is more tolerant to phase jitter and more successful to obtain compressed electron beam with symmetrical longitudinal distribution and low energy spread. We also present a transverse emittance compensation scheme to compensate the emittance growth caused by the increasing of the space charge force in the compressing process that is easy to be adjusted for different compressing factors.

  18. Discontinuous Galerkin finite element methods for gradient plasticity.

    SciTech Connect (OSTI)

    Garikipati, Krishna. (University of Michigan, Ann Arbor, MI); Ostien, Jakob T.

    2010-10-01T23:59:59.000Z

    In this report we apply discontinuous Galerkin finite element methods to the equations of an incompatibility based formulation of gradient plasticity. The presentation is motivated with a brief overview of the description of dislocations within a crystal lattice. A tensor representing a measure of the incompatibility with the lattice is used in the formulation of a gradient plasticity model. This model is cast in a variational formulation, and discontinuous Galerkin machinery is employed to implement the formulation into a finite element code. Finally numerical examples of the model are shown.

  19. Gradients of meteorological parameters in convective and nonconvective areas

    E-Print Network [OSTI]

    McCown, Milton Samuel

    1976-01-01T23:59:59.000Z

    . SYNOPTIC CONDITIONS 4. STRATIFICATION OF DATA 5. COMPUTATIONAL PROCEDURES 21 25 a. Gridding of rawinsonde data 25 b. Gradients 26 5'' lp t* 27 RESULTS 29 a. Gradients 29 1) Convective areas 29 2) Nonconvective areas 31 3) Combined areas 33 vi... air turbulence. By using airplane data from over the western United States, Scoggins (1975) has shown that CAT at 300 mb occurred 71% of the time when the magnitude of the vector horizontal wind shear -5 -1 exceeded 4. 5 x 10 sec . The horizontal...

  20. Gradient isolator for flow field of fuel cell assembly

    DOE Patents [OSTI]

    Ernst, W.D.

    1999-06-15T23:59:59.000Z

    Isolator(s) include isolating material and optionally gasketing material strategically positioned within a fuel cell assembly. The isolating material is disposed between a solid electrolyte and a metal flow field plate. Reactant fluid carried by flow field plate channel(s) forms a generally transverse electrochemical gradient. The isolator(s) serve to isolate electrochemically a portion of the flow field plate, for example, transversely outward from the channel(s), from the electrochemical gradient. Further, the isolator(s) serve to protect a portion of the solid electrolyte from metallic ions. 4 figs.

  1. Turbulent electron transport in edge pedestal by electron temperature gradient turbulence

    SciTech Connect (OSTI)

    Singh, R. [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of) [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 (India); Jhang, Hogun [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)] [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Diamond, P. H. [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of) [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); CMTFO and CASS, University of California, San Diego 92093-0424, California (United States)

    2013-11-15T23:59:59.000Z

    We present a model for turbulent electron thermal transport at the edge pedestal in high (H)-mode plasmas based on electron temperature gradient (ETG) turbulence. A quasi-linear analysis of electrostatic toroidal ETG modes shows that both turbulent electron thermal diffusivity and hyper-resistivity exhibits the Ohkawa scaling in which the radial correlation length of turbulence becomes the order of electron skin depth. Combination of the Ohkawa scales and the plasma current dependence results in a novel confinement scaling inside the pedestal region. It is also shown that ETG turbulence induces a thermoelectric pinch, which may accelerate the density pedestal formation.

  2. A strong polynomial gradient algorithm in Linear Programming

    E-Print Network [OSTI]

    peter bruijs

    2015-03-31T23:59:59.000Z

    Page 1 ... Karmarkar don't have the strong characteristic. ... Probably he had no notion of the concept of a convex space, so that is what will have to be .... For the best direction that is left now, one has to exclude from the gradient c exactly and.

  3. Seasonal mass balance gradients in Norway L. A. Rasmussen1

    E-Print Network [OSTI]

    Rasmussen, L.A.

    16 Aug 05 Seasonal mass balance gradients in Norway L. A. Rasmussen1 and L. M. Andreassen2 1 Norwegian Water Resources and Energy Directorate (NVE) P. O. Box 5091 Majorstua, N-0301 Oslo, Norway in Norway exists in their profiles of both seasonal balances, winter bw(z) and summer bs(z). Unlike many

  4. The Urban Environmental Gradient: Anthropogenic Influences on the

    E-Print Network [OSTI]

    Georgia, through Atlanta, to the Gulf of Mexico and reflects a steep gradient in population density from as vehicular traffic. Introduction Many of the common anthropogenic pollution problems are focused in urban geographic areas. Suburbia does not contribute much by way of industrial pollution, but it does serve

  5. Gradient expansion of superhorizon perturbations in G-inflation

    SciTech Connect (OSTI)

    Frusciante, Noemi; Zhou, Shuang-Yong; Sotiriou, Thomas P., E-mail: nfruscia@sissa.it, E-mail: szhou@sissa.it, E-mail: sotiriou@sissa.it [SISSA and INFN Sezione di Trieste, Via Bonomea 265, 34136, Trieste (Italy)

    2013-07-01T23:59:59.000Z

    We develop the gradient expansion formalism for shift-symmetric Galileon-type actions. We focus on backgrounds that undergo inflation, work in the synchronous gauge, and obtain a general solution up to second order without imposing extra conditions at first order. The solution simplifies during the late stages of inflation. We also define a curvature perturbation conserved up to first order.

  6. Continuous Edge Gradient-Based Template Matching for Articulated

    E-Print Network [OSTI]

    Zachmann, Gabriel

    Zachmann IfI Technical Report Series IfI-09-01 #12;Impressum Publisher: Institut für Informatik, Technische (Technical Computer Science) Prof. Dr. Gabriel Zachmann (Computer Graphics) #12;Continuous Edge Gradient-Based Template Matching for Articulated Objects Daniel Mohr and Gabriel Zachmann Abstract Detection

  7. Computing several eigenpairs of Hermitian problems by conjugate gradient iterations

    SciTech Connect (OSTI)

    Ovtchinnikov, E.E. [Harrow School of Computer Science, University of Westminster, Watford Road, Northwick Park, London HA1 3TP (United Kingdom)], E-mail: e_ovtchinnikov@hotmail.com

    2008-11-20T23:59:59.000Z

    The paper is concerned with algorithms for computing several extreme eigenpairs of Hermitian problems based on the conjugate gradient method. We analyse computational strategies employed by various algorithms of this kind reported in the literature and identify their limitations. Our criticism is illustrated by numerical tests on a set of problems from electronic structure calculations and acoustics.

  8. GEOTHERMAL GRADIENT DATA FOR UTAH Robert E. Blackett

    E-Print Network [OSTI]

    Laughlin, Robert B.

    GEOTHERMAL GRADIENT DATA FOR UTAH by Robert E. Blackett February 2004 UTAH GEOLOGICAL SURVEY ­ 1:750,000 scale map, showing geology; thermal wells, springs, and geothermal areas; and locations available sources including the Southern Methodist University Geothermal Laboratory, U.S. Geological Survey

  9. BIOGEOCHEMICAL GRADIENTS AS A FRAMEWORK FOR UNDERSTANDING WASTE SITE EVOLUTION

    SciTech Connect (OSTI)

    Denham, M; Karen Vangelas, K

    2008-10-17T23:59:59.000Z

    The migration of biogeochemical gradients is a useful framework for understanding the evolution of biogeochemical conditions in groundwater at waste sites contaminated with metals and radionuclides. This understanding is critical to selecting sustainable remedies and evaluating sites for monitored natural attenuation, because most attenuation mechanisms are sensitive to geochemical conditions such as pH and redox potential. Knowledge of how gradients in these parameters evolve provides insights into the behavior of contaminants with time and guides characterization, remedy selection, and monitoring efforts. An example is a seepage basin site at the Savannah River Site in South Carolina where low-level acidic waste has seeped into groundwater. The remediation of this site relies, in part, on restoring the natural pH of the aquifer by injecting alkaline solutions. The remediation will continue until the pH up-flow of the treatment zone increases to an acceptable value. The time required to achieve this objective depends on the time it takes the trailing pH gradient, the gradient separating the plume from influxing natural groundwater, to reach the treatment zone. Predictions of this length of time will strongly influence long-term remedial decisions.

  10. Soil macroaggregate dynamics in a mountain spatial climate gradient

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Soil macroaggregate dynamics in a mountain spatial climate gradient Lauric Cécillon1,2,* , Nilvania://lauric.cecillon.free.fr/ Key words: Mountain soils; Climate change; Soil aggregation; Soil organic matter; Near infrared reflectance spectroscopy; Soil threats Biogeochemistry 97: 31-43 (2010) http://dx.doi.org/10.1007/s10533

  11. Scaling limits for gradient systems in random environment

    E-Print Network [OSTI]

    P. Goncalves; M. D. Jara

    2007-02-17T23:59:59.000Z

    For interacting particle systems that satisfies the gradient condition, the hydrodynamic limit and the equilibrium fluctuations are well known. We prove that under the presence of a symmetric random environment, these scaling limits also hold for almost every choice of the environment, with homogenized coefficients that does not depend on the particular realization of the random environment.

  12. Overfitting in Neural Nets: Backpropagation, Conjugate Gradient, and Early Stopping

    E-Print Network [OSTI]

    Caruana, Rich

    Overfitting in Neural Nets: Backpropagation, Conjugate Gradient, and Early Stopping Rich Caruana is that backprop nets with excess hidden units generalize poorly. We show that nets with excess capacity generalize) Regardless of size, nets learn task subcomponents in similar sequence. Big nets pass through stages similar

  13. SUBMIT TO IEEE TIP 1 Motion-Aware Gradient Domain

    E-Print Network [OSTI]

    O'Brien, James F.

    SUBMIT TO IEEE TIP 1 Motion-Aware Gradient Domain Video Composition Tao Chen, Jun-Yan Zhu, Ariel blending boundary based on a user provided blending trimap for the source video. Our approach extends mean performance. We also provide a user interface and source object positioning method that can efficiently deal

  14. A distributed accelerated gradient algorithm for distributed model predictive

    E-Print Network [OSTI]

    Como, Giacomo

    of hydro power plants is to manage the available water resources efficiently, while following an optimal is applied to the power reference tracking problem of a hydro power valley (HPV) system. The applied power control, Distributed optimization, Accelerated gradient algorithm, Model predictive control

  15. A study of microbend test by strain gradient plasticity

    E-Print Network [OSTI]

    Hsia, K Jimmy

    A study of microbend test by strain gradient plasticity W. Wanga , Y. Huangb, *, K.J. Hsiac , K with plastic deformation is on the order of microns. This size effect cannot be explained by classical plasticity theories since their constitutive relations do not have an intrinsic material length. Strain

  16. Treated Wastewater Effluent Reduces Sperm Motility Along an Osmolality Gradient

    E-Print Network [OSTI]

    Julius, Matthew L.

    of the Metropolitan Wastewater Treatment Plant, St. Paul, Minnesota, and from an upstream site on the MississippiTreated Wastewater Effluent Reduces Sperm Motility Along an Osmolality Gradient H. L. Schoenfuss Æ 2008 Ó Springer Science+Business Media, LLC 2008 Abstract Many toxic effects of treated wastewater

  17. A dislocation-based, strain–gradient–plasticity strengthening model for deformation processed metal–metal composites

    SciTech Connect (OSTI)

    Tian, Liang [Ames Laboratory; Russell, Alan [Ames Laboratory; Anderson, Iver [Ames Laboratory

    2014-01-03T23:59:59.000Z

    Deformation processed metal–metal composites (DMMCs) are high-strength, high-electrical conductivity composites developed by severe plastic deformation of two ductile metal phases. The extraordinarily high strength of DMMCs is underestimated using the rule of mixture (or volumetric weighted average) of conventionally work-hardened metals. In this article, a dislocation-density-based, strain–gradient–plasticity model is proposed to relate the strain-gradient effect with the geometrically necessary dislocations emanating from the interface to better predict the strength of DMMCs. The model prediction was compared with the experimental findings of Cu–Nb, Cu–Ta, and Al–Ti DMMC systems to verify the applicability of the new model. The results show that this model predicts the strength of DMMCs better than the rule-of-mixture model. The strain-gradient effect, responsible for the exceptionally high strength of heavily cold worked DMMCs, is dominant at large deformation strain since its characteristic microstructure length is comparable with the intrinsic material length.

