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Sample records for high gradient wakefield

  1. High Frequency, High Gradient Dielectric Wakefield Acceleration Experiments at SLAC and BNL

    SciTech Connect (OSTI)

    Rosenzweig, J. B.; Andonian, G.; Niknejadi, P.; Travish, G.; Williams, O.; Xuan, K.; Muggli, P.; Yakimenko, V.

    2010-11-04

    Given the recent success of >GV/m dielectric wakefield accelerator (DWA) breakdown experiments at SLAC, and follow-on coherent Cerenkov radiation (CCR) production at the UCLA Neptune, a UCLA-USC-SLAC collaboration is now implementing a new set of experiments that explore various DWA scenarios. These experiments are motivated by the opportunities presented by the approval of the FACET facility at SLAC, as well as unique pulse-train wakefield drivers at BNL. The SLAC experiments permit further exploration of the multi-GeV/m envelope in DWAs, and will entail investigations of novel materials (e.g. CVD diamond) and geometries (Bragg cylindrical structures, slab-symmetric DWAs), and have an over-riding goal of demonstrating >GeV acceleration in {approx}33 cm DWA tubes. In the nearer term before FACET's commissioning, we are performing measurements at the BNL ATF, in which we drive {approx}50-200 MV/m fields with single pulses or pulse trains, and observe resonantly driven CCR as well as deflection modes. These experiments are of high relevance to enhancing linear collider DWA designs, as they will demonstrate potential for high efficiency operation with pulse trains, and explore transverse modes for the first time.

  2. High Frequency, High Gradient Dielectric Wakefield Acceleration Experiments at SLAC and BNL

    SciTech Connect (OSTI)

    Rosenzweig, James; Travish, Gil; Hogan, Mark; Muggli, Patric; /Southern California U.

    2012-07-05

    Given the recent success of >GV/m dielectric wakefield accelerator (DWA) breakdown experiments at SLAC, and follow-on coherent Cerenkov radiation production at the UCLA Neptune, a UCLA-USC-SLAC collaboration is now implementing a new set of experiments that explore various DWA scenarios. These experiments are motivated by the opportunities presented by the approval of FACET facility at SLAC, as well as unique pulse-train wakefield drivers at BNL. The SLAC experiments permit further exploration of the multi-GeV/m envelope in DWAs, and will entail investigations of novel materials (e.g. CVD diamond) and geometries (Bragg cylindrical structures, slab-symmetric DWAs), and have an over-riding goal of demonstrating >GeV acceleration in {approx}33 cm DWA tubes. In the nearer term before FACET's commissioning, we are planning measurements at the BNL ATF, in which we drive {approx}50-200 MV/m fields with single pulses or pulse trains. These experiments are of high relevance to enhancing linear collider DWA designs, as they will demonstrate potential for efficient operation with pulse trains.

  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.; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; Katsouleas, T.C.; Muggli, P.; Oz, E.; /Southern California U.

    2007-06-27

    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. Argonne Wakefield Accelerator Facility | Argonne National Laboratory

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

    Facilities 4 Tesla Magnet Facility Argonne Wakefield Accelerator Facility Argonne Wakefield Accelerator Facility Argonne Wakefield Accelerator Facility In order to achieve the high accelerating gradients needed to produce the tremendous energies required by a future particle accelerator, scientists have been looking for new ideas and solutions. Wakefield acceleration offers a potentially bold new path for the construction of the next generation of particle accelerators. The Argonne Wakefield

  5. 17 GHz High Gradient Accelerator Research

    SciTech Connect (OSTI)

    Temkin, Richard J.; Shapiro, Michael A.

    2013-07-10

    This is a report on the MIT High Gradient Accelerator Research program which has included: Operation of the 17 GHz, 25 MeV MIT/Haimson Research Corp. electron accelerator at MIT, the highest frequency, stand-alone accelerator in the world; collaboration with members of the US High Gradient Collaboration, including the design and test of novel structures at SLAC at 11.4 GHz; the design, construction and testing of photonic bandgap structures, including metallic and dielectric structures; the investigation of the wakefields in novel structures; and the training of the next generation of graduate students and postdoctoral associates in accelerator physics.

  6. 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

    2007-06-21

    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.

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

    SciTech Connect (OSTI)

    Lemery, F.; Mihalcea, D.; Piot, P.; Behrens, C.; Elsen, E.; Flottmann, K.; Gerth, C.; Kube, G.; Schmidt, B.; Osterhoff, J.; Stoltz, P.

    2011-09-07

    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.

  8. Interaction of an ultrarelativistic electron bunch train with a W-band accelerating structure: High power and high gradient

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

    Wang, D.; Antipov, S.; Jing, C.; Power, J. G.; Conde, M.; Wisniewski, E.; Liu, W.; Qiu, J.; Ha, G.; Dolgashev, V.; et al

    2016-02-05

    Electron beam interaction with high frequency structures (beyond microwave regime) has a great impact on future high energy frontier machines. We report on the generation of multimegawatt pulsed rf power at 91 GHz in a planar metallic accelerating structure driven by an ultrarelativistic electron bunch train. This slow-wave wakefield device can also be used for high gradient acceleration of electrons with a stable rf phase and amplitude which are controlled by manipulation of the bunch train. To achieve precise control of the rf pulse properties, a two-beam wakefield interferometry method was developed in which the rf pulse, due to themore » interference of the wakefields from the two bunches, was measured as a function of bunch separation. As a result, measurements of the energy change of a trailing electron bunch as a function of the bunch separation confirmed the interferometry method.« less

  9. High field gradient particle accelerator

    DOE Patents [OSTI]

    Nation, J.A.; Greenwald, S.

    1989-05-30

    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.; Greenwald, Shlomo

    1989-01-01

    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. Summary report of working group 3: High gradient and laser-structure based acceleration

    SciTech Connect (OSTI)

    Solyak, N.; Cowan, B.M.; /Tech-X, Boulder

    2010-01-01

    The charge for the working group on high gradient and laser-structure based acceleration was to assess the current challenges involved in developing an advanced accelerator based on electromagnetic structures, and survey state-of-the-art methods to address those challenges. The topics of more than 50 presentations in the working group covered a very broad range of issues, from ideas, theoretical models and simulations, to design and manufacturing of accelerating structures and, finally, experimental results on obtaining extremely high accelerating gradients in structures from conventional microwave frequency range up to THz and laser frequencies. Workshop discussion topics included advances in the understanding of the physics of breakdown and other phenomena, limiting high gradient performance of accelerating structures. New results presented in this workshop demonstrated significant progress in the fields of conventional vacuum structure-based acceleration, dielectric wakefield acceleration, and laser-structure acceleration.

  12. Dynamics of ionization-induced electron injection in the high density regime of laser wakefield acceleration

    SciTech Connect (OSTI)

    Desforges, F. G.; Paradkar, B. S. Ju, J.; Audet, T. L.; Maynard, G.; Cros, B.; Hansson, M.; Senje, L.; Persson, A.; Lundh, O.; Wahlström, C.-G.; Dobosz-Dufrénoy, S.; Monot, P.; Vay, J.-L.

    2014-12-15

    The dynamics of ionization-induced electron injection in high density (∼1.2 × 10{sup 19} cm{sup −3}) regime of laser wakefield acceleration is investigated by analyzing the betatron X-ray emission. In such high density operation, the laser normalized vector potential exceeds the injection-thresholds of both ionization-injection and self-injection due to self-focusing. In this regime, direct experimental evidence of early on-set of ionization-induced injection into the plasma wave is given by mapping the X-ray emission zone inside the plasma. Particle-In-Cell simulations show that this early on-set of ionization-induced injection, due to its lower trapping threshold, suppresses the trapping of self-injected electrons. A comparative study of the electron and X-ray properties is performed for both self-injection and ionization-induced injection. An increase of X-ray fluence by at least a factor of two is observed in the case of ionization-induced injection due to increased trapped charge compared to self-injection mechanism.

  13. Coreless Concept for High Gradient Induction Cell

    SciTech Connect (OSTI)

    Krasnykh, Anatoly; /SLAC

    2008-01-07

    An induction linac cell for a high gradient is discussed. The proposed solid state coreless approach for the induction linac topology (SLIM{reg_sign}) is based on nanosecond mode operation. This mode may have an acceleration gradient comparable with gradients of rf- accelerator structures. The discussed induction system has the high electric efficiency. The key elements are a solid state semiconductor switch and a high electric density dielectric with a thin section length. The energy in the induction system is storied in the magnetic field. The nanosecond current break-up produces the high voltage. The induced voltage is used for acceleration. This manner of an operation allows the use of low voltage elements in the booster part and achieves a high accelerating gradient. The proposed topology was tested in POP (proof of principle) experiments.

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

    SciTech Connect (OSTI)

    Jing, C.; Power, J.; Zholents, A. )

    2011-04-20

    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.

  15. High pressure liquid chromatographic gradient mixer

    DOE Patents [OSTI]

    Daughton, Christian G.; Sakaji, Richard H.

    1985-01-01

    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".

  16. High-pressure liquid chromatographic gradient mixer

    DOE Patents [OSTI]

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

    1982-09-08

    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.

  17. Theory of factors limiting high gradient operation of warm acceleratin...

    Office of Scientific and Technical Information (OSTI)

    Theory of factors limiting high gradient operation of warm accelerating structures Citation Details In-Document Search Title: Theory of factors limiting high gradient operation of ...

  18. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator

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

    Gessner, Spencer; Adli, Erik; Allen, James M.; An, Weiming; Clarke, Christine I.; Clayton, Chris E.; Corde, Sebastien; Delahaye, J. P.; Frederico, Joel; Green, Selina Z.; et al

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. In this study, we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel ismore » created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m-1 is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.« less

  19. 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.

    2014-05-15

    The 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 structures in the laser energy density produced by the combined pulses exist 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.

  20. Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

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

    Zhang, C. J.; Hua, J. F.; Xu, X. L.; Li, F.; Pai, C. -H.; Wan, Y.; Wu, Y. P.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; et al

    2016-07-11

    A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of themore » wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. As a result, the capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.« less

  1. High-efficiency acceleration in the laser wakefield by a linearly increasing plasma density

    SciTech Connect (OSTI)

    Dong, Kegong; Wu, Yuchi; Zhu, Bin; Zhang, Zhimeng; Zhao, Zongqing; Zhou, Weimin; Hong, Wei; Cao, Leifeng; Gu, Yuqiu

    2014-12-15

    The acceleration length and the peak energy of the electron beam are limited by the dephasing effect in the laser wakefield acceleration with uniform plasma density. Based on 2D-3V particle in cell simulations, the effects of a linearly increasing plasma density on the electron acceleration are investigated broadly. Comparing with the uniform plasma density, because of the prolongation of the acceleration length and the gradually increasing accelerating field due to the increasing plasma density, the electron beam energy is twice higher in moderate nonlinear wakefield regime. Because of the lower plasma density, the linearly increasing plasma density can also avoid the dark current caused by additional injection. At the optimal acceleration length, the electron energy can be increased from 350 MeV (uniform) to 760 MeV (linearly increasing) with the energy spread of 1.8%, the beam duration is 5 fs and the beam waist is 1.25 μm. This linearly increasing plasma density distribution can be achieved by a capillary with special gas-filled structure, and is much more suitable for experiment.

  2. High gradient accelerators for linear light sources

    SciTech Connect (OSTI)

    Barletta, W.A.

    1988-09-26

    Ultra-high gradient radio frequency linacs powered by relativistic klystrons appear to be able to provide compact sources of radiation at XUV and soft x-ray wavelengths with a duration of 1 picosecond or less. This paper provides a tutorial review of the physics applicable to scaling the present experience of the accelerator community to the regime applicable to compact linear light sources. 22 refs., 11 figs., 21 tabs.

  3. High gradient lens for charged particle beam

    DOE Patents [OSTI]

    Chen, Yu-Jiuan

    2014-04-29

    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.

  4. High-gradient compact linear accelerator

    DOE Patents [OSTI]

    Carder, B.M.

    1998-05-26

    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.

  5. High-gradient compact linear accelerator

    DOE Patents [OSTI]

    Carder, Bruce M.

    1998-01-01

    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.

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

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

    High-Energy, Concentration-Gradient Cathode Material for Plug-in Hybrids and All-Electric Vehicles Could Reduce Batteries' Cost and Size Illinois: High-Energy,...

  7. Giga-electronvolt electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

    SciTech Connect (OSTI)

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

    2014-12-15

    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 particle-in-cell simulations support this analysis and confirm the scenario.

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

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

    Merit Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C. PDF icon esp10amine.pdf More Documents & Publications New High Energy Gradient Concentration ...

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

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

    a high-energy, concentration-gradient cathode material for plug-in hybrid and all-electric vehicles. ... market growth, leading to reductions in carbon pollution and imported oil. ...

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

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

    Energy 6_amine_2011_p.pdf (1.42 MB) More Documents & Publications FY 2011 Annual Progress Report for Energy Storage R&D Design of Safer High-Energy Density Materials for Lithium-Ion Cells Developing new high energy gradient concentration cathode material

  11. Observation of Wakefield Suppression in a Photonic-Band-Gap Accelerator Structure

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

    Simakov, Evgenya I.; Arsenyev, Sergey A.; Buechler, Cynthia E.; Edwards, Randall L.; Romero, William P.; Conde, Manoel; Ha, Gwanghui; Power, John G.; Wisniewski, Eric E.; Jing, Chunguang

    2016-02-10

    We report experimental observation of higher order mode (HOM) wakefield suppression in a room-temperature traveling-wave photonic band gap (PBG) accelerating structure at 11.700 GHz. It has been long recognized that PBG structures have potential for reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in a room-temperature PBG structure was conducted in 2005. Since then, the importance of PBG accelerator research has been recognized by many institutions. However, the full experimental characterization of the wakefield spectrum and demonstration of wakefield suppression when the accelerating structure is excited by an electron beam has not been performed to date. Wemore » conducted an experiment at the Argonne Wakefield Accelerator (AWA) test facility and observed wakefields excited by a single high charge electron bunch when it passes through a PBG accelerator structure. Lastly, excellent HOM suppression properties of the PBG accelerator were demonstrated in the beam test.« less

  12. High-power radio frequency pulse generation and extration based on wakefield excited by an intense charged particle beam in dielectric-loaded waveguides.

    SciTech Connect (OSTI)

    Gao, F.; High Energy Physics; Illinois Inst. of Tech

    2009-07-24

    Power extraction using a dielectric-loaded (DL) waveguide is a way to generate high-power radio frequency (RF) waves for future particle accelerators, especially for two-beam-acceleration. In a two-beam-acceleration scheme, a low-energy, high-current particle beam is passed through a deceleration section of waveguide (decelerator), where the power from the beam is partially transferred to trailing electromagnetic waves (wakefields); then with a properly designed RF output coupler, the power generated in the decelerator is extracted to an output waveguide, where finally the power can be transmitted and used to accelerate another usually high-energy low-current beam. The decelerator, together with the RF output coupler, is called a power extractor. At Argonne Wakefield Accelerator (AWA), we designed a 7.8GHz power extractor with a circular DL waveguide and tested it with single electron bunches and bunch trains. The output RF frequency (7.8GHz) is the sixth harmonic of the operational frequency (1.3GHz) of the electron gun and the linac at AWA. In single bunch excitation, a 1.7ns RF pulse with 30MW of power was generated by a single 66nC electron bunch passing through the decelerator. In subsequent experiments, by employing different splitting-recombining optics for the photoinjector laser, electron bunch trains were generated and thus longer RF pulses could be successfully generated and extracted. In 16-bunch experiments, 10ns and 22ns RF pulses have been generated and extracted; and in 4-bunch experiments, the maximum power generated was 44MW with 40MW extracted. A 26GHz DL power extractor has also been designed to test this technique in the millimeter-wave range. A power level of 148MW is expected to be generated by a bunch train with a bunch spacing of 769ps and bunch charges of 20nC each. The arrangement for the experiment is illustrated in a diagram. Higher-order-mode (HOM) power extraction has also been explored in a dual-frequency design. By using a bunch

  13. High and ulta-high gradient quadrupole magnets

    SciTech Connect (OSTI)

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

    1985-05-01

    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%.

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

    SciTech Connect (OSTI)

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

    2014-12-01

    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.

  15. Fabrication of high gradient insulators by stack compression

    DOE Patents [OSTI]

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

    2014-04-29

    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.

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

    SciTech Connect (OSTI)

    Arntz, Floyd; Kardo-Sysoev, A.; Krasnykh, A.; /SLAC

    2008-12-16

    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

  17. Dielectric-Lined High-Gradient Accelerator Structure

    SciTech Connect (OSTI)

    Jay L. Hirshfield

    2012-04-24

    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

  18. Wakefield generation in magnetized plasmas

    SciTech Connect (OSTI)

    Holkundkar, Amol; Brodin, Gert; Marklund, Mattias

    2011-09-15

    We consider wakefield generation in plasmas by electromagnetic pulses propagating perpendicular to a strong magnetic field, in the regime where the electron cyclotron frequency is equal to or larger than the plasma frequency. Particle-in-cell simulations reveal that for moderate magnetic field strengths previous results are reproduced, and the wakefield wave number spectrum has a clear peak at the inverse skin depth. However, when the cyclotron frequency is significantly larger than the plasma frequency, the wakefield spectrum becomes broadband, and simultaneously the loss rate of the driving pulse is much enhanced. A set of equations for the scalar and vector potentials reproducing these results are derived, using only the assumption of a weakly nonlinear interaction.

  19. Charged particle beam scanning using deformed high gradient insulator

    DOE Patents [OSTI]

    Chen, Yu -Jiuan

    2015-10-06

    Devices and methods are provided to allow rapid deflection of a charged particle beam. The disclosed devices can, for example, be used as part of a hadron therapy system to allow scanning of a target area within a patient's body. The disclosed charged particle beam deflectors include a dielectric wall accelerator (DWA) with a hollow center and a dielectric wall that is substantially parallel to a z-axis that runs through the hollow center. The dielectric wall includes one or more deformed high gradient insulators (HGIs) that are configured to produce an electric field with an component in a direction perpendicular to the z-axis. A control component is also provided to establish the electric field component in the direction perpendicular to the z-axis and to control deflection of a charged particle beam in the direction perpendicular to the z-axis as the charged particle beam travels through the hollow center of the DWA.

  20. Modeling high gradient magnetic separation from biological fluids.

    SciTech Connect (OSTI)

    Bockenfeld, D.; Chen, H.; Rempfer, D.; Kaminski, M. D.; Rosengart, A. J.; Chemical Engineering; Illinois Inst. of Tech.; Univ. of Chicago, Pritzker School of Medicine

    2006-01-01

    A proposed portable magnetic separator consists of an array of biocompatible capillary tubing and magnetizable wires immersed in an externally applied homogeneous magnetic field. While subject to the homogeneous magnetic field, the wires create high magnetic field gradients, which aid in the collection of blood-borne magnetic nanospheres from blood flow. In this study, a 3-D numerical model was created using COMSOL Multiphysics 3.2 software to determine the configuration of the wire-tubing array from two possible configurations, one being an array with rows alternating between wires and tubing, and the other being an array where wire and tubing alternate in two directions. The results demonstrated that the second configuration would actually capture more of the magnetic spheres. Experimental data obtained by our group support this numerical result.

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

    SciTech Connect (OSTI)

    Jay L. Hirshfield

    2011-12-19

    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.

  2. A table-top x-ray FEL based on a laser wakefield accelerator-undulator system

    SciTech Connect (OSTI)

    Nakajima, K.; Kawakubo, T.; Nakanishi, H.

    1995-12-31

    Ultrahigh-gradient electron acceleration has been confirmed owing to the laser wakefield acceleration mechanism driven by an intense short laser wakefield acceleration mechanism driven by an intense short laser pulse in an underdense plasma. The laser wakefield acceleration makes it possible to build a compact electron linac capable of producing an ultra-short bunched electron beam. While the accelerator is attributed to longitudinal wakefields, transverse wakefields simultaneously generated by a short laser pulse can serve as a plasma undulator with a very short wavelength equal to a half of the plasma wavelength. We propose a new FEL concept for X-rays based on a laser wakefield accelerator-undulator system driven by intense short laser pulses delivered from table-top terawatt lasers. The system is composed of the accelerator stage and the undulator stage in a table-top size. A low energy electron beam is accelerated an bunched into microbunches due to laser wakefields in the accelerator stage. A micro-bunched beam travelling to the opposite direction of driving laser pulses produces coherent X-ray radiation in the undulator stage. A practical configuration and its analyses are presented.

  3. Latest Plasma Wakefield Acceleration Results from the FACET Project...

    Office of Scientific and Technical Information (OSTI)

    Latest Plasma Wakefield Acceleration Results from the FACET Project Citation Details In-Document Search Title: Latest Plasma Wakefield Acceleration Results from the FACET Project...

  4. Dechirper Wakefields for Short Bunches (Journal Article) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Dechirper Wakefields for Short Bunches Citation Details In-Document Search Title: Dechirper Wakefields for Short Bunches Authors: Bane, Karl ; Stupakov, Gennady ;...

  5. Dechirper Wakefields for Short Bunches (Journal Article) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Dechirper Wakefields for Short Bunches Citation Details In-Document Search Title: Dechirper Wakefields for Short Bunches You are accessing a document from the...

  6. Analytical theory of coherent synchrotron radiation wakefield...

    Office of Scientific and Technical Information (OSTI)

    Analytical theory of coherent synchrotron radiation wakefield of short bunches shielded by ... Word Cloud More Like This Full Text preview image File size NAView Full Text View Full ...

  7. Wakefield Municipal Gas & Light Department - Residential Conservation...

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

    Programmable Thermostats: 25 Water Heater: 100 Summary The Wakefield Municipal Gas & Light Department (WMGLD), in cooperation with the Massachusetts Municipal Wholesale Electric...

  8. A high-gradient high-duty-factor Rf photo-cathode electron gun

    SciTech Connect (OSTI)

    Rimmer, Robert A.; Hartman, Neal; Lidia, Steven M.; Wang, Shaoheng

    2002-05-22

    We describe the analysis and preliminary design of a high-gradient, high-duty factor RF photocathode gun. The gun is designed to operate at high repetition rate or CW, with high gradient on the cathode surface to minimize emittance growth due to space charge forces at high bunch charge. The gun may also be operated in a solenoidal magnetic field for emittance compensation. The design is intended for use in short-pulse, high-charge, and high-repetition rate applications such as linac based X-ray sources. We present and compare the results of gun simulations using different codes, as well as RF and thermal analysis of the structure.

  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)

    2013-06-01

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

    Office of Scientific and Technical Information (OSTI)

    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 ...

  11. 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)

    2010-11-04

    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.

  12. Measured and theoretical characterization of the RF properties of stacked, high-gradient insulator material

    SciTech Connect (OSTI)

    Houck, T. L., LLNL

    1997-05-09

    Recent high-voltage breakdown experiments of periodic metallic-dielectric insulating structures have suggested several interesting high-gradient applications. One such area is the employment of high-gradient insulators in high-current, electron-beam, accelerating induction modules. For this application, the understanding of the rf characteristics of the insulator plays an important role in estimating beam-cavity interactions. In this paper, we examine the rf properties of the insulator comparing simulation results with experiment. Different insulator designs are examined to determine their rf transmission properties in gap geometries.

  13. New results of development on high efficiency high gradient superconducting rf cavities

    SciTech Connect (OSTI)

    Geng, Rongli; Li, Z.; Hao, K.; Liu, K.-X.; Zhao, H.-Y.; Adolphsen, C.

    2015-09-01

    We report on the latest results of development on high efficiency high gradient superconducting radio frequency (SRF) cavities. Several 1-cell cavities made of large-grain niobium (Nb) were built, processed and tested. Two of these cavities are of the Low Surface Field (LSF) shape. Series of tests were carried out following controlled thermal cycling. Experiments toward zero-field cooling were carried out. The best experimentally achieved results are Eacc = 41 MV/m at Q0 = 6.5×1010 at 1.4 K by a 1-cell 1.3 GHz large-grain Nb TTF shape cavity and Eacc = 49 MV/m at Q0 = 1.5×1010 at 1.8 K by a 1-cell 1.5 GHz large-grain Nb CEBAF upgrade low-loss shape cavity.

  14. High gradient rf gun studies of CsBr photocathodes

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

    Vecchione, Theodore; Maldonado, Juan R.; Gierman, Stephen; Corbett, Jeff; Hartmann, Nick; Pianetta, Piero A.; Hesselink, Lambertus; Schmerge, John F.

    2015-04-03

    CsBr photocathodes have 10 times higher quantum efficiency with only 3 times larger intrinsic transverse emittance than copper. They are robust and can withstand 80 MV/m fields without breaking down or emitting dark current. They can operate in 2×10⁻⁹ torr vacuum and survive exposure to air. They are well suited for generating high pulse charge in rf guns without a photocathode transfer system.

  15. High gradient rf gun studies of CsBr photocathodes

    SciTech Connect (OSTI)

    Vecchione, Theodore; Maldonado, Juan R.; Gierman, Stephen; Corbett, Jeff; Hartmann, Nick; Pianetta, Piero A.; Hesselink, Lambertus; Schmerge, John F.

    2015-04-03

    CsBr photocathodes have 10 times higher quantum efficiency with only 3 times larger intrinsic transverse emittance than copper. They are robust and can withstand 80 MV/m fields without breaking down or emitting dark current. They can operate in 210?? torr vacuum and survive exposure to air. They are well suited for generating high pulse charge in rf guns without a photocathode transfer system.

  16. High Gradient Accelerator Cavities Using Atomic Layer Deposition

    SciTech Connect (OSTI)

    Ives, Robert Lawrence; Parsons, Gregory; Williams, Philip; Oldham, Christopher; Mundy, Zach; Dolgashev, Valery

    2014-12-09

    In the Phase I program, Calabazas Creek Research, Inc. (CCR), in collaboration with North Carolina State University (NCSU), fabricated copper accelerator cavities and used Atomic Layer Deposition (ALD) to apply thin metal coatings of tungsten and platinum. It was hypothesized that a tungsten coating would provide a robust surface more resistant to arcing and arc damage. The platinum coating was predicted to reduce processing time by inhibiting oxides that form on copper surfaces soon after machining. Two sets of cavity parts were fabricated. One was coated with 35 nm of tungsten, and the other with approximately 10 nm of platinum. Only the platinum cavity parts could be high power tested during the Phase I program due to schedule and funding constraints. The platinum coated cavity exhibit poor performance when compared with pure copper cavities. Not only did arcing occur at lower power levels, but the processing time was actually longer. There were several issues that contributed to the poor performance. First, machining of the base copper cavity parts failed to achieve the quality and cleanliness standards specified to SLAC National Accelerator Center. Secondly, the ALD facilities were not configured to provide the high levels of cleanliness required. Finally, the nanometer coating applied was likely far too thin to provide the performance required. The coating was ablated or peeled from the surface in regions of high fields. It was concluded that the current ALD process could not provide improved performance over cavities produced at national laboratories using dedicated facilities.

  17. Probing the laser wakefield in underdense plasmas by induced terahertz emission

    SciTech Connect (OSTI)

    Hu, Z. D.; Wang, W. M.; Chen, L. M.; Li, Y. T.; Sheng, Z. M.; Zhang, J.; Key Laboratory for Laser Plasmas and Department of Physics, Shanghai Jiao Tong University, Shanghai 200240

    2013-08-15

    Terahertz (THz) radiation can be produced from a laser wakefield driven in underdense plasmas in the presence of a transverse DC magnetic field. It is shown that the radiation usually contains a component at the electron plasma frequency and its harmonics when the wakefield is excited at high amplitudes. In the highly nonlinear bubble/blowout regime, the radiation contains a smooth component peaked at the reduced electron plasma frequency and an irregular spectrum extending to tens of the electron plasma frequency. The latter is due to the broken-wave structure behind the bubble. A theoretical model is presented and validated via two-dimensional particle-in-cell simulations. The measurement of such THz emission may provide a diagnostic of the laser wakefield structure.

  18. Design Studies of Nb3Sn High-Gradient Quadrupole Models for LARP

    SciTech Connect (OSTI)

    Andreev, Nikolai; Caspi, Shlomo; Dietderich, Daniel; Ferracin, Paolo; Ghosh, Arup; Kashikhin, Vadim; Lietzke, Al; Novitski, Igor; Zlobin, Alexander; McInturff, Alfred; Sabbi, GianLuca

    2007-06-01

    Insertion quadrupoles with large aperture and high gradient are required to achieve the luminosity upgrade goal of 10{sup 35} cm{sup -2} s{sup -1} at the Large Hadron Collider (LHC). In 2004, the US Department of Energy established the LHC Accelerator Research Program (LARP) to develop a technology base for the upgrade. Nb{sub 3}Sn conductor is required in order to operate at high field and with sufficient temperature margin. We report here on the conceptual design studies of a series of 1 m long 'High-gradient Quadrupoles' (HQ) that will explore the magnet performance limits in terms of peak fields, forces and stresses. The HQ design is expected to provide coil peak fields of more than 15 T, corresponding to gradients above 300 T/m in a 90 mm bore. Conductor requirements, magnetic, mechanical and quench protection issues for candidate HQ designs will be presented and discussed.

  19. AWAKE -- A Proton-driven Plasma Wakefield Experiment at

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

    AWAKE -- A Proton-driven Plasma Wakefield Experiment at CERN Swapan Chattopadhyay Fermilab March 9, 2016 4:00 p.m. - Wilson Hall, One West High energy intense proton beams such as the in the 7 TeV x 7 TeV Large Hadron Collider at CERN have sufficient energy stored per proton bunch to power and accelerate an electron beam to an energy of 600 GeV if a suitable mechanism could be found to transform all the stored proton beam energy into the electrons. A suitably designed plasma column could be such

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

    SciTech Connect (OSTI)

    Byer, Robert L.

    2013-11-07

    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.

  1. A Meter-Scale Plasma Wakefield Accelerator (Conference) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    Conference: A Meter-Scale Plasma Wakefield Accelerator Citation Details In-Document Search Title: A Meter-Scale Plasma Wakefield Accelerator No abstract prepared. Authors:...

  2. Positron jitter and wakefield effects in the SLC injector linac

    SciTech Connect (OSTI)

    Tian, F.; McCormick, D.; Ross, M.

    1994-06-01

    The positron beam in the SLC injector linac is a high current (7*10{sup 10} particles/bunch), large universe emittance ({gamma}{var_epsilon} = .01 m-rad) and long bunch length ({approximately}4 mm) beam. A large 5% positron intensity jitter was observed and correlated with the accelerating phase of the RF cavities in the positron source linac. For high transmission, the positron jitter must be reduced and strong wakefield effects cannot be ignored. A code was written to study causes of the positron jitter and wakefields in the SLC injector linac. The tracking results show that when the bunch lengths are 1.5, 2.1, 3.0, 4.0 mm, the injection apertures (leading to 30% loss) are 1.8, 1,6, 1.2, 1.0 sigma of transverse size at the beginning of the sector respectively. For the long bunches, the nominal 20% of beam size transverse pulse to pulse jitter causes an additional 3% loss. Also the bunch energy spread is more sensitive to the accelerating phase of the RF cavities.

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

    SciTech Connect (OSTI)

    Rassou, S.; Bourdier, A.; Drouin, M.

    2014-08-15

    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.

  4. Wakefield Municipal Gas & Light Department- Residential Conservation Services Program

    Broader source: Energy.gov [DOE]

    The Wakefield Municipal Gas & Light Department (WMGLD), offers the "Incentive Rebate Program" to encourage residential customers to improve the energy efficiency of their homes. After a home...

  5. Relativistic klystron driven compact high gradient accelerator as an injector to an X-ray synchrotron radiation ring

    DOE Patents [OSTI]

    Yu, David U. L.

    1990-01-01

    A compact high gradient accelerator driven by a relativistic klystron is utilized to inject high energy electrons into an X-ray synchrotron radiation ring. The high gradients provided by the relativistic klystron enables accelerator structure to be much shorter (typically 3 meters) than conventional injectors. This in turn enables manufacturers which utilize high energy, high intensity X-rays to produce various devices, such as computer chips, to do so on a cost effective basis.

  6. A compact high-gradient 25 MeV 17 GHz RF linac for free-electron laser research

    SciTech Connect (OSTI)

    Danly, B.G.; Chen, S.C.; Kreischer, K.E.

    1995-12-31

    A new compact high-gradient (60 MeV/m) high-frequency (17.136 GHz) RF linac is presently under construction by Haimson Research Corp. (HRC) for installation at the MIT Plasma Fusion Center in the High-Gradient Accelerator and High Power Microwave Laboratory. This accelerator will utilize an existing traveling-wave relativistic klystron (TWRK) which is now operation at MIT with 25 MW power, 67 dB gain, and 52% efficiency at 17.136 GHz.

  7. A new high-gradient correction quadrupole for the Fermilab luminosity upgrade

    SciTech Connect (OSTI)

    Mantsch, P.; Carson, J.; Riddiford, A.; Lamm, M.J.

    1989-03-01

    Special superconducting correction quadrupoles are needed for the luminosity upgrade of the Fermilab Tevatron Collider. These correctors are part of the low-beta system for the interaction regions at B/phi/ and D/phi/. The requirements are high gradient and low current. A quadrupole has been designed that meets the operating gradient of 0.63 T/cm at 1086 A. The one-layer quadrupole is wound with a cable consisting of five individually insulated rectangular strands. The five strands are overwrapped with Kapton and epoxy impregnated glass tape. The winding, curing and collaring of the magnet is accomplished in the same manner as Tevatron-like magnets using Rutherford style cable. Once the magnet is complete the five strands are connected in series. A prototype quadrupole has been assembled and tested. The magnet reached a plateau current of 1560 A corresponding to a gradient of 0.91 T/cm without training. The measured field harmonics are substantially better than required. 8 refs., 6 figs., 4 tabs.

  8. Method and apparatus for fabrication of high gradient insulators with parallel surface conductors spaced less than one millimeter apart

    DOE Patents [OSTI]

    Sanders, David M. (Livermore, CA); Decker, Derek E. (Livermore, CA)

    1999-01-01

    Optical patterns and lithographic techniques are used as part of a process to embed parallel and evenly spaced conductors in the non-planar surfaces of an insulator to produce high gradient insulators. The approach extends the size that high gradient insulating structures can be fabricated as well as improves the performance of those insulators by reducing the scale of the alternating parallel lines of insulator and conductor along the surface. This fabrication approach also substantially decreases the cost required to produce high gradient insulators.

  9. Latest Results of ILC High-Gradient R&D 9-cell Cavities at JLAB

    SciTech Connect (OSTI)

    Rongli Geng

    2008-02-11

    It has been over a year since JLAB started processing and testing ILC 9-cell cavities in the frame work of ILC high-gradient cavity R&D, aiming at the goal of a 35 MV/m gradient at a Q #4; of 1E10 with a yield of 90%. The necessary cavity processing steps include field flatness tuning, electropolishing (EP), hydrogen out-gassing under vacuum, high-pressure water rinsing, clean room assembly, and low temperature bake. These are followed by RF test at 2 Kelvin. Ultrasonic cleaning with Micro-90, an effective post-EP rinsing recipe discovered at JLAB, is routinely used. Seven industry manufactured 9-cell TESLAshape cavities are processed and tested repeatedly. So far, 33 EP cycles are accumulated, corresponding to more than 65 hours of active EP time. An emphasis put on RF testing is to discern cavity quench characteristics, including its nature and its location. Often times, the cavity performance is limited by thermal-magnetic quench instead of field emission. The quench field in some cavities is lower than 20 MV/m and remains unchanged despite repeated EP, implying material and/or fabrication defects. The quench field in some other cavities is high but changes unpredictably after repeated EP, suggesting processing induced defects. Based on our experience and results, several areas are identified where improvement is needed to improve cavity performance as well as yield.

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

    SciTech Connect (OSTI)

    Geng, Rongli [JLAB

    2009-11-01

    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.

  11. Numerical Verification of the Power Transfer and Wakefield Coupling in the Clic Two-Beam Accelerator

    SciTech Connect (OSTI)

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

    2011-08-19

    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.

  12. Wakefields of Sub-Picosecond Electron Bunches

    SciTech Connect (OSTI)

    Bane, Karl L.F.; /SLAC

    2006-04-19

    We discuss wakefields excited by short bunches in accelerators. In particular, we review some of what has been learned in recent years concerning diffraction wakes, roughness impedance, coherent synchrotron radiation wakes, and the resistive wall wake, focusing on analytical solutions where possible. As examples, we apply formulas for these wakes to various parts of the Linac Coherent Light Source (LCLS) project. The longitudinal accelerator structure wake of the SLAC linac is an important ingredient in the LCLS bunch compression process. Of the wakes in the undulator region, the dominant one is the resistive wall wake of the beam pipe.

  13. Laser wakefield acceleration of electrons with ionization injection in a pure N{sup 5+} plasma waveguide

    SciTech Connect (OSTI)

    Goers, A. J.; Yoon, S. J.; Elle, J. A.; Hine, G. A.; Milchberg, H. M.

    2014-05-26

    Ionization injection-assisted laser wakefield acceleration of electrons up to 120?MeV is demonstrated in a 1.5?mm long pure helium-like nitrogen plasma waveguide. The guiding structure stabilizes the high energy electron beam pointing and reduces the beam divergence. Our results are confirmed by 3D particle-in-cell simulations.

  14. Analytic model of electron self-injection in a plasma wakefield accelerator in the strongly nonlinear bubble regime

    SciTech Connect (OSTI)

    Yi, S. A.; Khudik, V.; Siemon, C.; Shvets, G.

    2012-12-21

    Self-injection of background electrons in plasma wakefield accelerators in the highly nonlinear bubble regime is analyzed using particle-in-cell and semi-analytic modeling. It is shown that the return current in the bubble sheath layer is crucial for accurate determination of the trapped particle trajectories.

  15. Dual effects of stochastic heating on electron injection in laser wakefield acceleration

    SciTech Connect (OSTI)

    Deng, Z. G.; Wang, X. G.; Yang, L.; Zhou, C. T.; Yu, M. Y.; Ying, H. P.

    2014-08-15

    Electron injection into the wakefield of an intense short laser pulse by a weaker laser pulse propagating in the opposite direction is reconsidered using two-dimensional (2D) particle-in-cell simulations as well as analytical modeling. It is found that for linearly polarized lasers the injection efficiency and the quality of the wakefield accelerated electrons increase with the intensity of the injection laser only up to a certain level, and then decreases. Theory and simulation tracking test electrons originally in the beat region of the two laser pulses show that the reduction of the injection efficiency at high injection-laser intensities is caused by stochastic overheating of the affected electrons.

  16. Heavy medium recovery in coal washing by continuous high gradient magnetic separation. Final report

    SciTech Connect (OSTI)

    Kelland, D.R.

    1983-09-01

    We have adapted high grade magnetic separation (HGMS) for magnetite recovery because of its insensitivity to coal/magnetite ratio and slurry density and its ability to capture fine magnetite at high velocity. An open vertical matrix able to capture 10 ..mu..m (avg. size) magnetite without entraining 2 mm coal has been incorporated in a 1.85 m diameter continuous high gradient magnetic separator. Three-quarter ton samples of magnetite (in 1000 gallons of water) have been recovered with the matrix ring turning at 40 cm/s through a field of 6 kOe. A laminated core demagnetizing coil followed by water sprays removes the recovered magnetite. The recovery is high, particularly for two passes which could be accomplished by two magnet heads on a single carousel ring. Coal entrainment is low for a wide range of operating conditions. A 4.8 m diameter separator, the largest currently available, with multiple heads, should be able to treat 350 tons of magnetite and coal per hour. 29 references, 52 figures, 13 tables.

  17. Physics of beam self-modulation in plasma wakefield accelerators

    SciTech Connect (OSTI)

    Lotov, K. V.

    2015-10-15

    The self-modulation instability is a key effect that makes possible the usage of nowadays proton beams as drivers for plasma wakefield acceleration. Development of the instability in uniform plasmas and in plasmas with a small density up-step is numerically studied with the focus at nonlinear stages of beam evolution. The step parameters providing the strongest established wakefield are found, and the mechanism of stable bunch train formation is identified.