  18. Generating spatially and temporally controllable long-range concentration gradients in a microfluidic device

    E-Print Network [OSTI]

    Vidula, Mahesh K.

    Concentration gradients have important applications in chemical and biological studies. Here we have achieved rapid generation of spatially and temporally controllable concentration gradients of diffusible molecules (i.e. ...

  19. PATTERNS OF LEAF WETTABILITY ALONG AN EXTREME MOISTURE GRADIENT IN WESTERN PATAGONIA, ARGENTINA

    E-Print Network [OSTI]

    Brewer, Carol

    PATTERNS OF LEAF WETTABILITY ALONG AN EXTREME MOISTURE GRADIENT IN WESTERN PATAGONIA, ARGENTINA Patagonia, Argentina. Morphological and structural characteristics of leaves significantly affected leaf surfaces. Keywords: leaf wetness, morphology, water droplet, Patagonia, gradient. Introduction A large

  20. INDUSTRIAL AND SYSTEMS ENGINEERING SEMINAR Semi-Stochastic Gradient Descent Methods

    E-Print Network [OSTI]

    Edinburgh, University of

    () of smooth convex loss functions. We propose a new method, S2GD (Semi-StochasticGradient Descent), which runs equivalent to the computation of a single gradient of the loss, is (log(1 / )). This is achieved by running

  1. Gradient Plasticity Model and its Implementation into MARMOT

    SciTech Connect (OSTI)

    Barker, Erin I.; Li, Dongsheng; Zbib, Hussein M.; Sun, Xin

    2013-08-01T23:59:59.000Z

    The influence of strain gradient on deformation behavior of nuclear structural materials, such as boby centered cubic (bcc) iron alloys has been investigated. We have developed and implemented a dislocation based strain gradient crystal plasticity material model. A mesoscale crystal plasticity model for inelastic deformation of metallic material, bcc steel, has been developed and implemented numerically. Continuum Dislocation Dynamics (CDD) with a novel constitutive law based on dislocation density evolution mechanisms was developed to investigate the deformation behaviors of single crystals, as well as polycrystalline materials by coupling CDD and crystal plasticity (CP). The dislocation density evolution law in this model is mechanism-based, with parameters measured from experiments or simulated with lower-length scale models, not an empirical law with parameters back-fitted from the flow curves.

  2. Shading curves: vector-based drawing with explicit gradient control

    E-Print Network [OSTI]

    Lieng, Henrik; Tasse, Flora; Kosinka, Ji?í; Dodgson, Neil A.

    2015-01-01T23:59:59.000Z

    gradient. We resolve this problem by using subdivision surfaces that are constructed from shading curves and their shading profiles. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Gene- ration... potential sources of visual artefacts in Illustrator’s tool: the rendering procedure, the deformation procedure, and blending with underlying layers. Figure 18 shows images coloured with Illustrator’s tool, where arte- facts are visible. In comparison, our...

  3. Determination of dispersivities from a natural-gradient dispersion test

    E-Print Network [OSTI]

    Hoover, Caroline Marie

    1985-01-01T23:59:59.000Z

    of H drolo can be valuable predictive tool s (Wang and Anderson, 1982). Since the late 1800's, mathematical models have been used in problems of groundwater flow. Their appl ication now extends to problems of contaminant transport and migration...DETERMINATION OF DISPERSIVITIES FROM A NATURAL-GRADIENT DISPERSION TEST A Thesis by CAROLINE MARIE HOOVER Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirements for the degree of MASTER...

  4. Solar rotation rate and its gradients during cycle 23

    E-Print Network [OSTI]

    H. M. Antia; Sarbani Basu; S. M. Chitre

    2008-05-22T23:59:59.000Z

    Available helioseismic data now span almost the entire solar activity cycle 23 making it possible to study solar-cycle related changes of the solar rotation rate in detail. In this paper we study how the solar rotation rate, in particular, the zonal flows change with time. In addition to the zonal flows that show a well known pattern in the solar convection zone, we also study changes in the radial and latitudinal gradients of the rotation rate, particularly in the shear layer that is present in the immediate sub-surface layers of the Sun. In the case of the zonal-flow pattern, we find that the band indicating fast rotating region close to the equator seems to have bifurcated around 2005. Our investigation of the rotation-rate gradients show that the relative variation in the rotation-rate gradients is about 20% or more of their average values, which is much larger than the relative variation in the rotation rate itself. These results can be used to test predictions of various solar dynamo models.

  5. Magnetic field gradients in solar wind plasma and geophysics periods

    E-Print Network [OSTI]

    A. Bershadskii

    2006-11-16T23:59:59.000Z

    Using recent data obtained by Advanced Composition Explorer (ACE) the pumping scale of the magnetic field gradients of the solar wind plasma has been calculated. This pumping scale is found to be equal to 24h $\\pm$ 2h. The ACE spacecraft orbits at the L1 libration point which is a point of Earth-Sun gravitational equilibrium about 1.5 million km from Earth. Since the Earth's magnetosphere extends into the vacuum of space from approximately 80 to 60,000 kilometers on the side toward the Sun the pumping scale cannot be a consequence of the 24h-period of the Earth's rotation. Vise versa, a speculation is suggested that for the very long time of the coexistence of Earth and of the solar wind the weak interaction between the solar wind and Earth could lead to stochastic synchronization between the Earth's rotation and the pumping scale of the solar wind magnetic field gradients. This synchronization could transform an original period of the Earth's rotation to the period close to the pumping scale of the solar wind magnetic field gradients.

  6. CONTINUOUS EDGE GRADIENT-BASED TEMPLATE MATCHING FOR ARTICULATED OBJECTS

    E-Print Network [OSTI]

    Daniel Mohr; Gabriel Zachmann

    template matching, deformable object detection, confidence map, edge feature, graphics hardware In this paper, we propose a novel edge gradient based template matching method for object detection. In contrast to other methods, ours does not perform any binarization or discretization during the online matching. This is facilitated by a new continuous edge gradient similarity measure. Its main components are a novel edge gradient operator, which is applied to query and template images, and the formulation as a convolution, which can be computed very efficiently in Fourier space. We compared our method to a state-of-the-art chamfer based matching method. The results demonstrate that our method is much more robust against weak edge response and yields much better confidence maps with fewer maxima that are also more significant. In addition, our method lends itself well to efficient implementation on GPUs: at a query image resolution of 320 × 256 and a template resolution of 80 × 80 we can generate about 330 confidence maps per second. 1

  7. Geothermal gradient map of the conterminous United States. Second edition

    SciTech Connect (OSTI)

    Kron, A.; Stix, J.

    1982-01-01T23:59:59.000Z

    The second edition of the Geothermal Gradient Map of the Conterminous United States (Kron and Stix 1982) is described and the changes made since the first edition (Kron and Heiken 1980) are compared. The second edition of the map presents a compilation of over 1700 wells that have been measured for temperature belwo 50 m and whose temperature/depth profiles are linear, or composed of linear segments which reflect changes in the thermal conductivity of the rocks rather than hydrology. The data are displayed at an enlarged scale of 1:2,500,000 and in a new format which shows the location, depth, and gradient of each well in a single color-coded symbol. This edition contains over two times the amount of data shown on the first map and is accompained by a table, listing for each well its location, depth, gradient, heat flow (where available), thermal conductivity (where available), and a reference. Over 200 references have been consulted and are presented with the data.

  8. Multiscale Analysis of the Gradient of Linear Polarisation

    E-Print Network [OSTI]

    Robitaille, J -F

    2015-01-01T23:59:59.000Z

    We propose a new multiscale method to calculate the amplitude of the gradient of the linear polarisation vector using a wavelet-based formalism. We demonstrate this method using a field of the Canadian Galactic Plane Survey (CGPS) and show that the filamentary structure typically seen in gradients of linear polarisation maps depends strongly on the instrumental resolution. Our analysis reveals that different networks of filaments are present on different angular scales. The wavelet formalism allows us to calculate the power spectrum of the fluctuations seen in gradients of linear polarisation maps and to determine the scaling behaviour of this quantity. The power spectrum is found to follow a power law with gamma ~ 2.1. We identify a small drop in power between scales of 80 well to the overlap in the u-v plane between the Effelsberg 100-m telescope and the DRAO 26-m telescope data. We suggest that this drop is due to undersampling present in the 26-m telescope data. I...

  9. Eddy currents in a gradient coil, modelled as circular loops of strips

    E-Print Network [OSTI]

    Eindhoven, Technische Universiteit

    Eddy currents in a gradient coil, modelled as circular loops of strips J.M.B. Kroot, S.J.L. van. Due to induction eddy currents occur which lead to the so-called edge-effect. The edge- effect depends the gradient coils themselves. Eddy currents occur, causing perturbations on the expected gradient field

  10. Experimental and theoretical studies of oxygen gradients in rat pial microvessels

    E-Print Network [OSTI]

    Popel, Aleksander S.

    no substantial impact on the transmural PO2 gradient. Journal of Cerebral Blood Flow & Metabolism (2008) 28, 1597Experimental and theoretical studies of oxygen gradients in rat pial microvessels Maithili Sharan1 near cortical arterioles and transmural PO2 gradients in the pial arterioles of the rat. Under control

  11. RAL-TR-2002-034 A Stopping Criterion for the Conjugate Gradient Algorithm in

    E-Print Network [OSTI]

    Mihajlovic, Milan D.

    Method Framework Mario Arioli 1 ABSTRACT The Conjugate Gradient method has always been successfully used for the conjugate gradient method 5 4 Numerical experiments 10 4.1 L-shape test problems stopping criterion for the conjugate gradient algorithm. The #12;nite element method approximates the weak

  12. Ilya Lashuk and Andrew Knyazev 1 Steepest descent and conjugate gradient methods

    E-Print Network [OSTI]

    Knyazev, Andrew

    Ilya Lashuk and Andrew Knyazev 1 Steepest descent and conjugate gradient methods with variable Mountain Conference 2006 Steepest descent and conjugate gradient methods with variable preconditioning #12 Steepest descent and conjugate gradient methods with variable preconditioning #12;Ilya Lashuk and Andrew

  13. Inverse estimation of surface heating condition in a three-dimensional object using conjugate gradient method

    E-Print Network [OSTI]

    Zhang, Yuwen

    heat conduction Laser Gaussian profile Conjugate gradient method a b s t r a c t Temperature and heat gradient method Jianhua Zhou, Yuwen Zhang *, J.K. Chen, Z.C. Feng Department of Mechanical and Aerospace gradient method (CGM) with temperature and heat flux measured on back surface (opposite to the heated

  14. A Set of Conjugate Gradient Routines for Real and Complex Arithmetics

    E-Print Network [OSTI]

    The Conjugate Gradient method was proposed in different versions in the early 50s in separate contributionsA Set of Conjugate Gradient Routines for Real and Complex Arithmetics Val´erie Frayss´e Luc Giraud of the preconditioned conjugate gradient (CG) algorithm for both real and complex, single and double precision

  15. Preconditioned conjugate gradient method for the sparse generalized eigenvalue problem in electronic structure

    E-Print Network [OSTI]

    Haynes, Peter

    Preconditioned conjugate gradient method for the sparse generalized eigenvalue problem based on the conjugate gradient method is presented. The method is applied to first­principles elec problem, cast into variational form, is solved by the conjugate gradient method without first transforming

  16. Performance and Scalability of Preconditioned Conjugate Gradient Methods on Parallel Computers \\Lambda

    E-Print Network [OSTI]

    Kumar, Vipin

    Performance and Scalability of Preconditioned Conjugate Gradient Methods on Parallel Computers­scale parallel computers, iterative methods such as the Conjugate Gradient method for solving such systems of an iteration of the Preconditioned Conjugate Gradient Algorithm on parallel architectures with a variety

  17. A Set of Conjugate Gradient Routines for Real and Complex Arithmetics

    E-Print Network [OSTI]

    systems, Krylov methods, CG, reverse communication, distributed mem­ ory. 1 The Conjugate Gradient algorithm 1.1 General description The Conjugate Gradient method was proposed in di#erent versions with the symmetric Lanczos matrix There is a close relationship between the conjugate gradient method and the Lanczos

  18. Solving a Two-Dimensional Elliptic Model Problem with the Conjugate Gradient Method Using

    E-Print Network [OSTI]

    Gobbert, Matthias K.