  18. A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory...

    Office of Scientific and Technical Information (OSTI)

    A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to Multi-TeV Citation Details In-Document Search Title: A Beam Driven Plasma-Wakefield Linear Collider: From Higgs ...

  19. 9 GeV energy gain in a beam-driven plasma wakefield accelerator...

    Office of Scientific and Technical Information (OSTI)

    9 GeV energy gain in a beam-driven plasma wakefield accelerator Citation Details In-Document Search Title: 9 GeV energy gain in a beam-driven plasma wakefield accelerator An ...

  20. Angular Dependence of Betatron X-Ray Spectra from a Laser Wakefield...

    Office of Scientific and Technical Information (OSTI)

    X-Ray Spectra from a Laser Wakefield Accelerator Citation Details In-Document Search Title: Angular Dependence of Betatron X-Ray Spectra from a Laser Wakefield Accelerator ...

  1. Imprinting high-gradient topographical structures onto optical surfaces using magnetorheological finishing: Manufacturing corrective optical elements for high-power laser applications

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

    Menapace, Joseph A.; Ehrmann, Paul E.; Bayramian, Andrew J.; Bullington, Amber; Di Nicola, Jean -Michel G.; Haefner, Constantin; Jarboe, Jeffrey; Marshall, Christopher; Schaffers, Kathleen I.; Smith, Cal

    2016-03-15

    Corrective optical elements form an important part of high-precision optical systems. We have developed a method to manufacture high-gradient corrective optical elements for high-power laser systems using deterministic magnetorheological finishing (MRF) imprinting technology. Several process factors need to be considered for polishing ultraprecise topographical structures onto optical surfaces using MRF. They include proper selection of MRF removal function and wheel sizes, detailed MRF tool and interferometry alignment, and optimized MRF polishing schedules. Dependable interferometry also is a key factor in high-gradient component manufacture. A wavefront attenuating cell, which enables reliable measurement of gradients beyond what is attainable using conventional interferometry,more » is discussed. The results of MRF imprinting a 23 μm deep structure containing gradients over 1.6 μm / mm onto a fused-silica window are presented as an example of the technique’s capabilities. As a result, this high-gradient element serves as a thermal correction plate in the high-repetition-rate advanced petawatt laser system currently being built at Lawrence Livermore National Laboratory.« less

  2. 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

    2009-10-19

    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.

  3. Two GeV Electrons Achieved by Laser Plasma Wakefield Acceleration | U.S.

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

    DOE Office of Science (SC) Two GeV Electrons Achieved by Laser Plasma Wakefield Acceleration High Energy Physics (HEP) HEP Home About Research Facilities Science Highlights Benefits of HEP Funding Opportunities Advisory Committees Community Resources Contact Information High Energy Physics U.S. Department of Energy SC-25/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3624 F: (301) 903-2597 E: Email Us More Information » 07.01.13 Two GeV Electrons Achieved

  4. Ultrafast pulse radiolysis using a terawatt laser wakefield accelerator

    SciTech Connect (OSTI)

    Oulianov, Dmitri A.; Crowell, Robert A.; Gosztola, David J.; Shkrob, Ilya A.; Korovyanko, Oleg J.; Rey-de-Castro, Roberto C.

    2007-03-01

    We report ultrafast pulse radiolysis transient absorption (TA) spectroscopy measurements from the Terawatt Ultrafast High Field Facility (TUHFF) at Argonne National Laboratory. TUHFF houses a 20 TW Ti:sapphire laser system that generates 2.5 nC subpicosecond pulses of multi-mega-electron-volt electrons at 10 Hz using laser wakefield acceleration. The system has been specifically optimized for kinetic TA measurements in a pump-probe fashion. This requires averaging over many shots which necessitates stable, reliable generation of electron pulses. The latter were used to generate excess electrons in pulse radiolysis of liquid water and concentrated solutions of perchloric acid. The hydronium ions in the acidic solutions react with the hydrated electrons resulting in the rapid decay of the transient absorbance at 800 nm on the picosecond time scale. Normalization of the TA signal leads to an improvement in the signal to noise ratio by a factor of 5 to 6. Due the pointing instability of the laser this improvement was limited to a 5 to 10 min acquisition period, requiring periodic recalibration and realignment. Time resolution, defined by the rise time of TA signal from hydrated electron in pulse radiolysis of liquid water, of a few picoseconds, has been demonstrated. The current time resolution is determined primarily by the physical dimensions of the sample and the detection sensitivity. Subpicosecond time resolution can be achieved by using thinner samples, more sensitive detection techniques, and improved electron beam quality.

  5. High energy X-ray diffraction study of a dental ceramics–titanium functional gradient material prepared by field assisted sintering technique

    SciTech Connect (OSTI)

    Witte, K.; Bodnar, W.; Schell, N.; Lang, H.; Burkel, E.

    2014-09-15

    A functional gradient material with eleven layers composed of a dental ceramics and titanium was successfully consolidated using field assisted sintering technique in a two-step sintering process. High energy X-ray diffraction studies on the gradient were performed at High Energy Material Science beamline at Desy in Hamburg. Phase composition, crystal unit edges and lattice mismatch along the gradient were determined applying Rietveld refinement procedure. Phase analysis revealed that the main crystalline phase present in the gradient is α-Ti. Crystallinity increases stepwisely along the gradient with a decreasing increment between every next layer, following rather the weight fraction of titanium. The crystal unit edge a of titanium remains approximately constant with a value of 2.9686(1) Å, while c is reduced with increasing amount of titanium. In the layer with pure titanium the crystal unit edge c is constant with a value of 4.7174(2) Å. The lattice mismatch leading to an internal stress was calculated over the whole gradient. It was found that the maximal internal stress in titanium embedded in the studied gradient is significantly smaller than its yield strength, which implies that the structure of titanium along the whole gradient is mechanically stable. - Highlights: • High energy XRD studies of dental ceramics–Ti gradient material consolidated by FAST. • Phase composition, crystallinity and lattice parameters are determined. • Crystallinity increases stepwisely along the gradient following weight fraction of Ti. • Lattice mismatch leading to internal stress is calculated over the whole gradient. • Internal stress in α-Ti embedded in the gradient is smaller than its yield strength.

  6. Modeling laser wakefield accelerators in a Lorentz boosted frame

    SciTech Connect (OSTI)

    Vay, J.-L.; Geddes, C.G.R.; Cormier-Michel, E.; Grote, D.P.

    2010-09-15

    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [1] is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing theframe of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.

  7. The phase-lock dynamics of the laser wakefield acceleration with an intensity-decaying laser pulse

    SciTech Connect (OSTI)

    Li, Wentao; Liu, Jiansheng Wang, Wentao; Zhang, Zhijun; Chen, Qiang; Tian, Ye; Qi, Rong; Yu, Changhai; Wang, Cheng; Li, Ruxin Xu, Zhizhan; Tajima, T.

    2014-03-03

    An electron beam with the maximum energy extending up to 1.8?GeV, much higher than the dephasing limit, is experimentally obtained in the laser wakefield acceleration with the plasma density of 3.5??10{sup 18}?cm{sup ?3}. With particle in cell simulations and theoretical analysis, we find that the laser intensity evolution plays a major role in the enhancement of the electron energy gain. While the bubble length decreases due to the intensity-decay of the laser pulse, the phase of the electron beam in the wakefield can be locked, which contributes to the overcoming of the dephasing. Moreover, the laser intensity evolution is described for the phase-lock acceleration of electrons in the uniform plasma, confirmed with our own simulation. Since the decaying of the intensity is unavoidable in the long distance propagation due to the pump depletion, the energy gain of the high energy laser wakefield accelerator can be greatly enhanced if the current process is exploited.

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

    SciTech Connect (OSTI)

    Lotov, K. V.; Minakov, V. A.; Sosedkin, A. P.

    2014-08-15

    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.

  9. Spectral diagnostics of laser wakefield in capillary tubes

    SciTech Connect (OSTI)

    Andreev, N.E.; Chegotov, M.V.; Cros, B.; Mora, P.; Vieux, G.

    2006-05-15

    The modification of the spectrum of a probe pulse traveling in a linear plasma wave created in the wake of a pump pulse guided inside a capillary tube is analyzed for the cases of narrow or broad chirped probe spectra. It is shown that in both cases the measurement of the spectrum can be used as a diagnostic for the amplitude of the plasma wave. The results of full-scale numerical modeling confirm the developed analytical theory of wake-field diagnostics.

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

    DOE Patents [OSTI]

    Humphries, David E.; Hong, Seok-Cheol; Cozzarelli, legal representative, Linda A.; Pollard, Martin J.; Cozzarelli, Nicholas R.

    2009-01-06

    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. Multi-gigaelectronvolt acceleration of positrons in a self-loaded plasma wakefield

    SciTech Connect (OSTI)

    Corde, Sebastien; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Delahaye, J. P.; Frederico, J.; Gessner, S.; Green, S. Z.; Hogan, M. J.; Joshi, C.; Lipkowitz, N.; Litos, M.; Lu, W.; Marsh, K. A.; Mori, W. B.; Schmeltz, M.; Vafaei-Najafabadi, N.; Walz, D.; Yakimenko, V.; Yocky, G.; Clayton, C. E.

    2015-08-26

    New accelerator concepts must be developed to make future particle colliders more compact and affordable. The Plasma Wakefield Accelerator (PWFA) is one such concept, where the electric field of a plasma wake excited by a charged-particle bunch is used to accelerate a trailing bunch of particles. To apply plasma acceleration to particle colliders, it is imperative that both the electrons and their antimatter counterpart, the positrons, are efficiently accelerated at high fields using plasmas1. While substantial progress has recently been reported on high-field, high-efficiency acceleration of electrons in a PWFA powered by an electron bunch 2, such an electron-driven wake is unsuitable for the acceleration and focusing of a positron bunch. Here we demonstrate a new regime of PWFA where particles in the front of a single positron bunch transfer their energy to a substantial number of those in the rear of the same bunch by exciting a wakefield in the plasma. In the process, the accelerating field is altered – self-loaded – so that about a billion positrons gain five gigaelectronvolts (GeV) of energy with a narrow energy spread in a distance of just 1.3 meters. They extract about 30% of the wake’s energy and form a spectrally distinct bunch with as low as a 1.8% r.m.s. energy spread. This demonstrated ability of positron-driven plasma wakes to efficiently accelerate a significant number of positrons with a small energy spread may overcome the long-standing challenge of positron acceleration in plasma-based accelerators.

  12. 9 GeV energy gain in a beam-driven plasma wakefield accelerator

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

    Litos, M.; Adli, E.; Allen, J. M.; An, W.; Clarke, C. I.; Corde, S.; Clayton, C. E.; Frederico, J.; Gessner, S. J.; Green, S. Z.; et al

    2016-02-15

    An electron beam has gained a maximum energy of 9 GeV per particle in a 1.3 m-long electron beam-driven plasma wakefield accelerator. The amount of charge accelerated in the spectral peak was 28.3 pC, and the root-mean-square energy spread was 5.0%. The mean accelerated charge and energy gain per particle of the 215 shot data set was 115 pC and 5.3 GeV, respectively, corresponding to an acceleration gradient of 4.0 GeV m-1 at the spectral peak. Moreover, the mean energy spread of the data set was 5.1%. Our results are consistent with the extrapolation of the previously reported energy gainmore » results using a shorter, 36 cm-long plasma source to within 10%, evincing a non-evolving wake structure that can propagate distances of over a meter in length. Wake-loading effects were evident in the data through strong dependencies observed between various spectral properties and the amount of accelerated charge.« less

  13. Multi-MW K-Band 7th Harmonic Multiplier for High-Gradient Accelerator R&D

    SciTech Connect (OSTI)

    Solyak, N.A.; Yakovlev, V.P.; Hirschfield, J.L.; Kazakevich, G.M.; LaPointe, M.A.; /Yale U.

    2009-05-01

    A preliminary design and current status are presented for a two-cavity 7th harmonic multiplier, intended as a high-power RF source for use in experiments aimed at developing high-gradient structures for a future collider. The harmonic multiplier is to produce power in K-band using as its RF driver an XK-5 S-band klystron (2.856 GHz). The multiplier is to be built with a TE{sub 111} rotating mode input cavity and interchangeable output cavities, a principal example being a TE{sub 711} rotating mode cavity running at 20 GHz. The design that is described uses a 250 kV, 20 A injected laminar electron beam. With 8.5 MW of S-band drive power, 4.4 MW of 20-GHz output power is predicted. The design uses a gun, magnetic coils, and beam collector from an existing waveguide 7th harmonic multiplier. The gun has been re-conditioned and the desired operating parameters have been achieved.

  14. Wakefield Computations for the CLIC PETS using the Parallel Finite Element Time-Domain Code T3P

    SciTech Connect (OSTI)

    Candel, A; Kabel, A.; Lee, L.; Li, Z.; Ng, C.; Schussman, G.; Ko, K.; Syratchev, I.; /CERN

    2009-06-19

    In recent years, SLAC's Advanced Computations Department (ACD) has developed the high-performance parallel 3D electromagnetic time-domain code, T3P, for simulations of wakefields and transients in complex accelerator structures. T3P is based on advanced higher-order Finite Element methods on unstructured grids with quadratic surface approximation. Optimized for large-scale parallel processing on leadership supercomputing facilities, T3P allows simulations of realistic 3D structures with unprecedented accuracy, aiding the design of the next generation of accelerator facilities. Applications to the Compact Linear Collider (CLIC) Power Extraction and Transfer Structure (PETS) are presented.

  15. Laser wakefield accelerator based light sources: potential applications and requirements

    SciTech Connect (OSTI)

    Albert, F; Thomas, A G; Mangles, S P; Banerjee, S; Corde, S; Flacco, A; Litos, M; Neely, D; Viera, J; Najmudin, Z; Bingham, R; Joshi, C; Katsouleas, T

    2015-01-15

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future eff orts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefi eld accelerators for these specifi c applications.

  16. HIGH AVERAGE CURRENT LOW EMITTANCE BEAM EMPLOYING CW NORMAL CONDUCTING GUN.

    SciTech Connect (OSTI)

    CHANG,X.; BEN-ZVI, I.; KEWISCH, J.; PAI, C.

    2007-06-25

    CW normal conducting guns usually do not achieve very high field gradient and waste much RF power at high field gradient compared to superconducting cavities. But they have less trapped modes and wakefields compared to the superconducting cavities due to their low Q. The external bucking coil can also be applied very close to the cathode to improve the beam quality. By using a low frequency gun with a recessed cathode and a carefully designed beam line we can get a high average current and a high quality beam with acceptable RF power loss on the cavity wall. This paper shows that the CW normal conducting gun can be a backup solution for those projects which need high peak and average current, low emittance electron beams such as the Relativistic Heavy Ion Collider (RHIC) e-cooling project and Energy Recovery Linac (Em) project.

  17. Plasma Wakefield Acceleration: How it Works

    SciTech Connect (OSTI)

    2014-11-05

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

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

    SciTech Connect (OSTI)

    Tenenbaum, P

    2003-10-07

    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.

  19. A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory...

    Office of Scientific and Technical Information (OSTI)

    A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to Multi-TeV Summarized for CSS2013 E. Adli, J.P.Delahaye, S.J.Gessner, M.J. Hogan, T. Raubenheimer (SLAC) W.An,...

  20. A broadband gamma-ray spectrometry using novel unfolding algorithms for characterization of laser wakefield-generated betatron radiation

    SciTech Connect (OSTI)

    Jeon, Jong Ho Nakajima, Kazuhisa Pathak, Vishwa Bandhu; Cho, Myung Hoon; Yoo, Byung Ju; Shin, Kang Woo; Kim, Hyung Taek; Sung, Jae Hee; Lee, Seung Ku; Choi, Il Woo; Rhee, Yong Joo; Shin, Jung Hun; Jo, Sung Ha; Hojbota, Calin; Cho, Byeoung Ick; Nam, Chang Hee

    2015-12-15

    We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime.

  1. Beam Matching to a Plasma Wakefield Accelerator Using a Ramped Density

    Office of Scientific and Technical Information (OSTI)

    Profile at the Plasma Boundary (Conference) | SciTech Connect Conference: Beam Matching to a Plasma Wakefield Accelerator Using a Ramped Density Profile at the Plasma Boundary Citation Details In-Document Search Title: Beam Matching to a Plasma Wakefield Accelerator Using a Ramped Density Profile at the Plasma Boundary An important aspect of plasma wake field accelerators (PWFA) is stable propagation of the drive beam. In the under dense plasma regime, the drive beam creates an ion channel

  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.; Syratchev, I.; Grudiev, A.; Wuensch, W.

    2010-10-27

    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. First Beam and High-Gradient Cryomodule Commissioning Results of the Advanced Superconducting Test Accelerator at Fermilab

    SciTech Connect (OSTI)

    Crawford, Darren; et al.

    2015-06-01

    The advanced superconducting test accelerator at Fermilab has accelerated electrons to 20 MeV and, separately, the International Linear Collider (ILC) style 8-cavity cryomodule has achieved the ILC performance milestone of 31.5 MV/m per cavity. When fully completed, the accelerator will consist of a photoinjector, one ILC-type cryomodule, multiple accelerator R&D beamlines, and a downstream beamline to inject 300 MeV electrons into the Integrable Optics Test Accelerator (IOTA). We report on the results of first beam, the achievement of our cryomodule to ILC gradient specifications, and near-term future plans for the facility.

  4. Demonstration of passive plasma lensing of a laser wakefield accelerated electron bunch

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

    Kuschel, S.; Hollatz, D.; Heinemann, T.; Karger, O.; Schwab, M. B.; Ullmann, D.; Knetsch, A.; Seidel, A.; Rodel, C.; Yeung, M.; et al

    2016-07-20

    We report on the first demonstration of passive all-optical plasma lensing using a two-stage setup. An intense femtosecond laser accelerates electrons in a laser wakefield accelerator (LWFA) to 100 MeV over millimeter length scales. By adding a second gas target behind the initial LWFA stage we introduce a robust and independently tunable plasma lens. We observe a density dependent reduction of the LWFA electron beam divergence from an initial value of 2.3 mrad, down to 1.4 mrad (rms), when the plasma lens is in operation. Such a plasma lens provides a simple and compact approach for divergence reduction well matchedmore » to the mm-scale length of the LWFA accelerator. The focusing forces are provided solely by the plasma and driven by the bunch itself only, making this a highly useful and conceptually new approach to electron beam focusing. Possible applications of this lens are not limited to laser plasma accelerators. Since no active driver is needed the passive plasma lens is also suited for high repetition rate focusing of electron bunches. As a result, its understanding is also required for modeling the evolution of the driving particle bunch in particle driven wake field acceleration.« less

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

    SciTech Connect (OSTI)

    Majumdar, Partha; Lee, Elizabeth; Chisholm, Bret J.; Dirk, Shawn M.; Weisz, Michael; Bahr, James; Schiele, Kris

    2010-01-01

    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

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

    SciTech Connect (OSTI)

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

    2008-07-07

    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.

  7. Measuring the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator

    SciTech Connect (OSTI)

    Albert, F.; Pollock, B. B.; Shaw, J. L.; Marsh, K. A.; Ralph, J. E.; Chen, Y. -H.; Alessi, D.; Pak, A.; Clayton, C. E.; Glenzer, S. H.; Joshi, C.

    2014-07-22

    This paper presents a new technique to measure the angular dependence of betatron x-ray spectra in a laser-wakefield accelerator. Measurements are performed with a stacked image plates spectrometer, capable of detecting broadband x-ray radiation up to 1 MeV. It can provide measurements of the betatron x-ray spectrum at any angle of observation (within a 40 mrad cone) and of the beam profile. A detailed description of our data analysis is given, along with comparison for several shots. As a result, these measurements provide useful information on the dynamics of the electrons are they are accelerated and wiggled by the wakefield.

  8. Analysis of radial and longitudinal force of plasma wakefield generated by a chirped pulse laser

    SciTech Connect (OSTI)

    Ghasemi, Leila; Afhami, Saeedeh; Eslami, Esmaeil

    2015-08-15

    In present paper, the chirp effect of an electromagnetic pulse via an analytical model of wakefield generation is studied. Different types of chirps are employed in this study. Our results show that by the use of nonlinear chirped pulse the longitudinal wakefield and focusing force is stronger than that of linear chirped pulse. It is indicated that quadratic nonlinear chirped pulses are globally much efficient than periodic nonlinear chirped pulses. Our calculations also predict that in nonlinear chirped pulse case, the overlap of focusing and accelerating regions is broader than that achieved in linear chirped pulse.

  9. A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to

    Office of Scientific and Technical Information (OSTI)

    Multi-TeV (Conference) | SciTech Connect Conference: A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to Multi-TeV Citation Details In-Document Search Title: A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to Multi-TeV Authors: Adli, E ; Delahaye, J.P. ; Gessner, S.J. ; Hogan, M.J. ; Raubenheimer, T. ; /SLAC ; An, W. ; Joshi, C. ; Mori, W. ; /UCLA, Los Angeles Publication Date: 2013-09-30 OSTI Identifier: 1074154 Report Number(s): SLAC-PUB-15426 DOE

  10. Flow directions and hydraulic gradients in the variable density flow system at the proposed high-level nuclear waste repository site in the Texas panhandle

    SciTech Connect (OSTI)

    Bair, E.S.; O'Donnell, T.P.

    1985-01-01

    Bedded salt, welded tuff, and basalt are the three rock types proposed as possible host rock for the nation's first high-level nuclear waste repository. Regional flow at the proposed bedded salt site in the Texas Panhandle is unique because it contains waters with highly variable fluid density. The site area is underlain by three regional hydrostratigraphic units: a shallow aquifer system developed in the Ogallala Formation and Dockum Group containing waters with less than 1500 mg/1 TDS, a shale and evaporite aquitard associated with the target salt horizon commonly containing waters with 300,000 mg/1 TDS, and a deep aquifer system developed in the Wolfcamp Series and Pennsylvanian System commonly containing waters with 50,000 to 200,000 mg/1 TDS. The associated fluid density variations can lead to miscalculation of flow directions, hydraulic gradients, and travel times. Pressure-depth diagrams based on shut-in pressure and specific-gravity data from drill-stem tests indicate that regionally the potential for downward flow exists in the shale and evaporite aquitard and the potential for horizontal flow exists in the deep aquifer system. Determination of the direction and magnitude of the vertical hydraulic gradient across the target salt horizon based on a method that solely uses pressure data and which incorporates the effects of variable fluid density indicates a downward-oriented hydraulic gradient at the proposed Texas Panhandle site. These methods do not require calculation of hydraulic head and, therefore, are a more realistic way of determining flow characteristics in variable density flow systems.

  11. The effect of gradients at stagnation on K-shell x-ray line emission in high-current Ar gas-puff implosions

    SciTech Connect (OSTI)

    Jones, B. Harvey-Thompson, A. J.; Ampleford, D. J.; Jennings, C. A.; Hansen, S. B.; Moore, N. W.; Lamppa, D. C.; Johnson, D.; Jones, M. C.; Waisman, E. M.; Coverdale, C. A.; Cuneo, M. E.; Rochau, G. A.; Apruzese, J. P.; Giuliani, J. L.; Thornhill, J. W.; Ouart, N. D.; Chong, Y. K.; Velikovich, A. L.; Dasgupta, A.; and others

    2015-02-15

    Argon gas puffs have produced 330 kJ ± 9% of x-ray radiation above 3 keV photon energy in fast z-pinch implosions, with remarkably reproducible K-shell spectra and power pulses. This reproducibility in x-ray production is particularly significant in light of the variations in instability evolution observed between experiments. Soft x-ray power measurements and K-shell line ratios from a time-resolved spectrum at peak x-ray power suggest that plasma gradients in these high-mass pinches may limit the K-shell radiating mass, K-shell power, and K-shell yield from high-current gas puffs.

  12. Wakefield computations for a corrugated pipe as a beam dechirper for FEL applications

    SciTech Connect (OSTI)

    Ng, C. K.; Bane, K. L.F.

    2015-06-09

    A beam “dechirper” based on a corrugated, metallic vacuum chamber has been proposed recently to cancel residual energy chirp in a beam before it enters the undulator in a linac-based X-ray FEL. Rather than the round geometry that was originally proposed, we consider a pipe composed of two parallel plates with corrugations. The advantage is that the strength of the wake effect can be tuned by adjusting the separation of the plates. The separation of the plates is on the order of millimeters, and the corrugations are fractions of a millimeter in size. The dechirper needs to be meters long in order to provide sufficient longitudinal wakefield to cancel the beam chirp. Considerable computation resources are required to determine accurately the wakefield for such a long structure with small corrugation gaps. Combining the moving window technique and parallel computing using multiple processors, the time domain module in the parallel finite-element electromagnetic suite ACE3P allows efficient determination of the wakefield through convergence studies. In this paper, we will calculate the longitudinal, dipole and quadrupole wakefields for the dechirper and compare the results with those of analytical and field matching approaches.

  13. Wakefields generated by collisional neutrinos in neutral-electron-positron plasma

    SciTech Connect (OSTI)

    Tinakiche, Nouara

    2013-02-15

    A classical fluid description is adopted to investigate nonlinear interaction between an electron-type neutrino beam and a relativistic collisionless unmagnetized neutral-electron-positron plasma. In this work, we consider the collisions of the neutrinos with neutrals in the plasma and study their effect on the generation of wakefields in this plasma.

  14. Wakefield Simulation of CLIC PETS Structure Using Parallel 3D Finite Element Time-Domain Solver T3P

    SciTech Connect (OSTI)

    Candel, A.; Kabel, A.; Lee, L.; Li, Z.; Ng, C.; Schussman, G.; Ko, K.; Syratchev, I.; /CERN

    2009-06-19

    In recent years, SLAC's Advanced Computations Department (ACD) has developed the parallel 3D Finite Element electromagnetic time-domain code T3P. Higher-order Finite Element methods on conformal unstructured meshes and massively parallel processing allow unprecedented simulation accuracy for wakefield computations and simulations of transient effects in realistic accelerator structures. Applications include simulation of wakefield damping in the Compact Linear Collider (CLIC) power extraction and transfer structure (PETS).

  15. Gradient Resources | Open Energy Information

    Open Energy Info (EERE)

    Gradient Resources Jump to: navigation, search Logo: Gradient Resources Name: Gradient Resources Address: 9670 Gateway Drive, Suite 200 Place: Reno, Nevada Zip: 89521 Region:...

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

    SciTech Connect (OSTI)

    Afhami, Saeedeh; Eslami, Esmaeil

    2014-06-15

    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.

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

    ScienceCinema (OSTI)

    Andrei Seryi

    2010-01-08

    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.  

  18. Wakefields generated by collisional neutrinos in neutral-electron-positron-ion plasma

    SciTech Connect (OSTI)

    Tinakiche, Nouara

    2015-12-15

    A classical fluid description is adopted to investigate nonlinear interaction between an electron-type neutrino beam and a relativistic collisionless unmagnetized neutral-electron-positron-ion plasma. In this work, we consider the collisions of the neutrinos with neutrals in the plasma and study their effect on the generation of wakefields in presence of a fraction of ions in a neutral-electron-positron plasma. The results obtained in the present work are interpreted and compared with previous studies.

  19. Long-Gradient Separations Coupled with Selected Reaction Monitoring for Highly Sensitive, Large Scale Targeted Protein Quantification in a Single Analysis

    SciTech Connect (OSTI)

    Shi, Tujin; Fillmore, Thomas L.; Gao, Yuqian; Zhao, Rui; He, Jintang; Schepmoes, Athena A.; Nicora, Carrie D.; Wu, Chaochao; Chambers, Justin L.; Moore, Ronald J.; Kagan, Jacob; Srivastava, Sudhir; Liu, Alvin Y.; Rodland, Karin D.; Liu, Tao; Camp, David G.; Smith, Richard D.; Qian, Weijun

    2013-10-01

    Long-gradient separations coupled to tandem MS were recently demonstrated to provide a deep proteome coverage for global proteomics; however, such long-gradient separations have not been explored for targeted proteomics. Herein, we investigate the potential performance of the long-gradient separations coupled with selected reaction monitoring (LG-SRM) for targeted protein quantification. Direct comparison of LG-SRM (5 h gradient) and conventional LC-SRM (45 min gradient) showed that the long-gradient separations significantly reduced background interference levels and provided an 8- to 100-fold improvement in LOQ for target proteins in human female serum. Based on at least one surrogate peptide per protein, an LOQ of 10 ng/mL was achieved for the two spiked proteins in non-depleted human serum. The LG-SRM detection of seven out of eight endogenous plasma proteins expressed at ng/mL or sub-ng/mL levels in clinical patient sera was also demonstrated. A correlation coefficient of >0.99 was observed for the results of LG-SRM and ELISA measurements for prostate-specific antigen (PSA) in selected patient sera. Further enhancement of LG-SRM sensitivity was achieved by applying front-end IgY14 immunoaffinity depletion. Besides improved sensitivity, LG-SRM offers at least 3 times higher multiplexing capacity than conventional LC-SRM due to ~3-fold increase in average peak widths for a 300-min gradient compared to a 45-min gradient. Therefore, LG-SRM holds great potential for bridging the gap between global and targeted proteomics due to its advantages in both sensitivity and multiplexing capacity.

  20. Experimental validation of a radio frequency photogun as external electron injector for a laser wakefield accelerator

    SciTech Connect (OSTI)

    Stragier, X. F. D.; Luiten, O. J.; Geer, S. B. van der; Wiel, M. J. van der; Brussaard, G. J. H.

    2011-07-15

    A purpose-built RF-photogun as external electron injector for a laser wakefield accelerator has been thoroughly tested. Different properties of the RF-photogun have been measured such as energy, energy spread and transverse emittance. The focus of this study is the investigation of the smallest possible focus spot and focus stability at the entrance of the plasma channel. For an electron bunch with 10 pC charge and 3.7 MeV kinetic energy, the energy spread was 0.5% with a shot-to-shot stability of 0.05%. After focusing the bunch by a pulsed solenoid lens at 140 mm from the middle of the lens, the focal spot was 40 {mu}m with a shot-to-shot stability of 5 {mu}m. Higher charge leads to higher energy spread and to a larger spot size, due to space charge effects. All properties were found to be close to design values. Given the limited energy of 3.7 MeV, the properties are sufficient for this gun to serve as injector for one particular version of laser wakefield acceleration, i.e., injection ahead of the laser pulse. These measured electron bunch properties were then used as input parameters for simulations of electron bunch injection in a laser wakefield accelerator. The arrival time jitter was deduced from measurements of the energy fluctuation, in combination with earlier measurements using THz coherent transition radiation, and is around 150 fs in the present setup. The bunch length in the focus, simulated using particle tracking, depends on the accelerated charge and goes from 100 fs at 0.1 pC to 1 ps at 50 pC. When simulating the injection of the 3.7 MeV electron bunch of 10 pC in front of a 25 TW laser pulse with a waist of 30 {mu}m in a plasma with a density of 0.7 x 10{sup 24} m{sup -3}, the maximum accelerated charge was found to be 1.2 pC with a kinetic energy of {approx}900 MeV and an energy spread of {approx}5%. The experiments combined with the simulations show the feasibility of external injection and give a prediction of the output parameters that can

  1. Simulation of quasimonoenergetic electron beams produced by colliding pulse wakefield acceleration

    SciTech Connect (OSTI)

    Davoine, X.; Lefebvre, E.; Lifschitz, A.

    2008-11-15

    The collision of two laser pulses can inject electrons into a wakefield accelerator, and has been found to produce stable and tunable quasimonoenergetic electron beams [J. Faure et al., Nature 444, 737 (2006)]. This colliding pulse scheme is studied here with 3D particle-in-cell simulations. The results are successfully compared with experimental data, showing the accuracy of the simulations. The involved mechanisms (laser propagation, wake inhibition, electron heating and trapping, beam loading) are presented in detail. We explain their interplay effects on the beam parameters. The experimental variations of beam charge and energy with collision position are explained.

  2. Temporal profile measurements of relativistic electron bunch based on wakefield generation

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

    Bettoni, S.; Craievich, P.; Lutman, A. A.; Pedrozzi, M.

    2016-02-25

    A complete characterization of the time-resolved longitudinal beam phase space is important to optimize the final performances of an accelerator, and in particular this is crucial for Free Electron Laser (FEL) facilities. In this study we propose a novel method to characterize the profile of a relativistic electron bunch by passively streaking the beam using its self-interaction with the transverse wakefield excited by the bunch itself passing off-axis through a dielectric-lined or a corrugated waveguide. Results of a proof-of-principle experiment at the SwissFEL Injector Test Facility are discussed.

  3. Sound beam manipulation based on temperature gradients

    SciTech Connect (OSTI)

    Qian, Feng; Quan, Li; Liu, Xiaozhou Gong, Xiufen

    2015-10-28

    Previous research with temperature gradients has shown the feasibility of controlling airborne sound propagation. Here, we present a temperature gradients based airborne sound manipulation schemes: a cylindrical acoustic omnidirectional absorber (AOA). The proposed AOA has high absorption performance which can almost completely absorb the incident wave. Geometric acoustics is used to obtain the refractive index distributions with different radii, which is then utilized to deduce the desired temperature gradients. Since resonant units are not applied in the scheme, its working bandwidth is expected to be broadband. The scheme is temperature-tuned and easy to realize, which is of potential interest to fields such as noise control or acoustic cloaking.

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

    SciTech Connect (OSTI)

    Paradkar, B. S.; Cros, B.; Maynard, G.; Mora, P.

    2013-08-15

    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.

  5. 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.

  6. Hot Pot Contoured Temperature Gradient Map

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

    Lane, Michael

    2013-06-28

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

  7. Sources of stress gradients in electrodeposited Ni MEMS. (Conference...

    Office of Scientific and Technical Information (OSTI)

    Title: Sources of stress gradients in electrodeposited Ni MEMS. The ability of future integrated metal-semiconductor micro-systems such as RF MEMS to perform highly complex ...

  8. Multiple quasi-monoenergetic electron beams from laser-wakefield acceleration with spatially structured laser pulse

    SciTech Connect (OSTI)

    Ma, Y.; Li, M. H.; Li, Y. F.; Wang, J. G.; Tao, M. Z.; Han, Y. J.; Zhao, J. R.; Huang, K.; Yan, W. C.; Ma, J. L.; Li, Y. T.; Chen, L. M.; Li, D. Z.; Chen, Z. Y.; Sheng, Z. M.; Zhang, J.

    2015-08-15

    By adjusting the focus geometry of a spatially structured laser pulse, single, double, and treble quasi-monoenergetic electron beams were generated, respectively, in laser-wakefield acceleration. Single electron beam was produced as focusing the laser pulse to a single spot. While focusing the laser pulse to two spots that are approximately equal in energy and size and intense enough to form their own filaments, two electron beams were produced. Moreover, with a proper distance between those two focal spots, three electron beams emerged with a certain probability owing to the superposition of the diffractions of those two spots. The energy spectra of the multiple electron beams are quasi-monoenergetic, which are different from that of the large energy spread beams produced due to the longitudinal multiple-injection in the single bubble.

  9. Enhancement of x-rays generated by a guided laser wakefield accelerator inside capillary tubes

    SciTech Connect (OSTI)

    Ju, J.; Doepp, A.; Cassou, K.; Neveu, O.; Cros, B.; Svensson, K.; Genoud, G.; Wojda, F.; Burza, M.; Persson, A.; Lundh, O.; Wahlstroem, C.-G.; Ferrari, H. E.

    2012-05-07

    Electrons accelerated in the nonlinear regime in a laser wakefield accelerator experience transverse oscillations inside the plasma cavity, giving rise to ultra-short pulsed x-rays, also called the betatron radiation. We show that the fluence of x-ray can be enhanced by more than one order of magnitude when the laser is guided by a 10 mm long capillary tube instead of interacting with a 2 mm gas jet. X-rays with a synchrotron-like spectrum and associated critical energy {approx}5 keV, with a peak brightness of {approx}1x10{sup 21} ph/s/mm{sup 2}/mrad{sup 2}/0.1%BW, were achieved by employing 16 TW laser pulses.

  10. Observation of laser multiple filamentation process and multiple electron beams acceleration in a laser wakefield accelerator

    SciTech Connect (OSTI)

    Li, Wentao; Liu, Jiansheng; Wang, Wentao; Chen, Qiang; Zhang, Hui; Tian, Ye; Zhang, Zhijun; Qi, Rong; Wang, Cheng; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2013-11-15

    The multiple filaments formation process in the laser wakefield accelerator (LWFA) was observed by imaging the transmitted laser beam after propagating in the plasma of different density. During propagation, the laser first self-focused into a single filament. After that, it began to defocus with energy spreading in the transverse direction. Two filaments then formed from it and began to propagate independently, moving away from each other. We have also demonstrated that the laser multiple filamentation would lead to the multiple electron beams acceleration in the LWFA via ionization-induced injection scheme. Besides, its influences on the accelerated electron beams were also analyzed both in the single-stage LWFA and cascaded LWFA.

  11. Electron self-injection in the proton-driven-plasma-wakefield acceleration

    SciTech Connect (OSTI)

    Hu, Zhang-Hu; Wang, You-Nian

    2013-12-15

    The self-injection process of plasma electrons in the proton-driven-plasma-wakefield acceleration scheme is investigated using a two-dimensional, electromagnetic particle-in-cell method. Plasma electrons are self-injected into the back of the first acceleration bucket during the initial bubble formation period, where the wake phase velocity is low enough to trap sufficient electrons. Most of the self-injected electrons are initially located within a distance of the skin depth c/ω{sub pe} to the beam axis. A decrease (or increase) in the beam radius (or length) leads to a significant reduction in the total charges of self-injected electron bunch. Compared to the uniform plasma, the energy spread, emittance and total charges of the self-injected bunch are reduced in the plasma channel case, due to a reduced injection of plasma electrons that initially located further away from the beam axis.

  12. Laser-seeded modulation instability in a proton driver plasma wakefield accelerator

    SciTech Connect (OSTI)

    Siemon, Carl; Khudik, Vladimir; Austin Yi, S.; Shvets, Gennady; Pukhov, Alexander

    2013-10-15

    A new method for initiating the modulation instability (MI) of a proton beam in a proton driver plasma wakefield accelerator using a short laser pulse preceding the beam is presented. A diffracting laser pulse is used to produce a plasma wave that provides a seeding modulation of the proton bunch with the period equal to that of the plasma wave. Using the envelope description of the proton beam, this method of seeding the MI is analytically compared with the earlier suggested seeding technique that involves an abrupt truncation of the proton bunch. The full kinetic simulation of a realistic proton bunch is used to validate the analytic results. It is further used to demonstrate that a plasma density ramp placed in the early stages of the laser-seeded MI leads to its stabilization, resulting in sustained accelerating electric fields (of order several hundred MV/m) over long propagation distances (∼100–1000 m)

  13. 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

    2009-06-02

    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.

  14. Energy in density gradient

    SciTech Connect (OSTI)

    Vranjes, J.; Kono, M.

    2015-01-15

    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 cylindrical 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 volume (per second) in quiet regions in the corona. Consequently, within the life-time of a magnetic structure such energy losses can easily be compensated by the stochastic drift wave heating.

  15. Non Linear Conjugate Gradient

    Energy Science and Technology Software Center (OSTI)

    2006-11-17

    Software that simulates and inverts electromagnetic field data for subsurface electrical properties (electrical conductivity) of geological media. The software treats data produced by a time harmonic source field excitation arising from the following antenna geometery: loops and grounded bipoles, as well as point electric and magnetic dioples. The inversion process is carried out using a non-linear conjugate gradient optimization scheme, which minimizes the misfit between field data and model data using a least squares criteria.more » The software is an upgrade from the code NLCGCS_MP ver 1.0. The upgrade includes the following components: Incorporation of new 1 D field sourcing routines to more accurately simulate the 3D electromagnetic field for arbitrary geologic& media, treatment for generalized finite length transmitting antenna geometry (antennas with vertical and horizontal component directions). In addition, the software has been upgraded to treat transverse anisotropy in electrical conductivity.« less

  16. 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)

    2012-10-15

    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.