    Solving a Two-Dimensional Elliptic Model Problem with the Conjugate Gradient Method Using Matrix Preconditioned Conjugate Gradient method in Matlab can be optimized in terms of wall clock time and, more-free Preconditioned Conjugate Gradient method. This superior algorithm computes the same numerical solution to our

  19. Conjugate gradient method for dual-dual mixed formulations Gabriel N. Gatica y Norbert Heuer z

    E-Print Network [OSTI]

    Heuer, Norbert

    Conjugate gradient method for dual-dual mixed formulations #3; Gabriel N. Gatica y Norbert Heuer z, the conjugate gradient method with this special inner product can be used as iterative solver. For a model-dual variational formulation, conjugate gradient method. Mathematics subject classi#12;cations (1991). 65N30, 65N22

  20. Convergence of Three-term Conjugate Gradient Methods Y. H. Dai and Y. Yuan

    E-Print Network [OSTI]

    Yuan, Ya-xiang

    Convergence of Three-term Conjugate Gradient Methods Y. H. Dai and Y. Yuan State Key Laboratory@lsec.cc.ac.cn, yyx@lsec.cc.ac.cn Abstract This paper studies the three-term conjugate gradient method for unconstrained opti- mization. The method includes the classical (two-term) conjugate gradient method

  1. Time Complexity of a Parallel Conjugate Gradient Solver for Light Scattering Simulations

    E-Print Network [OSTI]

    Hoffmann, Walter

    parallelization for distributed memory computers of a preconditioned Conjugate Gradient method, applied to solve of the Conjugate Gradient method is analyzed theoretically. First expressions for the execution time for three, preconditioned conjugate gradient method, data decomposition, time complexity analysis, performance measurement

  2. A fast GPU Implementation of the Deflated Preconditioned Conjugate Gradient method

    E-Print Network [OSTI]

    Boyer, Edmond

    A fast GPU Implementation of the Deflated Preconditioned Conjugate Gradient method List of authors to the fastest method: DIPCG2. · (CGVV) Conjugate Gradient - Vanilla Version, · (CGBIC) Conjugate Gradient Preconditioned Conjugate Gra- dient Method. Most of the important building blocks of this algorithm could

  3. The Role of the Inner Product in Stopping Criteria for Conjugate Gradient Iterations

    E-Print Network [OSTI]

    Holst, Michael J.

    stopping criteria are derived for conjugate gradient (CG) methods, based on iteration parameters criteria, conjugate gradient methods, B-normal matrices 1 Introduction Unlike a direct method, an iterative1 The Role of the Inner Product in Stopping Criteria for Conjugate Gradient Iterations S. F. Ashby

  4. Implementation of a parallel conjugate gradient method for simulation of elastic light scattering

    E-Print Network [OSTI]

    1 Implementation of a parallel conjugate gradient method for simulation of elastic light scattering solved with (preconditioned) conjugate gradient methods. For realistic problems the size of the matrix gradient method for this type of problems, with emphasis on coarse grain distributed memory implementations

  5. Copyright information to be inserted by the Publishers ANALYSIS ON THE CONJUGATE GRADIENT

    E-Print Network [OSTI]

    Yuan, Ya-xiang

    Copyright information to be inserted by the Publishers ANALYSIS ON THE CONJUGATE GRADIENT METHOD YA 17 January 1993) In this paper we analyze the conjugate gradient method when the objective function is quadratic. We apply backward analyses to study the quadratic termination of the conjugate gradient method

  6. Exploiting hyper-sparsity when computing preconditioners for conjugate gradients in interior point methods

    E-Print Network [OSTI]

    Hall, Julian

    for conjugate gradients in interior point methods 1 #12;Hyper-sparsity in operations with B-1 Represent B-1 computing preconditioners for conjugate gradients in interior point methods 3 #12;Interior point methods computing preconditioners for conjugate gradients in interior point methods 4 #12;Design

  7. Algorithm PREQN: Fortran 77 Subroutines for Preconditioning the Conjugate Gradient Method

    E-Print Network [OSTI]

    Nocedal, Jorge

    Algorithm PREQN: Fortran 77 Subroutines for Preconditioning the Conjugate Gradient Method Jos subroutines for automatically generating pre­ conditioners for the conjugate gradient method. It is designed the conjugate gradient method. They are designed for solving a sequence of linear systems, A i x = b i ; i = 1

  8. A conjugate-gradient based approach for approximate solutions of quadratic programs

    E-Print Network [OSTI]

    Forsgren, Anders

    on the two-norm of the columns, the method is equivalent to the conjugate-gradient method. Further, the above, the numerical results demonstrate that, like the conjugate-gradient method, a rapid decrease of the objective. column generation, conjugate-gradient method, intensity-modulated radiation therapy, step

  9. 3D Shape from Silhouette Points in Registered 2D Images Using Conjugate Gradient Method

    E-Print Network [OSTI]

    Hoff, William A.

    3D Shape from Silhouette Points in Registered 2D Images Using Conjugate Gradient Method Andrzej version of the conjugate gradient method. We take advantage of the structure of the problem to make polynomial function. The approximate problem is solved using a nonlinear conjugate gradient solver that takes

  10. Algorithm PREQN: Fortran 77 Subroutines for Preconditioning the Conjugate Gradient Method

    E-Print Network [OSTI]

    Nocedal, Jorge

    Algorithm PREQN: Fortran 77 Subroutines for Preconditioning the Conjugate Gradient Method Jose Luis for automatically generating pre- conditioners for the conjugate gradient method. It is designed for solving: Preconditioning, conjugate gradient method, quasi- Newton method, Hessian-free Newton method, limited memory

  11. PRECONDITIONED CONJUGATE GRADIENT METHODS FOR THE INCOMPRESSIBLE NAVIER-STOKES EQUATIONS

    E-Print Network [OSTI]

    Waterloo, University of

    PRECONDITIONED CONJUGATE GRADIENT METHODS FOR THE INCOMPRESSIBLE NAVIER-STOKES EQUATIONS P. CHIN of using a conjugate gradient type method with an incomplete LU factorization preconditioner for two is to use an iterative matrix method. Recently, several authors have applied conjugate gradient type methods

  12. Parallelizable Preconditioned Conjugate Gradient Methods for the Cray Y-MP and the TMC CM-2

    E-Print Network [OSTI]

    Navon, Michael

    Parallelizable Preconditioned Conjugate Gradient Methods for the Cray Y-MP and the TMC CM-2 William preconditioned conjugate gradient methods to the numerical solution of the diffusion equation governing the flow provides a comparison of the performance characteristics of several preconditioned conjugate gradient (PCG

  13. A MULTI-PRECONDITIONED CONJUGATE GRADIENT ROBERT BRIDSON AND CHEN GREIF

    E-Print Network [OSTI]

    Bridson, Robert

    propose a generalization of the conjugate gradient method that uses multiple preconditioners, combining and differences with the standard and block conjugate gradient methods. Numerical examples illustrate and validate, preconditioning, Krylov subspace solvers 1. Introduction. The conjugate gradient (CG) method is celebrating its 53

  14. A SURVEY OF NONLINEAR CONJUGATE GRADIENT METHODS WILLIAM W. HAGER AND HONGCHAO ZHANG

    E-Print Network [OSTI]

    Zhang, Hongchao

    A SURVEY OF NONLINEAR CONJUGATE GRADIENT METHODS WILLIAM W. HAGER AND HONGCHAO ZHANG Abstract. This paper reviews the development of different versions of nonlinear conjugate gradient methods, with special attention given to global convergence properties. Key words. Nonlinear conjugate gradient methods

  15. ON THE BEHAVIOR OF THE CONJUGATE-GRADIENT METHOD ON ILL-CONDITIONED PROBLEMS

    E-Print Network [OSTI]

    Forsgren, Anders

    ON THE BEHAVIOR OF THE CONJUGATE-GRADIENT METHOD ON ILL-CONDITIONED PROBLEMS Anders FORSGREN Abstract We study the behavior of the conjugate-gradient method for solving a set of linear equations. conjugate-gradient method, symmetric positive-definite ma- trix, ill-conditioning AMS subject

  16. On the Relation Between Steep Monoclinal Flexure Zones and Steep Hydraulic Gradients

    E-Print Network [OSTI]

    Lyakhovsky, Vladimir

    On the Relation Between Steep Monoclinal Flexure Zones and Steep Hydraulic Gradients by Y. Yechieli1, U. Kafri2, S. Wollman2, V. Lyakhovsky2, and R. Weinberger2 Abstract Steep hydraulic gradients of the hydraulic conductivity, which is responsible for the steep gradients, has seldom been studied. We present

  17. WORLD RECORD ACCELERATING GRADIENT ACHIEVED IN A SUPERCONDUCTING NIOBIUM RF CAVITY

    E-Print Network [OSTI]

    Geng, Rong-Li

    WORLD RECORD ACCELERATING GRADIENT ACHIEVED IN A SUPERCONDUCTING NIOBIUM RF CAVITY R.L. Geng On November 16, 2004, a CW accelerating gradient of 46 MV/m was achieved in a superconducting niobium cav- ity/m was achieved. This represents a world record gradient in a niobium RF resonator. At a reduced temperature of 1

  18. Thermal gradient-induced forces on geodetic reference masses for LISA

    E-Print Network [OSTI]

    L. Carbone; A. Cavalleri; G. Ciani; R. Dolesi; M. Hueller; D. Tombolato; S. Vitale; W. J. Weber

    2007-06-29T23:59:59.000Z

    The low frequency sensitivity of space-borne gravitational wave observatories will depend critically on the geodetic purity of the trajectories of orbiting test masses. Fluctuations in the temperature difference across the enclosure surrounding the free-falling test mass can produce noisy forces through several processes, including the radiometric effect, radiation pressure, and outgassing. We present here a detailed experimental investigation of thermal gradient-induced forces for the LISA gravitational wave mission and the LISA Pathfinder, employing high resolution torsion pendulum measurements of the torque on a LISA-like test mass suspended inside a prototype of the LISA gravitational reference sensor that will surround the test mass in orbit. The measurement campaign, accompanied by numerical simulations of the radiometric and radiation pressure effects, allows a more accurate and representative characterization of thermal-gradient forces in the specific geometry and environment relevant to LISA free-fall. The pressure dependence of the measured torques allows clear identification of the radiometric effect, in quantitative agreement with the model developed. In the limit of zero gas pressure, the measurements are most likely dominated by outgassing, but at a low level that does not threaten the LISA sensitivity goals.