  17. EA-2010: Alternating Gradient Synchrotron Complex Improvements...

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

    Gradient Synchrotron Complex Improvements at Brookhaven National Laboratory; Upton, New York EA-2010: Alternating Gradient Synchrotron Complex Improvements at Brookhaven ...

  18. Joining of Tungsten Armor Using Functional Gradients

    SciTech Connect (OSTI)

    John Scott O'Dell

    2006-12-31

    The joining of low thermal expansion armor materials such as tungsten to high thermal expansion heat sink materials has been a major problem in plasma facing component (PFC) development. Conventional planar bonding techniques have been unable to withstand the high thermal induced stresses resulting from fabrication and high heat flux testing. During this investigation, innovative functional gradient joints produced using vacuum plasma spray forming techniques have been developed for joining tungsten armor to copper alloy heat sinks. A model was developed to select the optimum gradient architecture. Based on the modeling effort, a 2mm copper rich gradient was selected. Vacuum plasma pray parameters and procedures were then developed to produce the functional gradient joint. Using these techniques, dual cooling channel, medium scale mockups (32mm wide x 400mm length) were produced with vacuum plasma spray formed tungsten armor. The thickness of the tungsten armor was up to 5mm thick. No evidence of debonding at the interface between the heat sink and the vacuum plasma sprayed material was observed.

  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.; Piot, P.; /Northern Illinois U. /Fermilab

    2012-07-08

    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. Parallel Higher-order Finite Element Method for Accurate Field Computations in Wakefield and PIC Simulations

    SciTech Connect (OSTI)

    Candel, A.; Kabel, A.; Lee, L.; Li, Z.; Limborg, C.; Ng, C.; Prudencio, E.; Schussman, G.; Uplenchwar, R.; Ko, K.; /SLAC

    2009-06-19

    Over the past years, SLAC's Advanced Computations Department (ACD), under SciDAC sponsorship, has developed a suite of 3D (2D) parallel higher-order finite element (FE) codes, T3P (T2P) and Pic3P (Pic2P), aimed at accurate, large-scale simulation of wakefields and particle-field interactions in radio-frequency (RF) cavities of complex shape. The codes are built on the FE infrastructure that supports SLAC's frequency domain codes, Omega3P and S3P, to utilize conformal tetrahedral (triangular)meshes, higher-order basis functions and quadratic geometry approximation. For time integration, they adopt an unconditionally stable implicit scheme. Pic3P (Pic2P) extends T3P (T2P) to treat charged-particle dynamics self-consistently using the PIC (particle-in-cell) approach, the first such implementation on a conformal, unstructured grid using Whitney basis functions. Examples from applications to the International Linear Collider (ILC), Positron Electron Project-II (PEP-II), Linac Coherent Light Source (LCLS) and other accelerators will be presented to compare the accuracy and computational efficiency of these codes versus their counterparts using structured grids.

  1. Gradient zone boundary control in salt gradient solar ponds

    DOE Patents [OSTI]

    Hull, John R.

    1984-01-01

    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 sizable fraction of the membrane area to allow sufficient salt diffusion while preventing turbulent entrainment into the gradient zone.

  2. New High Energy Gradient Concentration Cathode Material

    Broader source: Energy.gov [DOE]

    2010 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C.

  3. New High Energy Gradient Concentration Cathode Material

    Broader source: Energy.gov [DOE]

    2012 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting

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

    SciTech Connect (OSTI)

    Ali, S.; Khan, S.; Department of Physics, Gomal University, Dera Ismail Khan 29050

    2013-07-15

    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-Hckel and oscillatory wake potentials. Analytical and numerical results reveal that the Debye-Hckel 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.

  5. Variable metric conjugate gradient methods

    SciTech Connect (OSTI)

    Barth, T.; Manteuffel, T.

    1994-07-01

    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.

  6. Electron acceleration by laser wakefield and x-ray emission at moderate intensity and density in long plasmas

    SciTech Connect (OSTI)

    Ferrari, H. E.; Lifschitz, A. F.; Maynard, G.; Cros, B.

    2011-08-15

    The dynamics of electron acceleration by laser wakefield and the associated x-rays emission in long plasmas are numerically investigated for parameters close to the threshold of laser self-focusing. The plasma length is set by the use of dielectric capillary tubes that confine the gas and the laser energy. Electrons self-injection and acceleration to the 170 MeVs are obtained for densities as low as 5 x 10{sup 18} cm{sup -3} and a moderate input intensity (0.77 x 10{sup 18} W/cm{sup 2}). The associated x-ray emission at the exit of the capillary tube is shown to be an accurate diagnostic of the electrons self-injection and acceleration process.

  7. New results of development on high efficiency high gradient supercondu...

    Office of Scientific and Technical Information (OSTI)

    Thomas Jefferson National Accelerator Facility, Newport News, VA (United States) SLAC National Accelerator Lab., Menlo Park, CA (United States) Peking Univ., Beijing (China) OTIC, ...

  8. Tailoring the laser pulse shape to improve the quality of the self-injected electron beam in laser wakefield acceleration

    SciTech Connect (OSTI)

    Upadhyay, Ajay K.; Samant, Sushil A.; Krishnagopal, S.

    2013-01-15

    In laser wakefield acceleration, tailoring the shape of the laser pulse is one way of influencing the laser-plasma interaction and, therefore, of improving the quality of the self-injected electron beam in the bubble regime. Using three-dimensional particle-in-cell simulations, the evolution dynamics of the laser pulse and the quality of the self-injected beam, for a Gaussian pulse, a positive skew pulse (i.e., one with sharp rise and slow fall), and a negative skew pulse (i.e., one with a slow rise and sharp fall) are studied. It is observed that with a negative skew laser pulse there is a substantial improvement in the emittance (by around a factor of two), and a modest improvement in the energy-spread, compared to Gaussian as well as positive skew pulses. However, the injected charge is less in the negative skew pulse compared to the other two. It is also found that there is an optimal propagation distance that gives the best beam quality; beyond this distance, though the energy increases, the beam quality deteriorates, but this deterioration is least for the negative skew pulse. Thus, the negative skew pulse gives an improvement in terms of beam quality (emittance and energy spread) over what one can get with a Gaussian or positive skew pulse. In part, this is because of the lesser injected charge, and the strong suppression of continuous injection for the negative skew pulse.

  9. Thermal Gradient Holes | Open Energy Information

    Open Energy Info (EERE)

    Holes Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Thermal Gradient Holes Details Activities (67) Areas (48) Regions (4) NEPA(33) Exploration...

  10. Approximate error conjugation gradient minimization methods

    DOE Patents [OSTI]

    Kallman, Jeffrey S

    2013-05-21

    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.

  11. Gradient instabilities of electromagnetic waves in Hall thruster plasma

    SciTech Connect (OSTI)

    Tomilin, Dmitry

    2013-04-15

    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.

  12. Facilities | Argonne National Laboratory

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

    Facilities Argonne maintains two state-of-the-art facilities for high-energy physics research. The Argonne Wakefield Accelerator Facility is home to technology that produces high accelerating gradients that could form the basis of the next generation of particle accelerators. Additionally, the 4 Tesla Magnet Facility reuses hospital MRI magnets to provide benchmarking for new muon experiments that will be performed at Fermilab. 4 Tesla Magnet Facility Learn More » Argonne Wakefield Accelerator

  13. A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory...

    Office of Scientific and Technical Information (OSTI)

    Research Org: SLAC National Accelerator Laboratory (SLAC) Sponsoring Org: US DOE Office of Science (DOE SC);High Energy Physics (HEP) Country of Publication: United States ...

  14. SW New Mexico BHT geothermal gradient calculations

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

    Shari Kelley

    2015-07-24

    This file contains a compilation of BHT data from oil wells in southwestern New Mexico. Surface temperature is calculated using the collar elevation. An estimate of geothermal gradient is calculated using the estimated surface temperature and the uncorrected BHT data.

  15. Separation of carbon nanotubes in density gradients

    DOE Patents [OSTI]

    Hersam, Mark C.; Stupp, Samuel I.; Arnold, Michael S.

    2012-02-07

    The separation of single-walled carbon nanotubes (SWNTs), by chirality and/or diameter, using centrifugation of compositions of SWNTs in and surface active components in density gradient media.

  16. Separation of carbon nanotubes in density gradients

    DOE Patents [OSTI]

    Hersam, Mark C.; Stupp, Samuel I.; Arnold, Michael S.

    2010-02-16

    The separation of single-walled carbon nanotubes (SWNTs), by chirality and/or diameter, using centrifugation of compositions of SWNTs in and surface active components in density gradient media.

  17. Novel concepts in weld science: Role of gradients and composite structure

    SciTech Connect (OSTI)

    Matlock, D.K.; Olson, D.L.

    1992-08-31

    The effects of compositional and microstructural gradients on weld metal properties were investigated. The effects of compositional gradients were analyzed using thermodynamic and composite models. Brittle and ductile cracking behavior were investigated using both binary alloy single crystals and large grain castings. In both cases, the crack propagated along regions where the compositional gradients were the steepest. High temperature deformation of large wavelength compositonally modulated structures vas investigated to understand creep behavior in veld metal. At moderate temperatures, the creep behavior of cored materials was found to follow predictions based on the rule of mixtures composite analysis. At higher temperatures with the advent of dynamic mass transport the creep process is influenced by diffusion-promoted vacancy flow and time-dependent compositional gradient. The investigation found the critical gradient which will promote Kirkendall voids and has reported a creep rate behavior that suggests strong structural dependence, localized stress and vacancy transport influence. Weld metal, based on metal matrix composite, was also demonstrated.

  18. Category:Thermal Gradient Holes | Open Energy Information

    Open Energy Info (EERE)

    in category "Thermal Gradient Holes" This category contains only the following page. T Thermal Gradient Holes Retrieved from "http:en.openei.orgwindex.php?titleCategory:T...

  19. Gradient-Enhanced Universal Kriging for Uncertainty Propagation...

    Office of Scientific and Technical Information (OSTI)

    Gradient-Enhanced Universal Kriging for Uncertainty Propagation Citation Details In-Document Search Title: Gradient-Enhanced Universal Kriging for Uncertainty Propagation Authors: ...

  20. Thermal Gradient Holes At Chocolate Mountains Area (Alm, Et Al...

    Open Energy Info (EERE)

    Thermal Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes "Shallow temperature gradient drilling began at the CMAGR in January of 2010. 13 temperature...

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

    DOE Patents [OSTI]

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

    1995-01-17

    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. Fabrication process for a gradient index x-ray lens

    DOE Patents [OSTI]

    Bionta, Richard M.; Makowiecki, Daniel M.; Skulina, Kenneth M.

    1995-01-01

    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.

  3. Novel concepts in weld science: Role of gradients and composite structure. Final report

    SciTech Connect (OSTI)

    Matlock, D.K.; Olson, D.L.

    1994-03-01

    The effects of compositional and microstructural gradients on weld metal and simulated weld metal properties were evaluated in this multi-part study. The results obtained on single phase solid solution systems were used as a basis for a fundamental study of the effects of compositional gradients on crack growth, both at low temperatures, in fatigue and at high temperatures during creep. Methods to physically simulate gradients in weld metals with roll bonded laminate composites were applied to analyses of ferrite-austenite and ferrite-sigma-austenite multiphase systems. Finally, results of the physical simulation analyses were utilized to predict the effects of weld process parameters on weld metal properties.

  4. Generation of 500 MeV-1 GeV energy electrons from laser wakefield acceleration via ionization induced injection using CO{sub 2} mixed in He

    SciTech Connect (OSTI)

    Mo, M. Z.; Ali, A.; Fedosejevs, R.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.

    2013-04-01

    Laser wakefield acceleration of 500 MeV to 1 GeV electron bunches has been demonstrated using ionization injection in mixtures of 4% to 10% of CO{sub 2} in He. 80 TW laser pulses were propagated through 5 mm gas jet targets at electron densities of 0.4-1.5 Multiplication-Sign 10{sup 19}cm{sup -3}. Ionization injection led to lower density thresholds, a higher total electron charge, and an increased probability of producing electrons above 500 MeV in energy compared to self-injection in He gas alone. Electrons with GeV energies were also observed on a few shots and indicative of an additional energy enhancement mechanism.

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

    SciTech Connect (OSTI)

    Downer, Michael C.

    2014-12-19

    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

  6. Multi-gradient drilling method and system

    DOE Patents [OSTI]

    Maurer, William C.; Medley, Jr., George H.; McDonald, William J.

    2003-01-01

    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.

  7. Edge gradient and safety factor effects on electrostatic turbulent transport in tokamaks

    SciTech Connect (OSTI)

    Tan, Ing Hwie

    1992-05-01

    Electrostatic turbulence and transport measurements are performed on the Tokapole-II tokamak at the University of Wisconsin-Madison, as the safety-factor and the edge equilibrium gradients and varied substantially. Tokapole-II is a poloidal divertor tokamak capable of operating at a wide range of safety factors due to its unique magnetic limiter configuration. It also has retractable material limiters in a large scrape-off region, which permits the study of edge boundary conditions like density and temperature gradients. The turbulence is independent of safety factor, but strongly sensitive to the local density gradient, which itself depends upon the limiter configuration. When a material limiter is inserted in a high discharge, the density gradient is increased locally together with a local increase of the turbulence. On the other hand, limiter insertion in low discharges did not increase the density gradient as much and the turbulence properties are unchanged with respect to the magnetic limiter case. It is conducted then, that electrostatic turbulence is caused by the density gradient. Although the electrostatic fluctuation driven transport is enhanced in the large density gradient case, it is in all cases to small to explain the observed energy confinement times. To explore instabilities with small wavelengths, a 0.5 mm diameter shperical Langmuir probe was constructed, and its power compared with the power measured by larger cylindrical probes.

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

    DOE Patents [OSTI]

    Hull, J.R.

    1982-09-29

    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.

  9. Laser Wakefield Particle Acceleration

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

    in new capability for rapid data exploration and analysis. Investigators: Cameron Geddes, Jean-Luc Vay, Carl Schroeder, E. Cormier-Michel, E. Esarey, W.P. Leemans (LBNL); D.L....

  10. Automated apparatus for producing gradient gels

    DOE Patents [OSTI]

    Anderson, N.L.

    1983-11-10

    Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

  11. Automated apparatus for producing gradient gels

    DOE Patents [OSTI]

    Anderson, Norman L.

    1986-01-01

    Apparatus for producing a gradient gel which serves as a standard medium for a two-dimensional analysis of proteins, the gel having a density gradient along its height formed by a variation in gel composition, with the apparatus including first and second pumping means each including a plurality of pumps on a common shaft and driven by a stepping motor capable of providing small incremental changes in pump outputs for the gel ingredients, the motors being controlled, by digital signals from a digital computer, a hollow form or cassette for receiving the gel composition, means for transferring the gel composition including a filler tube extending near the bottom of the cassette, adjustable horizontal and vertical arms for automatically removing and relocating the filler tube in the next cassette, and a digital computer programmed to automatically control the stepping motors, arm movements, and associated sensing operations involving the filling operation.

  12. Longitudinal Bunch Lengthening Compensation in High Charge RF Photoinjector

    SciTech Connect (OSTI)

    Pei, S.; Adolphsen, C.; /SLAC

    2008-10-03

    In high charge RF photoinjectors for wakefield two beam acceleration studies, due to the strong longitudinal space charge, bunch lengthening between the photocathode and photoinjector exit is a critical issue. We present beam dynamics studies of bunch lengthening in an RF photoinjector for a high charge electron beam and describe methods to compensate the bunch lengthening to various degrees. In particular, the beam dynamics for bunch charge from 1nC to 30nC are studied for an S-band 2856 MHz photoinjector.

  13. High-gradient two-beam electron accelerator

    SciTech Connect (OSTI)

    Hirshfield, Jay L.

    2014-11-04

    The main goal for this project was to design, build, and evaluate a detuned-cavity, collinear, two-beam accelerator structure. Testing was to be at the Yale University Beam Physics Laboratory, under terms of a sub-grant from Omega-P to Yale. Facilities available at Yale for this project include a 6-MeV S-band RF gun and associated beam line for forming and transporting a ~1 A drive beam , a 300 kV beam source for use as a test beam, and a full panoply of laboratory infrastructure and test equipment. During the first year of this project, availability and functionality of the 6-MeV drive beam and 300 kV test beam were confirmed, and the beam line was restored to a layout to be used with the two-beam accelerator project. Major efforts during the first year were also focused on computational design and simulation of the accelerator structure itself, on beam dynamics, and on beam transport. Effort during the second year was focussed on building and preparing to test the structure, including extensive cold testing. Detailed results from work under this project have been published in twelve archival journal articles, listed in Section IV of the technical report.

  14. Developing new high energy gradient concentration cathode material

    Broader source: Energy.gov [DOE]

    2009 DOE Hydrogen Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C.

  15. Novel concepts in weld science: Role of gradients and composite structure. Technical progress report, June 1, 1990--August 31, 1992

    SciTech Connect (OSTI)

    Matlock, D.K.; Olson, D.L.

    1992-08-31

    The effects of compositional and microstructural gradients on weld metal properties were investigated. The effects of compositional gradients were analyzed using thermodynamic and composite models. Brittle and ductile cracking behavior were investigated using both binary alloy single crystals and large grain castings. In both cases, the crack propagated along regions where the compositional gradients were the steepest. High temperature deformation of large wavelength compositonally modulated structures vas investigated to understand creep behavior in veld metal. At moderate temperatures, the creep behavior of cored materials was found to follow predictions based on the rule of mixtures composite analysis. At higher temperatures with the advent of dynamic mass transport the creep process is influenced by diffusion-promoted vacancy flow and time-dependent compositional gradient. The investigation found the critical gradient which will promote Kirkendall voids and has reported a creep rate behavior that suggests strong structural dependence, localized stress and vacancy transport influence. Weld metal, based on metal matrix composite, was also demonstrated.

  16. Study of electron acceleration and x-ray radiation as a function of plasma density in capillary-guided laser wakefield accelerators

    SciTech Connect (OSTI)

    Ju, J.; Döpp, A.; Cros, B.; Svensson, K.; Genoud, G.; Wojda, F.; Burza, M.; Persson, A.; Lundh, O.; Wahlström, C.-G.; Ferrari, H.

    2013-08-15

    Laser wakefield electron acceleration in the blow-out regime and the associated betatron X-ray radiation were investigated experimentally as a function of the plasma density in a configuration where the laser is guided. Dielectric capillary tubes were employed to assist the laser keeping self-focused over a long distance by collecting the laser energy around its central focal spot. With a 40 fs, 16 TW pulsed laser, electron bunches with tens of pC charge were measured to be accelerated to an energy up to 300 MeV, accompanied by X-ray emission with a peak brightness of the order of 10{sup 21} ph/s/mm{sup 2}/mrad{sup 2}/0.1%BW. Electron trapping and acceleration were studied using the emitted X-ray beam distribution to map the acceleration process; the number of betatron oscillations performed by the electrons was inferred from the correlation between measured X-ray fluence and beam charge. A study of the stability of electron and X-ray generation suggests that the fluctuation of X-ray emission can be reduced by stabilizing the beam charge. The experimental results are in good agreement with 3D particle-in-cell (PIC) simulation.

  17. Constant field gradient planar coupled cavity structure

    DOE Patents [OSTI]

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

    1999-07-27

    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.

  18. Thermoacoustic mixture separation with an axial temperature gradient

    SciTech Connect (OSTI)

    Geller, Drew W; Swift, Gregory A

    2008-01-01

    The theory of thermoacoustic mixture separation is extended to include the effect of a nonzero axial temperature gradient. The analysis yields a new term in the second-order mole flux that is proportional to the temperature gradient and to the square of the volumetric velocity and is independent of the phasing of the wave. Because of this new term, thermoacoustic separation stops at a critical temperature gradient and changes direction above that gradient. For a traveling wave, this gradient is somewhat higher than that predicted by a simple four-step model. An experiment tests the theory for temperature gradients from 0 to 416 K/m in 50-50 He-Ar mixtures.

  19. Reversal of the cosmic ray density gradient perpendicular to the ecliptic plane

    SciTech Connect (OSTI)

    Swinson, D.B.; Kananen, H.

    1982-03-01

    Annual averages of the diurnal variation in cosmic ray intensity from neutron monitors in Deep River and Oulu and underground muon telescopes in Bolivia and at Embudo and Socorro, New Mexico, have been determined as a function of the sense of the interplantary magnetic field for the years 1965--1975. These data point to a cosmic ray density gradient, perpendicular to the ecliptic plane, pointing southward prior to 1969 and changing to a northward pointing gradient after the reversal of the sun's polar magnetic field in 1969--1971. This result supports numerical calculations for the prereversal and postreversal field configurations at intermediate and high cosmic ray rigidities.

  20. Laboratory experiment on EM backscatter from Farley-Buneman and gradient drift waves

    SciTech Connect (OSTI)

    Alport, M.J.; D'Angelo, N.; Pecseli, H.L.

    1981-09-01

    Results are reported of a laboratory experiment on Bragg backscatter of 3-cm microwaves by turbulent waves driven by the Farley-Buneman and gradient drift instabilities. The present work is the third in a series of laboratory experiments performed to test, under controlled conditions, prevalent ideas on EM scattering equatorial and high-latitude ionospheric waves and irregularities.

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

    SciTech Connect (OSTI)

    Gao, Dengliang

    2013-03-01

    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.

  2. 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.

    2015-03-12

    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

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

    SciTech Connect (OSTI)

    Majewski, Pawel W.; Yager, Kevin G.

    2015-03-12

    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 less 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.

  4. Finite ballooning angle effects on ion temperature gradient driven mode in gyrokinetic flux tube simulations

    SciTech Connect (OSTI)

    Singh, Rameswar, E-mail: rameswar.singh@lpp.polytechnique.fr [Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 (India) [Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 (India); Laboratoire de Physique des Plasmas, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau Cedex (France); Brunner, S. [CRPP, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland)] [CRPP, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Ganesh, R. [Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 (India)] [Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 (India); Jenko, F. [Max-Planck-Institut fur Plasmaphysik, EURATOM Association, D-85748 Garching (Germany)] [Max-Planck-Institut fur Plasmaphysik, EURATOM Association, D-85748 Garching (Germany)

    2014-03-15

    This paper presents effects of finite ballooning angles on linear ion temperature gradient (ITG) driven mode and associated heat and momentum flux in Gyrokinetic flux tube simulation GENE. It is found that zero ballooning angle is not always the one at which the linear growth rate is maximum. The ITG mode acquires a short wavelength (SW) branch (k{sub ?}?{sub i}?>?1) when growth rates maximized over all ballooning angles are considered. However, the SW branch disappears on reducing temperature gradient showing characteristics of zero ballooning angle SWITG in case of extremely high temperature gradient. Associated heat flux is even with respect to ballooning angle and maximizes at nonzero ballooning angle while the parallel momentum flux is odd with respect to the ballooning angle.

  5. Permafrost and organic layer interactions over a climate gradient...

    Office of Scientific and Technical Information (OSTI)

    in permafrost occurrence (PF) and organic layer thickness (OLT) in more than 3000 soil pedons across a mean annual temperature (MAT) gradient. Cause and effect relationships...

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

    Open Energy Info (EERE)

    Long Valley Caldera Geothermal Area (Conservation, 2009) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Long Valley...

  7. Thermal Gradient Holes At San Emidio Desert Area (DOE GTP) |...

    Open Energy Info (EERE)

    San Emidio Desert Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At San Emidio Desert Area (DOE GTP)...

  8. Numerical Simulation of Ni Grain Growth in a Thermal Gradient

    Office of Scientific and Technical Information (OSTI)

    665C Numerical Simulation of Ni Grain Growth in a Thermal Gradient Sandia National Laboratories John A. Mitchell and Veena Tikare Sandia National Laboratories, Albuquerque New ...

  9. Thermal Gradient Holes At Pilgrim Hot Springs Area (DOE GTP)...

    Open Energy Info (EERE)

    Pilgrim Hot Springs Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Pilgrim Hot Springs Area (DOE GTP)...

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

    Open Energy Info (EERE)

    Exploration Basis Thermal gradient holes were drilled in an effort to determine the feasibility of commercial geothermal energy generation at Blue Mountain Notes Ten temperature...

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

    Open Energy Info (EERE)

    crust. The boreholes which exhibited the lowest average gradient were several kilometers from the hot springs and up-dip. None of them penetrated the Dakota Sandstone ....

  12. Thermal Gradient Holes At Hawthorne Area (Lazaro, Et Al., 2010...

    Open Energy Info (EERE)

    Unknown Notes The Navy recently completed a temperature gradient hole (TGH) drilling campaign. Results suggest multiple resources may exist on HAD lands. To further define the...

  13. Thermal Gradient Holes At Cove Fort Area - Vapor (Warpinski,...

    Open Energy Info (EERE)

    Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes Update to Warpinski, et al., 2002 References N. R. Warpinski, A. R. Sattler, R. Fortuna, D....

  14. Thermal Gradient Holes At Cove Fort Area (Warpinski, Et Al.,...

    Open Energy Info (EERE)

    Gradient Holes Activity Date Usefulness not indicated DOE-funding Unknown Notes Update to Warpinski, et al., 2002 References N. R. Warpinski, A. R. Sattler, R. Fortuna, D....

  15. Thermal Gradient Holes At Newberry Caldera Area (DOE GTP) | Open...

    Open Energy Info (EERE)

    Newberry Caldera Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Newberry Caldera Area (DOE GTP)...

  16. Thermal Gradient Holes At Flint Geothermal Area (DOE GTP) | Open...

    Open Energy Info (EERE)

    Flint Geothermal Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Flint Geothermal Area (DOE GTP)...

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

    Office of Scientific and Technical Information (OSTI)

    Comparative systems biology across an evolutionary gradient within the Shewanella genus Citation Details In-Document Search Title: Comparative systems biology across an ...

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

    Open Energy Info (EERE)

    Edmunds & W., 1977) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At North Brawley Geothermal Area (Edmunds & W., 1977)...

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

    Open Energy Info (EERE)

    DOE-funding Unknown Exploration Basis Thermal gradient wells were drilled for initial exploration and assessment of the North Brawley Geothermal Area. Notes Union Oil Company...

  20. Thermal Gradient Holes At Mcgee Mountain Area (DOE GTP) | Open...

    Open Energy Info (EERE)

    Mcgee Mountain Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Mcgee Mountain Area (DOE GTP) Exploration...

  1. Thermal Gradient Holes At Tungsten Mountain Area (Kratt, Et Al...

    Open Energy Info (EERE)

    Gradient Holes Activity Date Usefulness useful DOE-funding Unknown Notes twenty-three gold exploration holes were drilled by Newcrest Resources, Inc. during 2005 and 2006 along...

  2. Ch. VII, Temperature, heat flow maps and temperature gradient...

    Open Energy Info (EERE)

    Report: Ch. VII, Temperature, heat flow maps and temperature gradient holes Author T. G. Zacharakis Editor T. G. Zacharakis Published Colorado Geological Survey in Cooperation...

  3. Temperature, heat flow maps and temperature gradient holes |...

    Open Energy Info (EERE)

    to library Report: Temperature, heat flow maps and temperature gradient holes Author T. G. Zacharakis Organization Colorado Geological Survey in Cooperation with the U.S....

  4. Thermal Gradient Holes At Mccoy Geothermal Area (DOE GTP) | Open...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Mccoy Geothermal Area (DOE GTP) Exploration Activity Details...

  5. Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski,...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Hot Springs Ranch Area (Szybinski, 2006) Exploration Activity...

  6. Thermal Gradient Holes At Lightning Dock Area (Warpinski, Et...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Lightning Dock Area (Warpinski, Et Al., 2004) Exploration Activity...

  7. Thermal Gradient Holes At Kilauea East Rift Geothermal Area ...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Kilauea East Rift Geothermal Area (Thomas, 1986) Exploration...

  8. Thermal Gradient Holes At Mt Princeton Hot Springs Geothermal...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Mt Princeton Hot Springs Geothermal Area (Held & Henderson, 2012)...

  9. Thermal Gradient Holes At Glass Mountain Area (Cumming And Mackie...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Glass Mountain Area (Cumming And Mackie, 2007) Exploration Activity...

  10. Thermal Gradient Holes At Crump's Hot Springs Area (DOE GTP)...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Crump's Hot Springs Area (DOE GTP) Exploration Activity Details...

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

    SciTech Connect (OSTI)

    Olander, D.R.

    1984-08-01

    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.

  12. Gradient maintenance: A new algorithm for fast online replanning

    SciTech Connect (OSTI)

    Ahunbay, Ergun E. Li, X. Allen

    2015-06-15

    Purpose: Clinical use of online adaptive replanning has been hampered by the unpractically long time required to delineate volumes based on the image of the day. The authors propose a new replanning algorithm, named gradient maintenance (GM), which does not require the delineation of organs at risk (OARs), and can enhance automation, drastically reducing planning time and improving consistency and throughput of online replanning. Methods: The proposed GM algorithm is based on the hypothesis that if the dose gradient toward each OAR in daily anatomy can be maintained the same as that in the original plan, the intended plan quality of the original plan would be preserved in the adaptive plan. The algorithm requires a series of partial concentric rings (PCRs) to be automatically generated around the target toward each OAR on the planning and the daily images. The PCRs are used in the daily optimization objective function. The PCR dose constraints are generated with dose–volume data extracted from the original plan. To demonstrate this idea, GM plans generated using daily images acquired using an in-room CT were compared to regular optimization and image guided radiation therapy repositioning plans for representative prostate and pancreatic cancer cases. Results: The adaptive replanning using the GM algorithm, requiring only the target contour from the CT of the day, can be completed within 5 min without using high-power hardware. The obtained adaptive plans were almost as good as the regular optimization plans and were better than the repositioning plans for the cases studied. Conclusions: The newly proposed GM replanning algorithm, requiring only target delineation, not full delineation of OARs, substantially increased planning speed for online adaptive replanning. The preliminary results indicate that the GM algorithm may be a solution to improve the ability for automation and may be especially suitable for sites with small-to-medium size targets surrounded by

  13. Mineral density volume gradients in normal and diseased human tissues

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

    Djomehri, Sabra I.; Candell, Susan; Case, Thomas; Browning, Alyssa; Marshall, Grayson W.; Yun, Wenbing; Lau, S. H.; Webb, Samuel; Ho, Sunita P.; Aikawa, Elena

    2015-04-09

    Clinical computed tomography provides a single mineral density (MD) value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca) to phosphorus (P) and Ca to zinc (Zn) elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT) benchtop unit were correlated with elemental mapping obtained from a microprobe X-raymore » fluorescence (XRF) using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males) contained significant mineral density variations (enamel: 2820-3095mg/cc, bone: 570-1415mg/cc, cementum: 1240-1340mg/cc, dentin: 1480-1590mg/cc, cementum affected by periodontitis: 1100-1220mg/cc, hypomineralized carious dentin: 345-1450mg/cc, hypermineralized carious dentin: 1815-2740mg/cc, and dental calculus: 1290-1770mg/cc). A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49), hypomineralized dentin (0.32-0.46), cementum (1.51), and bone (1.68) were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765) and in cementum (595-990), highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations.« less

  14. Mineral density volume gradients in normal and diseased human tissues

    SciTech Connect (OSTI)

    Djomehri, Sabra I.; Candell, Susan; Case, Thomas; Browning, Alyssa; Marshall, Grayson W.; Yun, Wenbing; Lau, S. H.; Webb, Samuel; Ho, Sunita P.; Aikawa, Elena

    2015-04-09

    Clinical computed tomography provides a single mineral density (MD) value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca) to phosphorus (P) and Ca to zinc (Zn) elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT) benchtop unit were correlated with elemental mapping obtained from a microprobe X-ray fluorescence (XRF) using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males) contained significant mineral density variations (enamel: 2820-3095mg/cc, bone: 570-1415mg/cc, cementum: 1240-1340mg/cc, dentin: 1480-1590mg/cc, cementum affected by periodontitis: 1100-1220mg/cc, hypomineralized carious dentin: 345-1450mg/cc, hypermineralized carious dentin: 1815-2740mg/cc, and dental calculus: 1290-1770mg/cc). A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49), hypomineralized dentin (0.32-0.46), cementum (1.51), and bone (1.68) were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765) and in cementum (595-990), highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations.

  15. Shape measurement biases from underfitting and ellipticity gradients

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

    Bernstein, Gary M.

    2010-08-21

    With this study, precision weak gravitational lensing experiments require measurements of galaxy shapes accurate to <1 part in 1000. We investigate measurement biases, noted by Voigt and Bridle (2009) and Melchior et al. (2009), that are common to shape measurement methodologies that rely upon fitting elliptical-isophote galaxy models to observed data. The first bias arises when the true galaxy shapes do not match the models being fit. We show that this "underfitting bias" is due, at root, to these methods' attempts to use information at high spatial frequencies that has been destroyed by the convolution with the point-spread function (PSF)more » and/or by sampling. We propose a new shape-measurement technique that is explicitly confined to observable regions of k-space. A second bias arises for galaxies whose ellipticity varies with radius. For most shape-measurement methods, such galaxies are subject to "ellipticity gradient bias". We show how to reduce such biases by factors of 20–100 within the new shape-measurement method. The resulting shear estimator has multiplicative errors < 1 part in 103 for high-S/N images, even for highly asymmetric galaxies. Without any training or recalibration, the new method obtains Q = 3000 in the GREAT08 Challenge of blind shear reconstruction on low-noise galaxies, several times better than any previous method.« less

  16. Shape measurement biases from underfitting and ellipticity gradients

    SciTech Connect (OSTI)

    Bernstein, Gary M.

    2010-08-21

    With this study, precision weak gravitational lensing experiments require measurements of galaxy shapes accurate to <1 part in 1000. We investigate measurement biases, noted by Voigt and Bridle (2009) and Melchior et al. (2009), that are common to shape measurement methodologies that rely upon fitting elliptical-isophote galaxy models to observed data. The first bias arises when the true galaxy shapes do not match the models being fit. We show that this "underfitting bias" is due, at root, to these methods' attempts to use information at high spatial frequencies that has been destroyed by the convolution with the point-spread function (PSF) and/or by sampling. We propose a new shape-measurement technique that is explicitly confined to observable regions of k-space. A second bias arises for galaxies whose ellipticity varies with radius. For most shape-measurement methods, such galaxies are subject to "ellipticity gradient bias". We show how to reduce such biases by factors of 20–100 within the new shape-measurement method. The resulting shear estimator has multiplicative errors < 1 part in 103 for high-S/N images, even for highly asymmetric galaxies. Without any training or recalibration, the new method obtains Q = 3000 in the GREAT08 Challenge of blind shear reconstruction on low-noise galaxies, several times better than any previous method.

  17. Efficient and robust gradient enhanced Kriging emulators.

    SciTech Connect (OSTI)

    Dalbey, Keith R.

    2013-08-01

    %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.

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

    SciTech Connect (OSTI)

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

    2015-02-15

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

  19. Electronic Bloch oscillation in bilayer graphene gradient superlattices

    SciTech Connect (OSTI)

    Cheng, Hemeng; Li, Changan; Song, Yun; Ma, Tianxing; Wang, Li-Gang; Lin, Hai-Qing

    2014-08-18

    We investigate the electronic Bloch oscillation in bilayer graphene gradient superlattices using transfer matrix method. By introducing two kinds of gradient potentials of square barriers along electrons propagation direction, we find that Bloch oscillations up to terahertz can occur. Wannier-Stark ladders, as the counterpart of Bloch oscillation, are obtained as a series of equidistant transmission peaks, and the localization of the electronic wave function is also signature of Bloch oscillation. Furthermore, the period of Bloch oscillation decreases linearly with increasing gradient of barrier potentials.

  20. Influence of composition gradients on weld metal creep behavior: An analysis based on laminate composites

    SciTech Connect (OSTI)

    Choi, I.

    1989-01-01

    The effects of weld metal microsegregation, as altered by post-weld heat treatments, on both low and high temperatures tensile properties were investigated on Monel alloy 400. Flat, all weld metal, tensile specimens were machined from single pass GTA welds and were heat treated in vacuum in the range of 600 C to 1000 C to produce samples with different composition gradients. Short-time tensile tests were run at room temperature and elevated temperature. Long-time constant load creep tests were performed at 500 C. The room temperature mechanical properties of the as-welded specimen and heat treated specimens were similar and thus unaffected by variations in composition gradients. In contrast, at high temperatures the steady state creep rates decreased, rupture strains increased, and rupture lives decreases with increases in heat treatment temperature, that is, with decreases in the amplitudes of composition gradients. The deformation behavior of solidified dendritic structure was modeled based on results obtained on laminate composites of nickel and copper. The laminates, prepared by roll bonding, were annealed to produce controlled composition gradients with dimensions equivalent to those observed in the weld metal. The steady state creep rates of laminate composites decreased with increases in heat treatment time, that is, with decreases in the amplitudes of composition gradients. To rationalize the creep properties of each component in laminate composites, nickel-copper solid solutions having systematic compositional variations were prepared and tested under the same conditions as the laminate composites. The creep rates of nickel-copper solid solutions showed a minimum with nickel composition.

  1. Critical gradients and plasma flows in the edge plasma of Alcator C-Mod

    SciTech Connect (OSTI)

    LaBombard, B.; Hughes, J. W.; Smick, N.; Marr, K.; McDermott, R.; Reinke, M.; Greenwald, M.; Lipschultz, B.; Terry, J. L.; Whyte, D. G.; Graf, A.; Zweben, S. J.

    2008-05-15

    Recent experiments have led to a fundamental shift in our view of edge transport physics; transport near the last-closed flux surface may be more appropriately described in terms of a critical gradient phenomenon rather than a diffusive and/or convective paradigm. Edge pressure gradients, normalized by the square of the poloidal magnetic field strength, appear invariant in plasmas with the same normalized collisionality, despite vastly different currents and magnetic fields--a behavior that connects with first-principles electromagnetic plasma turbulence simulations. Near-sonic scrape-off layer (SOL) flows impose a cocurrent rotation boundary condition on the confined plasma when Bx{nabla}B points toward the active x-point, suggesting a link to the concomitant reduction in input power needed to attain high-confinement modes. Indeed, low-confinement mode plasmas are found to attain higher edge pressure gradients in this configuration, independent of the direction of B, evidence that SOL flows may affect transport and 'critical gradient' values in the edge plasma.

  2. Observation of 690 MV m^-1 Electron Accelerating Gradient with...

    Office of Scientific and Technical Information (OSTI)

    Observation of 690 MV m-1 Electron Accelerating Gradient with a Laser-Driven Dielectric Microstructure Citation Details In-Document Search Title: Observation of 690 MV m-1...

  3. Thermal Gradient Holes At Neal Hot Springs Geothermal Area (U...

    Open Energy Info (EERE)

    small diameter temperature gradient wells have been drilled ranging in depth from 152-607 m. These wells were drilled across the Neal Hot Springs area in order to gather more...

  4. Thermal Gradient Holes At Coso Geothermal Area (1976) | Open...

    Open Energy Info (EERE)

    to depths up to 133 m in 22 boreholes with measurements being made at least four times in each borehole. Geothermal gradients ranged from 240Ckm to 450 0Ckm. References...

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

    Open Energy Info (EERE)

    consisting of several holes including: The CH8-10 thermal-gradient holes drilled by the U.S. Geological Survey prior to 1978 to relatively shallow depths ranging from about 55 to...

  6. 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...

  7. Edge Temperature Gradient as Intrinsic Rotation Drive in Alcator...

    Office of Scientific and Technical Information (OSTI)

    Title: Edge Temperature Gradient as Intrinsic Rotation Drive in Alcator C -Mod Tokamak Plasmas Authors: Rice, J. E. ; Hughes, J. W. ; Diamond, P. H. ; Kosuga, Y. ; Podpaly, Y. A. ; ...

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

    DOE Patents [OSTI]

    Rader, Daniel J.; Dykhuizen, Ronald C.; Geller, Anthony S.

    2000-01-01

    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.

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

    SciTech Connect (OSTI)

    Park, Sang-Gil; Jeong, Ki-Hun; Lee, Kanghee; Han, Daehoon; Ahn, Jaewook

    2014-09-01

    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.

  10. Edge Temperature Gradient as Intrinsic Rotation Drive in AlcatorC...

    Office of Scientific and Technical Information (OSTI)

    Edge Temperature Gradient as Intrinsic Rotation Drive in AlcatorC-Mod Tokamak Plasmas Citation Details In-Document Search Title: Edge Temperature Gradient as Intrinsic Rotation...

  11. Towards an Optimal Gradient-dependent Energy Functional of the PZ-SIC Form

    SciTech Connect (OSTI)

    Jónsson, Elvar Örn; Lehtola, Susi; Jónsson, Hannes

    2015-06-01

    Results of Perdew–Zunger self-interaction corrected (PZ-SIC) density functional theory calculations of the atomization energy of 35 molecules are compared to those of high-level quantum chemistry calculations. While the PBE functional, which is commonly used in calculations of condensed matter, is known to predict on average too high atomization energy (overbinding of the molecules), the application of PZ-SIC gives a large overcorrection and leads to significant underestimation of the atomization energy. The exchange enhancement factor that is optimal for the generalized gradient approximation within the Kohn-Sham (KS) approach may not be optimal for the self-interaction corrected functional. The PBEsol functional, where the exchange enhancement factor was optimized for solids, gives poor results for molecules in KS but turns out to work better than PBE in PZ-SIC calculations. The exchange enhancement is weaker in PBEsol and the functional is closer to the local density approximation. Furthermore, the drop in the exchange enhancement factor for increasing reduced gradient in the PW91 functional gives more accurate results than the plateaued enhancement in the PBE functional. A step towards an optimal exchange enhancement factor for a gradient dependent functional of the PZ-SIC form is taken by constructing an exchange enhancement factor that mimics PBEsol for small values of the reduced gradient, and PW91 for large values. The average atomization energy is then in closer agreement with the high-level quantum chemistry calculations, but the variance is still large, the F2 molecule being a notable outlier.

  12. Towards an Optimal Gradient-dependent Energy Functional of the PZ-SIC Form

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

    Jónsson, Elvar Örn; Lehtola, Susi; Jónsson, Hannes

    2015-06-01

    Results of Perdew–Zunger self-interaction corrected (PZ-SIC) density functional theory calculations of the atomization energy of 35 molecules are compared to those of high-level quantum chemistry calculations. While the PBE functional, which is commonly used in calculations of condensed matter, is known to predict on average too high atomization energy (overbinding of the molecules), the application of PZ-SIC gives a large overcorrection and leads to significant underestimation of the atomization energy. The exchange enhancement factor that is optimal for the generalized gradient approximation within the Kohn-Sham (KS) approach may not be optimal for the self-interaction corrected functional. The PBEsol functional, wheremore » the exchange enhancement factor was optimized for solids, gives poor results for molecules in KS but turns out to work better than PBE in PZ-SIC calculations. The exchange enhancement is weaker in PBEsol and the functional is closer to the local density approximation. Furthermore, the drop in the exchange enhancement factor for increasing reduced gradient in the PW91 functional gives more accurate results than the plateaued enhancement in the PBE functional. A step towards an optimal exchange enhancement factor for a gradient dependent functional of the PZ-SIC form is taken by constructing an exchange enhancement factor that mimics PBEsol for small values of the reduced gradient, and PW91 for large values. The average atomization energy is then in closer agreement with the high-level quantum chemistry calculations, but the variance is still large, the F2 molecule being a notable outlier.« less

  13. High power test results of the first SRRC/ANL high current L-band RF gun.

    SciTech Connect (OSTI)

    Ho, C. H.

    1998-09-11

    A joint program is underway between the SRRC (Synchrotrons Radiation Research Center, Taiwan) and ANL (Argonne National Laboratory, USA) for developing a high current L-band photocathode rf guns. We have constructed an L-Band (1.3 Ghz), single cell rf photocathode gun and conducted low power tests at SRRC. High power rf conditioning of the cavity has been completed at ANL. In this paper we report on the construction and high power test results. So far we have been able to achieve > 120 MV/m axial electric field with minimal dark current. This gun will be used to replace the AWA (Argonne Wakefield Accelerator)[l] high current gun.

  14. 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

    1996-07-15

    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.

  15. Enhanced magnetic reconnection in the presence of pressure gradients

    SciTech Connect (OSTI)

    Pueschel, M. J.; Terry, P. W.; Told, D.; Jenko, F.

    2015-06-15

    Magnetic reconnection in the presence of background pressure gradients is studied, with special attention to parallel (compressional) magnetic fluctuations. A process is reported that reconnects fields through coupling of drift-wave-type instabilities with current sheets. Its time scale is set not by the reconnecting field but by inhomogeneities of the background density or temperature. The observed features can be attributed to a pressure-gradient-driven linear instability which interacts with the reconnecting system but is fundamentally different from microtearing. In particular, this mode relies on parallel magnetic fluctuations and the associated drift. For turbulent reconnection, similar or even stronger enhancements are reported. In the solar corona, this yields a critical pressure gradient scale length of about 200 km below which this new process becomes dominant over the tearing instability.

  16. Gradient isolator for flow field of fuel cell assembly

    DOE Patents [OSTI]

    Ernst, William D.

    1999-01-01

    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. Gradient isolator for flow field of fuel cell assembly

    DOE Patents [OSTI]

    Ernst, W.D.

    1999-06-15

    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.

  18. Efficient gradient field generation providing a multi-dimensional arbitrary shifted field-free point for magnetic particle imaging

    SciTech Connect (OSTI)

    Kaethner, Christian Ahlborg, Mandy; Buzug, Thorsten M.; Knopp, Tobias; Sattel, Timo F.

    2014-01-28

    Magnetic Particle Imaging (MPI) is a tomographic imaging modality capable to visualize tracers using magnetic fields. A high magnetic gradient strength is mandatory, to achieve a reasonable image quality. Therefore, a power optimization of the coil configuration is essential. In order to realize a multi-dimensional efficient gradient field generator, the following improvements compared to conventionally used Maxwell coil configurations are proposed: (i) curved rectangular coils, (ii) interleaved coils, and (iii) multi-layered coils. Combining these adaptions results in total power reduction of three orders of magnitude, which is an essential step for the feasibility of building full-body human MPI scanners.

  19. Systematic Optimization of Long Gradient Chromatography Mass Spectrometry for Deep Analysis of Brain Proteome

    SciTech Connect (OSTI)

    Wang, Hong; Yang, Yanling; Li, Yuxin; Bai, Bing; Wang, Xusheng; Tan, Haiyan; Liu, Tao; Beach, Thomas G.; Peng, Junmun; Wu, Zhiping

    2015-02-06

    Development of high resolution liquid chromatography (LC) is essential for improving the sensitivity and throughput of mass spectrometry (MS)-based proteomics. Here we present systematic optimization of a long gradient LC-MS/MS platform to enhance protein identification from a complex mixture. The platform employed an in-house fabricated, reverse phase column (100 μm x 150 cm) coupled with Q Exactive MS. The column was capable of achieving a peak capacity of approximately 700 in a 720 min gradient of 10-45% acetonitrile. The optimal loading level was about 6 micrograms of peptides, although the column allowed loading as many as 20 micrograms. Gas phase fractionation of peptide ions further increased the number of peptide identification by ~10%. Moreover, the combination of basic pH LC pre-fractionation with the long gradient LC-MS/MS platform enabled the identification of 96,127 peptides and 10,544 proteins at 1% protein false discovery rate in a postmortem brain sample of Alzheimer’s disease. As deep RNA sequencing of the same specimen suggested that ~16,000 genes were expressed, current analysis covered more than 60% of the expressed proteome. Further improvement strategies of the LC/LC-MS/MS platform were also discussed.

  20. Thermal gradient-induced forces on geodesic reference masses for LISA

    SciTech Connect (OSTI)

    Carbone, L.; Ciani, G.; Dolesi, R.; Hueller, M.; Tombolato, D.; Vitale, S.; Weber, W. J.; Cavalleri, A.

    2007-11-15

    The low frequency sensitivity of space-borne gravitational wave observatories will depend critically on the geodesic 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 Laser Interferometer Space Antenna (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 current LISA noise estimate, which assumes a maximum net force per degree of temperature difference of 100(pN/K) for the overall thermal gradient-induced effects.

  1. Diffraction Profiles of Elasticity Bent Single Crystals with Constant Strain Gradients

    SciTech Connect (OSTI)

    Yan,H.; Kalenci, O.; Noyan, I.

    2007-01-01

    This work presents a set of equations that can be used to predict the dynamical diffraction profile from a non-transparent single crystal with a constant strain gradient examined in Bragg reflection geometry with a spherical incident X-ray beam. In agreement with previous work, the present analysis predicts two peaks: a primary diffraction peak, which would have still been observed in the absence of the strain gradient and which exits the specimen surface at the intersection point of the incident beam with the sample surface, and a secondary (mirage) peak, caused by the deflection of the wavefield within the material, which exits the specimen surface further from this intersection point. The integrated intensity of the mirage peak increases with increasing strain gradient, while its separation from the primary reflection peak decreases. The directions of the rays forming the mirage peak are parallel to those forming the primary diffraction peak. However, their spatial displacement might cause (fictitious) angular shifts in diffractometers equipped with area detectors or slit optics. The analysis results are compared with experimental data from an Si single-crystal strip bent in cantilever configuration, and the implications of the mirage peak for Laue analysis and high-precision diffraction measurements are discussed.

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

    SciTech Connect (OSTI)

    Singh, R.; Institute for Plasma Research, Bhat Gandhinagar, Gujarat 2382 428 ; Jhang, Hogun; Diamond, P. H.; CMTFO and CASS, University of California, San Diego 92093-0424, California

    2013-11-15

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

  3. Density gradient effects on transverse shear driven lower hybrid waves

    SciTech Connect (OSTI)

    DuBois, Ami M.; Thomas, Edward; Amatucci, William E.; Ganguli, Gurudas

    2014-06-15

    Shear driven instabilities are commonly observed in the near-Earth space, particularly in boundary layer plasmas. When the shear scale length (L{sub E}) is much less than the ion gyro-radius (?{sub i}) but greater than the electron gyro-radius (?{sub e}), the electrons are magnetized in the shear layer, but the ions are effectively un-magnetized. The resulting shear driven instability, the electron-ion hybrid (EIH) instability, is investigated in a new interpenetrating plasma configuration in the Auburn Linear EXperiment for Instability Studies. In order to understand the dynamics of magnetospheric boundary layers, the EIH instability is studied in the presence of a density gradient located at the boundary layer between two plasmas. This paper reports on a recent experiment in which electrostatic lower hybrid waves are identified as the EIH instability, and the effect of a density gradient on the instability properties are investigated.

  4. Gradient Plasticity Model and its Implementation into MARMOT

    SciTech Connect (OSTI)

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

    2013-08-01

    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.

  5. Radiography to measure the longitudinal density gradients of Pd compacts

    SciTech Connect (OSTI)

    Back, D.D.

    1992-05-14

    This study used radiography to detect and quantify density gradients in green compacts of Palladium powder. Ultrasonic velocity measurements had been tried previously, but they were affected by material properties, in addition to the density, so that an alternative was sought. The alternative technique used radiographic exposures of a series of standard compacts whose density is known and correlated with the radiographic film density. These correlations are used to predict the density in subsequent compacts.

  6. Atmospheric gradients and the stability of expanding jets. [Astrophysics

    SciTech Connect (OSTI)

    Hardee, P.E.; Koupelis, T.; Norman, M.L.; Clarke, D.A. Illinois, University, Urbana )

    1991-05-01

    Numerical simulations of adiabatically expanding slab jets in initial static pressure balance with an external atmosphere have been performed and compared to predictions made by a linear analysis of the stability of expanding jets. It is found that jets are stabilized by jet expansion as predicted by the linear analysis. It is also found that an expanding jet can be destabilized by a positive temperature gradient or temperature jump in the surrounding medium which lowers the Mach number defined by the external sound speed. A temperature gradient or jump is more destabilizing than would be predicted by a linear stability analysis. The enhanced instability compared to an isothermal atmosphere with identical pressure gradient is a result of the reduced external Mach number and a result of a higher jet density relative to the density in the external medium and higher ram speed. Other differences between predictions made by the linear theory and the simulations can be understood qualitatively as a result of a change in wave speed as the wave amplitude increases. 12 refs.

  7. Probability density function method for variable-density pressure-gradient-driven turbulence and mixing

    SciTech Connect (OSTI)

    Bakosi, Jozsef; Ristorcelli, Raymond J

    2010-01-01

    Probability density function (PDF) methods are extended to variable-density pressure-gradient-driven turbulence. We apply the new method to compute the joint PDF of density and velocity in a non-premixed binary mixture of different-density molecularly mixing fluids under gravity. The full time-evolution of the joint PDF is captured in the highly non-equilibrium flow: starting from a quiescent state, transitioning to fully developed turbulence and finally dissipated by molecular diffusion. High-Atwood-number effects (as distinguished from the Boussinesq case) are accounted for: both hydrodynamic turbulence and material mixing are treated at arbitrary density ratios, with the specific volume, mass flux and all their correlations in closed form. An extension of the generalized Langevin model, originally developed for the Lagrangian fluid particle velocity in constant-density shear-driven turbulence, is constructed for variable-density pressure-gradient-driven flows. The persistent small-scale anisotropy, a fundamentally 'non-Kolmogorovian' feature of flows under external acceleration forces, is captured by a tensorial diffusion term based on the external body force. The material mixing model for the fluid density, an active scalar, is developed based on the beta distribution. The beta-PDF is shown to be capable of capturing the mixing asymmetry and that it can accurately represent the density through transition, in fully developed turbulence and in the decay process. The joint model for hydrodynamics and active material mixing yields a time-accurate evolution of the turbulent kinetic energy and Reynolds stress anisotropy without resorting to gradient diffusion hypotheses, and represents the mixing state by the density PDF itself, eliminating the need for dubious mixing measures. Direct numerical simulations of the homogeneous Rayleigh-Taylor instability are used for model validation.

  8. 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,

    2008-08-22

    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.

  9. Microfluidic device having an immobilized pH gradient and page...

    Office of Scientific and Technical Information (OSTI)

    pH gradient and page gels for protein separation and analysis Citation Details In-Document Search Title: Microfluidic device having an immobilized pH gradient and page gels ...

  10. R655-1-8 Temperature Gradient Wells | Open Energy Information

    Open Energy Info (EERE)

    R655-1-8 Temperature Gradient Wells Jump to: navigation, search OpenEI Reference LibraryAdd to library Legal Document- RegulationRegulation: R655-1-8 Temperature Gradient...

  11. Acceleration in the linear non-scaling fixed-field alternating-gradient accelerator EMMA

    SciTech Connect (OSTI)

    Machida, S.; Barlow, R.; Berg, J.S.; Bliss, N.; Buckley, R.K.; Clarke, J.A.; Craddock, M.K.; D'Arcy, R.; Edgecock, R.; Garland, J.M.; Giboudot, Y.; /Rutherford /Huddersfield U. /Brookhaven /Daresbury /Cockcroft Inst. Accel. Sci. Tech. /TRIUMF /British Columbia U., Vancouver, Dept. Phys. Astron. /University Coll. London /Manchester U. /Brunel U. /ASP, Melbourne

    2012-03-01

    In a fixed-field alternating-gradient (FFAG) accelerator, eliminating pulsed magnet operation permits rapid acceleration to synchrotron energies, but with a much higher beam-pulse repetition rate. Conceived in the 1950s, FFAGs are enjoying renewed interest, fuelled by the need to rapidly accelerate unstable muons for future high-energy physics colliders. Until now a 'scaling' principle has been applied to avoid beam blow-up and loss. Removing this restriction produces a new breed of FFAG, a non-scaling variant, allowing powerful advances in machine characteristics. We report on the first non-scaling FFAG, in which orbits are compacted to within 10?mm in radius over an electron momentum range of 12-18 MeV/c. In this strictly linear-gradient FFAG, unstable beam regions are crossed, but acceleration via a novel serpentine channel is so rapid that no significant beam disruption is observed. This result has significant implications for future particle accelerators, particularly muon and high-intensity proton accelerators.

  12. Up-gradient particle flux in a drift wave-zonal flow system

    SciTech Connect (OSTI)

    Cui, L.; Tynan, G. R.; Thakur, S. C.; Diamond, P. H.; Brandt, C.

    2015-05-15

    We report a net inward, up-gradient turbulent particle flux in a cylindrical plasma when collisional drift waves generate a sufficiently strong sheared azimuthal flow that drives positive (negative) density fluctuations up (down) the background density gradient, resulting in a steepening of the mean density gradient. The results show the existence of a saturation mechanism for drift-turbulence driven sheared flows that can cause up-gradient particle transport and density profile steepening.

  13. On the hydrodynamics of salt-gradient solar ponds

    SciTech Connect (OSTI)

    Zangrando, F. )

    1991-01-01

    The objective of this paper is to discuss those hydrodynamical issues that affect the performance of the solar pond as an energy collector and storage system, e.g., mass and energy balance; formation, stability, and maintenance of the gradient layer; energy extraction from the bottom mixed layer; stability of stratified fluids to shearing flows; interface dynamics; and wall effects. Many of these topics are not fully understood and the discussion focuses on the present state of knowledge, some of the engineering correlations available at this time, and the research that is still required to resolve the relevant issues.

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

    SciTech Connect (OSTI)

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

    2012-08-15

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

  15. Gradient index liquid crystal devices and method of fabrication thereof

    DOE Patents [OSTI]

    Lee, J.C.; Jacobs, S.

    1991-10-29

    Laser beam apodizers using cholesteric liquid crystals provides soft edge profile by use of two separate cholesteric liquid crystal mixtures with different selective reflection bands which in an overlap region have a gradient index where reflectivity changes as a function of position. The apodizers can be configured as a one-dimensional beam apod INTRODUCTION The U.S. government has rights in the invention under Contract No. DE-FC03-85DP40200 between the University of Rochester and the Department of Energy.

  16. Gradient index liquid crystal devices and method of fabrication thereof

    DOE Patents [OSTI]

    Lee, Jae-Cheul; Jacobs, Stephen

    1991-01-01

    Laser beam apodizers using cholesteric liquid crystals provides soft edge profile by use of two separate cholesteric liquid crystal mixtures with different selective reflection bands which in an overlap region have a gradient index where reflectivity changes as a function of position. The apodizers can be configured as a one-dimensional beam apod INTRODUCTION The U.S. government has rights in the invention under Contract No. DE-FC03-85DP40200 between the University of Rochester and the Department of Energy.

  17. Growth of Sb-Bi gradient single crystals

    SciTech Connect (OSTI)

    Kozhemyakin, G. N. Lutskiy, D. V.; Rom, M. A.; Mateychenko, P. V.

    2008-12-15

    The growth conditions and structural quality of Sb-Bi gradient single crystals with Bi content from 2 to 18 at %, grown by the Czochralski method with solid phase feed, are investigated. Bi distribution in the crystals along their pulling direction are studied by electron probe microanalysis and the change in the interplanar spacing is analyzed by double-crystal X-ray diffraction. It is established that the pulling rate and feed mass affect the Bi distribution in Sb-Bi single crystals.

  18. 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)

    2012-06-15

    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.

  19. Evaluation of thermal gradients in longitudinal spin Seebeck effect measurements

    SciTech Connect (OSTI)

    Sola, A. Kuepferling, M.; Basso, V.; Pasquale, M.; Kikkawa, T.; Uchida, K.; Saitoh, E.

    2015-05-07

    In the framework of the longitudinal spin Seebeck effect (LSSE), we developed an experimental setup for the characterization of LSSE devices. This class of device consists in a layered structure formed by a substrate, a ferrimagnetic insulator (YIG) where the spin current is thermally generated, and a paramagnetic metal (Pt) for the detection of the spin current via the inverse spin-Hall effect. In this kind of experiments, the evaluation of a thermal gradient through the thin YIG layer is a crucial point. In this work, we perform an indirect determination of the thermal gradient through the measurement of the heat flux. We developed an experimental setup using Peltier cells that allow us to measure the heat flux through a given sample. In order to test the technique, a standard LSSE device produced at Tohoku University was measured. We find a spin Seebeck S{sub SSE} coefficient of 2.8×10{sup −7} V K{sup −1}.

  20. Superconducting open-gradient magnetic separation for the pretreatment of radioactive or mixed waste vitrification feeds. 1997 annual progress report

    SciTech Connect (OSTI)

    Doctor, R.; Nunez, L.; Cicero-Herman, C.A.; Ritter, J.A.; Landsberger, S.

    1997-01-01

    'Vitrification has been selected as a final waste form technology in the US for long-term storage of high-level radioactive wastes (HLW). However, a foreseeable problem during vitrification in some waste feed streams lies in the presence of elements (e.g., transition metals) in the HLW that may cause instabilities in the final glass product. The formation of spinel compounds, such as Fe{sub 3}O{sub 4} and FeCrO{sub 4}, results in glass phase separation and reduces vitrifier lifetime, and durability of the final waste form. A superconducting open gradient magnetic separation (OGMS) system maybe suitable for the removal of the deleterious transition elements (e.g. Fe, Co, and Ni) and other elements (lanthanides) from vitrification feed streams due to their ferromagnetic or paramagnetic nature. The OGMS systems are designed to deflect and collect paramagnetic minerals as they interact with a magnetic field gradient. This system has the potential to reduce the volume of HLW for vitrification and ensure a stable product. In order to design efficient OGMS and High gradient magnetic separation (HGMS) processes, a fundamental understanding of the physical and chemical properties of the waste feed streams is required. Using HLW simulant and radioactive fly ash and sludge samples from the Savannah River Technology Center, Rocky Flats site, and the Hanford reservation, several techniques were used to characterize and predict the separation capability for a superconducting OGMS system.'

  1. Highly collimated monoenergetic target-surface electron acceleration in near-critical-density plasmas

    SciTech Connect (OSTI)

    Mao, J. Y.; Chen, L. M.; Huang, K.; Ma, Y.; Zhao, J. R.; Yan, W. C.; Ma, J. L.; Wei, Z. Y.; Li, D. Z.; Aeschlimann, M.; Zhang, J.

    2015-03-30

    Optimized-quality monoenergetic target surface electron beams at MeV level with low normalized emittance (0.03π mm mrad) and high charge (30 pC) per shot have been obtained from 3 TW laser-solid interactions at a grazing incidence. The 2-Dimension particle-in-cell simulations suggest that electrons are wake-field accelerated in a large-scale, near-critical-density preplasma. It reveals that a bubble-like structure as an accelerating cavity appears in the near-critical-density plasma region and travels along the target surface. A bunch of electrons are pinched transversely and accelerated longitudinally by the wake field in the bubble. The outstanding normalized emittance and monochromaticity of such highly collimated surface electron beams could make it an ideal beam for fast ignition or may serve as an injector in traditional accelerators.

  2. Gradient corrections to the exchange-correlation free energy

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

    Sjostrom, Travis; Daligault, Jerome

    2014-10-07

    We develop the first-order gradient correction to the exchange-correlation free energy of the homogeneous electron gas for use in finite-temperature density functional calculations. Based on this, we propose and implement a simple temperature-dependent extension for functionals beyond the local density approximation. These finite-temperature functionals show improvement over zero-temperature functionals, as compared to path-integral Monte Carlo calculations for deuterium equations of state, and perform without computational cost increase compared to zero-temperature functionals and so should be used for finite-temperature calculations. Furthermore, while the present functionals are valid at all temperatures including zero, non-negligible difference with zero-temperature functionals begins at temperatures abovemore » 10 000 K.« less

  3. The density gradient effect on quantum Weibel instability

    SciTech Connect (OSTI)

    Mahdavi, M. Khodadadi Azadboni, F.

    2015-03-15

    The Weibel instability plays an important role in stopping the hot electrons and energy deposition mechanism in the fast ignition of inertial fusion process. In this paper, the effects of the density gradient and degeneracy on Weibel instability growth rate are investigated. Calculations show that decreasing the density degenerate in the plasma corona, near the relativistic electron beam emitting region by 8.5% leads to a 92% reduction in the degeneracy parameter and about 90% reduction in Weibel instability growth rate. Also, decreasing the degenerate density near the fuel core by 8.5% leads to 1% reduction in the degeneracy parameter and about 8.5% reduction in Weibel instability growth rate. The Weibel instability growth rate shrinks to zero and the deposition condition of relativistic electron beam energy can be shifted to the fuel core for a suitable ignition by increasing the degeneracy parameter in the first layer of plasma corona.

  4. Longitudinal Gradient Dipole Magnet Prototype for APS at ANL

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

    Kashikhin, V. S.; Borland, M.; Chlachidze, G.; Decker, G.; Dejus, R.; DiMarco, J.; Doose, C. L.; Gardner, T. J.; Harding, D. J.; Jaski, M. S.; et al

    2016-01-26

    We planned an upgrade of the Advanced Photon Source at Argonne National Laboratory (ANL). The main goal of the upgrade is to improve the storage ring performance based on more advanced optics. One of the key magnet system elements is bending dipole magnets having a field strength change along the electron beam path. Moreover, a prototype of one such longitudinal gradient dipole magnet has been designed, built, and measured in a collaborative effort of ANL and Fermilab. Our paper discusses various magnetic design options, the selected magnet design, and the fabrication technology. The prototype magnet has been measured by rotationalmore » coils, a stretched wire, and a Hall probe. Measurement results are discussed and compared with simulations.« less

  5. Salinity gradient solar pond technology applied to potash solution mining

    SciTech Connect (OSTI)

    Martell, J.A.; Aimone-Martin, C.T.

    2000-06-12

    A solution mining facility at the Eddy Potash Mine, Eddy County, New Mexico has been proposed that will utilize salinity gradient solar pond (SGSP) technology to supply industrial process thermal energy. The process will include underground dissolution of potassium chloride (KCl) from pillars and other reserves remaining after completion of primary room and pillar mining using recirculating solutions heated in the SGSP. Production of KCl will involve cold crystallization followed by a cooling pond stage, with the spent brine being recirculated in a closed loop back to the SGSP for reheating. This research uses SGSP as a renewable, clean energy source to optimize the entire mining process, minimize environmental wastes, provide a safe, more economical extraction process and reduce the need for conventional processing by crushing, grinding and flotation. The applications of SGSP technology will not only save energy in the extraction and beneficiation processes, but also will produce excess energy available for power generation, desalination, and auxiliary structure heating.

  6. Coherent structures in ion temperature gradient turbulence-zonal flow

    SciTech Connect (OSTI)

    Singh, Rameswar; Singh, R.; Kaw, P.; Grcan, . D.; Diamond, P. H.

    2014-10-15

    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.

  7. Gradient corrections to the exchange-correlation free energy

    SciTech Connect (OSTI)

    Sjostrom, Travis; Daligault, Jerome

    2014-10-07

    We develop the first-order gradient correction to the exchange-correlation free energy of the homogeneous electron gas for use in finite-temperature density functional calculations. Based on this, we propose and implement a simple temperature-dependent extension for functionals beyond the local density approximation. These finite-temperature functionals show improvement over zero-temperature functionals, as compared to path-integral Monte Carlo calculations for deuterium equations of state, and perform without computational cost increase compared to zero-temperature functionals and so should be used for finite-temperature calculations. Furthermore, while the present functionals are valid at all temperatures including zero, non-negligible difference with zero-temperature functionals begins at temperatures above 10 000 K.

  8. Wideband radar cross section reduction using two-dimensional phase gradient metasurfaces

    SciTech Connect (OSTI)

    Li, Yongfeng; Qu, Shaobo; Wang, Jiafu; Chen, Hongya; Zhang, Jieqiu; Xu, Zhuo; Zhang, Anxue

    2014-06-02

    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.

  9. Concentration of isotopic hydrogen by temperature gradient effect in soluble metal

    SciTech Connect (OSTI)

    Uhm, H.S.; Lee, W.W.

    1991-01-01

    This invention relates to the enrichment of isotopic hydrogen in a solid-state metal by use of temperature gradient effects, and is related to the subject matter disclosed in prior copending application Serial No. 07/724,083, filed July 1, 1991. High concentration of isotopic hydrogen in the form of deuterium atoms in a soluble metal such as palladium, is very useful for various electro-chemical studies including nuclear fusion investigations. A conventional technique used for deuterium enrichment purposes involves electrolysis, where a palladium rod is immersed in heavy water as the cathode. According to the prior copending application, aforementioned, deuterium density inside a palladium rod is increased by making use of plasma ion implantation. Patent Applications.

  10. The conjugate gradient NAS parallel benchmark on the IBM SP1

    SciTech Connect (OSTI)

    Trefethen, A.E.; Zhang, T.

    1994-12-31

    The NAS Parallel Benchmarks are a suite of eight benchmark problems developed at the NASA Ames Research Center. They are specified in such a way that the benchmarkers are free to choose the language and method of implementation to suit the system in which they are interested. In this presentation the authors will discuss the Conjugate Gradient benchmark and its implementation on the IBM SP1. The SP1 is a parallel system which is comprised of RS/6000 nodes connected by a high performance switch. They will compare the results of the SP1 implementation with those reported for other machines. At this time, such a comparison shows the SP1 to be very competitive.

  11. A synchrotron study of microstructure gradient in laser additively formed epitaxial Ni-based superalloy

    SciTech Connect (OSTI)

    Xue, Jiawei; Zhang, Anfeng; Li, Yao; Qian, Dan; Wan, Jingchun; Qi, Baolu; Tamura, Nobumichi; Song, Zhongxiao; Chen, Kai

    2015-10-08

    Laser additive forming is considered to be one of the promising techniques to repair single crystal Ni-based superalloy parts to extend their life and reduce the cost. Preservation of the single crystalline nature and prevention of thermal mechanical failure are two of the most essential issues for the application of this technique. Here we employ synchrotron X-ray microdiffraction to evaluate the quality in terms of crystal orientation and defect distribution of a Ni-based superalloy DZ125L directly formed by a laser additive process rooted from a single crystalline substrate of the same material. We show that a disorientation gradient caused by a high density of geometrically necessary dislocations and resultant subgrains exists in the interfacial region between the epitaxial and stray grains. This creates a potential relationship of stray grain formation and defect accumulation. In conclusion, the observation offers new directions on the study of performance control and reliability of the laser additive manufactured superalloys.

  12. Reduction of Solvent Effect in Reverse Phase Gradient Elution LC-ICP-MS

    SciTech Connect (OSTI)

    Patrick Allen Sullivan

    2005-12-17

    %-35% (simulated) and 8%-32% (actual). Quadrupole (low resolution) and sector field (high resolution) ICP-MS instrumentation were utilized in these studies. Once an AIS pair is determined, quantification studies can be performed. First, an analysis is performed by adding both elements of the AIS pair post-column while performing the gradient elution without sample injection. A comparison of the ratio of the measured intensities to the atomic ratio of the two standards is used to determine a correction factor that can be used to account for the matrix effects caused by the mobile phase. Then, organic and/or biological molecules containing one of the two elements in the AIS pair are injected into the LC column. A gradient method is used to vary the methanol-water mixture in the mobile phase and to separate out the compounds in a given sample. A standard solution of the second ion in the AIS pair is added continuously post-column. By comparing the ratio of the measured intensities to the atomic ratio of the eluting compound and internal standard, the concentration of the injected compound can be determined.

  13. Microfluidic device having an immobilized pH gradient and page gels for

    Office of Scientific and Technical Information (OSTI)

    protein separation and analysis (Patent) | SciTech Connect device having an immobilized pH gradient and page gels for protein separation and analysis Citation Details In-Document Search Title: Microfluidic device having an immobilized pH gradient and page gels for protein separation and analysis Disclosed is a novel microfluidic device enabling on-chip implementation of a two-dimensional separation methodology. Previously disclosed microscale immobilized pH gradients (IPG) are combined with

  14. Thermal Gradient Holes At Fish Lake Valley Area (DOE GTP) | Open...

    Open Energy Info (EERE)

    Fish Lake Valley Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Fish Lake Valley Area (DOE GTP)...

  15. Thermal Gradient Holes At Hot Pot Area (DOE GTP) | Open Energy...

    Open Energy Info (EERE)

    Pot Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Hot Pot Area (DOE GTP) Exploration Activity Details...

  16. Thermal Gradient Holes At Fort Bliss Area (DOE GTP) | Open Energy...

    Open Energy Info (EERE)

    Bliss Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Fort Bliss Area (DOE GTP) Exploration Activity...

  17. Thermal Gradient Holes At Alum Area (DOE GTP) | Open Energy Informatio...

    Open Energy Info (EERE)

    Alum Area (DOE GTP) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Alum Area (DOE GTP) Exploration Activity Details...

  18. Constraints on the Cosmic-Ray Density Gradient Beyond the Solar...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Constraints on the Cosmic-Ray Density Gradient Beyond the Solar Circle From Fermi Gamma-Ray Observations of the Third Galactic Quadrant Citation Details...

  19. Thermal Gradient Holes At Twenty-Nine Palms Area (Page, Et Al...

    Open Energy Info (EERE)

    gradient holes for the GPO. Samples taken from each hole were similar in nature; mixtures of sand and conglomerates with the occasional granite sections were...

  20. Effect of RF Gradient upon the Performance of the Wisconsin SRF Electron Gun

    SciTech Connect (OSTI)

    Bosch, Robert; Legg, Robert A.

    2013-12-01

    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. Thermal Gradient Holes At Twenty-Nine Palms Area (Sabin, Et Al...

    Open Energy Info (EERE)

    Sabin, Et Al., 2010) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Twenty-Nine Palms Area (Sabin, Et Al., 2010)...

  2. Approach to Fast Liquid Metal Flow Up a Magnetic Field Gradient | Princeton

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

    Plasma Physics Lab Approach to Fast Liquid Metal Flow Up a Magnetic Field Gradient Electrical and magnetic field (J x B) forces can be used to support flowing liquid metal against gravity. In a tokamak, the radial magnetic field gradient implies that JxB decreases inversely as the major radius, for constant current density in the liquid metal. This field gradient produces a pressure gradient along the support wall, which pushes the liquid metal towards the low field side. The invention

  3. Thermal Gradient Holes At Silver Peak Area (DOE GTP) | Open Energy...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Silver Peak Area (DOE GTP) Exploration Activity Details Location...

  4. Thermal Gradient Holes At Kilauea East Rift Area (Quane, Et Al...

    Open Energy Info (EERE)

    Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Kilauea East Rift Area (Quane, Et Al., 2000) Exploration Activity...

  5. 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...

  6. Modeling of Propagation of Interacting Cracks Under Hydraulic Pressure Gradient

    SciTech Connect (OSTI)

    Huang, Hai; Mattson, Earl Douglas; Podgorney, Robert Karl

    2015-04-01

    A robust and reliable numerical model for fracture initiation and propagation, which includes the interactions among propagating fractures and the coupling between deformation, fracturing and fluid flow in fracture apertures and in the permeable rock matrix, would be an important tool for developing a better understanding of fracturing behaviors of crystalline brittle rocks driven by thermal and (or) hydraulic pressure gradients. In this paper, we present a physics-based hydraulic fracturing simulator based on coupling a quasi-static discrete element model (DEM) for deformation and fracturing with conjugate lattice network flow model for fluid flow in both fractures and porous matrix. Fracturing is represented explicitly by removing broken bonds from the network to represent microcracks. Initiation of new microfractures and growth and coalescence of the microcracks leads to the formation of macroscopic fractures when external and/or internal loads are applied. The coupled DEM-network flow model reproduces realistic growth pattern of hydraulic fractures. In particular, simulation results of perforated horizontal wellbore clearly demonstrate that elastic interactions among multiple propagating fractures, fluid viscosity, strong coupling between fluid pressure fluctuations within fractures and fracturing, and lower length scale heterogeneities, collectively lead to complicated fracturing patterns.

  7. Gradient Flow and Scale Setting on MILC HISQ Ensembles

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

    Bazavov, A.; Bernard, C.; Brown, N.; Komijani, J.; DeTar, C.; Foley, J.; Levkova, L.; Gottlieb, Steven; Heller, U. M.; Laiho, J.; et al

    2016-05-25

    We report on a scale determination with gradient-flow techniques on the Nf = 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 p √t0/a and w0/a and their tree-level improvements,√t0;imp and w0;imp, are computed on each ensemble using Symanzik ow 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 extrapolatedmore » to the continuum and interpolated to physical quark masses. We also determine the scales p t0 = 0:1416(+8-5) fm and w0 = 0:1717(+12-11) fm, where the errors are sums, in quadrature, of statistical and all systematic errors. The precision of w0 and √t0 is comparable to or more precise than the best previous estimates, respectively. We also find the continuum mass-dependence of w0 that will be useful for estimating the scales of other ensembles. Furthermore, we estimate the integrated autocorrelation length of . For long flow times, the autocorrelation length of appears to be comparable to or smaller than that of the topological charge.« less

  8. A constrained conjugate gradient algorithm for computed tomography

    SciTech Connect (OSTI)

    Azevedo, S.G.; Goodman, D.M.

    1994-11-15

    Image reconstruction from projections of x-ray, gamma-ray, protons and other penetrating radiation is a well-known problem in a variety of fields, and is commonly referred to as computed tomography (CT). Various analytical and series expansion methods of reconstruction and been used in the past to provide three-dimensional (3D) views of some interior quantity. The difficulties of these approaches lie in the cases where (a) the number of views attainable is limited, (b) the Poisson (or other) uncertainties are significant, (c) quantifiable knowledge of the object is available, but not implementable, or (d) other limitations of the data exist. We have adapted a novel nonlinear optimization procedure developed at LLNL to address limited-data image reconstruction problems. The technique, known as nonlinear least squares with general constraints or constrained conjugate gradients (CCG), has been successfully applied to a number of signal and image processing problems, and is now of great interest to the image reconstruction community. Previous applications of this algorithm to deconvolution problems and x-ray diffraction images for crystallography have shown the great promise.

  9. GRADIENT INDEX SPHERES BY THE SEQUENTIAL ACCRETION OF GLASS POWDERS

    SciTech Connect (OSTI)

    MARIANO VELEZ

    2008-06-15

    The Department of Energy is seeking a method for fabricating mm-scale spheres having a refractive index that varies smoothly and continuously from the center to its surface [1]. The fabrication procedure must allow the creation of a range of index profiles. The spheres are to be optically transparent and have a refractive index differential greater than 0.2. The sphere materials can be either organic or inorganic and the fabrication technique must be capable of scaling to low cost production. Mo-Sci Corporation proposed to develop optical quality gradient refractive index (GRIN) glass spheres of millimeter scale (1 to 2 mm diameter) by the sequential accretion and consolidation of glass powders. Other techniques were also tested to make GRIN spheres as the powder-accretion method produced non-concentric layers and poor optical quality glass spheres. Potential ways to make the GRIN spheres were (1) by "coating" glass spheres (1 to 2 mm diameter) with molten glass in a two step process; and (2) by coating glass spheres with polymer layers.

  10. 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.

    1988-01-01

    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.

  11. Accurate gradient approximation for complex interface problems in 3D by an improved coupling interface method

    SciTech Connect (OSTI)

    Shu, Yu-Chen, E-mail: ycshu@mail.ncku.edu.tw [Department of Mathematics, National Cheng Kung University, Tainan 701, Taiwan (China); Mathematics Division, National Center for Theoretical Sciences (South), Tainan 701, Taiwan (China); Chern, I-Liang, E-mail: chern@math.ntu.edu.tw [Department of Applied Mathematics, National Chiao Tung University, Hsin Chu 300, Taiwan (China); Department of Mathematics, National Taiwan University, Taipei 106, Taiwan (China); Mathematics Division, National Center for Theoretical Sciences (Taipei Office), Taipei 106, Taiwan (China); Chang, Chien C., E-mail: mechang@iam.ntu.edu.tw [Institute of Applied Mechanics, National Taiwan University, Taipei 106, Taiwan (China); Department of Mathematics, National Taiwan University, Taipei 106, Taiwan (China)

    2014-10-15

    Most elliptic interface solvers become complicated for complex interface problems at those exceptional points where there are not enough neighboring interior points for high order interpolation. Such complication increases especially in three dimensions. Usually, the solvers are thus reduced to low order accuracy. In this paper, we classify these exceptional points and propose two recipes to maintain order of accuracy there, aiming at improving the previous coupling interface method [26]. Yet the idea is also applicable to other interface solvers. The main idea is to have at least first order approximations for second order derivatives at those exceptional points. Recipe 1 is to use the finite difference approximation for the second order derivatives at a nearby interior grid point, whenever this is possible. Recipe 2 is to flip domain signatures and introduce a ghost state so that a second-order method can be applied. This ghost state is a smooth extension of the solution at the exceptional point from the other side of the interface. The original state is recovered by a post-processing using nearby states and jump conditions. The choice of recipes is determined by a classification scheme of the exceptional points. The method renders the solution and its gradient uniformly second-order accurate in the entire computed domain. Numerical examples are provided to illustrate the second order accuracy of the presently proposed method in approximating the gradients of the original states for some complex interfaces which we had tested previous in two and three dimensions, and a real molecule ( (1D63)) which is double-helix shape and composed of hundreds of atoms.