  19. Observation of pressure gradient and related flow rate effect on the plasma parameters in plasma processing reactor

    SciTech Connect (OSTI)

    Lee, Hyo-Chang; Kim, Aram; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Moon, Se Youn [Solar Energy Group, LG Electronics Advanced Research Institute, 16 Woomyeon-Dong, Seocho-Gu, Seoul 137-724 (Korea, Republic of)

    2011-02-15T23:59:59.000Z

    In industrial plasma processes, flow rate has been known to a key to control plasma processing results and has been discussed with reactive radical density, gas residence time, and surface reaction. In this study, it was observed that the increase in the flow rate can also change plasma parameters (electron temperature and plasma density) and electron energy distribution function in plasma processing reactor. Based on the measurement of gas pressure between the discharge region and the pumping port region, the considerable differences in the gas pressure between the two regions were found with increasing flow rate. It was also observed that even in the discharge region, the pressure gradient occurs at the high gas flow rate. This result shows that increasing the flow rate results in the pressure gradient and causes the changes in the plasma parameters.

  20. Gradient effects on the fracture of inhomogeneous materials

    SciTech Connect (OSTI)

    Becker, T.L.

    2000-05-01T23:59:59.000Z

    Functionally Graded Materials (FGMs) have a spatial variation in physical properties that can be tailored to meet the needs of a specific application and/or to minimize internal stresses arising from thermal and elastic mismatch. Modeling these materials as inhomogeneous continua allows assessment of the role of the gradient without requiring detailed knowledge of the microstructure. Motivated by the relative difficulty of obtaining analytical solutions to boundary value problems for FGMs, an accurate finite-element code is developed for obtaining numerical planar and axisymmetric linear thermoelastic solutions. In addition an approximate analytical technique for mapping homogeneous-modulus solutions to those for FGMs is assessed and classes of problems to which it applies accurately are identified. The fracture mechanics analysis of FGMs can be characterized by the classic stress intensities, KI and KII, but there has been scarce progress in understanding the role of the modulus gradient in determining fracture initiation and propagation. To address this question, a statistical fracture model is used to correlate near-tip stresses with brittle fracture initiation behavior. This describes the behavior of a material experiencing fracture initiation away from the crack tip. Widely dispersed zones of fracture initiation sites are expected. Finite-length kinks are analyzed to describe the crack path for continuous crack growth. For kink lengths much shorter than the gradient dimension, a parallel stress term describes the deviation of the kinking angle from that for homogeneous materials. For longer kinks there is a divergence of the kink angle predicted by the maximum energy release rate and the pure opening mode criteria.

  1. Potential use of hollow spheres in dual gradient drilling

    E-Print Network [OSTI]

    Vera Vera, Liliana

    2002-01-01T23:59:59.000Z

    . 53 4-18 Relation between the mud level drop inside the drillstring obtained by using both our Spreadsheet and the SMD simulator. A strong linear relationship is depicted. . 53 LIST OF TABLES TABLE Page 2-1 Current subsea pump lifting projects... to the surface, and makes dual gradient possible by keeping the mud hydrostatic pressure in the return lines from being trarismitted to the wellbore. Operationally, the mud returns are diverted from the annulus to the pump suction by a subsea diverter. Some...

  2. Formation of Complex Structures in Dusty Plasmas under Temperature Gradients

    SciTech Connect (OSTI)

    Vasilyak, L.M.; Vetchinin, S.P.; Polyakov, D.N.; Fortov, V.E. [Institute for High Energy Densities, Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, 125412 (Russian Federation)

    2005-05-01T23:59:59.000Z

    Thermophoretic effects on dust structures under temperature gradients in glow and radio-frequency discharge plasmas are studied experimentally. The geometry of dust structures consisting of micrometer-sized polydisperse grains depends on heat release in the plasma. Thermophoretic forces associated with heat release can control the formation of dust structures of different geometries. A theoretical model is proposed to describe dust separation with respect to grain size caused by the effects of radial electrostatic and thermophoretic forces. The glow discharge currents under critical conditions for grain separation predicted by the model agree with those observed experimentally.

  3. Manipulation of Colloids by Nonequilibrium Depletion Force in Temperature Gradient

    E-Print Network [OSTI]

    Hong-Ren Jiang; Hirofumi Wada; Natsuhiko Yoshinaga; Masaki Sano

    2009-04-22T23:59:59.000Z

    The non-equilibrium distribution of colloids in a polymer solution under a temperature gradient is studied experimentally. A slight increase of local temperature by a focused laser drives the colloids towards the hot region, resulting in the trapping of the colloids irrespective of their own thermophoretic properties. An amplification of the trapped colloid density with the polymer concentration is measured, and is quantitatively explained by hydrodynamic theory. The origin of the attraction is a migration of colloids driven by a non-uniform polymer distribution sustained by the polymer's thermophoresis. These results show how to control thermophoretic properties of colloids.

  4. Relationships between geology and geothermal gradients in Kansas

    SciTech Connect (OSTI)

    Stavnes, S.A.; Steeples, D.W.; Ruscetta, C.A. (ed.)

    1982-07-01T23:59:59.000Z

    Bottom hole temperature values from existing oil and gas wells and thermal logging data from geothermal wells are used to determine the factors responsible for geographic variation in the subsurface temperature distribution in Kansas. Geothermal gradient data range from 25/sup 0/C/km to 55/sup 0/C/km in the upper 300 m. The geologic factors proposed to explain this variation are: (1) topography of the crystalline basement surface; (2) variation in rates of heat production in the crystalline basement; (3) variation in thermal conductivity in the sedimentary section; and (4) possible convection upward and eastward from the Denver-Julesberg Basin. (MJF)

  5. 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)

    2012-08-15T23:59:59.000Z

    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.

  6. k-line iterative methods: a conjugate-gradient approach

    SciTech Connect (OSTI)

    Kratzer, D.; Parter, S.V.; Steuerwalt, M.

    1981-03-29T23:59:59.000Z

    The generalized conjugate gradient scheme based on the k-line block Jacobi splitting A = M-N was studied for solving model two-dimensional parabolic and elliptic difference equations AU = F tilde. A represents the matrix ch/sup ..cap alpha../-h/sup 2/..delta../sub h/. Eigenvalues of M/sup -1/N cluster, and the cluster radii decrease as ch/sup ..cap alpha../ or k increases. Computations with k = 4, 8, 16, 32, and ch/sup ..cap alpha../ = 0, h, 2 are discussed.

  7. A stable, rapidly converging conjugate gradient method for energy minimization

    SciTech Connect (OSTI)

    Watowich, S.J.; Meyer, E.S.; Hagstrom, R.; Josephs, R.

    1989-01-01T23:59:59.000Z

    We apply Shanno's conjugate gradient algorithm to the problem of minimizing the potential energy function associated with molecular mechanical calculations. Shanno's algorithm is stable with respect to roundoff errors and inexact line searches and converges rapidly to a minimum. Equally important, this algorithm can improve the rate of convergence to a minimum by a factor of 5 relative to Fletcher-Reeves or Polak-Ribiere minimizers when used within the molecular mechanics package AMBER. Comparable improvements are found for a limited number of simulations when the Polak-Ribiere direction vector is incorporated into the Shanno algorithm. 24 refs., 4 figs., 3 tabs.

  8. A high voltage pulsed power supply for capillary discharge waveguide applications

    SciTech Connect (OSTI)

    Abuazoum, S.; Wiggins, S. M.; Issac, R. C.; Welsh, G. H.; Vieux, G.; Jaroszynski, D. A. [Department of Physics, Scottish Universities Physics Alliance, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Ganciu, M. [Low Temperature Plasma Department, National Institute of Lasers, Plasma and Radiation Physics, 077125, Magurele, Bucharest (Romania)

    2011-06-15T23:59:59.000Z

    We present an all solid-state, high voltage pulsed power supply for inducing stable plasma formation (density {approx}10{sup 18} cm{sup -3}) in gas-filled capillary discharge waveguides. The pulser (pulse duration of 1 {mu}s) is based on transistor switching and wound transmission line transformer technology. For a capillary of length 40 mm and diameter 265 {mu}m and gas backing pressure of 100 mbar, a fast voltage pulse risetime of 95 ns initiates breakdown at 13 kV along the capillary. A peak current of {approx}280 A indicates near complete ionization, and the r.m.s. temporal jitter in the current pulse is only 4 ns. Temporally stable plasma formation is crucial for deploying capillary waveguides as plasma channels in laser-plasma interaction experiments, such as the laser wakefield accelerator.

  9. A linear helicon plasma device with controllable magnetic field gradient

    SciTech Connect (OSTI)

    Barada, Kshitish K.; Chattopadhyay, P. K.; Ghosh, J.; Kumar, Sunil; Saxena, Y. C. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2012-06-15T23:59:59.000Z

    Current free double layers (CFDLs) are localized potential structures having spatial dimensions - Debye lengths and potential drops of more than local electron temperature across them. CFDLs do not need a current for them to be sustained and hence they differ from the current driven double layers. Helicon antenna produced plasmas in an expanded chamber along with an expanding magnetic field have shown the existence of CFDL near the expansion region. A helicon plasma device has been designed, fabricated, and installed in the Institute for Plasma Research, India to study the role of maximum magnetic field gradient as well as its location with respect to the geometrical expansion region of the chamber in CFDL formation. The special feature of this machine consisting of two chambers of different radii is its capability of producing different magnetic field gradients near the physical boundary between the two chambers either by changing current in one particular coil in the direction opposite to that in other coils and/or by varying the position of this particular coil. Although, the machine is primarily designed for CFDL experiments, it is also capable of carrying out many basic plasma physics experiments such as wave propagation, wave coupling, and plasma instabilities in a varying magnetic field topology. In this paper, we will present the details of the machine construction, its specialties, and some preliminary results about the production and characterization of helicon plasma in this machine.

  10. Feedback Mechanism for Microtubule Length Regulation by Stathmin Gradients

    E-Print Network [OSTI]

    Maria Zeitz; Jan Kierfeld

    2014-12-09T23:59:59.000Z

    We formulate and analyze a theoretical model for the regulation of microtubule (MT) polymerization dynamics by the signaling proteins Rac1 and stathmin. In cells, the MT growth rate is inhibited by cytosolic stathmin, which, in turn, is inactivated by Rac1. Growing MTs activate Rac1 at the cell edge, which closes a positive feedback loop. We investigate both tubulin sequestering and catastrophe promotion as mechanisms for MT growth inhibition by stathmin. For a homogeneous stathmin concentration in the absence of Rac1, we find a switch-like regulation of the MT mean length by stathmin. For constitutively active Rac1 at the cell edge, stathmin is deactivated locally, which establishes a spatial gradient of active stathmin. In this gradient, we find a stationary bimodal MT length distributions for both mechanisms of MT growth inhibition by stathmin. One subpopulation of the bimodal length distribution can be identified with fast growing and long pioneering MTs in the region near the cell edge, which have been observed experimentally. The feedback loop is closed through Rac1 activation by MTs. For tubulin sequestering by stathmin, this establishes a bistable switch with two stable states: one stable state corresponds to upregulated MT mean length and bimodal MT length distributions, i.e., pioneering MTs; the other stable state corresponds to an interrupted feedback with short MTs. Stochastic effects as well as external perturbations can trigger switching events. For catastrophe promoting stathmin we do not find bistability.

  11. Compensated geothermal gradient: new map of old data

    SciTech Connect (OSTI)

    Ibrahim, M.W.

    1986-05-01T23:59:59.000Z

    Bottom-hole temperature measurement is one of the oldest forms of downhole information acquired by the oil industry. Old and new geothermal maps that are based on these measurements have invariably been drawn with an assumed constant or average ground surface temperature over the mapped areas. However, near ground-surface equilibrium temperature is a variable rather than a constant over any region; therefore, old and current geothermal gradient mapping methods give a false impression of the true thermal level of subsurface strata, and may lead to erroneous results of temperature-based calculations, such as the TTI. In this paper, a geothermal mapping method is presented in which extrapolated surface temperature is coupled with the corresponding geothermal gradient over the mapped area. The method was tested on areas in the Middle East and Africa. Results indicate that it is especially effective in delineating loci of vertical geothermal heat flux carried upwards by ascending subsurface fluids; such areas are preferential sites for hydrocarbon entrapment, especially in young sedimentary basins where migration is still in progress.

  12. Convergence in gradient systems with branching of equilibria

    SciTech Connect (OSTI)

    Galaktionov, V A [University of Bath (United Kingdom); Pohozaev, Stanislav I [Steklov Mathematical Institute, Russian Academy of Sciences (Russian Federation); Shishkov, A E [Institute of Applied Mathematics and Mechanics of the National Academy of Sciences of Ukraine, Donetsk (Ukraine)

    2007-06-30T23:59:59.000Z

    The basic model is a semilinear elliptic equation with coercive C{sup 1} non-linearity: {delta}{psi}+f({psi})=0 in {omega}, {psi}=0 on {partial_derivative}{omega}, where {omega} subset of R{sup N} is a bounded smooth domain. The main hypothesis (H{sub R}) about resonance branching is as follows: if a branching of equilibria occurs at a point {psi} with k-dimensional kernel of the linearized operator {delta}+f'({psi})I, then the branching subset S{sub k} at {psi} is a locally smooth k-dimensional manifold. For N=1 the first result on the stabilization to a single equilibrium is due to Zelenyak (1968). It is shown that Zelenyak's approach, which is based on the analysis of Lyapunov functions, can be extended to general gradient systems in Hilbert spaces with smooth resonance branching. The case of asymptotically small non-autonomous perturbations of such systems is also considered. The approach developed here represents an alternative to Hale's stabilization method (1992) and other similar techniques in the theory of gradient systems. Bibliography: 32 titles.

  13. Electron acceleration by cascading reconnection in the solar corona I Magnetic gradient and curvature effects

    E-Print Network [OSTI]

    Zhou, X; Barta, M; Gan, W; Liu, S

    2015-01-01T23:59:59.000Z

    Aims: We investigate the electron acceleration in convective electric fields of cascading magnetic reconnection in a flaring solar corona and show the resulting hard X-ray (HXR) radiation spectra caused by Bremsstrahlung for the coronal source. Methods: We perform test particle calculation of electron motions in the framework of a guiding center approximation. The electromagnetic fields and their derivatives along electron trajectories are obtained by linearly interpolating the results of high-resolution adaptive mesh refinement (AMR) MHD simulations of cascading magnetic reconnection. Hard X-ray (HXR) spectra are calculated using an optically thin Bremsstrahlung model. Results: Magnetic gradients and curvatures in cascading reconnection current sheet accelerate electrons: trapped in magnetic islands, precipitating to the chromosphere and ejected into the interplanetary space. The final location of an electron is determined by its initial position, pitch angle and velocity. These initial conditions also influ...

  14. Concentration of carbon types from fly ash by density gradient centrifugation

    SciTech Connect (OSTI)

    Maroto-Valer, M.M.; Taulbee, D.N.; Hower, J.C. [Univ. of Kentucky, Lexington, KY (United States). Center for Applied Energy Research

    1998-12-31T23:59:59.000Z

    Although the increasing amount of unburned carbon in fly ash is known to preclude the use of ash in the cement industry, very little is known about the characteristics of the unburned carbon. Three types of carbon particles have been identified microscopically: inertinite, isotropic coke and anisotropic coke. This manuscript describes a method to isolate these three types of carbon. A preliminary enrichment, followed by density gradient centrifugation (DGC) with a high-density polytungstate media (2.85 g/cm{sup 3} max), resulted in an enrichment of inertinites from a starting concentration of 3.8% to 61%, isotropic coke from 13.4% to 65%, and anisotropic coke from 19.2% to 74%. Large scale runs (LS) have been conducted to accumulate sufficient sample for subsequent analyses. The recovery weights and petrography composition of the PS and LS fractions are very similar.

  15. Grain-scale thermoelastic stresses and spatiotemporal temperature gradients on airless bodies, implications for rock breakdown

    E-Print Network [OSTI]

    Molaro, Jamie L; Langer, Steve A

    2015-01-01T23:59:59.000Z

    Thermomechanical processes such as fatigue and shock have been suggested to cause and contribute to rock breakdown on Earth, and on other planetary bodies, particularly airless bodies in the inner solar system. In this study, we modeled grain-scale stresses induced by diurnal temperature variations on simple microstructures made of pyroxene and plagioclase on various solar system bodies. We found that a heterogeneous microstructure on the Moon experiences peak tensile stresses on the order of 100 MPa. The stresses induced are controlled by the coefficient of thermal expansion and Young's modulus of the mineral constituents, and the average stress within the microstructure is determined by relative volume of each mineral. Amplification of stresses occurs at surface-parallel boundaries between adjacent mineral grains and at the tips of pore spaces. We also found that microscopic spatial and temporal surface temperature gradients do not correlate with high stresses, making them inappropriate proxies for investig...

  16. Wideband radar cross section reduction using two-dimensional phase gradient metasurfaces

    SciTech Connect (OSTI)

    Li, Yongfeng; Qu, Shaobo; Wang, Jiafu; Chen, Hongya [College of Science, Air Force Engineering University, Xi'an, Shaanxi 710051 (China); Zhang, Jieqiu [College of Science, Air Force Engineering University, Xi'an, Shaanxi 710051 (China); Electronic Materials Research Laboratory, Key Laboratory of Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China); Xu, Zhuo [Electronic Materials Research Laboratory, Key Laboratory of Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China); Zhang, Anxue [School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)

    2014-06-02T23:59:59.000Z

    Phase gradient metasurface (PGMs) are artificial surfaces that can provide pre-defined in-plane wave-vectors to manipulate the directions of refracted/reflected waves. In this Letter, we propose to achieve wideband radar cross section (RCS) reduction using two-dimensional (2D) PGMs. A 2D PGM was designed using a square combination of 49 split-ring sub-unit cells. The PGM can provide additional wave-vectors along the two in-plane directions simultaneously, leading to either surface wave conversion, deflected reflection, or diffuse reflection. Both the simulation and experiment results verified the wide-band, polarization-independent, high-efficiency RCS reduction induced by the 2D PGM.

  17. Tripolar vortex formation in dense quantum plasma with ion-temperature-gradients

    SciTech Connect (OSTI)

    Qamar, Anisa; Ata-ur-Rahman [Institute of Physics and Electronics, University of Peshawar, Khyber Pakhtoon Khwa 25000 (Pakistan); National Center for Physics Shahdrah Valley Road, Islamabad 44000 (Pakistan); Mirza, Arshad M. [Theoretical Plasma Physics Group, Physics Department, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2012-05-15T23:59:59.000Z

    We have derived system of nonlinear equations governing the dynamics of low-frequency electrostatic toroidal ion-temperature-gradient mode for dense quantum magnetoplasma. For some specific profiles of the equilibrium density, temperature, and ion velocity gradients, the nonlinear equations admit a stationary solution in the form of a tripolar vortex. These results are relevant to understand nonlinear structure formation in dense quantum plasmas in the presence of equilibrium ion-temperature and density gradients.

  18. Coherent structures in ion temperature gradient turbulence-zonal flow

    SciTech Connect (OSTI)

    Singh, Rameswar, E-mail: rameswar.singh@lpp.polytechnique.fr [Laboratoire de Physique des Plasmas, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India); Singh, R. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India); WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Kaw, P. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India); Gürcan, Ö. D. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Diamond, P. H. [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); CMTFO and CASS, University of California, San Diego, California 92093 (United States)

    2014-10-15T23:59:59.000Z

    Nonlinear stationary structure formation in the coupled ion temperature gradient (ITG)-zonal flow system is investigated. The ITG turbulence is described by a wave-kinetic equation for the action density of the ITG mode, and the longer scale zonal mode is described by a dynamic equation for the m?=?n?=?0 component of the potential. Two populations of trapped and untrapped drift wave trajectories are shown to exist in a moving frame of reference. This novel effect leads to the formation of nonlinear stationary structures. It is shown that the ITG turbulence can self-consistently sustain coherent, radially propagating modulation envelope structures such as solitons, shocks, and nonlinear wave trains.

  19. On O($a^2$) effects in gradient flow observables

    E-Print Network [OSTI]

    Alberto Ramos; Stefan Sint

    2015-04-18T23:59:59.000Z

    In lattice gauge theories, the gradient flow has been used extensively both, for scale setting and for defining finite volume renormalization schemes for the gauge coupling. Unfortunately, rather large cutoff effects have been observed in some cases. We here investigate these effects to leading order in perturbation theory, considering various definitions of the lattice observable, the lattice flow equation and the Yang Mills lattice action. These considerations suggest an improved set- up for which we perform a scaling test in the pure SU(3) gauge theory, demonstrating strongly reduced cutoff effects. We then attempt to obtain a more complete understanding of the structure of O($a^2$) effects by applying Symanzik's effective theory approach to the 4+1 dimensional local field theory with flow time as the fifth dimension. From these considerations we are led to a fully O($a^2$) improved set-up the study of which is left to future work.

  20. Effect of RF Gradient upon the Performance of the Wisconsin SRF Electron Gun

    SciTech Connect (OSTI)

    Bosch, Robert [SRC U. Wisconsin-Madison; Legg, Robert A. [JLAB

    2013-12-01T23:59:59.000Z

    The performance of the Wisconsin 200-MHz SRF electron gun is simulated for several values of the RF gradient. Bunches with charge of 200 pC are modeled for the case where emittance compensation is completed during post-acceleration to 85 MeV in a TESLA module. We first perform simulations in which the initial bunch radius is optimal for the design gradient of 41 MV/m. We then optimize the radius as a function of RF gradient to improve the performance for low gradients.

  1. Evolution of aquatic insect behaviours across a gradient of disturbance predictability

    E-Print Network [OSTI]

    Evolution of aquatic insect behaviours across a gradient of disturbance predictability David A `sufficient'. At one extreme, large infrequent disturbances such as hurricanes and tsunamis may devastate

  2. On the behavior of the conjugate-gradient method on ill-conditioned ...

    E-Print Network [OSTI]

    Anders Forsgren

    2006-01-09T23:59:59.000Z

    Jan 9, 2006 ... Abstract: We study the behavior of the conjugate-gradient method for solving a set of linear equations, where the matrix is symmetric and ...

  3. Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management...

    Open Energy Info (EERE)

    Salt Wells Area (Bureau of Land Management, 2009) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Salt Wells Area...