  12. Growth of large aluminum nitride single crystals with thermal-gradient control

    DOE Patents [OSTI]

    Bondokov, Robert T; Rao, Shailaja P; Gibb, Shawn Robert; Schowalter, Leo J

    2015-05-12

    In various embodiments, non-zero thermal gradients are formed within a growth chamber both substantially parallel and substantially perpendicular to the growth direction during formation of semiconductor crystals, where the ratio of the two thermal gradients (parallel to perpendicular) is less than 10, by, e.g., arrangement of thermal shields outside of the growth chamber.

  13. Testing thermal gradient driving force for grain boundary migration using molecular dynamics simulations

    SciTech Connect (OSTI)

    Bai, Xian-Ming; Zhang, Yongfeng; Tonks, Michael R.

    2015-02-01

    Strong thermal gradients in low-thermal-conductivity ceramics may drive extended defects, such as grain boundaries and voids, to migrate in preferential directions. In this work, molecular dynamics simulations are conducted to study thermal gradient driven grain boundary migration and to verify a previously proposed thermal gradient driving force equation, using uranium dioxide as a model system. It is found that a thermal gradient drives grain boundaries to migrate up the gradient and the migration velocity increases under a constant gradient owing to the increase in mobility with temperature. Different grain boundaries migrate at very different rates due to their different intrinsic mobilities. The extracted mobilities from the thermal gradient driven simulations are compared with those calculated from two other well-established methods and good agreement between the three different methods is found, demonstrating that the theoretical equation of the thermal gradient driving force is valid, although a correction of one input parameter should be made. The discrepancy in the grain boundary mobilities between modeling and experiments is also discussed.

  14. A novel permanently magnetised high gradient magnetic filter using assisted capture for fine particles

    SciTech Connect (OSTI)

    Watson, J.H.P.

    1995-02-01

    This paper describes the structure and properties of a novel permanently magnetised magnetic filter for fine friable radioactive material. Previously a filter was described and tested. This filter was designed so that the holes in the filter are left open as capture proceeds which means the pressure drop builds up only slowly. This filter is not suitable for friable composite particles which can be broken by mechanical forces. The structure of magnetic part of the second filter has been changed so as to strongly capture particles composed of fine particles weakly bound together which tend to break when captured. This uses a principle of assisted-capture in which coarse particles aid the capture of the fine fragments. The technique has the unfortunate consequence that the pressure drop across the filter rises faster as capture capture proceeds than the filter described previously. These filters have the following characteristics: (1) No external magnet is required. (2) No external power is required. (3) Small is size and portable. (4) Easily interchangeable. (5) Can be cleaned without demagnetising.

  15. EERE Success Story-Illinois: High-Energy, Concentration-Gradient...

    Energy Savers [EERE]

    These characteristics will allow manufacturers to build smaller battery packs and reduce ... The 2011 Chevrolet Volt at a charging station. Its battery is based on a cathode ...

  16. Latest Results of ILC High-Gradient R&D 9-cell Cavities at JLAB...

    Office of Scientific and Technical Information (OSTI)

    Resource Type: Conference Resource Relation: Conference: 13th Workshop on RF Superconductivity, Beijing, China, Oct. 14 - 19, 2007 Research Org: Thomas Jefferson National ...

  17. Spatially addressable design of gradient index structures through spatial light modulator based holographic lithography

    SciTech Connect (OSTI)

    Ohlinger, Kris; Lutkenhaus, Jeff [Department of Physics, University of North Texas, Denton, Texas 76203 (United States); Arigong, Bayaner; Zhang, Hualiang [Department of Electrical Engineering, University of North Texas, Denton, Texas 76203 (United States); Lin, Yuankun, E-mail: yuankun.lin@unt.edu [Department of Physics, University of North Texas, Denton, Texas 76203 (United States); Department of Electrical Engineering, University of North Texas, Denton, Texas 76203 (United States)

    2013-12-07

    In this paper, we present an achievable gradient refractive index in bi-continuous holographic structures that are formed through five-beam interference. We further present a theoretic approach for the realization of gradient index devices by engineering the phases of the interfering beams with a pixelated spatial light modulator. As an example, the design concept of a gradient index Luneburg lens is verified through full-wave electromagnetic simulations. These five beams with desired phases can be generated through programming gray level super-cells in a diffractive spatial light modulator. As a proof-of-concept, gradient index structures are demonstrated using synthesized and gradient phase patterns displayed in the spatial light modulator.

  18. Gradient Flow and Scale Setting on MILC HISQ Ensembles

    SciTech Connect (OSTI)

    Bazavov, A.; Bernard, C.; Brown, N.; Komijani, J.; DeTar, C.; Foley, J.; Levkova, L.; Gottlieb, Steven; Heller, U. M.; Laiho, J.; Sugar, R. L.; Toussaint, D.; Van de Water, R. S.

    2015-03-25

    We report on a scale determination with gradient-ow techniques on the Nf = 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 p √t0/a and w0/a and their tree-level improvements,√t0;imp and w0;imp, are computed on each ensemble using Symanzik ow and the cloverleaf de_nition 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 also determine the scales p t0 = 0:1416(+8-5) fm and w0 = 0:1717(+12-11) fm, where the errors are sums, in quadrature, of statistical and all systematic errors. The precision of w0 and √t0 is comparable to or more precise than the best previous estimates, respectively. We also find the continuum mass-dependence of w0 that will be useful for estimating the scales of other ensembles. Furthermore, we estimate the integrated autocorrelation length of . For long ow times, the autocorrelation length of appears to be comparable to or smaller than that of the topological charge.

  19. Gradient Theory simulations of pure fluid interfaces using a generalized expression for influence parameters and a Helmholtz energy equation of state for fundamentally consistent two-phase calculations

    SciTech Connect (OSTI)

    Dahms, Rainer N.

    2014-12-31

    The fidelity of Gradient Theory simulations depends on the accuracy of saturation properties and influence parameters, and require equations of state (EoS) which exhibit a fundamentally consistent behavior in the two-phase regime. Widely applied multi-parameter EoS, however, are generally invalid inside this region. Hence, they may not be fully suitable for application in concert with Gradient Theory despite their ability to accurately predict saturation properties. The commonly assumed temperature-dependence of pure component influence parameters usually restricts their validity to subcritical temperature regimes. This may distort predictions for general multi-component interfaces where temperatures often exceed the critical temperature of vapor phase components. Then, the calculation of influence parameters is not well defined. In this paper, one of the first studies is presented in which Gradient Theory is combined with a next-generation Helmholtz energy EoS which facilitates fundamentally consistent calculations over the entire two-phase regime. Illustrated on pentafluoroethane as an example, reference simulations using this method are performed. They demonstrate the significance of such high-accuracy and fundamentally consistent calculations for the computation of interfacial properties. These reference simulations are compared to corresponding results from cubic PR EoS, widely-applied in combination with Gradient Theory, and mBWR EoS. The analysis reveals that neither of those two methods succeeds to consistently capture the qualitative distribution of obtained key thermodynamic properties in Gradient Theory. Furthermore, a generalized expression of the pure component influence parameter is presented. This development is informed by its fundamental definition based on the direct correlation function of the homogeneous fluid and by presented high-fidelity simulations of interfacial density profiles. As a result, the new model preserves the accuracy of previous

  20. Gradient Theory simulations of pure fluid interfaces using a generalized expression for influence parameters and a Helmholtz energy equation of state for fundamentally consistent two-phase calculations

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

    Dahms, Rainer N.

    2014-12-31

    The fidelity of Gradient Theory simulations depends on the accuracy of saturation properties and influence parameters, and require equations of state (EoS) which exhibit a fundamentally consistent behavior in the two-phase regime. Widely applied multi-parameter EoS, however, are generally invalid inside this region. Hence, they may not be fully suitable for application in concert with Gradient Theory despite their ability to accurately predict saturation properties. The commonly assumed temperature-dependence of pure component influence parameters usually restricts their validity to subcritical temperature regimes. This may distort predictions for general multi-component interfaces where temperatures often exceed the critical temperature of vapor phasemore » components. Then, the calculation of influence parameters is not well defined. In this paper, one of the first studies is presented in which Gradient Theory is combined with a next-generation Helmholtz energy EoS which facilitates fundamentally consistent calculations over the entire two-phase regime. Illustrated on pentafluoroethane as an example, reference simulations using this method are performed. They demonstrate the significance of such high-accuracy and fundamentally consistent calculations for the computation of interfacial properties. These reference simulations are compared to corresponding results from cubic PR EoS, widely-applied in combination with Gradient Theory, and mBWR EoS. The analysis reveals that neither of those two methods succeeds to consistently capture the qualitative distribution of obtained key thermodynamic properties in Gradient Theory. Furthermore, a generalized expression of the pure component influence parameter is presented. This development is informed by its fundamental definition based on the direct correlation function of the homogeneous fluid and by presented high-fidelity simulations of interfacial density profiles. As a result, the new model preserves the accuracy of

  1. 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....

  2. Beam plasma electromagnetic instabilities in a smooth density gradient: Application to the fast ignition scenario

    SciTech Connect (OSTI)

    Bret, A.; Deutsch, C.

    2005-10-01

    The integrated growth rate of various relativistic beam/plasma instabilities in a weakly varying plasma density gradient is calculated using a WKB-like approximation. It is proven that such an assumption can be made in fast ignition scenario conditions. The formalism is applied to the two-stream, the filamentation, and the two-stream/filamentation instabilities, the latter instability being a mixture of the former two, and is the fastest growing one. The results are restricted to collisionless plasmas and nonrelativistic beam and plasma temperatures. Filamentation instability is reduced by the density gradient and eventually does not develop in the core, whereas two-stream and two-stream/filamentation instabilities should saturate even before they feel the gradient. Various effects connected to the density gradient are discussed. It is found they should be negligible as long as these later instabilities remain in their respective linear regime.

  3. Microfluidic device having an immobilized pH gradient and page...

    Office of Scientific and Technical Information (OSTI)

    and page gels for protein separation and analysis Title: Microfluidic device having an immobilized pH gradient and page gels for protein separation and analysis Disclosed is a ...

  4. Comparison between kinetic-ballooning-mode-driven turbulence and ion-temperature-gradient-driven turbulence

    SciTech Connect (OSTI)

    Maeyama, S. Nakata, M.; Miyato, N.; Yagi, M.; Ishizawa, A.; Watanabe, T.-H.; Idomura, Y.

    2014-05-15

    Electromagnetic turbulence driven by kinetic ballooning modes (KBMs) in high-? plasma is investigated based on the local gyrokinetic model. Analysis of turbulent fluxes, norms, and phases of fluctuations shows that KBM turbulence gives narrower spectra and smaller phase factors than those in ion-temperature-gradient (ITG)-driven turbulence. This leads to the smaller transport fluxes in KBM turbulence than those in ITG turbulence even when they have similar linear growth rates. From the analysis of the entropy balance relation, it is found that the entropy transfer from ions to electrons through the field-particle interactions mainly drives electron perturbations, which creates radial twisted modes by rapid parallel motions of electrons in a sheared magnetic geometry. The nonlinear coupling between the dominant unstable mode and its twisted modes is important for the saturation of KBM turbulence, in contrast to the importance of zonal flow shearing in ITG turbulence. The coupling depends on the flux-tube domain with the one-poloidal-turn parallel length and on the torus periodicity constraint.

  5. A synchrotron study of microstructure gradient in laser additively formed epitaxial Ni-based superalloy

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

    Xue, Jiawei; Zhang, Anfeng; Li, Yao; Qian, Dan; Wan, Jingchun; Qi, Baolu; Tamura, Nobumichi; Song, Zhongxiao; Chen, Kai

    2015-10-08

    Laser additive forming is considered to be one of the promising techniques to repair single crystal Ni-based superalloy parts to extend their life and reduce the cost. Preservation of the single crystalline nature and prevention of thermal mechanical failure are two of the most essential issues for the application of this technique. Here we employ synchrotron X-ray microdiffraction to evaluate the quality in terms of crystal orientation and defect distribution of a Ni-based superalloy DZ125L directly formed by a laser additive process rooted from a single crystalline substrate of the same material. We show that a disorientation gradient caused bymore » a high density of geometrically necessary dislocations and resultant subgrains exists in the interfacial region between the epitaxial and stray grains. This creates a potential relationship of stray grain formation and defect accumulation. In conclusion, the observation offers new directions on the study of performance control and reliability of the laser additive manufactured superalloys.« less

  6. Experiment and analysis of practical-scale solar pond stabilized with salt gradient

    SciTech Connect (OSTI)

    Kanayama, Kimio; Inaba, Hideo; Baba, Hiromu; Fukuda, Takeyuki )

    1991-01-01

    A large-scale solar pond with salty water was constructed in the suburbs of Kitami in 1985. Its performance has been measured and analyzed by the authors after that. The solar pond body is circular of 44 m diameter, and the pond water is of 3 min total depth. After, 15 months, the depth of the salt gradient zone (S.G.Z.) was thinned by 10 cm in the top and by 20 cm in the bottom due to convection of the top and bottom zones. The temperature in the convective storage zone (C.S.Z.) reached 70C, its maximum, at the beginning of September in 1985, however, it was not as high in 1986 due to contamination of the pond water. The temperature of the storage zone was reduced from November to April due to ice covering on the pond surface. The collected heat yielded largely and the collection efficiency reached more than 30% in summer, but decreased to negative values in winter. The thermal performance of the solar pond was predicted by a simulation calculation, and the calculated result compared well with the measurements.

  7. Magneto-Seebeck effect in spin-valve with in-plane thermal gradient

    SciTech Connect (OSTI)

    Jain, S. Bose, A. Palkar, V. R. Tulapurkar, A. A.; Lam, D. D. Suzuki, Y.; Sharma, H. Tomy, C. V.

    2014-12-15

    We present measurements of magneto-Seebeck effect on a spin valve with in-plane thermal gradient. We measured open circuit voltage and short circuit current by applying a temperature gradient across a spin valve stack, where one of the ferromagnetic layers is pinned. We found a clear hysteresis in these two quantities as a function of magnetic field. From these measurements, the magneto-Seebeck effect was found to be same as magneto-resistance effect.

  8. 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

    2008-04-30

    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.

  9. Simultaneous measurement of gravity acceleration and gravity gradient with an atom interferometer

    SciTech Connect (OSTI)

    Sorrentino, F.; Lien, Y.-H.; Rosi, G.; Tino, G. M.; Bertoldi, A.; Bodart, Q.; Cacciapuoti, L.; Angelis, M. de; Prevedelli, M.

    2012-09-10

    We demonstrate a method to measure the gravitational acceleration with a dual cloud atom interferometer; the use of simultaneous atom interferometers reduces the effect of seismic noise on the gravity measurement. At the same time, the apparatus is capable of accurate measurements of the vertical gravity gradient. The ability to determine the gravity acceleration and gravity gradient simultaneously and with the same instrument opens interesting perspectives in geophysical applications.

  10. Applications of salinity gradient solar technologies in the Southwest -- An overview

    SciTech Connect (OSTI)

    Swift, A.H.P.; Lu, H.

    1996-12-31

    This paper is an overview of recent applications of salinity gradient solar technologies (SGST) in the Southwest and especially in the State of Texas. SGST is a generic title for using a salinity gradient in a body of water to suppress convection and collect solar energy for a desired application, for example, salinity gradient solar ponds. Following initial work in the early 1980s at the El Paso Solar Pond project and funding of the Texas Solar Pond Consortium by the State of Texas and the Bureau of Reclamation, several applications involving the use of salinity gradient solar technologies have emerged. These applications include a biomass waste to energy project using heat from a solar pond at Bruce Foods Corporation; an industrial process heat application for sodium sulfate mining near Seagraves, Texas; overwintering thermal refuges for mariculture in Palacios, Texas; a potential salt management project on the Brazos River near Abilene, Texas; and use of solar ponds for brine disposal at a water desalting project in a small colonia east of El Paso. This paper discusses salinity gradient solar technology requirements and the abundance of resources available in Texas and the Southwest which makes this an attractive location for the commercial development of salinity gradient projects. Barriers to development as well as catalysts are discussed before a brief overview of the projects listed above is provided.

  11. Novel concepts in weld metal science: Role of gradients and composite structure

    SciTech Connect (OSTI)

    Matlock, D.K.; Olson, D.L.

    1991-12-01

    The effects of compositional and microstructural gradients on weld metal properties are being investigated. Crack propagation is solidified alloy structures is being characterized as to solidification orientation and the profile of the compositional variations. The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a compositional gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Special techniques to produce laboratory samples with microstructures which simulate the composition and microstructure gradients in solidified weld metal are used, along with appropriate mathematical models, to evaluate the properties of the composite weld metals. The composite modeling techniques are being applied to describe the effects of compositional and microstructural gradients on weld metal properties in Ni-Cu alloys. The development of metal matrix composition weld deposits on austenitic stainless steels has been studied. The particulate metal matrix composites were produced with ceramic or refractory metal powder filled cored wire, which was gas tungsten arc and gas metal arc welded.

  12. Exclusion of cosmic rays in protoplanetary disks. II. Chemical gradients and observational signatures

    SciTech Connect (OSTI)

    Cleeves, L. Ilsedore; Bergin, Edwin A.; Adams, Fred C.

    2014-10-20

    The chemical properties of protoplanetary disks are especially sensitive to their ionization environment. Sources of molecular gas ionization include cosmic rays (CRs), stellar X-rays, and short-lived radionuclides, each of which varies with location in the disk. This behavior leads to a significant amount of chemical structure, especially in molecular ion abundances, which is imprinted in their submillimeter rotational line emission. Using an observationally motivated disk model, we make predictions for the dependence of chemical abundances on the assumed properties of the ionizing field. We calculate the emergent line intensity for abundant molecular ions and simulate sensitive observations with the Atacama Large Millimeter/Sub-millimeter Array (ALMA) for a disk at D = 100 pc. The models readily distinguish between high ionization rates (ζ ≳ 10{sup –17} s{sup –1} per H{sub 2}) and below, but it becomes difficult to distinguish between low ionization models when ζ ≲ 10{sup –19} s{sup –1}. We find that H{sub 2}D{sup +} emission is not detectable for sub-interstellar CR rates with ALMA (6h integration), and that N{sub 2}D{sup +} emission may be a more sensitive tracer of midplane ionization. HCO{sup +} traces X-rays and high CR rates (ζ{sub CR} ≳ 10{sup –17} s{sup –1}), and provides a handle on the warm molecular ionization properties where CO is present in the gas. Furthermore, species like HCO{sup +}, which emits from a wide radial region and samples a large gradient in temperature, can exhibit ring-like emission as a consequence of low-lying rotational level de-excitation near the star. This finding highlights a scenario where rings are not necessarily structural or chemical in nature, but simply a result of the underlying line excitation properties.

  13. 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

    2014-10-14

    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.

  14. Analytical theory of coherent synchrotron radiation wakefield...

    Office of Scientific and Technical Information (OSTI)

    Authors: Stupakov, Gennady ; SLAC ; Zhou, Demin ; KEK, Tsukuba Publication Date: 2016-01-22 OSTI Identifier: 1236428 Report Number(s): SLAC-PUB-16459 arXiv:1601.04008 DOE ...

  15. Controllable high-quality electron beam generation by phase slippage effect in layered targets

    SciTech Connect (OSTI)

    Yu, Q.; Li, X. F.; Huang, S.; Zhang, F.; Kong, Q.; Gu, Y. J.; Ma, Y. Y.; Kawata, S.

    2014-11-15

    The bubble structure generated by laser-plasma interactions changes in size depending on the local plasma density. The self-injection electrons' position with respect to wakefield can be controlled by tailoring the longitudinal plasma density. A regime to enhance the energy of the wakefield accelerated electrons and to improve the beam quality is proposed and achieved using layered plasmas with increasing densities. Both the wakefield size and the electron bunch duration are significantly contracted in this regime. The electrons remain in the strong acceleration phase of the wakefield, while their energy spread decreases because of their tight spatial distribution. An electron beam of 0.5?GeV with less than 1% energy spread is obtained through 2.5D particle-in-cell simulations.

  16. Density gradient free electron collisionally excited x-ray laser

    DOE Patents [OSTI]

    Campbell, E.M.; Rosen, M.D.

    1984-11-29

    An operational x-ray laser is provided that amplifies 3p-3s transition x-ray radiation along an approximately linear path. The x-ray laser is driven by a high power optical laser. The driving line focused optical laser beam illuminates a free-standing thin foil that may be associated with a substrate for improved structural integrity. This illumination produces a generally cylindrically shaped plasma having an essentially uniform electron density and temperature, that exists over a long period of time, and provides the x-ray laser gain medium. The x-ray laser may be driven by more than one optical laser beam. The x-ray laser has been successfully demonstrated to function in a series of experimental tests.

  17. Density gradient free electron collisionally excited X-ray laser

    DOE Patents [OSTI]

    Campbell, Edward M.; Rosen, Mordecai D.

    1989-01-01

    An operational X-ray laser (30) is provided that amplifies 3p-3s transition X-ray radiation along an approximately linear path. The X-ray laser (30) is driven by a high power optical laser. The driving line focused optical laser beam (32) illuminates a free-standing thin foil (34) that may be associated with a substrate (36) for improved structural integrity. This illumination produces a generally cylindrically shaped plasma having an essentially uniform electron density and temperature, that exists over a long period of time, and provides the X-ray laser gain medium. The X-ray laser (30) may be driven by more than one optical laser beam (32, 44). The X-ray laser (30) has been successfully demonstrated to function in a series of experimental tests.

  18. Optimization of viral resuspension methods for carbon-rich soils along a permafrost thaw gradient

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

    Trubl, Gareth; Solonenko, Natalie; Chittick, Lauren; Solonenko, Sergei A.; Rich, Virginia I.; Sullivan, Matthew B.

    2016-05-17

    Permafrost stores approximately 50% of global soil carbon (C) in a frozen form; it is thawing rapidly under climate change, and little is known about viral communities in these soils or their roles in C cycling. In permafrost soils, microorganisms contribute significantly to C cycling, and characterizing them has recently been shown to improve prediction of ecosystem function. In other ecosystems, viruses have broad ecosystem and community impacts ranging from host cell mortality and organic matter cycling to horizontal gene transfer and reprogramming of core microbial metabolisms. Here we developed an optimized protocol to extract viruses from three types ofmore » high organic-matter peatland soils across a permafrost thaw gradient (palsa, moss-dominated bog, and sedge-dominated fen). Three separate experiments were used to evaluate the impact of chemical buffers, physical dispersion, storage conditions, and concentration and purification methods on viral yields. The most successful protocol, amended potassium citrate buffer with bead-beating or vortexing and BSA, yielded on average as much as 2-fold more virus-like particles (VLPs) g–1of soil than other methods tested. All method combinations yielded VLPs g–1of soil on the 108order of magnitude across all three soil types. The different storage and concentration methods did not yield significantly more VLPs g–1of soil among the soil types. In conclusion, this research provides much-needed guidelines for resuspending viruses from soils, specifically carbon-rich soils, paving the way for incorporating viruses into soil ecology studies.« less

  19. Flux- and gradient-driven global gyrokinetic simulation of tokamak turbulence

    SciTech Connect (OSTI)

    Goerler, Tobias; Jenko, Frank; Marcus, Patrick; Merz, Florian; Told, Daniel; Lapillonne, Xavier; Brunner, Stephan; Aghdam, Sohrab Khosh; McMillan, Ben F.; Sauter, Olivier; Villard, Laurent; Dannert, Tilman

    2011-05-15

    The Eulerian gyrokinetic turbulence code gene has recently been extended to a full torus code. Moreover, it now provides Krook-type sources for gradient-driven simulations where the profiles are maintained on average as well as localized heat sources for a flux-driven type of operation. Careful verification studies and benchmarks are performed successfully. This setup is applied to address three related transport issues concerning nonlocal effects. First, it is confirmed that in gradient-driven simulations, the local limit can be reproduced--provided that finite aspect ratio effects in the geometry are treated carefully. In this context, it also becomes clear that the profile widths (not the device width) may constitute a more appropriate measure for finite-size effects. Second, the nature and role of heat flux avalanches are discussed in the framework of both local and global, flux- and gradient-driven simulations. Third, simulations dedicated to discharges with electron internal barriers are addressed.

  20. Core density gradient fluctuation measurement by differential interferometry in the helically symmetric experiment stellarator

    SciTech Connect (OSTI)

    Deng, C. B.; Brower, D. L.

    2012-10-15

    The interferometer system on the Helically Symmetric eXperiment (HSX) stellarator uses an expanded beam and linear detector array to realize a multichord measurement. Unlike conventional interferometry which determines the plasma phase shift with respect to a reference, directly evaluating the phase between two adjacent chords can be employed to measure the change in plasma phase with impact parameter. This approach provides a measure of the equilibrium density gradient or the density gradient fluctuations and is referred to as differential interferometry. For central chords, measurements are spatially localized due to a geometrical weighting factor and can provide information on core density gradient fluctuations. The measurement requires finite coherence between fluctuations in the two spatially offset chords. This technique is applied on the HSX stellarator to measure both broadband turbulence and coherent modes. Spatial localization is exploited to isolate core turbulence changes associated with change in magnetic configuration or heating location.

  1. A transient FGM interlayer based approach to joining ceramics. [Functionally gradient materials

    SciTech Connect (OSTI)

    Glaeser, A.M.; Shalz, M.L.; Dalgleish, B.J.; Tomsia, A.P.

    1993-01-01

    In most cases, functionally gradient materials have been designed to produce a desirable property gradient in a material or in a joint region. In this paper, the concept of a transient gradient structure is introduced. The function of the intentional property discontinuities in these multilayer interlayers is to facilitate processing of assemblies and materials combinations that would be difficult to process using conventional bonding approaches. Specifically, the methods make use of a thin or partial layer of a low melting point transient liquid phase to facilitate bonding via brazing, yet produce refractory joints. Several mechanisms for consuming the transient liquid former are outlined, and examples of interlayer designs that exploit these mechanisms are presented. Specific results from experiments joining alumina to alumina via Cu/Pt/Cu, Cu/Ni/Cu, Cu/Nb/Cu and Sn/Nb/Sn interlayers are presented.

  2. A single-gradient junction technique to replace multiple-junction shifts for craniospinal irradiation treatment

    SciTech Connect (OSTI)

    Hadley, Austin; Ding, George X.

    2014-01-01

    Craniospinal irradiation (CSI) requires abutting fields at the cervical spine. Junction shifts are conventionally used to prevent setup errorinduced overdosage/underdosage from occurring at the same location. This study compared the dosimetric differences at the cranial-spinal junction between a single-gradient junction technique and conventional multiple-junction shifts and evaluated the effect of setup errors on the dose distributions between both techniques for a treatment course and single fraction. Conventionally, 2 lateral brain fields and a posterior spine field(s) are used for CSI with weekly 1-cm junction shifts. We retrospectively replanned 4 CSI patients using a single-gradient junction between the lateral brain fields and the posterior spine field. The fields were extended to allow a minimum 3-cm field overlap. The dose gradient at the junction was achieved using dose painting and intensity-modulated radiation therapy planning. The effect of positioning setup errors on the dose distributions for both techniques was simulated by applying shifts of 3 and 5 mm. The resulting cervical spine doses across the field junction for both techniques were calculated and compared. Dose profiles were obtained for both a single fraction and entire treatment course to include the effects of the conventional weekly junction shifts. Compared with the conventional technique, the gradient-dose technique resulted in higher dose uniformity and conformity to the target volumes, lower organ at risk (OAR) mean and maximum doses, and diminished hot spots from systematic positioning errors over the course of treatment. Single-fraction hot and cold spots were improved for the gradient-dose technique. The single-gradient junction technique provides improved conformity, dose uniformity, diminished hot spots, lower OAR mean and maximum dose, and one plan for the entire treatment course, which reduces the potential human error associated with conventional 4-shifted plans.

  3. Method and apparatus for producing a carbon based foam article having a desired thermal-conductivity gradient

    DOE Patents [OSTI]

    Klett, James W. [Knoxville, TN; Cameron, Christopher Stan [Sanford, NC

    2010-03-02

    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.

  4. Coexistence of colossal stress and texture gradients in sputter deposited nanocrystalline ultra-thin metal films

    SciTech Connect (OSTI)

    Kuru, Yener; Welzel, Udo; Mittemeijer, Eric J.

    2014-12-01

    This paper demonstrates experimentally that ultra-thin, nanocrystalline films can exhibit coexisting colossal stress and texture depth gradients. Their quantitative determination is possible by X-ray diffraction experiments. Whereas a uniform texture by itself is known to generally cause curvature in so-called sin{sup 2}? plots, it is shown that the combined action of texture and stress gradients provides a separate source of curvature in sin{sup 2}? plots (i.e., even in cases where a uniform texture does not induce such curvature). On this basis, the texture and stress depth profiles of a nanocrystalline, ultra-thin (50?nm) tungsten film could be determined.

  5. Plasma size and power scaling of ion temperature gradient driven turbulence

    SciTech Connect (OSTI)

    Idomura, Yasuhiro; Nakata, Motoki

    2014-02-15

    The transport scaling with respect to plasma size and heating power is studied for ion temperature gradient driven turbulence using a fixed-flux full-f gyrokinetic Eulerian code. It is found that when heating power is scaled with plasma size, the ion heat diffusivity increases with plasma size in a local limit regime, where fixed-gradient ?f simulations predict a gyro-Bohm scaling. In the local limit regime, the transport scaling is strongly affected by the stiffness of ion temperature profiles, which is related to the power degradation of confinement.

  6. Direct Simulation of a Zero-pressure-gradient Turbulent Boundary Layer up

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

    to Reθ = 6650 | Argonne Leadership Computing Facility a Zero-pressure-gradient Turbulent Boundary Layer up to Reθ = 6650 Authors: Sillero, J., Jiménez, J., Moser, R.D., Malaya, N.P A direct simulation of an incompressible zero-pressure-gradient turbulent boundary layer over a flat plate is performed in Reθ = 1100-6650 (Reτ ≈ 2025), matching the range of the available numerical channels. The logarithmic region and the separation of scales are clearly observed. Proper turbulent inflow

  7. Effect of trapped electrons on soliton propagation in a plasma having a density gradient

    SciTech Connect (OSTI)

    Aziz, Farah; Stroth, Ulrich

    2009-03-15

    A Korteweg-deVries equation with an additional term due to the density gradient is obtained using reductive perturbation technique in an unmagnetized plasma having a density gradient, finite temperature ions, and two-temperature nonisothermal (trapped) electrons. This equation is solved to get the solitary wave solution using sine-cosine method. The phase velocity, soliton amplitude, and width are examined under the effect of electron and ion temperatures and their concentrations. The effect of ion (electron) temperature is found to be more significant in the presence of larger (smaller) number of trapped electrons in the plasma.

  8. Pore and grain boundary migration under a temperature gradient: A phase-field model study

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

    Biner, S. B.

    2016-03-16

    In this study, the collective migration behavior of pores and grain boundaries under a temperature gradient is studied for simple single crystal, bi-crystal and polycrystal configurations with a phase-field model formulism. For simulation of the microstructure of solids, composed of pores and grain boundaries, the results indicate that not only the volume fraction of pores, but also its spatial partitioning between the grain boundary junctions and the grain boundary segments appears to be important. In addition to various physical properties, the evolution kinetics, under given temperature gradients, will be strongly influenced with the initial morphology of a poly-crystalline microstructure.

  9. Non-preconditioned conjugate gradient on cell and FPCA-based hybrid supercomputer nodes

    SciTech Connect (OSTI)

    Dubois, David H; Dubois, Andrew J; Boorman, Thomas M; Connor, Carolyn M

    2009-03-10

    This work presents a detailed implementation of a double precision, Non-Preconditioned, Conjugate Gradient algorithm on a Roadrunner heterogeneous supercomputer node. These nodes utilize the Cell Broadband Engine Architecture{trademark} in conjunction with x86 Opteron{trademark} processors from AMD. We implement a common Conjugate Gradient algorithm, on a variety of systems, to compare and contrast performance. Implementation results are presented for the Roadrunner hybrid supercomputer, SRC Computers, Inc. MAPStation SRC-6 FPGA enhanced hybrid supercomputer, and AMD Opteron only. In all hybrid implementations wall clock time is measured, including all transfer overhead and compute timings.

  10. Non-preconditioned conjugate gradient on cell and FPGA based hybrid supercomputer nodes

    SciTech Connect (OSTI)

    Dubois, David H; Dubois, Andrew J; Boorman, Thomas M; Connor, Carolyn M

    2009-01-01

    This work presents a detailed implementation of a double precision, non-preconditioned, Conjugate Gradient algorithm on a Roadrunner heterogeneous supercomputer node. These nodes utilize the Cell Broadband Engine Architecture{sup TM} in conjunction with x86 Opteron{sup TM} processors from AMD. We implement a common Conjugate Gradient algorithm, on a variety of systems, to compare and contrast performance. Implementation results are presented for the Roadrunner hybrid supercomputer, SRC Computers, Inc. MAPStation SRC-6 FPGA enhanced hybrid supercomputer, and AMD Opteron only. In all hybrid implementations wall clock time is measured, including all transfer overhead and compute timings.

  11. An Enhanced Nonlinear Critical Gradient for Electron Turbulent Transport due to Reversed Magnetic Shear

    SciTech Connect (OSTI)

    Peterson, J. L.; Hammet, G. W.; Mikkelsen, D. R.; Yuh, H. Y.; Candy, J.; Guttenfelder, W.; Kaye, S. M.; LeBlanc, B.

    2011-05-11

    The first nonlinear gyrokinetic simulations of electron internal transport barriers (e-ITBs) in the National Spherical Torus Experiment show that reversed magnetic shear can suppress thermal transport by increasing the nonlinear critical gradient for electron-temperature-gradient-driven turbulence to three times its linear critical value. An interesting feature of this turbulence is non- linearly driven off-midplane radial streamers. This work reinforces the experimental observation that magnetic shear is likely an effective way of triggering and sustaining e-ITBs in magnetic fusion devices.

  12. Superconducting Open-Gradient Magnetic Separation for the Pretreatment of Radioactive or Mixed Waste Vitrification Feeds

    SciTech Connect (OSTI)

    Nunez', L.; Kaminsky', M.D.,; Crawford, C.; Ritter, J.A.

    1999-12-31

    An open-gradient magnetic separation (OGMS) process is being considered to separate deleterious elements from radioactive and mixed waste streams prior to vitrification or stabilization. By physically segregating solid wastes and slurries based on the magnetic properties of the solid constituents, this potentially low-cost process may serve the U.S. Department of Energy (DOE) by reducing the large quantities of glass produced from defense-related high-level waste (HLW). Furthermore, the separation of deleterious elements from low-level waste (LLW) also can reduce the total quantity of waste produced in LLW immobilization activities. Many HLW 'and LLW waste' streams at both Hanford and the Savannah River Site (SRS) include constituents deleterious to the durability of borosilicate glass and the melter many of the constituents also possess paramagnetism. For example, Fe, Cr, Ni, and other transition metals may limit the waste loading and affect the durability of the glass by forming spine1 phases at the high operating temperature used in vitrification. Some magnetic spine1 phases observed in glass formation are magnetite (Fe,O,), chromite (FeCrO,), and others [(Fe, Ni, Mg, Zn, Mn)(Al, Fe, Ti, Cr)O,] as described elsewhere [Bates-1994, Wronkiewicz-1994] Stable spine1 phases can cause segregation between the glass and the crystalline phases. As a consequence of the difference in density, the spine1 phases tend to accumulate at the bottom of the glass melter, which decreases the conductivity and melter lifetime [Sproull-1993]. Crystallization also can affect glass durability [Jantzen-1985, Turcotte- 1979, Buechele-1990] by changing the chemical composition of the matrix glass surrounding the crystals or causing stress at the glass/crystal interface. These are some of the effects that can increase leaching [Jantzen-1985]. A SRS glass that was partially crystallized to contain 10% vol. crystals composed of spinels, nepheline, and acmite phases showed minimal changes in

  13. Digital Manufacturing of Gradient Meshed SOFC Sealing Composites with Self-Healing Capabilities

    SciTech Connect (OSTI)

    Kathy Lu; Christopher Story; W.T. Reynolds

    2007-12-21

    Solid oxide fuel cells (SOFC) hold great promise for clean power generation. However, high temperature stability and long term durability of the SOFC components have presented serious problems in SOFC technological advancement and commercialization. The seals of the fuel cells are the most challenging area to address. A high temperature gas seal is highly needed which is durable against cracking and gas leakage during thermal cycling and extended operation. This project investigates a novel composite seal by integrating 3D printed shape memory alloy (SMA) wires into a glass matrix. The SMA we use is TiNiHf and the glass matrix we use is SrO-La{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-SiO{sub 2} (SLABS). Dilatometry shows to be an extremely useful tool in providing the CTEs. It pinpoints regions of different CTEs under simulated SOFC thermal cycles for the same glass. For the studied SLABS glass system, the region with the greatest CTE mismatch between the glass seal and the adjacent components is 40-500 C, the typical heating and cooling regions for SOFCs. Even for low temperature SOFC development, this region is still present and needs to be addressed. We have demonstrated that the proposed SLABS glass has great potential in mitigating the thermal expansion mismatch issues that are limiting the operation life of SOFCs. TiNiHf alloy has been successfully synthesized with the desired particle size for the 3DP process. The TiNiHf SMA shape memory effect very desirably overlaps with the problematic low CTE region of the glass. This supports the design intent that the gradient structure transition, phase transformation toughening, and self-healing of the SMA can be utilized to mitigate/eliminate the seal problem. For the 3DP process, a new binder has been identified to match with the specific chemistry of the SMA particles. This enables us to directly print SMA particles. Neutron diffraction shows to be an extremely useful tool in providing information

  14. EA-2010: Alternating Gradient Synchrotron Complex Improvements at Brookhaven National Laboratory; Upton, New York

    Broader source: Energy.gov [DOE]

    DOE is proposing to upgrade the Brookhaven National Laboratory Alternating Gradient Synchrotron Complex to ensure long-term operational efficiencies of the complex and to increase the energy level of the Accelerator Test Facility Upgrade up to 10 Giga-electron-volt while expanding its use as a user facility.

  15. Cosmological constraints from the redshift dependence of the Alcock-Paczynski test: galaxy density gradient field

    SciTech Connect (OSTI)

    Li, Xiao-Dong; Park, Changbom; Forero-Romero, J. E.; Kim, Juhan E-mail: cbp@kias.re.kr E-mail: kjhan@kias.re.kr

    2014-12-01

    We propose a method based on the redshift dependence of the Alcock-Paczynski (AP) test to measure the expansion history of the universe. It uses the isotropy of the galaxy density gradient field to constrain cosmological parameters. If the density parameter ? {sub m} or the dark energy equation of state w are incorrectly chosen, the gradient field appears to be anisotropic with the degree of anisotropy varying with redshift. We use this effect to constrain the cosmological parameters governing the expansion history of the universe. Although redshift-space distortions (RSD) induced by galaxy peculiar velocities also produce anisotropies in the gradient field, these effects are close to uniform in magnitude over a large range of redshift. This makes the redshift variation of the gradient field anisotropy relatively insensitive to the RSD. By testing the method on mock surveys drawn from the Horizon Run 3 cosmological N-body simulations, we demonstrate that the cosmological parameters can be estimated without bias. Our method is complementary to the baryon acoustic oscillation or topology methods as it depends on D{sub AH} , the product of the angular diameter distance and the Hubble parameter.