  4. Tailored electron bunches with smooth current profiles for enhanced transformer ratios in beam-driven acceleration

    E-Print Network [OSTI]

    Lemery, Francois

    2015-01-01T23:59:59.000Z

    Collinear high-gradient ${\\cal O} (GV/m)$ beam-driven wakefield methods for charged-particle acceleration could be critical to the realization of compact, cost-efficient, accelerators, e.g., in support of TeV-scale lepton colliders or multiple-user free-electron laser facilities. To make these options viable, the high accelerating fields need to be complemented with large transformer ratios $>2$, a parameter characterizing the efficiency of the energy transfer between a wakefield-exciting "drive" bunch to an accelerated "witness" bunch. While several potential current distributions have been discussed, their practical realization appears challenging due to their often discontinuous nature. In this paper we propose several alternative current profiles which are smooth which also lead to enhanced transformer ratios. We especially explore a laser-shaping method capable of generating one the suggested distributions directly out of a photoinjector and discuss a linac concept that could possible drive a dielectric ...

  5. MPC for Wind Power Gradients --Utilizing Forecasts, Rotor Inertia, and Central Energy Storage

    E-Print Network [OSTI]

    MPC for Wind Power Gradients -- Utilizing Forecasts, Rotor Inertia, and Central Energy Storage define an extremely low power output gradient and demonstrate how decentralized energy storage conservative bids on the power market. Energy storage strikes the major problems of wind power and joining

  6. MOSSBAUER SPECTRA IN THE PRESENCE OF A FLUCTUATING ELECTRIC l?IEI,D GRADIENT

    E-Print Network [OSTI]

    Boyer, Edmond

    MOSSBAUER SPECTRA IN THE PRESENCE OF A FLUCTUATING ELECTRIC l?IEI,D GRADIENT A. GERARD and F, un mod61e de calcul des spectres Mossbauer en presence d'un gradient de champ electrique fluctuant Recherchesdu F. N. R. S. MAGNETIC INTERACTIONS IN GOLD (11)-BIS (MALEONITRILEDITHIOLATE) OBSERVED BY lg7AuMOSSBAUER

  7. Eddy currents in a gradient coil, modeled as circular loops of strips

    E-Print Network [OSTI]

    Eindhoven, Technische Universiteit

    Eddy currents in a gradient coil, modeled as circular loops of strips J.M.B. Kroot, S.J.L. van to induction, eddy currents occur, resulting in a so-called edge-effect. Higher frequencies cause stronger edge by a gradient coil induces eddy currents in the conducting structures. The eddy currents cause perturbations

  8. Stem respiration in tropical forests along an elevation gradient in the Amazon and Andes

    E-Print Network [OSTI]

    Malhi, Yadvinder

    Stem respiration in tropical forests along an elevation gradient in the Amazon and Andes A M A N D metabolism, resulting in the release of carbon dioxide as a by-product. Little is known of how autotrophic respiration components vary across environmental gradients, particularly in tropical ecosystems. Here, we

  9. Intra--modality Image Registration using Gradients Mutawarra Hussain and Ela Claridge

    E-Print Network [OSTI]

    Claridge, Ela

    Intra--modality Image Registration using Gradients Mutawarra Hussain and Ela Claridge School--subject volumetric images has been achieved by using the variance of gradient ratios (VGR) technique. This technique intensity provides functional information on the metabolism of the region to be studied. The temporal

  10. Sediment Respiration and Nitrogen Cycling along a Eutrophic Gradient in a Shallow, Coastal Estuary

    E-Print Network [OSTI]

    Vallino, Joseph J.

    Sediment Respiration and Nitrogen Cycling along a Eutrophic Gradient in a Shallow, Coastal Estuary Respiration and Nitrogen Cycling along a Eutrophic Gradient in a Shallow, Coastal Estuary Semester and denitrification potentials. We found that the more eutrophic sites had higher respiration and ammonification. Our

  11. Ionosphere Spatial Gradient Threat for LAAS: Mitigation and Tolerable Threat Space

    E-Print Network [OSTI]

    Stanford University

    1 Ionosphere Spatial Gradient Threat for LAAS: Mitigation and Tolerable Threat Space Ming Luo, Sam and a threat space was extrapolated based on the 6 April 2000 ionospheric storm. It was showed that the impact of the ionospheric anomalies depends on the threat parameters, namely, the ionospheric gradient, the slope width

  12. Gradient-based optimization of mother wavelets Nicola Neretti Nathan Intrator

    E-Print Network [OSTI]

    Intrator, Nathan

    . We develop an unconstrained gradient-based optimization algorithm for a discrete wavelet transform wavelet transforms. In is paper we describe a novel optimization for the pur- pose of wavelet filter1 Gradient-based optimization of mother wavelets Nicola Neretti Nathan Intrator Abstract-- We

  13. The gradient flow running coupling in SU2 with 8 flavors

    E-Print Network [OSTI]

    Jarno Rantaharju; Tuomas Karavirta; Viljami Leino; Teemu Rantalaiho; Kari Rummukainen; Kimmo Tuominen

    2014-11-18T23:59:59.000Z

    We present preliminary results of the gradient flow running coupling with Dirichlet boundary condition in the SU(2) gauge theory with 8 fermion flavours. Improvements to the gradient flow measurement allow us to obtain a robust continuum limit. The results are consistent with perturbative running in the weak coupling region.

  14. ENERGY SCAVENGING BASED ON TRANSIENT THERMAL GRADIENTS: APPLICATION TO STRUCTURAL HEALTH MONITORING OF AIRCRAFTS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ENERGY SCAVENGING BASED ON TRANSIENT THERMAL GRADIENTS: APPLICATION TO STRUCTURAL HEALTH MONITORING from its environment [2]. A possible source of energy could be thermal gradients. This paper, INSA 3 Thalès Alenia Space, Toulouse, France Abstract: Results about energy capture from

  15. Exploration geothermal gradient drilling, Platanares, Honduras, Central America

    SciTech Connect (OSTI)

    Goff, S.J.; Laughlin, A.W.; Ruefenacht, H.D.; Goff, F.E.; Heiken, G.; Ramos, N.

    1988-01-01T23:59:59.000Z

    This paper is a review and summary of the core drilling operations component of the Honduras Geothermal Resource Development Project at the Platanares geothermal prospect in Honduras, Central America. Three intermediate depth (428 to 679 m) coreholes are the first continuously cored geothermal exploration boreholes in Honduras. These coring operations are part of the Central America Energy Resource Project (CAERP) effort funded by the Agency for International Development (AID) and implemented by the Los Alamos National Laboratory (Los Alamos) in cooperation with the Empresa Nacional de Energia Electrica (ENEE) and the United States Geological Survey (USGS). This report emphasizes coring operations with reference to the stratigraphy, thermal gradient, and flow test data of the boreholes. The primary objectives of this coring effort were (1) to obtain quantitative information on the temperature distribution as a function of depth, (2) to recover fluids associated with the geothermal reservoir, (3) to recover 75% or better core from the subsurface rock units, and (4) to drill into the subsurface rock as deeply as possible in order to get information on potential reservoir rocks, fracture density, permeabilities, and alteration histories of the rock units beneath the site. The three exploration coreholes drilled to depths of 650, 428 and 679 m, respectively, encountered several hot water entries. Coring operations and associated testing began in mid-October 1986 and were completed at the end of June 1987.

  16. Gradient flow and scale setting on MILC HISQ ensembles

    E-Print Network [OSTI]

    Bazavov, A; Brown, N; DeTar, C; Foley, J; Gottlieb, Steven; Heller, U M; Komijani, J; Laiho, J; Levkova, L; Sugar, R L; Toussaint, D; Van de Water, R S

    2015-01-01T23:59:59.000Z

    We report on a scale determination with gradient-flow techniques on the $N_f=2+1+1$ HISQ ensembles generated by the MILC collaboration. The ensembles include four lattice spacings, ranging from approximately 0.15 to 0.06 fm, and both physical and unphysical values of the quark masses. The scales $\\sqrt{t_0}/a$ and $w_0/a$ and their tree-level improvements, $\\sqrt{t_{0,{\\rm imp}}}$ and $w_{0,{\\rm imp}}$, are computed on each ensemble using Symanzik flow and the cloverleaf definition of the energy density $E$. Using a combination of continuum chiral perturbation theory and a Taylor-series ansatz for the lattice-spacing and strong-coupling dependence, the results are simultaneously extrapolated to the continuum and interpolated to physical quark masses. We determine the scales $\\sqrt{t_0} = 0.1416({}_{-5}^{+8})$ fm and $w_0 = 0.1717({}_{-11}^{+12})$ fm, where the errors are sums, in quadrature, of statistical and all systematic errors. The precision of $w_0$ and $\\sqrt{t_0}$ is comparable to or more precise than...

  17. Dielectric-Loaded Microwave Cavity for High-Gradient Testing of Superconducting Materials

    E-Print Network [OSTI]

    Pogue, Nathaniel Johnston

    2011-08-08T23:59:59.000Z

    in the department. Simply put, I wouldn?t have wanted to obtain my Ph.D. with anyone else. I would also like to give special thanks to Al \\Mac" McIntur for being a constant source of wisdom, in both the scienti c and personal realms. He is a great wall on which... during these Guinness Guys Wednesday night sessions; An- drew Jaisle also lent a hand in advising. Andrew is source of order. Keeping things clean, keeping a schedule, and getting you stu done are what are needed to be a pro- ductive member in a group...

  18. Preparations for a high gradient inverse free electron laser experiment at Brookhaven national laboratory

    SciTech Connect (OSTI)

    Duris, J.; Li, R. K.; Musumeci, P.; Sakai, Y.; Threlkeld, E.; Williams, O.; Fedurin, M.; Kusche, K.; Pogorelsky, I.; Polyanskiy, M.; Yakimenko, V. [UCLA Department of Physics and Astronomy, Los Angeles, CA 90095 (United States); Accelerator Test Facility, Brookhaven National Laboratory, Upton, NY, 11973 (United States)

    2012-12-21T23:59:59.000Z

    Preparations for an inverse free electron laser experiment at Brookhaven National Laboratory's Accelerator Test Facilty are presented. Details of the experimental setup including beam and laser transport optics are first discussed. Next, the driving laser pulse structure is investigated and initial diagnostics are explored and compared to simulations. Finally, planned improvements to the experimental setup are discussed.

  19. THE FREE ELECTRON LASER AS A POWER SOURCE FOR A HIGH-GRADIENT ACCELERATING STRUCTURE

    E-Print Network [OSTI]

    Sessler, A.M.

    2008-01-01T23:59:59.000Z

    18-23, 1982 THE FREE ELECTRON LASER AS A POWER SOURCE FOR AAC03-76SF00098 THE FREE ELECTRON LASER AS A POWER SOURCE FORVariable Parameter Free Electron Laser", to be pub 1 i shed

  20. Highly Parallel Magnetic Resonance Imaging with a Fourth Gradient Channel for Compensation of RF Phase Patterns

    E-Print Network [OSTI]

    Bosshard, John 1983-

    2012-08-20T23:59:59.000Z

    70% increase in SNR [62]. The same group used an array of four arc shaped coils around a cylinder for microscopy for SENSE and GRAPPA accelerated imaging [63]. The greater field of view provided by an array of small coils was noted by Laistler et...

  1. Dielectric-Loaded Microwave Cavity for High-Gradient Testing of Superconducting Materials 

    E-Print Network [OSTI]

    Pogue, Nathaniel Johnston

    2011-08-08T23:59:59.000Z

    for each piece and order of the welds. : : : : : : : : : : : : : : : 37 21 Upper Left: The thermometry shown is for a single cell cavity. The thermometers used in this particular set up are 576 Allen Bradly resistors that have the capability to measure... spring loaded plate to keep the faces together and to handle the expansion and contraction of the metal during the welding process. : : : : : : : : : : : : : : : : : : : : : : : 63 33 Sciaky 6-axis E-beam welder located at Je erson Lab. Pictured here...