  16. Manufacture of gradient micro-structures of magnesium alloys using two stage extrusion dies

    SciTech Connect (OSTI)

    Hwang, Yeong-Maw; Huang, Tze-Hui [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, No. 70, Lien-Hai Rd., Kaohsiung, 804, Taiwan (China); Alexandrov, Sergei [Institute for Problems in Mechanics, Russian Academy of Sciences, Moscow (Russian Federation); Naimark, Oleg Borisovich [Institute of Continuous Media Mechanics, Russian Academy of Sciences, Perm (Russian Federation); Jeng, Yeau-Ren [Department of Mechanical Engineering and Advanced Institute of Manufacturing with High-tech Innovations, National Chung Cheng University, Ming-Hsiung, Chia-Yi 621, Taiwan (China)

    2013-12-16

    This paper aims to manufacture magnesium alloy metals with gradient micro-structures using hot extrusion process. The extrusion die was designed to have a straight channel part combined with a conical part. Materials pushed through this specially-designed die generate a non-uniform velocity distribution at cross sections inside the die and result in different strain and strain rate distributions. Accordingly, a gradient microstructure product can be obtained. Using the finite element analysis, the forming temperature, effective strain, and effective strain rate distributions at the die exit were firstly discussed for various inclination angles in the conical die. Then, hot extrusion experiments with a two stage die were conducted to obtain magnesium alloy products with gradient micro-structures. The effects of the inclination angle on the grain size distribution at cross sections of the products were also discussed. Using a die of an inclination angle of 15, gradient micro-structures of the grain size decreasing gradually from 17 ?m at the center to 4 ?m at the edge of product were achieved.

  17. Full-waveform inversion in the time domain with an energy-weighted gradient

    SciTech Connect (OSTI)

    Zhang, Zhigang; Huang, Lianjie; Lin, Youzuo

    2011-01-01

    When applying full-waveform inversion to surface seismic reflection data, one difficulty is that the deep region of the model is usually not reconstructed as well as the shallow region. We develop an energy-weighted gradient method for the time-domain full-waveform inversion to accelerate the convergence rate and improve reconstruction of the entire model without increasing the computational cost. Three different methods can alleviate the problem of poor reconstruction in the deep region of the model: the layer stripping, depth-weighting and pseudo-Hessian schemes. The first two approaches need to subjectively choose stripping depths and weighting functions. The third one scales the gradient with only the forward propagation wavefields from sources. However, the Hessian depends on wavefields from both sources and receivers. Our new energy-weighted method makes use of the energies of both forward and backward propagated wavefields from sources and receivers as weights to compute the gradient. We compare the reconstruction of our new method with those of the conjugate gradient and pseudo-Hessian methods, and demonstrate that our new method significantly improves the reconstruction of both the shallow and deep regions of the model.

  18. Pulsed Gradient Spin Echo Nuclear Magnetic Resonance Imaging of Diffusion in Granular Flow

    SciTech Connect (OSTI)

    Seymour, Joseph D.; Caprihan, Arvind; Altobelli, Stephen A.; Fukushima, Eiichi

    2000-01-10

    We derive the formalism to obtain spatial distributions of collisional correlation times for macroscopic particles undergoing granular flow from pulsed gradient spin echo nuclear magnetic resonance diffusion data. This is demonstrated with an example of axial motion in the shear flow regime of a 3D granular flow in a horizontal rotating cylinder at one rotation rate. (c) 2000 The American Physical Society.

  19. On the combined gradient-stochastic plasticity model: Application to Mo-micropillar compression

    SciTech Connect (OSTI)

    Konstantinidis, A. A.; Zhang, X.; Aifantis, E. C.

    2015-02-17

    A formulation for addressing heterogeneous material deformation is proposed. It is based on the use of a stochasticity-enhanced gradient plasticity model implemented through a cellular automaton. The specific application is on Mo-micropillar compression, for which the irregularities of the strain bursts observed have been experimentally measured and theoretically interpreted through Tsallis' q-statistics.

  20. Results of geothermal gradient core hole TCB-1, Tecuamburro volcano geothermal site, Guatemala, Central America

    SciTech Connect (OSTI)

    Adams, A.I.; Chipera, S.; Counce, D.; Gardner, J.; Goff, S.; Goff, F.; Heiken, G.; Laughlin, A.W.; Musgrave, J.; Trujillo, P.E. Jr. ); Aycinena, S.; Martinelli, L. ); Castaneda, O.; Revolorio, M.; Roldan, A. . Inst. Nacional de Electrificacion); D

    1992-02-01

    Results of geological, volcanological, hydrogeochemical, and geophysical field studies conducted in 1988 and 1989 at the Tecuamburro volcano geothermal site in Guatemala indicated that there is a substantial shallow heat source beneath the area of youngest volcanism. To obtain information on subsurface temperatures and temperature gradients, stratigraphy, hydrothermal alteration, fracturing, and possible inflows of hydrothermal fluids, a geothermal gradient core hole (TCB-1) was drilled to 808 m low on the northern flank of the Tecuamburro volcano Complex, 300 km south of a 300-m-diameter phreatic crater, Laguna Ixpaco, dated at 2,910 years. Gases from acid-sulfate springs near Laguna Ixpaco consistently yield maximum estimated subsurface temperatures of 250--300{degrees}C. The temperature versus depth curve from TCB-1 does not show isothermal conditions and the calculated thermal gradients from 500--800 m is 230{degrees}C/km. Bottom hole temperature is 238{degrees}C. Calculated heat flow values are nearly 9 heat flow units (HFU). The integration of results from the TCB-1 gradient core hole with results from field studies provides strong evidence that the Tecuamburro area holds great promise for containing a commercial geothermal resource.

  1. Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition

    SciTech Connect (OSTI)

    Ahn, Cheol Hyoun; Hee Kim, So; Gu Yun, Myeong; Koun Cho, Hyung

    2014-12-01

    In this study, we proposed the artificially designed channel structure in oxide thin-film transistors (TFTs) called a “step-composition gradient channel.” We demonstrated Al step-composition gradient Al-Zn-O (AZO) channel structures consisting of three AZO layers with different Al contents. The effects of stacking sequence in the step-composition gradient channel on performance and electrical stability of bottom-gate TFT devices were investigated with two channels of inverse stacking order (ascending/descending step-composition). The TFT with ascending step-composition channel structure (5 → 10 → 14 at. % Al composition) showed relatively negative threshold voltage (−3.7 V) and good instability characteristics with a reduced threshold voltage shift (Δ 1.4 V), which was related to the alignment of the conduction band off-set within the channel layer depending on the Al contents. Finally, the reduced Al composition in the initial layer of ascending step-composition channel resulted in the best field effect mobility of 4.5 cm{sup 2}/V s. We presented a unique active layer of the “step-composition gradient channel” in the oxide TFTs and explained the mechanism of adequate channel design.

  2. Thermal lens elimination by gradient-reduced zone coupling of optical beams

    DOE Patents [OSTI]

    Page, Ralph H. (San Ramon, CA); Beach, Raymond J. (Livermore, CA)

    2000-01-01

    A thermal gradient-reduced-zone laser includes a laser medium and an optically transparent plate with an index of refraction that is less than the index of refraction of the laser medium. The pump face of the laser medium is bonded to a surface of the optically transparent member. Pump light is directed through the transparent plate to optically pump the solid state laser medium. Heat conduction is mainly through the surface of the laser medium where the heat is introduced by the pump light. Heat flows in a direction opposite to that of the pump light because the side of the laser medium that is opposite to that of the pump face is not in thermal contact with a conductor and thus there is no heat flux (and hence, no temperature gradient), thus producing a thermal gradient-reduced zone. A laser cavity is formed around the laser medium such that laser light oscillating within the laser cavity reflects by total-internal-reflection from the interface between the pump face and the optically transparent plate and enters and exits through a thermal gradient-reduced zone.

  3. 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 [Fakultt fr Physik and Astronomie, Theoretische Physik I, Ruhr-Universitt Bochum, D-44780 Bochum (Germany)

    2013-12-20

    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.

  4. Analytic calculations of hyper-Raman spectra from density functional theory hyperpolarizability gradients

    SciTech Connect (OSTI)

    Ringholm, Magnus; Ruud, Kenneth; Bast, Radovan; Oggioni, Luca; Ekström, Ulf

    2014-10-07

    We present the first analytic calculations of the geometrical gradients of the first hyperpolarizability tensors at the density-functional theory (DFT) level. We use the analytically calculated hyperpolarizability gradients to explore the importance of electron correlation effects, as described by DFT, on hyper-Raman spectra. In particular, we calculate the hyper-Raman spectra of the all-trans and 11-cis isomers of retinal at the Hartree-Fock (HF) and density-functional levels of theory, also allowing us to explore the sensitivity of the hyper-Raman spectra on the geometrical characteristics of these structurally related molecules. We show that the HF results, using B3LYP-calculated vibrational frequencies and force fields, reproduce the experimental data for all-trans-retinal well, and that electron correlation effects are of minor importance for the hyper-Raman intensities.

  5. Non-linear Conjugate Gradient Time-Domain Controlled Inversion Source

    Energy Science and Technology Software Center (OSTI)

    2006-11-16

    Software that simulates and inverts time-domain electromagnetic field data for subsurface electrical properties (electrical conductivity) of geological media. The software treats data produced by a step-wise source signal from either galvanic (grounded wires) or inductive (magnetic loops) sources. The inversion process is carried inductive (magnetic loops) sources. The inversion process is carried out using a non-linear conjugate gradient optimization scheme, which minimizes the misfit between field data and model data using a least squares criteria.more » The software is an upgrade from the code TEM3D ver. 2.0. The upgrade includes the following components: (1) Improved (faster)memory access during gradient computation. (2) Data parellelization scheme: Multiple transmitters (sources) can be distributed accross several banks of processors (daa-planes). Similarly, the receivers of each source are also distributed accross the corresponding data-plane. (3) Improved data-IO.« less

  6. The effect of density gradient on the growth rate of relativistic Weibel instability

    SciTech Connect (OSTI)

    Mahdavi, M.; Khodadadi Azadboni, F.

    2014-02-15

    In this paper, the effect of density gradient on the Weibel instability growth rate is investigated. The density perturbations in the near corona fuel, where temperature anisotropy, η, is larger than the critical temperature anisotropy, η{sub c}, (η > η{sub c}), enhances the growth rate of Weibel instability due to the sidebands coupled with the electron oscillatory velocity. But for η < η{sub c}, the thermal spread of the energetic electrons reduces the growth rate. Also, the growth rate can be reduced if the relativistic parameter (Lorentz factor) is sufficiently large, γ > 2. The analysis shows that relativistic effects and density gradient tend to stabilize the Weibel instability. The growth rate can be reduced by 88% by reducing η by a factor of 100 and increasing relativistic parameter by a factor of 3.

  7. Dynamic microscale temperature gradient in a gold nanorod solution measured by diffraction-limited nanothermometry

    SciTech Connect (OSTI)

    Li, Chengmingyue; Gan, Xiaosong; Li, Xiangping; Gu, Min

    2015-09-21

    We quantify the dynamic microscale temperature gradient in a gold nanorod solution using quantum-dot-based microscopic fluorescence nanothermometry. By incorporating CdSe quantum dots into the solution as a nanothermometer, precise temperature mapping with diffraction-limited spatial resolution and sub-degree temperature resolution is achieved. The acquired data on heat generation and dissipation show an excellent agreement with theoretical simulations. This work reveals an effective approach for noninvasive temperature regulation with localized nanoheaters in microfluidic environment.

  8. METALLICITY GRADIENT OF A LENSED FACE-ON SPIRAL GALAXY AT REDSHIFT 1.49

    SciTech Connect (OSTI)

    Yuan, T.-T.; Kewley, L. J.; Swinbank, A. M.; Richard, J.; Livermore, R. C.

    2011-05-01

    We present the first metallicity gradient measurement for a grand-design face-on spiral galaxy at z {approx} 1.5. This galaxy has been magnified by a factor of 22x by a massive, X-ray luminous galaxy cluster MACS J1149.5+2223 at z = 0.544. Using the Laser Guide Star Adaptive Optics aided integral field spectrograph OSIRIS on KECK II, we target the H{alpha} emission and achieve a spatial resolution of 0.''1, corresponding to a source-plane resolution of 170 pc. The galaxy has well-developed spiral arms and the nebular emission line dynamics clearly indicate a rotationally supported disk with V{sub rot}/{sigma} {approx} 4. The best-fit disk velocity field model yields a maximum rotation of V{sub rot}sin i = 150 {+-} 15 km s{sup -1}, and a dynamical mass of M{sub dyn} = (1.3 {+-} 0.2) x 10{sup 10} cosec{sup 2}(i) M{sub sun} (within 2.5 kpc), where the inclination angle i = 45{sup 0} {+-} 10{sup 0}. Based on the [N II] and H{alpha} ratios, we measured the radial chemical abundance gradient from the inner hundreds of parsecs out to {approx}5 kpc. The slope of the gradient is -0.16 {+-} 0.02 dex kpc{sup -1}, significantly steeper than the gradient of late-type or early-type galaxies in the local universe. If representative of disk galaxies at z {approx} 1.5, our results support an 'inside-out' disk formation scenario in which early infall/collapse in the galaxy center builds a chemically enriched nucleus, followed by slow enrichment of the disk over the next 9 Gyr.

  9. Effect of entropy on anomalous transport in electron-temperature-gradient-modes

    SciTech Connect (OSTI)

    Yaqub Khan, M.; Iqbal, J.; Ul Haq, A.

    2014-05-15

    Due to the interconnection of entropy with temperature and density of plasma, it would be interesting to investigate plasma related phenomena with respect to entropy. By employing Braginskii transport equations, it is proved that entropy is proportional to a function of potential and distribution function of entropy is re-defined, ∇S–drift in obtained. New dispersion relation is derived; it is found that the anomalous transport depends on the gradient of the entropy.

  10. A study of self organized criticality in ion temperature gradient mode driven gyrokinetic turbulence

    SciTech Connect (OSTI)

    Mavridis, M.; Isliker, H.; Vlahos, L.; Grler, T.; Jenko, F.; Told, D.

    2014-10-15

    An investigation on the characteristics of self organized criticality (Soc) in ITG mode driven turbulence is made, with the use of various statistical tools (histograms, power spectra, Hurst exponents estimated with the rescaled range analysis, and the structure function method). For this purpose, local non-linear gyrokinetic simulations of the cyclone base case scenario are performed with the GENE software package. Although most authors concentrate on global simulations, which seem to be a better choice for such an investigation, we use local simulations in an attempt to study the locally underlying mechanisms of Soc. We also study the structural properties of radially extended structures, with several tools (fractal dimension estimate, cluster analysis, and two dimensional autocorrelation function), in order to explore whether they can be characterized as avalanches. We find that, for large enough driving temperature gradients, the local simulations exhibit most of the features of Soc, with the exception of the probability distribution of observables, which show a tail, yet they are not of power-law form. The radial structures have the same radial extent at all temperature gradients examined; radial motion (transport) though appears only at large temperature gradients, in which case the radial structures can be interpreted as avalanches.

  11. Coronal heating driven by a magnetic gradient pumping mechanism in solar plasmas

    SciTech Connect (OSTI)

    Tan, Baolin

    2014-11-10

    The heating of the solar corona is a longstanding mystery in astrophysics. Considering that the solar magnetic field is spatially inhomogeneous with a considerable magnetic gradient from the solar surface to the corona, this work proposes a magnetic gradient pumping (MGP) mechanism to try to explain the formation of hot plasma upflows, such as hot type II spicules and hot plasma ejections. In the MGP mechanism, the magnetic gradient may drive the energetic particles to move upward from the underlying solar atmosphere and form hot upflows. These upflow energetic particles are deposited in the corona, causing it to become very hot. Rough estimations indicate that the solar corona can be heated to above 1 million degrees, and the upflow velocity is about 40 km s{sup –1} in the chromosphere and about 130 km s{sup –1} in the corona. The solar magnetic flux tubes act as pumpers to extract energetic particles from the underlying thermal photosphere, convey them, and deposit them in the corona. The deposit of these energetic particles causes the corona to become hot, and the escape of such particles from the photosphere leaves it a bit cold. This mechanism can present a natural explanation to the mystery of solar coronal heating.

  12. Effect of resistivity gradient on laser-driven electron transport and ion acceleration

    SciTech Connect (OSTI)

    Zhuo, H. B.; Yang, X. H.; Ma, Y. Y.; Li, X. H.; Zhou, C. T.; Institute of Applied Physics and Computational Mathematics, Beijing 100094 ; Yu, M. Y.; Institute for Theoretical Physics I, Ruhr University, Bochum D-44780

    2013-09-15

    The effect of resistivity gradient on laser-driven electron transport and ion acceleration is investigated using collisional particle-in-cell simulation. The study is motivated by recent proton acceleration experiments [Gizzi et al., Phys. Rev. ST Accel. Beams 14, 011301 (2011)], which showed significant effect of the resistivity gradient in layered targets on the proton angular spread. This effect is reproduced in the present simulations. It is found that resistivity-gradient generation of magnetic fields and inhibition of electron transport is significantly enhanced when the feedback interaction between the magnetic field and the fast-electron current is included. Filamentation of the laser-generated hot electron jets inside the target, considered as the origin of the nonuniform proton patterns observed in the experiments, is clearly suppressed by the resistive magnetic field. As a result, the electrostatic sheath field at the target back surface acquires a relatively smooth profile, which contributes to the superior quality of the proton beams accelerated off layered targets in the experiments.

  13. Effect of Temperature Gradient on Industrial Coal Slag Infiltration into Porous Refractory Materials in Slagging Gasifiers

    SciTech Connect (OSTI)

    Kaneko, Tetsuya Kenneth; Bennett, James P.; Dridhar, Seetharaman

    2011-12-01

    Infiltration characteristics of industrial coal slag into alumina (Al{sub 2}O{sub 3}) refractory material with a temperature gradient induced along the slag's penetration direction are compared to those obtained under near-isothermal conditions. Experiments were conducted with a hot-face temperature of 1450°C and a CO/CO{sub 2} ratio of 1.8, which corresponds to an oxygen partial pressure of ~10{sup −8} atm. The refractory under the near-isothermal temperature profile, with higher average temperatures, demonstrated a greater penetration depth than its counterpart that was under the steeper temperature gradient. Slag that did not infiltrate into the refractory due to the induced temperature gradient, pooled and solidified on the top of the sample. Within the pool, a conglomerated mass of troilite (FeS) formed separately from the surrounding slag. Microscopy of the cross-sectioned infiltrated refractories revealed that the slag preferentially corroded the matrix regions closer to the top surface. Furthermore, the formation of a thick layer of hercynite (FeAl{sub 2}O{sub 4}) at the top of refractory/slag interface significantly depleted the slag of its iron-oxide content with respect to its virgin composition. A qualitative description of the penetration process is provided in this article.

  14. The role of Rnf in ion gradient formation in Desulfovibrio alaskensis

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

    Wang, Luyao; Bradstock, Peter; Li, Chuang; McInerney, Michael J.; Krumholz, Lee R.

    2016-04-14

    Rnf is a membrane protein complex that has been shown to be important in energy conservation. Here, Desulfovibrio alaskensisG20 and Rnf mutants of G20 were grown with different electron donor and acceptor combinations to determine the importance of Rnf in energy conservation and the type of ion gradient generated. The addition of the protonophore TCS strongly inhibited lactate-sulfate dependent growth whereas the sodium ionophore ETH2120 had no effect, indicating a role for the proton gradient during growth. Mutants inrnfAandrnfDwere more sensitive to the protonophore at 5 µM than the parental strain, suggesting the importance of Rnf in the generation ofmore » a proton gradient. The electrical potential (ΔΨ), ΔpH and proton motive force were lower in thernfAmutant than in the parental strain of D.alaskensisG20. In conclusion, these results provide evidence that the Rnf complex inD. alaskensisfunctions as a primary proton pump whose activity is important for growth.« less

  15. Microsoft Word - Argonne Infrastructure - Final Report 2-26-15...

    Energy Savers [EERE]

    ... Laboratory Plan identified as an urgent need because funding for future research at the Office of High Energy Physics (HEP) Argonne Wakefield Accelerator had already been received. ...

  16. How Accelerator Physicists Save Time | U.S. DOE Office of Science...

    Office of Science (SC) Website

    The wakefield accelerates the electron bunch, shown in green. Physicists rely on ... systems that may extend the physics reach of next-generation high energy accelerators. ...

  17. HIGH CURRENT L-BAND LINAC

    SciTech Connect (OSTI)

    S. RUSSELL; B. CARLSTEN; J. GOETTEE

    2001-02-01

    The Sub-Picosecond Accelerator (SPA) at the Los Alamos National Laboratory is an L-band photoinjector. Using magnetic compression, the SPA routinely compresses 8 MeV, 1 nC per bunch electron beams from an initial temporal FWHM bunch length of 20 ps to less than 1 ps. In recent plasma wakefield accelerator experiments, we have compressed a 2 nC per bunch electron beam to an approximate temporal length of 1 ps.

  18. Numerical simulations of the bending of narrow-angle-tail radio jets by ram pressure or pressure gradients

    SciTech Connect (OSTI)

    Soker, N.; Sarazin, C.L.; O'Dea, C.P.

    1988-04-01

    Three-dimensional numerical hydrodynamic simulations are used to study the bending of radio jets. The simulations are compared with observations of jets in narrow-angle-tail radio sources. Two mechanisms for the observed bending are considered: direct bending of quasi-continuous jets by ram pressure from intergalactic gas and bending by pressure gradients in the interstellar gas of the host galaxy, the pressure gradients themselves being the result of ram pressure by intergalactic gas. It is shown that the pressure gradients are much less effective in bending jets, implying that the jets have roughly 30 times lower momentum fluxes if they are bent by this mechanism. Ram-pressure bending produces jets with kidney-shaped cross sections; when observed from the side, these jets appear to have diffuse extensions on the downstream side. On the other hand, pressure-gradient bending causes the jets to be densest near their upstream side. 31 references.

  19. Vehicle Technologies Office Merit Review 2015: NMR and Pulse Field Gradient Studies of SEI and Electrode Structure

    Broader source: Energy.gov [DOE]

    Presentation given by U. of Cambridge at 2015 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about NMR and pulse field gradient...

  20. Gradient Echo MRI Characterization of Development of Atherosclerosis in the Abdominal Aorta in Watanabe Heritable Hyperlipidemic Rabbits

    SciTech Connect (OSTI)

    Wang, Yi-Xiang J. Kuribayashi, Hideto; Wagberg, Maria; Holmes, Andrew P.; Tessier, Jean J.; Waterton, John C.

    2006-08-15

    age (p < 0.001). There was a small increase in aortic wall thickness between 50 and 73 weeks of age, but this was not significant (p > 0.05). The corresponding differences in lumen cross-sectional areas at 20, 50, and 73 weeks of age were not significant. These results were consistent with in-house historical histology data on this strain of rabbits. Conclusions. High-resolution gradient echo MRI can follow disease progression in the WHHL rabbit spontaneous atherosclerosis disease model.

  1. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

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

    Cho, Herman

    2016-02-28

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2,5/2,7/2, and 9/2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Furthermore, applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  2. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    DOE Patents [OSTI]

    Yeung, E.S.; Chen, G.

    1990-05-01

    A method and means are disclosed for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived. 15 figs.

  3. Method and means for a spatial and temporal probe for laser-generated plumes based on density gradients

    DOE Patents [OSTI]

    Yeung, Edward S.; Chen, Guoying

    1990-05-01

    A method and means for a spatial and temporal probe for laser generated plumes based on density gradients includes generation of a plume of vaporized material from a surface by an energy source. The probe laser beam is positioned so that the plume passes through the probe laser beam. Movement of the probe laser beam caused by refraction from the density gradient of the plume is monitored. Spatial and temporal information, correlated to one another, is then derived.

  4. Multi-MW 22.8 GHz Harmonic Multiplier - RF Power Source for High-Gradient Accelerator R&D

    SciTech Connect (OSTI)

    Jay L. Hirshfield

    2012-07-26

    Electrodynamic and particle simulation studies have been carried out to optimize design of a two-cavity harmonic frequency multiplier, in which a linear electron beam is energized by rotating fields near cyclotron resonance in a TE111 cavity in a uniform magnetic field, and in which the beam then radiates coherently at the nth harmonic into a TEn11 output cavity. Examples are worked out in detail for 7th and 2nd harmonic converters, showing RF-to-RF conversion efficiencies of 45% and 88%, respectively at 19.992 GHz (K-band) and 5.712 GHz (C-band), for a drive frequency of 2.856 GHz. Details are shown of RF infrastructure (S-band klystron, modulator) and harmonic converter components (drive cavity, output cavities, electron beam source and modulator, beam collector) for the two harmonic converters to be tested. Details are also given for the two-frequency (S- and C-band) coherent multi-MW test stand for RF breakdown and RF gun studies.

  5. Mitigating illumination gradients in a SAR image based on the image data and antenna beam pattern

    DOE Patents [OSTI]

    Doerry, Armin W.

    2013-04-30

    Illumination gradients in a synthetic aperture radar (SAR) image of a target can be mitigated by determining a correction for pixel values associated with the SAR image. This correction is determined based on information indicative of a beam pattern used by a SAR antenna apparatus to illuminate the target, and also based on the pixel values associated with the SAR image. The correction is applied to the pixel values associated with the SAR image to produce corrected pixel values that define a corrected SAR image.

  6. A silicon-nanowire memory driven by optical gradient force induced bistability

    SciTech Connect (OSTI)

    Dong, B.; Cai, H. Gu, Y. D.; Kwong, D. L.; Chin, L. K.; Ng, G. I.; Ser, W.; Huang, J. G.; Yang, Z. C.; Liu, A. Q.

    2015-12-28

    In this paper, a bistable optical-driven silicon-nanowire memory is demonstrated, which employs ring resonator to generate optical gradient force over a doubly clamped silicon-nanowire. Two stable deformation positions of a doubly clamped silicon-nanowire represent two memory states (“0” and “1”) and can be set/reset by modulating the light intensity (<3 mW) based on the optical force induced bistability. The time response of the optical-driven memory is less than 250 ns. It has applications in the fields of all optical communication, quantum computing, and optomechanical circuits.

  7. Tune-stabilized, non-scaling, fixed-field, alternating gradient accelerator

    DOE Patents [OSTI]

    Johnstone, Carol J.

    2011-02-01

    A FFAG is a particle accelerator having turning magnets with a linear field gradient for confinement and a large edge angle to compensate for acceleration. FODO cells contain focus magnets and defocus magnets that are specified by a number of parameters. A set of seven equations, called the FFAG equations relate the parameters to one another. A set of constraints, call the FFAG constraints, constrain the FFAG equations. Selecting a few parameters, such as injection momentum, extraction momentum, and drift distance reduces the number of unknown parameters to seven. Seven equations with seven unknowns can be solved to yield the values for all the parameters and to thereby fully specify a FFAG.

  8. Temperature, thermal efficiency, and gradient performance from two seawater-SZ solar ponds

    SciTech Connect (OSTI)

    Collado, F.; Lowrey, P. )

    1991-01-01

    This paper presents 10 months of experience with two seawater-SZ (Storage Zone) solar ponds operated as a source of warm seawater which could have been used in an adjacent mariculture facility. Observations and extensive temperature, gradient and efficiency data are presented. This work demonstrated operation of and heat extraction from seawater-SZ solar ponds over a much longer interval than in previous work. It confirmed that seawater-SZ solar ponds can consistently give useful temperature elevations. A few phenomena not characteristic of conventional solar ponds were identified and are discussed.

  9. Cosmic-ray gradient measurements and modulation beyond the inner solar wind termination shock

    SciTech Connect (OSTI)

    Quenby, J.J.; Lockwood, J.A.; Webber, W.R. New Hampshire Univ., Durham )

    1990-12-01

    Data provided by the IMP, Voyager, and Pioneer spacecraft for the cosmic-ray particles with E greater than 60 MeV show the existence of integral radial cosmic-ray-density gradients which were nearly constant from 1977 to 1982. In this paper, these measurements are explained using a model in which significant modulation occurs in the turbulent shocked plasma flow between the inner solar wind termination and the outer contact discontinuity separating the interstellar medium flow from the heliospheric plasma. 54 refs.

  10. Rotating-frame gradient fields for magnetic resonance imaging and nuclear magnetic resonance in low fields

    DOE Patents [OSTI]

    Bouchard, Louis-Serge; Pines, Alexander; Demas, Vasiliki

    2014-01-21

    A system and method for Fourier encoding a nuclear magnetic resonance (NMR) signal is disclosed. A static magnetic field B.sub.0 is provided along a first direction. An NMR signal from the sample is Fourier encoded by applying a rotating-frame gradient field B.sub.G superimposed on the B.sub.0, where the B.sub.G comprises a vector component rotating in a plane perpendicular to the first direction at an angular frequency .omega.in a laboratory frame. The Fourier-encoded NMR signal is detected.

  11. Local pressure gradients due to incipience of boiling in subcooled flows

    SciTech Connect (OSTI)

    Ruggles, A.E.; McDuffee, J.L.

    1995-09-01

    Models for vapor bubble behavior and nucleation site density during subcooled boiling are integrated with boundary layer theory in order to predict the local pressure gradient and heat transfer coefficient. Models for bubble growth rate and bubble departure diameter are used to scale the movement of displaced liquid in the laminar sublayer. An added shear stress, analogous to a turbulent shear stress, is derived by considering the liquid movement normal to the heated surface. The resulting mechanistic model has plausible functional dependence on wall superheat, mass flow, and heat flux and agrees well with data available in the literature.

  12. Functionally gradient material for membrane reactors to convert methane gas into value-added products

    DOE Patents [OSTI]

    Balachandran, U.; Dusek, J.T.; Kleefisch, M.S.; Kobylinski, T.P.

    1996-11-12

    A functionally gradient material for a membrane reactor for converting methane gas into value-added-products includes an outer tube of perovskite, which contacts air; an inner tube which contacts methane gas, of zirconium oxide, and a bonding layer between the perovskite and zirconium oxide layers. The bonding layer has one or more layers of a mixture of perovskite and zirconium oxide, with the layers transitioning from an excess of perovskite to an excess of zirconium oxide. The transition layers match thermal expansion coefficients and other physical properties between the two different materials. 7 figs.

  13. Functionally gradient material for membrane reactors to convert methane gas into value-added products

    DOE Patents [OSTI]

    Balachandran, Uthamalingam; Dusek, Joseph T.; Kleefisch, Mark S.; Kobylinski, Thadeus P.

    1996-01-01

    A functionally gradient material for a membrane reactor for converting methane gas into value-added-products includes an outer tube of perovskite, which contacts air; an inner tube which contacts methane gas, of zirconium oxide, and a bonding layer between the perovskite and zirconium oxide layers. The bonding layer has one or more layers of a mixture of perovskite and zirconium oxide, with the layers transitioning from an excess of perovskite to an excess of zirconium oxide. The transition layers match thermal expansion coefficients and other physical properties between the two different materials.

  14. Beam-driven acceleration in ultra-dense plasma media

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

    Shin, Young-Min

    2014-09-15

    Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 1025 m-3 and 1.6 x 1028 m-3 plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers 20 % higher acceleration gradient by enlarging the channel radius (r)morefrom 0.2 ?p to 0.6 ?p in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g. nanotubes) of high electron plasma density.less

  15. Numerical simulation of supercritical heat transfer under severe axial density gradient in a narrow vertical tube

    SciTech Connect (OSTI)

    Bae, Y. Y.; Hong, S. D.; Kim, Y. W.

    2012-07-01

    A number of computational works have been performed so far for the simulation of heat transfer in a supercritical fluid. The simulations, however, faced a lot of difficulties when heat transfer deteriorates due either to buoyancy or by acceleration. When the bulk temperature approaches the pseudo-critical temperature the fluid experiences a severe axial density gradient on top of a severe radial one. Earlier numerical calculations showed, without exception, unrealistic over-predictions, as soon as the bulk temperature exceeded the pseudo-critical temperature. The over-predictions might have been resulted from an inapplicability of widely-used turbulence models. One of the major causes for the difficulties may probably be an assumption of a constant turbulent Prandtl number. Recent research, both numerical and experimental, indicates that the turbulent Prandtl number is never a constant when the gradient of physical properties is significant. This paper describes the applicability of a variable turbulent Prandtl number to the numerical simulation of heat transfer in supercritical fluids flowing in narrow vertical tubes. (authors)

  16. Measurement of laser heating in spin exchange optical pumping by NMR diffusion sensitization gradients

    SciTech Connect (OSTI)

    Parnell, Steven R.; Deppe, Martin H.; Ajraoui, Salma; Parra-Robles, Juan; Wild, Jim M.; Boag, Stephen

    2010-05-15

    This paper details pulsed gradient NMR measurements of the {sup 3}He diffusion coefficient in sealed cells during spin exchange optical pumping. The potential of ultra low field magnetic resonance imgaing (MRI) and NMR for noninvasive measurement of cell pressure is demonstrated. Diffusion sensitization gradients allow measurement of the {sup 3}He diffusion coefficient from which the pressure and/or temperature of the gas can be determined during optical pumping. The pressure measurements were compared with neutron time of flight transmission measurements. Good agreement was observed between the temperature/pressure measurements and predictions based on Chapman-Enskog theory. The technique had sufficient sensitivity to observe the diffusion coefficient increasing with temperature in a sealed cell. With this method, evidence for laser heating of the {sup 3}He during optical pumping was found. The results show that NMR diffusion measurements allow noninvasive measurement of the cell temperature and/or pressure in an optical pumping setup. The method can be expanded using MRI to probe the spatial distribution of the diffusion coefficient. These techniques can be applied to the further investigation of polarization limiting effects such as laser heating.

  17. A magnetically shielded room with ultra low residual field and gradient

    SciTech Connect (OSTI)

    Altarev, I.; Chesnevskaya, S.; Gutsmiedl, E.; Kuchler, F.; Lins, T.; Marino, M.; McAndrew, J.; Niessen, B.; Paul, S.; Petzoldt, G.; Singh, J.; Stoepler, R.; Stuiber, S.; Sturm, M.; Taubenheim, B.; Babcock, E.; Beck, D.; Sharma, S.; Burghoff, M.; Fan, I.; and others

    2014-07-15

    A versatile and portable magnetically shielded room with a field of (700 ± 200) pT within a central volume of 1 m × 1 m × 1 m and a field gradient less than 300 pT/m, achieved without any external field stabilization or compensation, is described. This performance represents more than a hundredfold improvement of the state of the art for a two-layer magnetic shield and provides an environment suitable for a next generation of precision experiments in fundamental physics at low energies; in particular, searches for electric dipole moments of fundamental systems and tests of Lorentz-invariance based on spin-precession experiments. Studies of the residual fields and their sources enable improved design of future ultra-low gradient environments and experimental apparatus. This has implications for developments of magnetometry beyond the femto-Tesla scale in, for example, biomagnetism, geosciences, and security applications and in general low-field nuclear magnetic resonance (NMR) measurements.

  18. Formation of compressed flat electron beams with high transverse-emittance ratios

    SciTech Connect (OSTI)

    Zhu, J.; Piot, P.; Mihalcea, D.; Prokop, C. R.

    2014-08-01

    Flat beamsbeams with asymmetric transverse emittanceshave important applications in novel light-source concepts and advanced-acceleration schemes and could possibly alleviate the need for damping rings in lepton colliders. Over the last decade, a flat beam generation technique based on the conversion of an angular-momentum-dominated beam was proposed and experimentally tested. In this paper we explore the production of compressed flat beams. We especially investigate and optimize the flat beam transformation for beams with substantial fractional energy spread. We use as a simulation example the photoinjector of Fermilabs Advanced Superconducting Test Accelerator. The optimizations of the flat beam generation and compression at Advanced Superconducting Test Accelerator were done via start-to-end numerical simulations for bunch charges of 3.2 nC, 1.0 nC, and 20 pC at ?37??MeV. The optimized emittances of flat beams with different bunch charges were found to be 0.25???m (emittance ratio is ?400), 0.13????m, 15 nm before compression, and 0.41???m, 0.20???m, 16 nm after full compression, respectively, with peak currents as high as 5.5 kA for a 3.2?nC flat beam. These parameters are consistent with requirements needed to excite wakefields in asymmetric dielectric-lined waveguides or produce significant photon flux using small-gap micro-undulators.

  19. Ion-temperature-gradient sensitivity of the hydrodynamic instability caused by shear in the magnetic-field-aligned plasma flow

    SciTech Connect (OSTI)

    Mikhailenko, V. V.; Mikhailenko, V. S.; Lee, Hae June; Koepke, M. E.

    2014-07-15

    The cross-magnetic-field (i.e., perpendicular) profile of ion temperature and the perpendicular profile of the magnetic-field-aligned (parallel) plasma flow are sometimes inhomogeneous for space and laboratory plasma. Instability caused either by a gradient in the ion-temperature profile or by shear in the parallel flow has been discussed extensively in the literature. In this paper, (1) hydrodynamic plasma stability is investigated, (2) real and imaginary frequency are quantified over a range of the shear parameter, the normalized wavenumber, and the ratio of density-gradient and ion-temperature-gradient scale lengths, and (3) the role of inverse Landau damping is illustrated for the case of combined ion-temperature gradient and parallel-flow shear. We find that increasing the ion-temperature gradient reduces the instability threshold for the hydrodynamic parallel-flow shear instability, also known as the parallel Kelvin-Helmholtz instability or the D'Angelo instability. We also find that a kinetic instability arises from the coupled, reinforcing action of both free-energy sources. For the case of comparable electron and ion temperature, we illustrate analytically the transition of the D'Angelo instability to the kinetic instability as (a) the shear parameter, (b) the normalized wavenumber, and (c) the ratio of density-gradient and ion-temperature-gradient scale lengths are varied and we attribute the changes in stability to changes in the amount of inverse ion Landau damping. We show that near a normalized wavenumber k{sub ?}?{sub i} of order unity (i) the real and imaginary values of frequency become comparable and (ii) the imaginary frequency, i.e., the growth rate, peaks.

  20. Can surface cracks and unipolar arcs explain breakdown and gradient limits?

    SciTech Connect (OSTI)

    Insepov, Zeke; Norem, Jim

    2013-01-15

    The authors argue that the physics of unipolar arcs and surface cracks can help understand rf breakdown and vacuum arc data. They outline a model of the basic mechanisms involved in breakdown and explore how the physics of unipolar arcs and cracks can simplify the picture of breakdown and gradient limits in accelerators, tokamaks as well as laser ablation, micrometeorites, and other applications. Cracks are commonly seen in SEM images of arc damage and they are produced as the liquid metal cools. They can produce the required field enhancements to explain field emission data and can produce mechanical failure of the surface that would trigger breakdown events. Unipolar arcs can produce currents sufficient to short out rf structures, and can cause the sort of damage seen in SEM images. They should be unstable, and possibly self-quenching, as seen in optical fluctuations and surface damage. The authors describe some details and consider the predictions of this simple model.

  1. In-situ plasma processing to increase the accelerating gradients of SRF cavities

    SciTech Connect (OSTI)

    Doleans, Marc; Afanador, Ralph; Barnhart, Debra L.; Degraff, Brian D.; Gold, Steven W.; Hannah, Brian S.; Howell, Matthew P.; Kim, Sang-Ho; Mammosser, John; McMahan, Christopher J.; Neustadt, Thomas S.; Saunders, Jeffrey W.; Tyagi, Puneet V.; Vandygriff, Daniel J.; Vandygriff, David M.; Ball, Jeffrey Allen; Blokland, Willem; Crofford, Mark T.; Lee, Sung-Woo; Stewart, Stephen; Strong, William Herb

    2015-12-31

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipacting issues. This article discusses the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus.