  2. Design and fabrication of a microfluidies gradient generator system for high-throughput molecular interaction studies

    E-Print Network [OSTI]

    Chen, Guan-Jong, 1981-

    2004-01-01T23:59:59.000Z

    Design and fabrication of a microfluidics system capable of generating reproducible and controlled micro-biochemical environments that can be used as a diagnostic assay and microreactor is important. Here, a simple technique ...

  3. Illinois: High-Energy, Concentration-Gradient Cathode Material for Plug-in

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directed off Energy.gov.Energy02.pdf7 OPAM Flash2011-37EnergySubmitRoad | DepartmentIllinoisHybrids

  4. Illinois: High-Energy, Concentration-Gradient Cathode Material for Plug-in

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't YourTransport(Fact Sheet),Energy Petroleum TechnologyEnergy Rules4 AUDITIllinois

  5. A high-level framework for PDE-constrained optimisation

    E-Print Network [OSTI]

    Simon Funke

    2013-02-21T23:59:59.000Z

    Its main features are an intuitive mathematical interface, a high degree of ... Engineering; J.6 [Computer Applications]: Computer-Aided Engineering; D.2 ... By contrast, the adjoint method computes the gradient of a scalar functional with a.

  6. Design of diamond turned holograms by the nonlinear conjugate gradients method Colin Dankwart, Claas Falldorf and Jurgen Jahns

    E-Print Network [OSTI]

    Jahns, Jürgen

    Design of diamond turned holograms by the nonlinear conjugate gradients method Colin Dankwart investigate a different optimization approach, the nonlinear conjugate gradients (NCG) method. The NGC method design algorithm, based on the generalized projections method (GPM) [?] was established, taking

  7. An Elementary Extension of Korn's First Inequality to H(Curl) motivated by Gradient Plasticity with Plastic Spin

    E-Print Network [OSTI]

    Patrizio Neff; Dirk Pauly; Karl-Josef Witsch

    2011-06-30T23:59:59.000Z

    We prove a Korn-type inequality for tensor fields without gradient structure, which generalizes Korn's first inequality.

  8. JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS: Vol. 66, No. 1, JULY 1990 Vectorization of Conjugate-Gradient Methods

    E-Print Network [OSTI]

    Navon, Michael

    of Conjugate-Gradient Methods for Large-Scale Minimization in Meteorology' Io M. NAVON, 2 P. K. H. PHUA, 3 conjugate-gradient methods designed to solve symmetric linear systems of algebraic equations, arising mainly or parallel processing, no such effort was undertaken for the nonlinear conjugate-gradient method for large

  9. Proton Gradient Regulation 5-Mediated Cyclic Electron Flow under ATP-or Redox-Limited Conditions: A Study of

    E-Print Network [OSTI]

    Proton Gradient Regulation 5-Mediated Cyclic Electron Flow under ATP- or Redox-Limited Conditions.K.N.) The Chlamydomonas reinhardtii proton gradient regulation5 (Crpgr5) mutant shows phenotypic and functional traits discriminate two pathways for CEF and determine their maximum electron flow rates. The PGR5/proton gradient

  10. Structural Evolution and Li Dynamics in Nanophase Li3PS4 by Solid-State and Pulsed Field Gradient NMR

    SciTech Connect (OSTI)

    Gobet, Mallory [Hunter College of the City University of New York] [Hunter College of the City University of New York; Greenbaum, Steve [Hunter College of the City University of New York] [Hunter College of the City University of New York; Sahu, Gayatri [ORNL] [ORNL; Liang, Chengdu [ORNL] [ORNL

    2014-01-01T23:59:59.000Z

    The ceramic lithium ion conductor -Li3PS4 has a disordered and nanoporous structure that leads to an enhancement in ionic conductivity by some three orders of magnitude compared to the crystalline phase. The phase is prepared by thermal treatment of an inorganic-organic complex based on Li3PS4 and THF. Multinuclear (1H, 6,7Li, 31P) solid state NMR spectroscopy is used to characterize the structural phase evolution of the starting material at various steps in the thermal treatment. The phase formed after high temperature treatment is recognized as spectroscopically distinct from the bulk -Li3PS4 compound. Also formed is an amorphous lithium thiophosphate phase that is metastable as verified by annealing over an extended period. Lithium ion self-diffusion coefficients are measurable by standard pulsed gradient NMR methods at 100oC and with values consistent with the high ionic conductivity previously reported for this material.

  11. On the maintenance of weak meridional temperature gradients during warm climates

    E-Print Network [OSTI]

    Korty, Robert Lindsay

    2005-01-01T23:59:59.000Z

    This thesis examines the dynamics of equable climates. The underlying physics of two mechanisms by which weak meridional temperature gradients might be maintained are studied. First, I examine the evolution of stratospheric ...

  12. Bell-Plesset effects for an accelerating interface with contiguous density gradients

    SciTech Connect (OSTI)

    Amendt, P

    2005-12-20T23:59:59.000Z

    A Plesset-type treatment [J. Appl. Phys. 25, 96 (1954)] is used to assess the effects of contiguous density gradients at an accelerating spherical classical interface on Rayleigh-Taylor and Bell-Plesset perturbation growth. Analytic expressions are obtained that describe enhanced Rayleigh-Taylor instability growth from contiguous density gradients aligned with the acceleration and which increase the effective Atwood number of the perturbed interface. A new pathway for geometric amplification of surface perturbations on an accelerating interface with contiguous density gradients is identified. A resonance condition between the density-gradient scalelength and the radius of the interface is also predicted based on a linearized analysis of Bernoulli's equation, potentially leading to enhanced perturbation growth. Comparison of the analytic treatment with detailed two-dimensional single-mode growth-factor simulations shows good agreement for low-mode numbers where the effects of spherical geometry are most manifested.

  13. Critical gradient for internal erosion in earthen d ams : a comparative analysis of two predictive methodologies

    E-Print Network [OSTI]

    Donohue, Catherine, M. Eng. Massachusetts Institute of Technology

    2013-01-01T23:59:59.000Z

    Minimizing the uncertainty in predicting the critical gradient of a dam (i.e. the critical reservoir pool level) is important during the risk analysis of dams. Uncertainty leads to inexact relative risk in portfolio ...

  14. One dimensional electron spin imaging for single spin detection and manipulation using a gradient field 

    E-Print Network [OSTI]

    Shin, Chang-Seok

    2009-05-15T23:59:59.000Z

    magnetic field gradients. These fabricated devices are used to demonstrate this subwavelength imaging technique by imaging single electron spins of the nitrogen-vacancy (NV) defect in diamond. In this demonstration, multiple NV defects, unresolved in a...

  15. Inversion of TEM sounding data using the steepest descent and the conjugate gradients methods

    E-Print Network [OSTI]

    Alsabti, Abdallah S

    2001-01-01T23:59:59.000Z

    In this study, the inversion of TEM sounding is investigated. I solved the over-determined and the under-determined inversion problems using the steepest descent and the conjugate gradients methods. The study depends on results from the inversion...

  16. Toward Understanding and Modeling Compressibility Effects on Velocity Gradients in Turbulence

    E-Print Network [OSTI]

    Suman, Sawan

    2011-02-22T23:59:59.000Z

    gradients hold the key to understanding several non-linear processes like material element deformation, energy cascading, intermittency and mixing. Experiments, direct numerical simulation (DNS) and simple mathematical models are three approaches to study...

  17. Theoretical analysis of degradation mechanisms in the formation of morphogen gradients

    E-Print Network [OSTI]

    Bozorgui, Behnaz; Kolomeisky, Anatoly B

    2015-01-01T23:59:59.000Z

    The fundamental biological processes of development of tissues and organs in multicellular organisms is governed by various signaling molecules, which are called morphogens. It is known that spatial and temporal variations in concentration profiles of signaling molecules, which are frequently referred as morphogen gradients, lead to cell differentiation via activating specific genes in a concentration-dependent manner. It is widely accepted that the establishment of the morphogen gradients involves multiple biochemical reactions and diffusion processes. One of the critical elements in the formation of morphogen gradients is a degradation of signaling molecules. We develop a new theoretical approach that provides a comprehensive description of the degradation mechanisms. It is based on the idea that the degradation works as an effective potential that drives the signaling molecules away from the source region. Utilizing the method of first-passage processes, the dynamics of the formation of morphogen gradients...

  18. Quadrature Rotating-Frame Gradient Fields for Ultra-Low Field Nuclear Magnetic Resonance and Imaging

    E-Print Network [OSTI]

    Bouchard, Louis-Serge

    2005-01-01T23:59:59.000Z

    Frame Gradient Fields For Ultra-Low Field Nuclear Magneticslow, as in the limit of ultra-low ?elds. In the ?rst case,B. Slice selection in ultra-low ?elds We ?rst examine the

  19. Osteochondral Tissue Engineering for the TMJ Condyle Using a Novel Gradient Scaffold

    E-Print Network [OSTI]

    Singh, Milind

    2008-10-22T23:59:59.000Z

    . Beyond these vital biomechanical characterization efforts, novel microsphere-based gradient scaffolds were developed to address functional osteochondral tissue regeneration. Novel microsphere sintering routes, using ethanol as an anti-solvent or sub-critical...

  20. A PRECONDITIONED CONJUGATE GRADIENT METHOD FOR NONSELFADJOINT OR INDEFINITE ORTHOGONAL SPLINE

    E-Print Network [OSTI]

    Aitbayev, Rakhim

    value problem, orthogonal spline collocation, conjugate gradient method, preconditioner, matrix . While the divergence form is natural for the standard finite element Galerkin method, the nondivergence form is more appropriate for the orthogonal spline collocation (OSC) method since, in this case

  1. On the role of material property gradients in noncontacting thermoelectric NDE

    E-Print Network [OSTI]

    Nagy, Peter B.

    On the role of material property gradients in noncontacting thermoelectric NDE Hector Carreon that sense the thermoelectric currents produced by directional heating and cooling of the specimen and tangential magnetic fields produced by the resulting thermoelectric currents. Experimental results from

  2. Change in biomass of benthic and planktonic algae along a disturbance gradient for 24 Great

    E-Print Network [OSTI]

    McMaster University

    Change in biomass of benthic and planktonic algae along a disturbance gradient for 24 Great Lakes a content of planktonic algae and benthic algae in periphyton on acrylic rods and in epiphyton growing

  3. One dimensional electron spin imaging for single spin detection and manipulation using a gradient field

    E-Print Network [OSTI]

    Shin, Chang-Seok

    2009-05-15T23:59:59.000Z

    magnetic field gradients. These fabricated devices are used to demonstrate this subwavelength imaging technique by imaging single electron spins of the nitrogen-vacancy (NV) defect in diamond. In this demonstration, multiple NV defects, unresolved in a...

  4. Effect of Density Gradient Centrifugation on Quality and Recovery Rate of Equine Sperm

    E-Print Network [OSTI]

    Edmond, Ann J.

    2010-07-14T23:59:59.000Z

    gradient volume (height) on stallion sperm quality and recovery rate in sperm pellets following centrifugation. In all three experiments, equine semen was initially centrifuged to increase sperm concentration. In Experiment 1, one-mL aliquots were layered...

  5. MILLIMETER-SCALE GENETIC GRADIENTS AND COMMUNITY-LEVEL MOLECULAR CONVERGENCE IN A HYPERSALINE MICROBIAL MAT

    SciTech Connect (OSTI)

    Fenner, Marsha W; Kunin, Victor; Raes, Jeroen; Harris, J. Kirk; Spear, John R.; Walker, Jeffrey J.; Ivanova, Natalia; Mering, Christian von; Bebout, Brad M.; Pace, Norman R.; Bork, Peer; Hugenholtz, Philip

    2008-04-30T23:59:59.000Z

    To investigate the extent of genetic stratification in structured microbial communities, we compared the metagenomes of 10 successive layers of a phylogenetically complex hypersaline mat from Guerrero Negro, Mexico. We found pronounced millimeter-scale genetic gradients that are consistent with the physicochemical profile of the mat. Despite these gradients, all layers displayed near identical and acid-shifted isoelectric point profiles due to a molecular convergence of amino acid usage indicating that hypersalinity enforces an overriding selective pressure on the mat community.