  2. In-situ plasma processing to increase the accelerating gradients of SRF cavities

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

    Doleans, Marc; Afanador, Ralph; Barnhart, Debra L.; Degraff, Brian D.; Gold, Steven W.; Hannah, Brian S.; Howell, Matthew P.; Kim, Sang-Ho; Mammosser, John; McMahan, Christopher J.; et al

    2015-12-31

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipactingmore » issues. This article discusses the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus.« less

  3. A second gradient theoretical framework for hierarchical multiscale modeling of materials

    SciTech Connect (OSTI)

    Luscher, Darby J; Bronkhorst, Curt A; Mc Dowell, David L

    2009-01-01

    A theoretical framework for the hierarchical multiscale modeling of inelastic response of heterogeneous materials has been presented. Within this multiscale framework, the second gradient is used as a non local kinematic link between the response of a material point at the coarse scale and the response of a neighborhood of material points at the fine scale. Kinematic consistency between these scales results in specific requirements for constraints on the fluctuation field. The wryness tensor serves as a second-order measure of strain. The nature of the second-order strain induces anti-symmetry in the first order stress at the coarse scale. The multiscale ISV constitutive theory is couched in the coarse scale intermediate configuration, from which an important new concept in scale transitions emerges, namely scale invariance of dissipation. Finally, a strategy for developing meaningful kinematic ISVs and the proper free energy functions and evolution kinetics is presented.

  4. Generation of charge imbalance in a superconductor by a temperature gradient

    SciTech Connect (OSTI)

    Entin-Wohlman, O.; Orbach, R.

    1980-11-01

    The charge-imbalance voltage in a superconductor carrying a current in the presence of a temperature gradient is calculated from the Boltzmann equation in the clean limit. We demonstrate why the Green's-function approach in the dirty limit, first performed by Schmid and Schoem, generates the same Boltzmann-like equation for the distribution function. In addition, the charge-imbalance voltage in the absence of an impressed current is calculated. It is shown to depend on del/sup 2/T+(delT)/sup 2//T, and not solely on (delT)/sup 2/. The calculations are limited to the temperature regime near T/sub c/, such that ..delta..<

  5. Double-hybrid density-functional theory with meta-generalized-gradient approximations

    SciTech Connect (OSTI)

    Souvi, Sidi M. O. Sharkas, Kamal; Toulouse, Julien; CNRS, UMR 7616, Laboratoire de Chimie Thorique, F-75005 Paris

    2014-02-28

    We extend the previously proposed one-parameter double-hybrid density-functional theory [K. Sharkas, J. Toulouse, and A. Savin, J. Chem. Phys. 134, 064113 (2011)] to meta-generalized-gradient-approximation (meta-GGA) exchange-correlation density functionals. We construct several variants of one-parameter double-hybrid approximations using the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA functional and test them on test sets of atomization energies and reaction barrier heights. The most accurate variant uses the uniform coordinate scaling of the density and of the kinetic energy density in the correlation functional, and improves over both standard Kohn-Sham TPSS and second-order Mller-Plesset calculations.

  6. Viscous effects on the Rayleigh-Taylor instability with background temperature gradient

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

    Gerashchenko, Sergiy; Livescu, Daniel

    2016-07-28

    Here we studied the growth rate of the compressible Rayleigh-Taylor instability in the presence of a background temperature gradient, Θ, using a normal mode analysis. The effect of Θ variation is examined for three interface types corresponding to the combinations of the viscous properties of the fluids (inviscid-inviscid, viscous-viscous, and viscous-inviscid) at different Atwood numbers, At, and when at least one of the fluids' viscosity is non-zero, as a function of the Grashof number. For the general case, the resulting ordinary differential equations are solved numerically; however, dispersion relations for the growth rate are presented for several limiting cases. Anmore » analytical solution is found for the inviscid-inviscid interface and the corresponding dispersion equation for the growth rate is obtained in the limit of large Θ. For the viscous-inviscid case, a dispersion relation is derived in the incompressible limit and Θ=0. Compared to Θ=0 case, the role of Θ<0 (hotter light fluid) is destabilizing and becomes stabilizing when Θ>0 (colder light fluid). The most pronounced effect of Θ ≠ 0 is found at low At and/or at large perturbation wavelengths relative to the domain size for all interface types. On the other hand, at small perturbation wavelengths relative to the domain size, the growth rate for the Θ<0 case exceeds the infinite domain incompressible constant density result. The results are applied to two practical examples, using sets of parameters relevant to Inertial Confinement Fusion coasting stage and solar corona plumes. The role of viscosity on the growth rate reduction is discussed together with highlighting the range of wavenumbers most affected by viscosity. The viscous effects further increase in the presence of background temperature gradient, when the viscosity is temperature dependent.« less

  7. Analytical gradients of the state-average complete active space self-consistent field method with density fitting

    SciTech Connect (OSTI)

    Delcey, Mickaël G.; Pedersen, Thomas Bondo; Aquilante, Francesco; Lindh, Roland

    2015-07-28

    An efficient implementation of the state-averaged complete active space self-consistent field (SA-CASSCF) gradients employing density fitting (DF) is presented. The DF allows a reduction both in scaling and prefactors of the different steps involved. The performance of the algorithm is demonstrated on a set of molecules ranging up to an iron-Heme b complex which with its 79 atoms and 811 basis functions is to our knowledge the largest SA-CASSCF gradient computed. For smaller systems where the conventional code could still be used as a reference, both the linear response calculation and the gradient formation showed a clear timing reduction and the overall cost of a geometry optimization is typically reduced by more than one order of magnitude while the accuracy loss is negligible.

  8. Solvent effects in time-dependent self-consistent field methods. II. Variational formulations and analytical gradients

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

    Bjorgaard, J. A.; Velizhanin, K. A.; Tretiak, S.

    2015-08-06

    This study describes variational energy expressions and analytical excited state energy gradients for time-dependent self-consistent field methods with polarizable solvent effects. Linear response, vertical excitation, and state-specific solventmodels are examined. Enforcing a variational ground stateenergy expression in the state-specific model is found to reduce it to the vertical excitation model. Variational excited state energy expressions are then provided for the linear response and vertical excitation models and analytical gradients are formulated. Using semiempiricalmodel chemistry, the variational expressions are verified by numerical and analytical differentiation with respect to a static external electric field. Lastly, analytical gradients are further tested by performingmore » microcanonical excited state molecular dynamics with p-nitroaniline.« less

  9. Solvent effects in time-dependent self-consistent field methods. II. Variational formulations and analytical gradients

    SciTech Connect (OSTI)

    Bjorgaard, J. A.; Velizhanin, K. A.; Tretiak, S.

    2015-08-06

    This study describes variational energy expressions and analytical excited state energy gradients for time-dependent self-consistent field methods with polarizable solvent effects. Linear response, vertical excitation, and state-specific solventmodels are examined. Enforcing a variational ground stateenergy expression in the state-specific model is found to reduce it to the vertical excitation model. Variational excited state energy expressions are then provided for the linear response and vertical excitation models and analytical gradients are formulated. Using semiempiricalmodel chemistry, the variational expressions are verified by numerical and analytical differentiation with respect to a static external electric field. Lastly, analytical gradients are further tested by performing microcanonical excited state molecular dynamics with p-nitroaniline.

  10. PROPERTIES OF M31. III. CANDIDATE BEAT CEPHEIDS FROM PS1 PANDROMEDA DATA AND THEIR IMPLICATION ON METALLICITY GRADIENT

    SciTech Connect (OSTI)

    Lee, C.-H.; Kodric, M.; Seitz, S.; Riffeser, A.; Koppenhoefer, J.; Bender, R.; Hopp, U.; Gssl, C.; Snigula, J.; Burgett, W. S.; Chambers, K. C.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Tonry, J. L.; Wainscoat, R. J.; Price, P. A.

    2013-11-01

    We present a sample of M31 beat Cepheids from the Pan-STARRS 1 PAndromeda campaign. By analyzing 3 years of PAndromeda data, we identify 17 beat Cepheids, spreading over a galactocentric distance of 10-16 kpc. Since the relation between the fundamental mode period and the ratio of the fundamental to the first overtone period places a tight constraint on metallicity, we are able to derive the metallicity at the position of the beat Cepheids using the relations from the model of Buchler. Our metallicity estimates show sub-solar values within 15 kpc, similar to the metallicities from H II regions. We then use the metallicity estimates to calculate the metallicity gradient of the M31 disk, which we find to be closer to the metallicity gradient derived from planetary nebula than the metallicity gradient from H II regions.

  11. Giant optical enhancement of strain gradient in ferroelectric BiFeO3 thin films and its physical origin

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

    Li, Yuelin; Adamo, C.; Chen, Pice; Evans, Paul G.; Nakhmanson, Serge M.; Parker, William; Rowland, Clare E.; Schaller, Richard D.; Schlom, Darrell G.; Walko, Donald A.; et al

    2015-11-20

    Through mapping of the spatiotemporal strain profile in ferroelectric BiFeO3 epitaxial thin films, we report an optically initiated dynamic enhancement of the strain gradient of 105–106 m-1 that lasts up to a few ns depending on the film thickness. Correlating with transient optical absorption measurements, the enhancement of the strain gradient is attributed to a piezoelectric effect driven by a transient screening field mediated by excitons. In conclusion, these findings not only demonstrate a new possible way of controlling the flexoelectric effect, but also reveal the important role of exciton dynamics in photostriction and photovoltaic effects in ferroelectrics.

  12. THE RADIAL METALLICITY GRADIENTS IN THE MILKY WAY THICK DISK AS FOSSIL SIGNATURES OF A PRIMORDIAL CHEMICAL DISTRIBUTION

    SciTech Connect (OSTI)

    Curir, A.; Serra, A. L.; Spagna, A.; Lattanzi, M. G.; Re Fiorentin, P.; Diaferio, A.

    2014-04-01

    In this Letter we examine the evolution of the radial metallicity gradient induced by secular processes, in the disk of an N-body Milky Way-like galaxy. We assign a [Fe/H] value to each particle of the simulation according to an initial, cosmologically motivated, radial chemical distribution and let the disk dynamically evolve for ∼6 Gyr. This direct approach allows us to take into account only the effects of dynamical evolution and to gauge how and to what extent they affect the initial chemical conditions. The initial [Fe/H] distribution increases with R in the inner disk up to R ≈ 10 kpc and decreases for larger R. We find that the initial chemical profile does not undergo major transformations after ∼6 Gyr of dynamical evolution. The final radial chemical gradients predicted by the model in the solar neighborhood are positive and of the same order as those recently observed in the Milky Way thick disk. We conclude that (1) the spatial chemical imprint at the time of disk formation is not washed out by secular dynamical processes and (2) the observed radial gradient may be the dynamical relic of a thick disk originated from a stellar population showing a positive chemical radial gradient in the inner regions.

  13. Assessment of plasma impedance probe for measuring electron density and collision frequency in a plasma with spatial and temporal gradients

    SciTech Connect (OSTI)

    Hopkins, Mark A. King, Lyon B.

    2014-05-15

    Numerical simulations and experimental measurements were combined to determine the ability of a plasma impedance probe (PIP) to measure plasma density and electron collision frequency in a plasma containing spatial gradients as well as time-varying oscillations in the plasma density. A PIP is sensitive to collision frequency through the width of the parallel resonance in the Re[Z]-vs.-frequency characteristic, while also being sensitive to electron density through the zero-crossing of the Im[Z]-vs.-frequency characteristic at parallel resonance. Simulations of the probe characteristic in a linear plasma gradient indicated that the broadening of Re[Z] due to the spatial gradient obscured the broadening due to electron collision frequency, preventing a quantitative measurement of the absolute collision frequency for gradients considered in this study. Simulation results also showed that the PIP is sensitive to relative changes in electron collision frequency in a spatial density gradient, but a second broadening effect due to time-varying oscillations made collision frequency measurements impossible. The time-varying oscillations had the effect of causing multiple zero-crossings in Im[Z] at parallel resonance. Results of experiments and simulations indicated that the lowest-frequency zero-crossing represented the lowest plasma density in the oscillations and the highest-frequency zero-crossing represented the highest plasma density in the oscillations, thus the PIP probe was found to be an effective tool to measure both the average plasma density as well as the maximum and minimum densities due to temporal oscillations.

  14. Analytical energy gradient for the two-component normalized elimination of the small component method

    SciTech Connect (OSTI)

    Zou, Wenli; Filatov, Michael; Cremer, Dieter

    2015-06-07

    The analytical gradient for the two-component Normalized Elimination of the Small Component (2c-NESC) method is presented. The 2c-NESC is a Dirac-exact method that employs the exact two-component one-electron Hamiltonian and thus leads to exact Dirac spin-orbit (SO) splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000)]. The effect of spin-orbit coupling (SOC) on molecular geometries is analyzed utilizing the properties of the frontier orbitals and calculated SO couplings. It is shown that bond lengths can either be lengthened or shortened under the impact of SOC where in the first case the influence of low lying excited states with occupied antibonding orbitals plays a role and in the second case the jj-coupling between occupied antibonding and unoccupied bonding orbitals dominates. In general, the effect of SOC on bond lengths is relatively small (≤5% of the scalar relativistic changes in the bond length). However, large effects are found for van der Waals complexes Hg{sub 2} and Cn{sub 2}, which are due to the admixture of more bonding character to the highest occupied spinors.

  15. The effect of diffusion in internal gradients on nuclear magnetic resonance transverse relaxation measurements

    SciTech Connect (OSTI)

    Muncaci, S.; Ardelean, I.; Boboia, S.

    2013-11-13

    In the present work we study the internal gradient effects on diffusion attenuation of the echo train appearing in the well-known Carr-Purcell-Meiboom-Gill (CPMG) technique, extensively used for transverse relaxation measurements. Our investigations are carried out on two porous ceramics, prepared with the same amount of magnetic impurities (Fe{sub 2}O{sub 3}) but different pore sizes. It is shown that diffusion effects on the CPMG echo train attenuation are strongly influenced by the pore size for the same magnetic susceptibility of the two samples. The experimental results were compared with a theoretical model taking into account the limit of free or restricted diffusion on echo train attenuation. The NMR experiments were performed on water filled samples using a low-field NMR instrument. The porous ceramics were prepared using both the replica technique and the powder compression technique. Magnetic susceptibility measurements indicated close values of the susceptibility constant for the two samples whereas the SEM images indicated different pore sizes. The results reported here may have impact in the interpretation of NMR relaxation measurements of water in soils or concrete samples.

  16. Effect of the field gradient of an intense electromagnetic beam on electrons and atoms

    SciTech Connect (OSTI)

    Askaryan, G.A.

    1991-01-02

    It is demonstrated that the transverse inhomogeneity of a strong electromagnetic ray can exert a strong effect on electrons and atoms of a medium. Thus, if the wave frequency exceeds the proper frequency the electron oscillations (in a plasma or in atoms), the electrons or atoms will be forced-out of the ray field. At sub-resonance frequencies the particles will be pulled in, the force being especially large at resonance. As a result of this effect a rarefication or compression may occur in the ray or in the focus of the radiation; moreover the pressure gradient near the hole connecting the evacuated vessel with the atmosphere may be maintained and a channel conducting charged particles may be created in the medium. It is mentioned that a strong thermal, ionizing and separating effect of ray on the medium can be used for setting up wave guide conditions of propagation and for eliminating divergency of the ray (self-focusing). It is noted that hollow rays may ensure directed flow and ejection of the plasma along the ray axis for plasma transport and creation of plasma current conductors. The possibilities of acceleration and heating of plasma electrons by a modulated ray are indicated.

  17. 1983 temperature gradient and heat flow drilling project for the State of Washington

    SciTech Connect (OSTI)

    Korosec, M.A.

    1983-11-01

    During the Summer of 1983, a three-hole drilling program was carried out to collect temperature gradient and heat flow information near potential geothermal resource target areas. The general locations of the project areas are shown. The first hole, DNR 83-1, was located within the Green River valley northwest of Mount St. Helens. This site is near the Green River Soda Springs and along the projection of the Mount St. Helens - Elk Lake seismic zone. The other two holes were drilled near Mount Baker. Hole DNR 83-3 was sited about 1/4 km west of the Baker Hot Springs, 10.5 km east of Mount Baker, while hole DNR 83-5 was located along Rocky Creek in the Sulphur Creek Valley. The Rocky Creek hole is about 10 km south-southwest of the peak. Two other holes, DNR 83-2 and DNR 83-4, were located on the north side of the Sulphur Creek Valley. Both holes were abandoned at early stages of drilling because of deep overburden and severe caving problems. The sites were apparently located atop old landslide deposits.

  18. The 1983 Temperature Gradient and Heat Flow Drilling Project for the State of Washington

    SciTech Connect (OSTI)

    Korosec, Michael A.

    1983-11-01

    During the Summer of 1983, the Washington Division of Geology and Earth Resources carried out a three-hole drilling program to collect temperature gradient and heat flow information near potential geothermal resource target areas. The project was part of the state-coupled US Department of Energy Geothermal Program. Richardson Well Drilling of Tacoma, Washington was subcontracted through the State to perform the work. The general locations of the project areas are shown in figure 1. The first hole, DNR 83-1, was located within the Green River valley northwest of Mount St. Helens. This site is near the Green River Soda Springs and along the projection of the Mount St. Helens--Elk Lake seismic zone. The other two holes were drilled near Mount Baker. Hole DNR 83-3 was sited about 1/4 km west of the Baker Hot Springs, 10.5 km east of Mount Baker, while hole DNR 83-5 was located along Rocky Creek in the Sulphur Creek Valley. The Rocky Creek hole is about 10 km south-southwest of the peak. Two other holes, DNR 83-2 and DNR 83-4, were located on the north side of the Sulphur Creek Valley. Both holes were abandoned at early stages of drilling because of deep overburden and severe caving problems. The sites were apparently located atop old landslide deposits.

  19. The application of projected conjugate gradient solvers on graphical processing units

    SciTech Connect (OSTI)

    Lin, Youzuo; Renaut, Rosemary

    2011-01-26

    Graphical processing units introduce the capability for large scale computation at the desktop. Presented numerical results verify that efficiencies and accuracies of basic linear algebra subroutines of all levels when implemented in CUDA and Jacket are comparable. But experimental results demonstrate that the basic linear algebra subroutines of level three offer the greatest potential for improving efficiency of basic numerical algorithms. We consider the solution of the multiple right hand side set of linear equations using Krylov subspace-based solvers. Thus, for the multiple right hand side case, it is more efficient to make use of a block implementation of the conjugate gradient algorithm, rather than to solve each system independently. Jacket is used for the implementation. Furthermore, including projection from one system to another improves efficiency. A relevant example, for which simulated results are provided, is the reconstruction of a three dimensional medical image volume acquired from a positron emission tomography scanner. Efficiency of the reconstruction is improved by using projection across nearby slices.

  20. The VMC survey. XI. Radial stellar population gradients in the galactic globular cluster 47 Tucanae

    SciTech Connect (OSTI)

    Li, Chengyuan; De Grijs, Richard; Deng, Licai; Rubele, Stefano; Girardi, Leo; Gullieuszik, Marco; Wang, Chuchu; Bekki, Kenji; For, Bi-Qing; Cioni, Maria-Rosa L.; Clementini, Gisella; Emerson, Jim; Groenewegen, Martin A. T.; Guandalini, Roald; Marconi, Marcella; Ripepi, Vincenzo; Piatti, Andrs E.; Van Loon, Jacco Th. E-mail: grijs@pku.edu.cn

    2014-07-20

    We present a deep near-infrared color-magnitude diagram of the Galactic globular cluster 47 Tucanae, obtained with the Visible and Infrared Survey Telescope for Astronomy (VISTA) as part of the VISTA near-infrared Y, J, K{sub s} survey of the Magellanic System (VMC). The cluster stars comprising both the subgiant and red giant branches exhibit apparent, continuous variations in color-magnitude space as a function of radius. Subgiant branch stars at larger radii are systematically brighter than their counterparts closer to the cluster core; similarly, red-giant-branch stars in the cluster's periphery are bluer than their more centrally located cousins. The observations can very well be described by adopting an age spread of ?0.5 Gyr as well as radial gradients in both the cluster's helium abundance (Y) and metallicity (Z), which change gradually from (Y = 0.28, Z = 0.005) in the cluster core to (Y = 0.25, Z = 0.003) in its periphery. We conclude that the cluster's inner regions host a significant fraction of second-generation stars, which decreases with increasing radius; the stellar population in the 47 Tuc periphery is well approximated by a simple stellar population.

  1. Thermally-assisted-occupation density functional theory with generalized-gradient approximations

    SciTech Connect (OSTI)

    Chai, Jeng-Da

    2014-05-14

    We extend the recently proposed thermally-assisted-occupation density functional theory (TAO-DFT) [J.-D. Chai, J. Chem. Phys. 136, 154104 (2012)] to generalized-gradient approximation (GGA) exchange-correlation density functionals. Relative to our previous TAO-LDA (i.e., the local density approximation to TAO-DFT), the resulting TAO-GGAs are significantly superior for a wide range of applications, such as thermochemistry, kinetics, and reaction energies. For noncovalent interactions, TAO-GGAs with empirical dispersion corrections are shown to yield excellent performance. Due to their computational efficiency for systems with strong static correlation effects, TAO-LDA and TAO-GGAs are applied to study the electronic properties (e.g., the singlet-triplet energy gaps, vertical ionization potentials, vertical electron affinities, fundamental gaps, and symmetrized von Neumann entropy) of acenes with different number of linearly fused benzene rings (up to 100), which is very challenging for conventional electronic structure methods. The ground states of acenes are shown to be singlets for all the chain lengths studied here. With the increase of acene length, the singlet-triplet energy gaps, vertical ionization potentials, and fundamental gaps decrease monotonically, while the vertical electron affinities and symmetrized von Neumann entropy (i.e., a measure of polyradical character) increase monotonically.

  2. Zonal flows and ion temperature gradient instabilities in multiple-helicity magnetic fields

    SciTech Connect (OSTI)

    Ferrando-Margalet, S.; Sugama, H.; Watanabe, T.-H.

    2007-12-15

    The effects of multiple-helicity magnetic fields on the ion temperature gradient (ITG) instability and on the zonal flow (ZF) evolution are studied with the linear gyrokinetic Vlasov code GKV [T.-H. Watanabe and H. Sugama, Nucl. Fusion 46, 24 (2006)]. The model helical fields corresponding to the standard and inward-shifted axis configurations of the Large Helical Device [O. Motojima, N. Ohyabu, A. Komori et al., Nucl. Fusion 43, 1674 (2003)] are used to investigate how ITG mode properties and ZF evolution response to a given source are influenced by the field geometry. It is shown that, in the inward-shifted configuration, the ITG mode growth rate increases slightly while the ZF is sustained for a longer time. In addition, velocity-space structures of the ion perturbed distribution function are numerically obtained which illustrate the validity of the analytical prediction that the plasma inward shift retards the radial drift of the helically trapped particles leading to the enhancement of the ZF response. This supports the conjecture that anomalous transport can be reduced by the ZF generated in the configurations optimized to decrease the neoclassical transport.

  3. High voltage RF feedthrough bushing

    DOE Patents [OSTI]

    Grotz, Glenn F.

    1984-01-01

    Described is a multi-element, high voltage radio frequency bushing for trmitting RF energy to an antenna located in a vacuum container. The bushing includes a center conductor of complex geometrical shape, an outer coaxial shield conductor, and a thin-walled hollow truncated cone insulator disposed between central and outer conductors. The shape of the center conductor, which includes a reverse curvature portion formed of a radially inwardly directed shoulder and a convex portion, controls the uniformity of the axial surface gradient on the insulator cone. The outer shield has a first substantially cylindrical portion and a second radially inwardly extending truncated cone portion.

  4. Gradient Analysis and Classification of Carolina Bay Vegetation: A Framework for Bay Wetlands Conservation and Restoration

    SciTech Connect (OSTI)

    Diane De Steven,Ph.D.; Maureen Tone,PhD.

    1997-10-01

    This report address four project objectives: (1) Gradient model of Carolina bay vegetation on the SRS--The authors use ordination analyses to identify environmental and landscape factors that are correlated with vegetation composition. Significant factors can provide a framework for site-based conservation of existing diversity, and they may also be useful site predictors for potential vegetation in bay restorations. (2) Regional analysis of Carolina bay vegetation diversity--They expand the ordination analyses to assess the degree to which SRS bays encompass the range of vegetation diversity found in the regional landscape of South Carolina's western Upper Coastal Plain. Such comparisons can indicate floristic status relative to regional potentials and identify missing species or community elements that might be re-introduced or restored. (3) Classification of vegetation communities in Upper Coastal Plain bays--They use cluster analysis to identify plant community-types at the regional scale, and explore how this classification may be functional with respect to significant environmental and landscape factors. An environmentally-based classification at the whole-bay level can provide a system of templates for managing bays as individual units and for restoring bays to desired plant communities. (4) Qualitative model for bay vegetation dynamics--They analyze present-day vegetation in relation to historic land uses and disturbances. The distinctive history of SRS bays provides the possibility of assessing pathways of post-disturbance succession. They attempt to develop a coarse-scale model of vegetation shifts in response to changing site factors; such qualitative models can provide a basis for suggesting management interventions that may be needed to maintain desired vegetation in protected or restored bays.

  5. The double-gradient magnetic instability: Stabilizing effect of the guide field

    SciTech Connect (OSTI)

    Korovinskiy, D. B. Semenov, V. S.; Ivanova, V. V.; Divin, A. V.; Erkaev, N. V.; Artemyev, A. V.; Lapenta, G.; Markidis, S.; Biernat, H. K.

    2015-01-15

    The role of the dawn-dusk magnetic field component in stabilizing of the magnetotail flapping oscillations is investigated in the double-gradient model framework (Erkaev et al., Phys. Rev. Lett. 99, 235003 (2007)), extended for the magnetotail-like configurations with non-zero guide field B{sub y}. Contribution of the guide field is examined both analytically and by means of linearized 2-dimensional (2D) and non-linear 3-dimensional (3D) MHD modeling. All three approaches demonstrate the same properties of the instability: stabilization of current sheet oscillations for short wavelength modes, appearing of the typical (fastest growing) wavelength λ{sub peak} of the order of the current sheet width, decrease of the peak growth rate with increasing B{sub y} value, and total decay of the mode for B{sub y}∼0.5 in the lobe magnetic field units. Analytical solution and 2D numerical simulations claim also the shift of λ{sub peak} toward the longer wavelengths with increasing guide field. This result is barely visible in 3D simulations. It may be accounted for the specific background magnetic configuration, the pattern of tail-like equilibrium provided by approximated solution of the conventional Grad-Shafranov equation. The configuration demonstrates drastically changing radius of curvature of magnetic field lines, R{sub c}. This, in turn, favors the “double-gradient” mode (λ > R{sub c}) in one part of the sheet and classical “ballooning” instability (λ < R{sub c}) in another part, which may result in generation of a “combined” unstable mode.

  6. Geothermal Resource/Reservoir Investigations Based on Heat Flow and Thermal Gradient Data for the United States

    SciTech Connect (OSTI)

    D. D. Blackwell; K. W. Wisian; M. C. Richards; J. L. Steele

    2000-04-01

    Several activities related to geothermal resources in the western United States are described in this report. A database of geothermal site-specific thermal gradient and heat flow results from individual exploration wells in the western US has been assembled. Extensive temperature gradient and heat flow exploration data from the active exploration of the 1970's and 1980's were collected, compiled, and synthesized, emphasizing previously unavailable company data. Examples of the use and applications of the database are described. The database and results are available on the world wide web. In this report numerical models are used to establish basic qualitative relationships between structure, heat input, and permeability distribution, and the resulting geothermal system. A series of steady state, two-dimensional numerical models evaluate the effect of permeability and structural variations on an idealized, generic Basin and Range geothermal system and the results are described.

  7. High Energy Density Microwaves

    SciTech Connect (OSTI)

    Phillips, R.M. [Stanford Linear Accelerator Center, Stanford, CA 94309 (United States)

    1999-04-01

    These proceedings represent papers presented at the RF98 Workshop entitled `High Energy Density Microwaves` held in California in October, 1998. The topics discussed were predominantly accelerator{minus}related. The Workshop dealt, for the most part, with the generation and control of electron beams, the amplification of RF signals, the design of mode converters, and the effect of very high RF field gradients. This Workshop was designed to address the concerns of the microwave tube industry worldwide, the plasma physicists who deal with very high beam currents and gigawatts of RF power, and researchers in accelerator centers around the world. Papers were presented on multibeam klystrons, gyrotron development, plasmas in microwave tubes, RF breakdown, and alternatives to conventional linear coliders at 1 TeV and above. The Workshop was partially sponsored by the US Department of Energy. There were 46 papers presented at the conference,out of which 19 have been abstracted for the Energy,Science and Technology database.(AIP)

  8. Laser-Doppler acoustic probing of granular media with in-depth property gradient and varying pore pressures

    SciTech Connect (OSTI)

    Bodet, L.; Dhemaied, A.; Mourgues, R.; Tournat, V.; Rejiba, F.

    2012-05-24

    Non-contacting ultrasonic techniques recently proved to be efficient in the physical modeling of seismic-wave propagation at various application scales, as for instance in the context of geological analogue and seismic modeling. An innovative experimental set-up is proposed here to perform laser-Doppler acoustic probing of unconsolidated granular media with varying pore pressures. The preliminary experiments presented here provide reproducible results and exploitable data, thus validating both the proposed medium preparation and pressure gradient generation procedure.

  9. A three-colour graph as acomplete topological invariant for gradient-like diffeomorphisms of surfaces

    SciTech Connect (OSTI)

    Grines, V Z; Pochinka, O V; Kapkaeva, S Kh

    2014-10-31

    In apaper of Oshemkov and Sharko, three-colour graphs were used to make the topological equivalence of Morse-Smale flows on surfaces obtained by Peixoto more precise. In the present paper, in the language of three-colour graphs equipped with automorphisms, we obtain acomplete (including realization) topological classification of gradient-like cascades on surfaces. Bibliography: 25 titles.

  10. SU-E-T-262: Planning for Proton Pencil Beam Scanning (PBS): Applications of Gradient Optimization for Field Matching

    SciTech Connect (OSTI)

    Lin, H; Kirk, M; Zhai, H; Ding, X; Liu, H; Hill-Kayser, C; Lustig, R; Tochner, Z; Deville, C; Vapiwala, N; McDonough, J; Both, S

    2014-06-01

    Purpose: To propose the gradient optimization(GO) approach in planning for matching proton PBS fields and present two commonly used applications in our institution. Methods: GO is employed for PBS field matching in the scenarios that when the size of the target is beyond the field size limit of the beam delivery system or matching is required for beams from different angles to either improve the sparing of important organs or to pass through a short and simple beam path. Overlap is designed between adjacent fields and in the overlapped junction, the dose was optimized such that it gradually decreases in one field and the decrease is compensated by increase from another field. Clinical applications of this approach on craniospinal irradiation(CSI) and whole pelvis treatment were presented. Mathematical model was developed to study the relationships between dose errors, setup errors and junction lengths. Results: Uniform and conformal dose coverage to the entire target volumes was achieved for both applications using GO approach. For CSI, the gradient matching (6.7cm junction) between fields overcame the complexity of planning associated with feathering match lines. A slow dose gradient in the junction area significantly reduced the sensitivity of the treatment to setup errors. For whole pelvis, gradient matching (4cm junction) between posterior fields for superior target and bilateral fields for inferior target provided dose sparing to organs such as bowel, bladder and rectum. For a setup error of 3 mm in longitudinal direction from one field, mathematical model predicted dose errors of 10%, 6% and 4.3% for junction length of 3, 5 and 7cm. Conclusion: This GO approach improves the quality of the PBS treatment plan with matching fields while maintaining the safety of treatment delivery relative to potential misalignments.

  11. High-Intensity Proton Accelerator

    SciTech Connect (OSTI)

    Jay L. Hirshfield

    2011-12-27

    Analysis is presented for an eight-cavity proton cyclotron accelerator that could have advantages as compared with other accelerators because of its potentially high acceleration gradient. The high gradient is possible since protons orbit in a sequence of TE111 rotating mode cavities of equally diminishing frequencies with path lengths during acceleration that greatly exceed the cavity lengths. As the cavities operate at sequential harmonics of a basic repetition frequency, phase synchronism can be maintained over a relatively wide injection phase window without undue beam emittance growth. It is shown that use of radial vanes can allow cavity designs with significantly smaller radii, as compared with simple cylindrical cavities. Preliminary beam transport studies show that acceptable extraction and focusing of a proton beam after cyclic motion in this accelerator should be possible. Progress is also reported on design and tests of a four-cavity electron counterpart accelerator for experiments to study effects on beam quality arising from variations injection phase window width. This device is powered by four 500-MW pulsed amplifiers at 1500, 1800, 2100, and 2400 MHz that provide phase synchronous outputs, since they are driven from a with harmonics derived from a phase-locked 300 MHz source.

  12. LIAR -- A computer program for the modeling and simulation of high performance linacs

    SciTech Connect (OSTI)

    Assmann, R.; Adolphsen, C.; Bane, K.; Emma, P.; Raubenheimer, T.; Siemann, R.; Thompson, K.; Zimmermann, F.

    1997-04-01

    The computer program LIAR (LInear Accelerator Research Code) is a numerical modeling and simulation tool for high performance linacs. Amongst others, it addresses the needs of state-of-the-art linear colliders where low emittance, high-intensity beams must be accelerated to energies in the 0.05-1 TeV range. LIAR is designed to be used for a variety of different projects. LIAR allows the study of single- and multi-particle beam dynamics in linear accelerators. It calculates emittance dilutions due to wakefield deflections, linear and non-linear dispersion and chromatic effects in the presence of multiple accelerator imperfections. Both single-bunch and multi-bunch beams can be simulated. Several basic and advanced optimization schemes are implemented. Present limitations arise from the incomplete treatment of bending magnets and sextupoles. A major objective of the LIAR project is to provide an open programming platform for the accelerator physics community. Due to its design, LIAR allows straight-forward access to its internal FORTRAN data structures. The program can easily be extended and its interactive command language ensures maximum ease of use. Presently, versions of LIAR are compiled for UNIX and MS Windows operating systems. An interface for the graphical visualization of results is provided. Scientific graphs can be saved in the PS and EPS file formats. In addition a Mathematica interface has been developed. LIAR now contains more than 40,000 lines of source code in more than 130 subroutines. This report describes the theoretical basis of the program, provides a reference for existing features and explains how to add further commands. The LIAR home page and the ONLINE version of this manual can be accessed under: http://www.slac.stanford.edu/grp/arb/rwa/liar.htm.

  13. Town of Wakefield, Massachusetts (Utility Company) | Open Energy...

    Open Energy Info (EERE)

    - File1a1 EIA Form 861 Data Utility Id 19979 Utility Location Yes Ownership M NERC Location NPCC NERC NPCC Yes Activity Buying Transmission Yes Activity Distribution Yes...

  14. Results From Plasma Wakefield Acceleration Experiments at FACET...

    Office of Scientific and Technical Information (OSTI)

    Resource Relation: Journal Name: Conf.Proc.C110904:2814-2816,2011; Conference: Presented at the 2nd International Particle Accelerator Conference (IPAC-2011), San Sebastian, Spain, ...

  15. Mesurement of the Decelerating Wake in a Plasma Wakefield Accelerator...

    Office of Scientific and Technical Information (OSTI)

    Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 43 PARTICLE ACCELERATORS; ACCELERATION; ACCELERATORS; ELECTRON BEAMS; ELECTRONS; METERS; ...

  16. Emittance and Current of Electrons Trapped in a Plasma Wakefield...

    Office of Scientific and Technical Information (OSTI)

    Research Org: Stanford Linear Accelerator Center (SLAC) Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 43 PARTICLE ACCELERATORS; ...

  17. Beam Matching to a Plasma Wakefield Accelerator Using a Ramped...

    Office of Scientific and Technical Information (OSTI)

    ... Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 43 PARTICLE ACCELERATORS; ACCELERATORS; BETATRON OSCILLATIONS; FOCUSING; PLASMA; STANFORD ...

  18. Beam Matching to a Plasma Wakefield Accelerator Using a Ramped...

    Office of Scientific and Technical Information (OSTI)

    Sponsoring Org: USDOE Country of Publication: United States Language: English Subject: 43 PARTICLE ACCELERATORS; ACCELERATORS; BETATRON OSCILLATIONS; FOCUSING; PLASMA; STANFORD ...

  19. Emittance and Current of Electrons Trapped in a Plasma Wakefield...

    Office of Scientific and Technical Information (OSTI)

    Publication Date: 2008-09-24 OSTI Identifier: 938639 Report Number(s): SLAC-PUB-13389 TRN: ... Concepts Workshop (AAC08), Santa Cruz, California, 27 Jul - 2 Aug 2008 Research ...

  20. Mesurement of the Decelerating Wake in a Plasma Wakefield Accelerator...

    Office of Scientific and Technical Information (OSTI)

    Publication Date: 2008-09-24 OSTI Identifier: 938638 Report Number(s): SLAC-PUB-13390 TRN: ... Concepts Workshop (AAC08), Santa Cruz, California, 27 Jul - 2 Aug 2008 Research ...

  1. Latest Plasma Wakefield Acceleration Results from the FACET Project...

    Office of Scientific and Technical Information (OSTI)

    Resource Relation: Conference: Invited paper at the North American Particle Accelerator Conference (PAC 2013), 29 Sep - 4 Oct 2013, Pasadena, CA, USA Research Org: SLAC National ...

  2. Results From Plasma Wakefield Acceleration Experiments at FACET...

    Office of Scientific and Technical Information (OSTI)

    International Particle Accelerator Conference (IPAC-2011), San Sebastian, Spain, 4-9 Sep 2011 Research Org: SLAC National Accelerator Laboratory (SLAC) Sponsoring Org: US DOE ...

  3. Dispersion in the Presence of Strong Transverse Wakefields (Conference...

    Office of Scientific and Technical Information (OSTI)

    Science, Technology and Applications, 12-16 May 1997, Vancouver, British Columbia, Canada Research Org: SLAC National Accelerator Laboratory (SLAC) Sponsoring Org: USDOE ...

  4. Dispersion in the Presence of Strong Transverse Wakefields (Conference...

    Office of Scientific and Technical Information (OSTI)

    Resource Type: Conference Resource Relation: Journal Name: Conf.Proc.C970512:1523,1997; Conference: 17th IEEE Particle Accelerator Conference (PAC 97): Accelerator Science, ...

  5. Meter Scale Plasma Source for Plasma Wakefield Experiments (Journal...

    Office of Scientific and Technical Information (OSTI)

    Subject: Accelerators,ACCPHY Word Cloud More Like This Full Text Journal Articles Find in Google Scholar Find in Google Scholar Search WorldCat Search WorldCat to find libraries ...

  6. Modeling Laser Wakefield Accelerators in a Lorentz Boosted Frame

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

    Lorentz Boosted Frame VayBoost.gif An image showing the "boosted frame," in which the observer moves at near light speed. The laser pulse is represented in blue and red; the...