  6. A gradient system on the quantum information space realizing the averaged learning equation of Hebb type

    E-Print Network [OSTI]

    Yoshio Uwano; Hiromi Yuya

    2009-12-17T23:59:59.000Z

    The averaged learning equation (ALEH) applicable to the principal component analyzer is studied from both quantum information geometry and dynamical system viewpoints. On the quantum information space (QIS), the space of regular density matrices endowed with the quantum SLD-Fisher metric, a gradient system is given as an extension of the ALEH; on the submanifold, consisting of the diagonal matrices, of the QIS, the gradient flow coincides with the ALEH up to a local diffeomorphism.

  7. Poblano v1.0 : a Matlab toolbox for gradient-based optimization.

    SciTech Connect (OSTI)

    Dunlavy, Daniel M.; Acar, Evrim (Sandia National Laboratories, Livermore, CA); Kolda, Tamara Gibson (Sandia National Laboratories, Livermore, CA)

    2010-03-01T23:59:59.000Z

    We present Poblano v1.0, a Matlab toolbox for solving gradient-based unconstrained optimization problems. Poblano implements three optimization methods (nonlinear conjugate gradients, limited-memory BFGS, and truncated Newton) that require only first order derivative information. In this paper, we describe the Poblano methods, provide numerous examples on how to use Poblano, and present results of Poblano used in solving problems from a standard test collection of unconstrained optimization problems.

  8. Effect of pressure gradient on the drag reduction performance of two and three dimensional riblets

    E-Print Network [OSTI]

    Hall, Aaron Chenault

    1991-01-01T23:59:59.000Z

    EFFECT OF PRESSURE GRADIENT ON THE DRAG REDUCTION PERFORMANCE OF TWO AND THREE DIMENSIONAL RIBLETS A Thesis by AARON CHENAULT HALL Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1991 Major Subject: Aerospace Engineering EFFECT OF PRESSURE GRADIENT ON THE DRAG REDUCTION PERFORMANCE OF TWO AND THREE DIMENSIONAL RIBLETS A Thesis by AARON CHENAULT HALL Approved as to style and content by...

  9. Risk Distance: The Loss of Strength Gradient and Colombia's Geography of Impunity

    E-Print Network [OSTI]

    Demarest, Geoffrey

    2013-12-31T23:59:59.000Z

    material under- performance and organized violence. The opposite certainly appears true; close proximity of a 4 group of violent armed men can quickly diminish the material well-being of a geographically isolated community. Trying to paint, adjust..., is known as the Loss of Strength Gradient, a term proposed 7 by economist Kenneth Boulding in 1962. (Boulding 1962). Although Professor Boulding used the term in relation to global strategy, the loss of strength gradient applies equally well...

  10. Double active shielded magnetic field gradient design with minimum inductance method

    E-Print Network [OSTI]

    Wang, Xu

    1992-01-01T23:59:59.000Z

    DOUBLE ACTIVE SHIELDED MAGNETIC FIELD GRADIENT DESIGN WITH MINIMUM INDUCTANCE METHOD A Thesis by XU WANG Submitted to the Oflice of Graduate Studies of Texas ASM University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE May 1992 Major Subject: Physics DOUBLE ACTIVE SHIELDED MAGNETIC FIELD GRADIENT DESIGN WITH MINIMUM INDUCTANCE METHOD A Thesis by XU WANG Approved as to style and content by: F. R. Huson (Chair of Committee) Steve Wry (Member) Edward...

  11. Penetration mechanism and distribution gradients of sodium tripolyphosphate in peeled and deveined shrimp

    E-Print Network [OSTI]

    Tenhet, Vickie Lynn

    1979-01-01T23:59:59.000Z

    PENETRATION MECHANISM AND DISTRIBUTION GRADIENTS OF SODIUM TRIPOLYPHOSPHATE IN PEELED AND DEVEINED SHRIMP A Thesis by VICKIE LYNN TENHET Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE December 1979 Major Subject: Food Science and Technology PENETRATION MECHANISM AND DISTRIBUTION GRADIENTS OF SODIUM TRIPOLYPHOSPHATE IN PEELED AND DEVEINED SHRIMP A Thesis by VICKIE LYNN TENHET Approved as to style...

  12. Intraarterial Pressure Gradients After Randomized Angioplasty or Stenting of Iliac Artery Lesions

    SciTech Connect (OSTI)

    Tetteroo, Eric; Haaring, Cees [Department of Radiology, Room E.01.132, University Hospital Utrecht, Heidelberglaan 100, NL-3584 CX Utrecht (Netherlands); Graaf, Yolanda van der [Department of Clinical Epidemiology, University Hospital Utrecht, Heidelberglaan 100, NL-3584 CX Utrecht (Netherlands); Schaik, Jan P.J. van; Engelen, A.D. van; Mali, Willem P.T.M. [Department of Radiology, Room E.01.132, University Hospital Utrecht, Heidelberglaan 100, NL-3584 CX Utrecht (Netherlands)

    1996-11-15T23:59:59.000Z

    Purpose: To determine initial technical results of percutaneous transluminal angioplasty (PTA) and stent procedures in the iliac artery, mean intraarterial pressure gradients were recorded before and after each procedure. Methods: We randomly assigned 213 patients with typical intermittent claudication to primary stent placement (n= 107) or primary PTA (n= 106), with subsequent stenting in the case of a residual mean pressure gradient of > 10 mmHg (n= 45). Eligibility criteria included angiographic iliac artery stenosis (> 50% diameter reduction) and/or a peak systolic velocity ratio > 2.5 on duplex examination. Mean intraarterial pressures were simultaneously recorded above and below the lesion, at rest and also during vasodilatation in the case of a resting gradient {<=} 10 mmHg. Results: Pressure gradients in the primary stent group were 14.9 {+-} 10.4 mmHg before and 2.9 {+-} 3.5 mmHg after stenting. Pressure gradients in the primary PTA group were 17.3 {+-} 11.3 mmHg pre-PTA, 4.2 {+-} 5.4 mmHg post-PTA, and 2.5 {+-} 2.8 mmHg after selective stenting. Compared with primary stent placement, PTA plus selective stent placement avoided application of a stent in 63% (86/137) of cases, resulting in a considerable cost saving. Conclusion: Technical results of primary stenting and PTA plus selective stenting are similar in terms of residual pressure gradients.

  13. Computational studies and optimization of wakefield accelerators

    E-Print Network [OSTI]

    Geddes, C.G.R.

    2010-01-01T23:59:59.000Z

    France [1] ILC- www.linearcollider.org/cms ; LCLS- www-ssrl.slac.stanford.edu/lcls/ [2] T. Tajima and J. M. Dawson,while machines such as the LCLS will use km-scale linacs to

  14. Laser Wakefield Particle Accelerators Project at NERSC

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated Codes |Is Your Home asLCLSLaboratoryRowlandRevolutionizingLaser

  15. Thermal Gradient Holes At Fenton Hill HDR Geothermal Area (Purtymun...

    Open Energy Info (EERE)

    Valles caldera in order to locate an of high heat flow that would serve as a favorable test site for the HDR concept. Notes Data from these wells are report in Reiter et al....

  16. High-Sensitivity Analysis of Human Plasma Proteome by Immobilized Isoelectric Focusing Fractionation Coupled to Mass

    E-Print Network [OSTI]

    Tian, Weidong

    High-Sensitivity Analysis of Human Plasma Proteome by Immobilized Isoelectric Focusing of complex biological samples. Keywords: plasma · immobilized pH gradients · isoelectric focusing of Sciences, Shanghai, 200031, China Received December 24, 2004 Immobilized pH gradients isoelectric focusing

  17. Muon acceleration in cosmic-ray sources

    SciTech Connect (OSTI)

    Klein, Spencer R.; Mikkelsen, Rune E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Becker Tjus, Julia [Fakultät für Physik and Astronomie, Theoretische Physik I, Ruhr-Universität Bochum, D-44780 Bochum (Germany)

    2013-12-20T23:59:59.000Z

    Many models of ultra-high energy cosmic-ray production involve acceleration in linear accelerators located in gamma-ray bursts, magnetars, or other sources. These transient sources have short lifetimes, which necessitate very high accelerating gradients, up to 10{sup 13} keV cm{sup –1}. At gradients above 1.6 keV cm{sup –1}, muons produced by hadronic interactions undergo significant acceleration before they decay. This muon acceleration hardens the neutrino energy spectrum and greatly increases the high-energy neutrino flux. Using the IceCube high-energy diffuse neutrino flux limits, we set two-dimensional limits on the source opacity and matter density, as a function of accelerating gradient. These limits put strong constraints on different models of particle acceleration, particularly those based on plasma wake-field acceleration, and limit models for sources like gamma-ray bursts and magnetars.

  18. Method and apparatus for producing a carbon based foam article having a desired thermal-conductivity gradient

    DOE Patents [OSTI]

    Klett, James W. (Knoxville, TN) [Knoxville, TN; Cameron, Christopher Stan (Sanford, NC) [Sanford, NC

    2010-03-02T23:59:59.000Z

    A carbon based foam article is made by heating the surface of a carbon foam block to a temperature above its graphitizing temperature, which is the temperature sufficient to graphitize the carbon foam. In one embodiment, the surface is heated with infrared pulses until heat is transferred from the surface into the core of the foam article such that the graphitizing temperature penetrates into the core to a desired depth below the surface. The graphitizing temperature is maintained for a time sufficient to substantially entirely graphitize the portion of the foam article from the surface to the desired depth below the surface. Thus, the foam article is an integral monolithic material that has a desired conductivity gradient with a relatively high thermal conductivity in the portion of the core that was graphitized and a relatively low thermal conductivity in the remaining portion of the foam article.

  19. Muon Acceleration in Cosmic-ray Sources

    E-Print Network [OSTI]

    Spencer R. Klein; Rune Mikkelsen; Julia K. Becker Tjus

    2012-08-09T23:59:59.000Z

    Many models of ultra-high energy cosmic-ray production involve acceleration in linear accelerators located in Gamma-Ray Bursts magnetars, or other sources. These source models require very high accelerating gradients, $10^{13}$ keV/cm, with the minimum gradient set by the length of the source. At gradients above 1.6 keV/cm, muons produced by hadronic interactions undergo significant acceleration before they decay. This acceleration hardens the neutrino energy spectrum and greatly increases the high-energy neutrino flux. We rule out many models of linear acceleration, setting strong constraints on plasma wakefield accelerators and on models for sources like Gamma Ray Bursts and magnetars.

  20. Method to create gradient index in a polymer

    DOE Patents [OSTI]

    Dirk, Shawn M; Johnson, Ross Stefan; Boye, Robert; Descour, Michael R; Sweatt, William C; Wheeler, David R; Kaehr, Bryan James

    2014-10-14T23:59:59.000Z

    Novel photo-writable and thermally switchable polymeric materials exhibit a refractive index change of .DELTA.n.gtoreq.1.0 when exposed to UV light or heat. For example, lithography can be used to convert a non-conjugated precursor polymer to a conjugated polymer having a higher index-of-refraction. Further, two-photon lithography can be used to pattern high-spatial frequency structures.