  7. Topological characterization of the transition from laminar regime to fully developed turbulence in the resistive pressure-gradient-driven turbulence model

    SciTech Connect (OSTI)

    Garcia, L.; Carreras, B. A.; Llerena, I.; Calvo, I. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes, Madrid (Spain); Departament d'Algebra i Geometria, Facultat de Matematiques, Universitat de Barcelona, Barcelona (Spain); Laboratorio Nacional de Fusion, Asociacion EURATOM-CIEMAT, 28040 Madrid (Spain)

    2009-10-15

    For the resistive pressure-gradient-driven turbulence model, the transition from laminar regime to fully developed turbulence is not simple and goes through several phases. For low values of the plasma parameter {beta}, a single quasicoherent structure forms. As {beta} increases, several of these structures may emerge and in turn take the dominant role. Finally, at high {beta}, fully developed turbulence with a broad spectrum is established. A suitable characterization of this transition can be given in terms of topological properties of the flow. Here, we analyze these properties that provide an understanding of the turbulence-induced transport and give a measure of the breaking of the homogeneity of the turbulence. To this end, an approach is developed that allows discriminating between topological properties of plasma turbulence flows that are relevant to the transport dynamics and the ones that are not. This is done using computational homology tools and leads to a faster convergence of numerical results for a fixed level of resolution than previously presented in Phys. Rev. E 78, 066402 (2008)

  8. TV-based conjugate gradient method and discrete L-curve for few-view CT reconstruction of X-ray in vivo data

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

    Yang, Xiaoli; Hofmann, Ralf; Dapp, Robin; van de Kamp, Thomas; Rolo, Tomy dos Santos; Xiao, Xianghui; Moosmann, Julian; Kashef, Jubin; Stotzka, Rainer

    2015-01-01

    High-resolution, three-dimensional (3D) imaging of soft tissues requires the solution of two inverse problems: phase retrieval and the reconstruction of the 3D image from a tomographic stack of two-dimensional (2D) projections. The number of projections per stack should be small to accommodate fast tomography of rapid processes and to constrain X-ray radiation dose to optimal levels to either increase the duration o fin vivo time-lapse series at a given goal for spatial resolution and/or the conservation of structure under X-ray irradiation. In pursuing the 3D reconstruction problem in the sense of compressive sampling theory, we propose to reduce the numbermoreof projections by applying an advanced algebraic technique subject to the minimisation of the total variation (TV) in the reconstructed slice. This problem is formulated in a Lagrangian multiplier fashion with the parameter value determined by appealing to a discrete L-curve in conjunction with a conjugate gradient method. The usefulness of this reconstruction modality is demonstrated for simulated and in vivo data, the latter acquired in parallel-beam imaging experiments using synchrotron radiation.less

  9. TV-based conjugate gradient method and discrete L-curve for few-view CT reconstruction of X-ray in vivo data

    SciTech Connect (OSTI)

    Yang, Xiaoli; Hofmann, Ralf; Dapp, Robin; van de Kamp, Thomas; Rolo, Tomy dos Santos; Xiao, Xianghui; Moosmann, Julian; Kashef, Jubin; Stotzka, Rainer

    2015-01-01

    High-resolution, three-dimensional (3D) imaging of soft tissues requires the solution of two inverse problems: phase retrieval and the reconstruction of the 3D image from a tomographic stack of two-dimensional (2D) projections. The number of projections per stack should be small to accommodate fast tomography of rapid processes and to constrain X-ray radiation dose to optimal levels to either increase the duration of in vivo time-lapse series at a given goal for spatial resolution and/or the conservation of structure under X-ray irradiation. In pursuing the 3D reconstruction problem in the sense of compressive sampling theory, we propose to reduce the number of projections by applying an advanced algebraic technique subject to the minimisation of the total variation (TV) in the reconstructed slice. This problem is formulated in a Lagrangian multiplier fashion with the parameter value determined by appealing to a discrete L-curve in conjunction with a conjugate gradient method. The usefulness of this reconstruction modality is demonstrated for simulated and in vivo data, the latter acquired in parallel-beam imaging experiments using synchrotron radiation. (C) 2015 Optical Society of America

  10. Nonlinear electronic excitations in crystalline solids using meta-generalized gradient approximation and hybrid functional in time-dependent density functional theory

    SciTech Connect (OSTI)

    Sato, Shunsuke A.; Taniguchi, Yasutaka; Shinohara, Yasushi; Yabana, Kazuhiro

    2015-12-14

    We develop methods to calculate electron dynamics in crystalline solids in real-time time-dependent density functional theory employing exchange-correlation potentials which reproduce band gap energies of dielectrics; a meta-generalized gradient approximation was proposed by Tran and Blaha [Phys. Rev. Lett. 102, 226401 (2009)] (TBm-BJ) and a hybrid functional was proposed by Heyd, Scuseria, and Ernzerhof [J. Chem. Phys. 118, 8207 (2003)] (HSE). In time evolution calculations employing the TB-mBJ potential, we have found it necessary to adopt the predictor-corrector step for a stable time evolution. We have developed a method to evaluate electronic excitation energy without referring to the energy functional which is unknown for the TB-mBJ potential. For the HSE functional, we have developed a method for the operation of the Fock-like term in Fourier space to facilitate efficient use of massive parallel computers equipped with graphic processing units. We compare electronic excitations in silicon and germanium induced by femtosecond laser pulses using the TB-mBJ, HSE, and a simple local density approximation (LDA). At low laser intensities, electronic excitations are found to be sensitive to the band gap energy: they are close to each other using TB-mBJ and HSE and are much smaller in LDA. At high laser intensities close to the damage threshold, electronic excitation energies do not differ much among the three cases.

  11. The role of composition and microstructure gradients on weld metal properties and behavior: Progress report, 1 January 1988--31 December 1988

    SciTech Connect (OSTI)

    Matlock, D.K.; Olson, D.L.

    1989-01-01

    The effects of weld metal compositional and microstructural gradients on phase transformation, microstructural stability, and mechanical properties are considered from a fundamental basis in weld metal alloys which are primarily austenitic (e.g., stainless steels). Models which incorporate compositional gradients are developed to predict the resulting weld metal properties and behavior. The mechanical properties of weld metal are modeled based on composite theory in which individual weld metal zones are considered as discrete elements within a composite structure. 17 refs., 28 figs.

  12. A comparison of conjugate gradient, SIP, and other iterative methods for the solution of Poisson's equation with irregular boundary conditions

    SciTech Connect (OSTI)

    Bergmann, D.J.

    1990-06-01

    Several well known iterative methods for solving Poisson's equation, including Strongly Implicit Procedure and several preconditioned conjugate gradient methods are first applied to a problem with simple boundary conditions and a known solution. Then a problem with more complicated boundary conditions, similar to those encountered when modeling AVLIS plasmas, is solved. Differences in the solutions of the various methods are examined through the use of Fourier analysis. It was found that combinations of different iterative schemes will in some cases be the most efficient method of solution. 22 refs., 29 figs.

  13. Microfluidic device having an immobilized pH gradient and PAGE gels for protein separation and analysis

    DOE Patents [OSTI]

    Sommer, Gregory J.; Hatch, Anson V.; Singh, Anup K.; Wang, Ying-Chih

    2012-12-11

    Disclosed is a novel microfluidic device enabling on-chip implementation of a two-dimensional separation methodology. Previously disclosed microscale immobilized pH gradients (IPG) are combined with perpendicular polyacrylamide gel electrophoresis (PAGE) microchannels to achieve orthogonal separations of biological samples. Device modifications enable inclusion of sodium dodecyl sulfate (SDS) in the second dimension. The device can be fabricated to use either continuous IPG gels, or the microscale isoelectric fractionation membranes we have also previously disclosed, for the first dimension. The invention represents the first all-gel two-dimensional separation microdevice, with significantly higher resolution power over existing devices.

  14. Microfluidic device having an immobilized pH gradient and page gels for protein separation and analysis

    DOE Patents [OSTI]

    Sommer, Gregory J; Hatch, Anson V; Singh, Anup K; Wang, Ying-Chih

    2014-05-20

    Disclosed is a novel microfluidic device enabling on-chip implementation of a two-dimensional separation methodology. Previously disclosed microscale immobilized pH gradients (IPG) are combined with perpendicular polyacrylamide gel electrophoresis (PAGE) microchannels to achieve orthogonal separations of biological samples. Device modifications enable inclusion of sodium dodecyl sulfate (SDS) in the second dimension. The device can be fabricated to use either continuous IPG gels, or the microscale isoelectric fractionation membranes we have also previously disclosed, for the first dimension. The invention represents the first all-gel two-dimensional separation microdevice, with significantly higher resolution power over existing devices.

  15. Effect of electron-density gradients on propagation of radio waves in the mid-latitude trough. Master's thesis

    SciTech Connect (OSTI)

    Citrone, P.J.

    1991-01-01

    Partial contents of this thesis include: (1) Radio-wave propagation and the mid-latitude trough; (2) Ionospheric measurements; (3) Modification of time-dependent ionospheric model output with latitudinal electron-density profiles from digisonde trough depictions; (4) Ray-tracing simulations to examine ground range; and (5) Effects of three-dimensional gradients in electron density on radio-wave propagation in the trough region. Data is tabulated for geophysical conditions, solar activity level, geomagnetic activity level, conditions for vertical ray refraction to surface, and ray-tracing fixed-input conditions.

  16. Novel concepts in weld metal science: Role of gradients and composite structure. Annual technical progress report, January 1, 1991--December 31, 1991

    SciTech Connect (OSTI)

    Matlock, D.K.; Olson, D.L.

    1991-12-01

    The effects of compositional and microstructural gradients on weld metal properties are being investigated. Crack propagation is solidified alloy structures is being characterized as to solidification orientation and the profile of the compositional variations. The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a compositional gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Special techniques to produce laboratory samples with microstructures which simulate the composition and microstructure gradients in solidified weld metal are used, along with appropriate mathematical models, to evaluate the properties of the composite weld metals. The composite modeling techniques are being applied to describe the effects of compositional and microstructural gradients on weld metal properties in Ni-Cu alloys. The development of metal matrix composition weld deposits on austenitic stainless steels has been studied. The particulate metal matrix composites were produced with ceramic or refractory metal powder filled cored wire, which was gas tungsten arc and gas metal arc welded.

  17. Gradient Meshed and Toughened SOEC (Solid Oxide Electrolyzer Cell) Composite Seal with Self-Healing Capabilities

    SciTech Connect (OSTI)

    Kathy Lu; W. T. Reynolds, Jr.

    2010-06-08

    High-temperature electrolysis of water steam is a promising approach for hydrogen production. The potential is even more promising when abundant heat source from nuclear power reactors can be efficiently utilized. Hydrogen production through the above approach also allows for low electric consumption. Overall energy conversion efficiencies for high temperature electrolysis are in the 45-50% range compared to ~30% for the conventional electrolysis. Under such motivation, this research is focused on increasing the operation time and high temperature stability of solid oxide electrolyzer cells (SOEC) for splitting water into hydrogen. Specifically, our focus is to improve the SOEC seal thermal stability and performances by alleviating thermal stress and seal cracking issues.

  18. Coupling of ion temperature gradient and trapped electron modes in the presence of impurities in tokamak plasmas

    SciTech Connect (OSTI)

    Du, Huarong; Wang, Zheng-Xiong, E-mail: zxwang@dlut.edu.cn [MOE Key Laboratory of Materials Modification by Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [MOE Key Laboratory of Materials Modification by Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Dong, J. Q. [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China) [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Southwestern Institute of Physics, Chengdu 610041 (China); Liu, S. F. [School of Physics, Nankai University, Tianjin 300071 (China)] [School of Physics, Nankai University, Tianjin 300071 (China)

    2014-05-15

    The coupling of ion temperature gradient (ITG or ?{sub i}) mode and trapped electron mode (TEM) in the presence of impurity ions is numerically investigated in toroidal collisionless plasmas, using the gyrokinetic integral eigenmode equation. A framework for excitations of the ITG modes and TEMs with respect to their driving sources is formulated first, and then the roles of impurity ions played in are analyzed comprehensively. In particular, the characteristics of the ITG and TEM instabilities in the presence of impurity ions are emphasized for both strong and weak coupling (hybrid and coexistent) cases. It is found that the impurity ions with inwardly (outwardly) peaked density profiles have stabilizing (destabilizing) effects on the hybrid (namely the TE-ITG) modes in consistence with previous works. A new finding of this work is that the impurity ions have stabilizing effects on TEMs in small ?{sub i} (?{sub i}?1) regime regardless of peaking directions of their density profiles whereas the impurity ions with density gradient L{sub ez}=L{sub ne}/L{sub nz}>1 (L{sub ez}<1) destabilize (stabilize) the TEMs in large ?{sub i} (?{sub i}?1) regime. In addition, the dependences of the growth rate, real frequency, eigenmode structure, and wave spectrum on charge concentration, charge number, and mass of impurity ions are analyzed in detail. The necessity for taking impurity ion effects on the features of turbulence into account in future transport experimental data analyses is also discussed.

  19. Molecular quantum mechanical gradients within the polarizable embedding approach—Application to the internal vibrational Stark shift of acetophenone

    SciTech Connect (OSTI)

    List, Nanna Holmgaard Jensen, Hans Jørgen Aagaard; Kongsted, Jacob; Beerepoot, Maarten T. P.; Gao, Bin; Ruud, Kenneth; Olsen, Jógvan Magnus Haugaard

    2015-01-21

    We present an implementation of analytical quantum mechanical molecular gradients within the polarizable embedding (PE) model to allow for efficient geometry optimizations and vibrational analysis of molecules embedded in large, geometrically frozen environments. We consider a variational ansatz for the quantum region, covering (multiconfigurational) self-consistent-field and Kohn–Sham density functional theory. As the first application of the implementation, we consider the internal vibrational Stark effect of the C=O group of acetophenone in different solvents and derive its vibrational linear Stark tuning rate using harmonic frequencies calculated from analytical gradients and computed local electric fields. Comparisons to PE calculations employing an enlarged quantum region as well as to a non-polarizable embedding scheme show that the inclusion of mutual polarization between acetophenone and water is essential in order to capture the structural modifications and the associated frequency shifts observed in water. For more apolar solvents, a proper description of dispersion and exchange–repulsion becomes increasingly important, and the quality of the optimized structures relies to a larger extent on the quality of the Lennard-Jones parameters.

  20. Heat flow and geothermal gradients of Irian Jaya-Papua New Guinea: Implications for regional hydrocarbon exploration

    SciTech Connect (OSTI)

    Bettis, P.K. ); Pigott, J.D. )

    1990-06-01

    Compilation of published and unpublished bottom hole temperatures (corrected for circulation times) obtained from open files and reports of the Indonesian Petroleum Association, Papua Geologic Survey, and the Southeast Asia Petroleum Society, together with published oceanographic heat flow analyses from the surrounding seas, allow an analysis of the regional heat flow and geothermal gradients of New Guinea. In two dimensions the thermal trends may be described as a pervasive west-northwest striking Cordilleran core of cool (<1 HFU-<2{degree}C/ 100 m) strata surrounded by warm to hotter regions (>2 HFU->4{degree}C/100 m) on the northwest, northeast, east, and southwest. As a first approximation, the heat flow may be viewed as directly proportional to the crustal thickness (as demonstrated from north-south transects across the Central Cordillera), inversely proportional to the age of the ocean crust (offshore), and perturbed by crustal heterogeneities proximal to plate boundaries (e.g., the Northern New Guinea Fault System). As a result, the heat flow distribution affords a record of post-Cretaceous tectonic activities of New Guinea. Using the spatial distribution of geothermal gradients and specific source rock ages, kinetic calculations of hydrocarbon maturities confirmed by recent drilling results suggest thermal variations through space and time that cannot be modeled simply as a function of present day static temperatures. Therefore, in terms of utilizing the present thermal information, hydrocarbon basin exploration strategies must also take into account the tectonically perturbed heat flow history of the region.

  1. Electromagnetic drift instabilities in high-beta plasma under conditions of a field reversed configuration

    SciTech Connect (OSTI)

    Chirkov, A. Yu.; Khvesyuk, V. I.

    2010-01-15

    Electromagnetic drift instabilities are studied in the conditions of a field reversed configuration (FRC). Dispersion equation is based on the set of Vlasov-Maxwell equations taking into account nonadiabatic responses both of ions and electrons. Considered drift instabilities are caused by density and temperature gradients. It is assumed that magnetic field of the FRC is purely poloidal. Two kinds of magnetic field nonuniformity are considered: (i) perpendicular gradient due to high beta values (beta is the plasma pressure/magnetic pressure) and (ii) curvature of magnetic lines. There is low frequency drift instability existing for high-beta regimes. Modes of such instability can propagate transversally to the unperturbed magnetic field lines.

  2. High-Temperature High-Efficiency Solar Thermoelectric Generators

    SciTech Connect (OSTI)

    Baranowski, LL; Warren, EL; Toberer, ES

    2014-03-01

    Inspired by recent high-efficiency thermoelectric modules, we consider thermoelectrics for terrestrial applications in concentrated solar thermoelectric generators (STEGs). The STEG is modeled as two subsystems: a TEG, and a solar absorber that efficiently captures the concentrated sunlight and limits radiative losses from the system. The TEG subsystem is modeled using thermoelectric compatibility theory; this model does not constrain the material properties to be constant with temperature. Considering a three-stage TEG based on current record modules, this model suggests that 18% efficiency could be experimentally expected with a temperature gradient of 1000A degrees C to 100A degrees C. Achieving 15% overall STEG efficiency thus requires an absorber efficiency above 85%, and we consider two methods to achieve this: solar-selective absorbers and thermally insulating cavities. When the TEG and absorber subsystem models are combined, we expect that the STEG modeled here could achieve 15% efficiency with optical concentration between 250 and 300 suns.

  3. The influence of composition gradients on tensile properties of weld metal

    SciTech Connect (OSTI)

    Choi, I.D.; Matlock, D.K.; Olson, D.L.

    1988-09-01

    In this study, the effects of weld metal microsegregation, as altered by post-weld heat treatments, on both low and high temperature tensile properties were investigated on an alloy system which exhibits significant segregation of the major alloying elements without complex transformations or precipitation. Monel alloy 400, which consists primarily of nickel and copper, was chosen as a model system. This system is a single phase FCC solid solution at all temperatures, and has a low distribution coefficient, k. On solidification, significant microsegregation occurs with copper segregating to the interdendritic boundaries.

  4. High voltage switch triggered by a laser-photocathode subsystem

    DOE Patents [OSTI]

    Chen, Ping; Lundquist, Martin L.; Yu, David U. L.

    2013-01-08

    A spark gap switch for controlling the output of a high voltage pulse from a high voltage source, for example, a capacitor bank or a pulse forming network, to an external load such as a high gradient electron gun, laser, pulsed power accelerator or wide band radar. The combination of a UV laser and a high vacuum quartz cell, in which a photocathode and an anode are installed, is utilized as triggering devices to switch the spark gap from a non-conducting state to a conducting state with low delay and low jitter.

  5. The correction of linear lattice gradient errors using an AC dipole

    SciTech Connect (OSTI)

    Wang,G.; Bai, M.; Litvinenko, V.N.; Satogata, T.

    2009-05-04

    Precise measurement of optics from coherent betatron oscillations driven by ac dipoles have been demonstrated at RHIC and the Tevatron. For RHIC, the observed rms beta-beat is about 10%. Reduction of beta-beating is an essential component of performance optimization at high energy colliders. A scheme of optics correction was developed and tested in the RHIC 2008 run, using ac dipole optics for measurement and a few adjustable trim quadruples for correction. In this scheme, we first calculate the phase response matrix from the. measured phase advance, and then apply singular value decomposition (SVD) algorithm to the phase response matrix to find correction quadruple strengths. We present both simulation and some preliminary experimental results of this correction.

  6. Contribution to the Study of Ferrite Nanobeads: Synthesis, Characterization and Investigation of Horizontal Low Gradient Magnetophoresis Behaviour

    SciTech Connect (OSTI)

    Benelmekki, Maria; Caparros, Cristina; Goncalves, Renao; Lanceros-Mendez, Senenxu; Montras, Anna; Martinez, Lluis Miquel

    2010-12-02

    In this work we investigate the possibilities of the use of Horizontal Low Gradient Magnetic Field (HLGMF)(<100 T/m) for filtration, control and separation of the synthesized magnetic particles, considering, the characteristics of the suspension, the size and the type of nanoparticles (NPs) and focusing on the process scale up. Reversible aggregation is considered in the different steps of magnetic nanobeads synthesis. For these purpose, we synthesized Fe{sub 2}O{sub 3}-silica core-shell nanobeads by co-precipitation, monodispersion and silica coating. SQUID, TEM, XRD, and Zeta potential techniques were used to characterize the synthesized nanobeads. An extensive magnetophoresis study was performed at different magnetophoretic conditions. Different reversible aggregation times were observed at different HLGMF, at each step of the synthesis route: Several orders of magnitude differences where observed when comparing citric acid (CA) suspension with silicon coated beads. Reversible aggregation times are correlated with the properties of the NPs at different steps of synthesis.

  7. Momentum transport in the vicinity of q{sub min} in reverse shear tokamaks due to ion temperature gradient turbulence

    SciTech Connect (OSTI)

    Singh, Rameswar; Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay, 91128 Palaiseau Cedex ; Singh, R; WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 ; Jhang, Hogun; Diamond, P. H.; Center for Momentum Transport and Flow Organization, University of California, San Diego, California 92093; Center for Astrophysics and Space Sciences, University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0424

    2014-01-15

    We present an analytic study of momentum transport of tokamak plasmas in the vicinity of minimum safety factor (q) position in reversed magnetic shear configuration. Slab ion temperature gradient modes with an equilibrium flow profile are considered in this study. Quasi-linear calculations of momentum flux clearly show the novel effects of q-curvature on the generation of intrinsic rotation and mean poloidal flow without invoking reflectional symmetry breaking of parallel wavenumber (k{sub ?}). This q-curvature effect originates from the inherent asymmetry in k{sub ?} populations with respect to a rational surface due to the quadratic proportionality of k{sub ?} when q-curvature is taken into account. Discussions are made of possible implications of q-curvature induced plasma flows on internal transport barrier formation in reversed shear tokamaks.

  8. Rapid processing of carbon-carbon composites by forced flow-thermal gradient chemical vapor infiltration (FCVI)

    SciTech Connect (OSTI)

    Vaidyaraman, S.; Lackey, W.J.; Agrawal, P.K.; Freeman, G.B.; Langman, M.D.

    1995-10-01

    Carbon fiber-carbon matrix composites were fabricated using the forced flow-thermal gradient chemical vapor infiltration (FCVI) process. Preforms were prepared by stacking 40 layers of plain weave carbon cloth in a graphite holder. The preforms were infiltrated using propylene, propane, and methane. The present work showed that the FCVI process is well suited for fabricating carbon-carbon composites; without optimization of the process, the authors have achieved uniform and thorough densification. Composites with porosities as low as 7% were fabricated in 8--12 h. The highest deposition rate obtained in the present study was {approximately}3 {micro}m/h which is more than an order of magnitude faster than the typical value of 0.1--0.25 {micro}m/h for the isothermal process. It was also found that the use of propylene and propane as reagents resulted in faster infiltration compared to methane.

  9. 4D STUDY OF STRAIN GRADIENTS EVOLUTION IN TWINNED NiMnGa SINGLE CRYSTALS UNDER MAGNETIC FIELD

    SciTech Connect (OSTI)

    Barabash, Rozaliya; Xu, Ruqing; Barabash, Oleg M; Sozinov, Alexei

    2014-01-01

    Time-resolved 3D X-ray microscopy with a submicron beam size was used to follow the evolution of strains in off-stoichiometric NiMnGa twinned crystals near type I (hard) twin boundary under magnetic field. Laminate A/B microstructure was revealed near the twin boundaries in A variant. Large strain gradients are observed in the C variant in the immediate vicinity of the type I twin boundary: the lattice is under large tensile strains ~0.4% along the c- axes within first micron. Distinct a and b lattice parameter evolution with temperature and magnetic field is demonstrated. In an applied magnetic field the strain field was observed at larger distances from the twin boundary and becomes more complex. Stochastic twin boundary motion was observed after the magnetic field reaches a certain critical value.

  10. Communication: Smoothing out excited-state dynamics: Analytical gradients for dynamically weighted complete active space self-consistent field

    SciTech Connect (OSTI)

    Glover, W. J.

    2014-11-07

    State averaged complete active space self-consistent field (SA-CASSCF) is a workhorse for determining the excited-state electronic structure of molecules, particularly for states with multireference character; however, the method suffers from known issues that have prevented its wider adoption. One issue is the presence of discontinuities in potential energy surfaces when a state that is not included in the state averaging crosses with one that is. In this communication I introduce a new dynamical weight with spline (DWS) scheme that mimics SA-CASSCF while removing energy discontinuities due to unweighted state crossings. In addition, analytical gradients for DWS-CASSCF (and other dynamically weighted schemes) are derived for the first time, enabling energy-conserving excited-state ab initio molecular dynamics in instances where SA-CASSCF fails.

  11. Large-scale spatial variability of riverbed temperature gradients in Snake River fall Chinook salmon spawning areas

    SciTech Connect (OSTI)

    Hanrahan, Timothy P.

    2007-02-01

    In the Snake River basin of the Pacific northwestern United States, hydroelectric dam operations are often based on the predicted emergence timing of salmon fry from the riverbed. The spatial variability and complexity of surface water and riverbed temperature gradients results in emergence timing predictions that are likely to have large errors. The objectives of this study were to quantify the thermal heterogeneity between the river and riverbed in fall Chinook salmon spawning areas and to determine the effects of thermal heterogeneity on fall Chinook salmon emergence timing. This study quantified river and riverbed temperatures at 15 fall Chinook salmon spawning sites distributed in two reaches throughout 160 km of the Snake River in Hells Canyon, Idaho, USA, during three different water years. Temperatures were measured during the fall Chinook salmon incubation period with self-contained data loggers placed in the river and at three different depths below the riverbed surface. At all sites temperature increased with depth into the riverbed, including significant differences (p<0.05) in mean water temperature of up to 3.8°C between the river and the riverbed among all the sites. During each of the three water years studied, river and riverbed temperatures varied significantly among all the study sites, among the study sites within each reach, and between sites located in the two reaches. Considerable variability in riverbed temperatures among the sites resulted in fall Chinook salmon emergence timing estimates that varied by as much as 55 days, depending on the source of temperature data used for the estimate. Monitoring of riverbed temperature gradients at a range of spatial scales throughout the Snake River would provide better information for managing hydroelectric dam operations, and would aid in the design and interpretation of future empirical research into the ecological significance of physical riverine processes.

  12. Terahertz-driven linear electron acceleration

    SciTech Connect (OSTI)

    Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.

    2015-10-06

    The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeVm-1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. As a result, these ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams.

  13. Optimization of the Low-Loss SRF Cavity for the ILC

    SciTech Connect (OSTI)

    Z. Li; L. Ge; K. Ko; L. Lee; C.-K. Ng; G. L. Schussman; L. Xiao; T. Higo; Y. Morozumi; K. Saito; P. Kneisel; J. S. Sekutowicz

    2007-08-01

    The Low-Loss shape cavity design has been proposed as a possible alternative to the baseline TESLA cavity design for the ILC. The advantages of this design over the TESLA cavity are its lower cryogenic loss, and higher achievable gradient due to lower surface fields. High gradient prototypes for such designs have been tested at KEK (ICHIRO) and JLab (LL). However, issues related to HOM damping and multipacting (MP) still need to be addressed. Preliminary numerical studies of the prototype cavities have shown unacceptable damping for some higher-order dipole modes if the typical TESLA HOM couplers are directly adapted to the design. The resulting wakefield will dilute the beam emittance thus reduces the machine luminosity. Furthermore, high gradient tests on a 9-cell prototype at KEK have experienced MP barriers although a single LL cell had achieved a high gradient. From simulations, MP activities are found to occur in the end-groups of the cavity. In this paper, we will present the optimization results of the end-groups for the Low-Loss shape for effective HOM damping and alleviation of multipacting. Comparisons of simulation results with measurements will also be presented.

  14. Optimization of the Low Loss SRF Cavity for the ILC

    SciTech Connect (OSTI)

    Sekutowicz, J.S.; Kneisel, P.; Higo, T.; Morozumi, Y.; Saito, K.; Ge, L.; Ko, Yong-kyu; Lee, L.; Li, Z.; Ng, C.K.; Schussman, G.L.; Xiao, L.; /SLAC

    2008-01-18

    The Low-Loss shape cavity design has been proposed as a possible alternative to the baseline TESLA cavity design for the ILC main linacs. The advantages of this design over the TESLA cavity are its lower cryogenic loss, and higher achievable gradient due to lower surface fields. High gradient prototypes for such designs have been tested at KEK (ICHIRO) and TJNAF (LL). However, issues related to HOM damping and multipacting still need to be addressed. Preliminary numerical studies of the prototype cavities have shown unacceptable damping factors for some higher-order dipole modes if the typical TESLA HOM couplers are directly adapted to the design. The resulting wakefield will dilute the beam emittance thus reducing the machine luminosity. Furthermore, high gradient tests on a 9-cell prototype at KEK have experienced multipacting barriers although a single LL cell had achieved a high gradient. From simulations, multipacting activities are found to occur in the end-groups of the cavity. In this paper, we will present the optimization results of the end-groups for the Low-Loss designs for effective HOM damping and alleviation of multipacting.

  15. Terahertz-driven linear electron acceleration

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

    Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.

    2015-10-06

    The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeVm-1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton acceleratorsmore » with simple accelerating structures, high repetition rates and significant charge per bunch. As a result, these ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams.« less

  16. Linking Automated Data Analysis and Visualization with Applications in Developmental Biology and High-Energy Physics

    SciTech Connect (OSTI)

    Ruebel, Oliver

    2009-12-01

    Knowledge discovery from large and complex collections of today's scientific datasets is a challenging task. With the ability to measure and simulate more processes at increasingly finer spatial and temporal scales, the increasing number of data dimensions and data objects is presenting tremendous challenges for data analysis and effective data exploration methods and tools. Researchers are overwhelmed with data and standard tools are often insufficient to enable effective data analysis and knowledge discovery. The main objective of this thesis is to provide important new capabilities to accelerate scientific knowledge discovery form large, complex, and multivariate scientific data. The research covered in this thesis addresses these scientific challenges using a combination of scientific visualization, information visualization, automated data analysis, and other enabling technologies, such as efficient data management. The effectiveness of the proposed analysis methods is demonstrated via applications in two distinct scientific research fields, namely developmental biology and high-energy physics.Advances in microscopy, image analysis, and embryo registration enable for the first time measurement of gene expression at cellular resolution for entire organisms. Analysis of high-dimensional spatial gene expression datasets is a challenging task. By integrating data clustering and visualization, analysis of complex, time-varying, spatial gene expression patterns and their formation becomes possible. The analysis framework MATLAB and the visualization have been integrated, making advanced analysis tools accessible to biologist and enabling bioinformatic researchers to directly integrate their analysis with the visualization. Laser wakefield particle accelerators (LWFAs) promise to be a new compact source of high-energy particles and radiation, with wide applications ranging from medicine to physics. To gain insight into the complex physical processes of particle

  17. Influence of river level on temperature and hydraulic gradients in chum and fall Chinook salmon spawning areas downstream of Bonneville Dam, Columbia River

    SciTech Connect (OSTI)

    Geist, David R.; Arntzen, Evan V.; Murray, Christopher J.; McGrath, Kathy; Bott, Yi-Ju; Hanrahan, Timothy P.

    2008-02-01

    Chum (Oncorhynchus keta) and fall Chinook (O. tshawytscha) salmon segregate spatially during spawning in the Ives Island side channel of the lower Columbia River downstream from Bonneville Dam. Previous research during one spawning season (2000) suggested that these species selected spawning habitats based on differences in hyporheic temperature and vertical hydraulic gradient (VHG) with the river. In this study, we confirmed the spatial segregation of spawning based on hyporheic characteristics over four years (2001–2004) and examined the effects of load-following operations (power generation to meet short-term electrical demand) at Bonneville Dam on hyporheic function and characteristics. We found that during the study period, hyporheic temperature and VHG in chum salmon spawning areas were highly variable during periods of load-following operation when river levels fluctuated. In contrast, hyporheic water temperature and VHG within chum spawning areas fluctuated less when river levels were not changing due to load-following operation. Variable temperature and VHG could affect chum and fall Chinook salmon spawning segregation and incubation success by altering the cues each species uses to select redd sites. Alterations in site selection would result in a breakdown in the spatial segregation of spawning between chum and fall Chinook salmon, which would expose earlier spawning fall Chinook eggs to a greater risk of dislodgement from later spawning chum salmon. Additional research will be required to fully assess the effects of load-following operations on the hyporheic environment and spawning and incubation success of chum and fall Chinook salmon downstream from Bonneville Dam.

  18. Illinois: High-Energy, Concentration-Gradient Cathode Material for Plug-in Hybrids and All-Electric Vehicles Could Reduce Batteries' Cost and Size

    Broader source: Energy.gov [DOE]

    Batteries for electric drive vehicles and renewable energy storage will reduce petroleum usage, improving energy security and reducing harmful emissions.

  19. High PRF high current switch

    DOE Patents [OSTI]

    Moran, Stuart L.; Hutcherson, R. Kenneth

    1990-03-27

    A triggerable, high voltage, high current, spark gap switch for use in pu power systems. The device comprises a pair of electrodes in a high pressure hydrogen environment that is triggered by introducing an arc between one electrode and a trigger pin. Unusually high repetition rates may be obtained by undervolting the switch, i.e., operating the trigger at voltages much below the self-breakdown voltage of the device.

  20. Differential heating: A versatile method for thermal conductivity measurements in high-energy-density matter

    SciTech Connect (OSTI)

    Ping, Y.; Fernandez-Panella, A.; Sio, H.; Correa, A.; Shepherd, R.; Landen, O.; London, R. A.; Sterne, P. A.; Whitley, H. D.; Fratanduono, D.; Boehly, T. R.; Collins, G. W.

    2015-09-04

    We propose a method for thermal conductivity measurements of high energy density matter based on differential heating. A temperature gradient is created either by surface heating of one material or at an interface between two materials by different energy deposition. The subsequent heat conduction across the temperature gradient is observed by various time-resolved probing techniques. Conceptual designs of such measurements using laser heating, proton heating, and x-ray heating are presented. As a result, the sensitivity of the measurements to thermal conductivity is confirmed by simulations.

  1. Application of Plasma Waveguides to High Energy Accelerators

    SciTech Connect (OSTI)

    Milchberg, Howard M

    2013-03-30

    will continue our development of advanced simulation tools by modifying the QuickPIC algorithm to allow for the simulation of plasma particle pick-up by the wake fields. We have also performed extensive simulations of plasma slow wave structures for efficient THz generation by guided laser beams or accelerated electron beams. We will pursue experimental studies of direct laser acceleration, and THz generation by two methods, ponderomotive-induced THz polarization, and THz radiation by laser accelerated electron beams. We also plan to study both conventional and corrugated plasma channels using our new 30 TW in our new lab facilities. We will investigate production of very long hydrogen plasma waveguides (5 cm). We will study guiding at increasing power levels through the onset of laser-induced cavitation (bubble regime) to assess the role played by the preformed channel. Experiments in direct acceleration will be performed, using laser plasma wakefields as the electron injector. Finally, we will use 2-colour ionization of gases as a high frequency THz source (<60 THz) in order for femtosecond measurements of low plasma densities in waveguides and beams.

  2. Toward Oxide Scale Behavior Management At High Temperature

    SciTech Connect (OSTI)

    Deltombe, R.; Dubar, M.; Dubois, A.; Dubar, L.

    2011-01-17

    Oxide scales grow freely on bare metallic surface under environmental conditions such as high temperature and oxygen. These act as thermal and mechanical shields, especially during high hot forming processes (>1000 deg. C). But product quality can be impacted by these oxide scales due to scale remaining on product or sticking on tools. Thus the TEMPO laboratory has created an original methodology in order to characterize oxide scale under high temperature, pressure and strain gradients. An experimental device has been developed. The final purpose of this work is to understand the scale behavior as a function of temperature, reduction ratio and steel composition.

  3. Method of depositing a high-emissivity layer

    DOE Patents [OSTI]

    Wickersham, Charles E.; Foster, Ellis L.

    1983-01-01

    A method of depositing a high-emissivity layer on a substrate comprising RF sputter deposition of a carbide-containing target in an atmosphere of a hydrocarbon gas and a noble gas. As the carbide is deposited on the substrate the hydrocarbon gas decomposes to hydrogen and carbon. The carbon deposits on the target and substrate causing a carbide/carbon composition gradient to form on the substrate. At a sufficiently high partial pressure of hydrocarbon gas, a film of high-emissivity pure carbon will eventually form over the substrate.

  4. The High Intensity Horizon at Fermilab

    SciTech Connect (OSTI)

    Tschirhart, R.S.; /Fermilab

    2012-05-01

    Fermilab's high intensity horizon is 'Project-X' which is a US led initiative with strong international participation that aims to realize a next generation proton source that will dramatically extend the reach of Intensity Frontier research. The Project-X research program includes world leading sensitivity in long-baseline and short-baseline neutrino experiments, a rich program of ultra-rare muon and kaon decays, opportunities for next-generation electric dipole moment experiments and other nuclear/particle physics probes, and a platform to investigate technologies for next generation energy applications. A wide range of R&D activities has supported mission critical accelerator subsystems, such as high-gradient superconducting RF accelerating structures, efficient RF power systems, cryo-modules and cryogenic refrigeration plants, advanced beam diagnostics and instrumentation, high-power targetry, as well as the related infrastructure and civil construction preparing for a construction start of a staged program as early as 2017.

  5. Orbital-optimized MP2.5 and its analytic gradients: Approaching CCSD(T) quality for noncovalent interactions

    SciTech Connect (OSTI)

    Bozkaya, Uğur; Sherrill, C. David

    2014-11-28

    Orbital-optimized MP2.5 [or simply “optimized MP2.5,” OMP2.5, for short] and its analytic energy gradients are presented. The cost of the presented method is as much as that of coupled-cluster singles and doubles (CCSD) [O(N{sup 6}) scaling] for energy computations. However, for analytic gradient computations the OMP2.5 method is only half as expensive as CCSD because there is no need to solve λ{sub 2}-amplitude equations for OMP2.5. The performance of the OMP2.5 method is compared with that of the standard second-order Møller–Plesset perturbation theory (MP2), MP2.5, CCSD, and coupled-cluster singles and doubles with perturbative triples (CCSD(T)) methods for equilibrium geometries, hydrogen transfer reactions between radicals, and noncovalent interactions. For bond lengths of both closed and open-shell molecules, the OMP2.5 method improves upon MP2.5 and CCSD by 38%–43% and 31%–28%, respectively, with Dunning's cc-pCVQZ basis set. For complete basis set (CBS) predictions of hydrogen transfer reaction energies, the OMP2.5 method exhibits a substantially better performance than MP2.5, providing a mean absolute error of 1.1 kcal mol{sup −1}, which is more than 10 times lower than that of MP2.5 (11.8 kcal mol{sup −1}), and comparing to MP2 (14.6 kcal mol{sup −1}) there is a more than 12-fold reduction in errors. For noncovalent interaction energies (at CBS limits), the OMP2.5 method maintains the very good performance of MP2.5 for closed-shell systems, and for open-shell systems it significantly outperforms MP2.5 and CCSD, and approaches CCSD(T) quality. The MP2.5 errors decrease by a factor of 5 when the optimized orbitals are used for open-shell noncovalent interactions, and comparing to CCSD there is a more than 3-fold reduction in errors. Overall, the present application results indicate that the OMP2.5 method is very promising for open-shell noncovalent interactions and other chemical systems with difficult electronic structures.

  6. Accelerating Particles with Plasma

    SciTech Connect (OSTI)

    Litos, Michael; Hogan, Mark

    2014-11-05

    Researchers at SLAC explain how they use plasma wakefields to accelerate bunches of electrons to very high energies over only a short distance. Their experiments offer a possible path for the future of particle accelerators.

  7. High concentration of deuterium in palladium

    SciTech Connect (OSTI)

    Uhm, H.S.; Lee, W.M. )

    1992-01-01

    In this paper, based on theoretical calculations, new schemes to increase the deuterium density in palladium over its initial value are presented. A high deuterium concentration in palladium is needed for application to solid-state fusion. The first deuterium enrichment scheme makes use of plasma ion implantation, which consists of a cylindrical palladium rod (target) preloaded with deuterium atoms, coated with diffusion barrier material, and immersed in a deuterium plasma. The palladium rod is connected to a high-power modulator, which provides a series of negative voltage pulses. During these negative pulses, deuterium ions fall on the target, penetrate the diffusion barrier, and are implanted inside the palladium. For reasonable system parameters allowed by current technology, theoretical calculations indicate that the saturation deuterium density after prolonged ion implantation can be several times the palladium atomic number density. The second deuterium enrichment scheme makes use of temperature gradient effects on the deuterium solubility in palladium. A heat source at temperature T{sub 2} and a heat sink at temperature T{sub 1} (where T{sub 2} {gt} T{sub 1}) are in contact with two different parts of a palladium sample, which has been presoaked with deuterium atoms and has been coated with diffusion barrier material or has been securely locked in a metal case. The temperature gradient created in the sample from such an arrangement forces the deuterium atoms in the hot region to migrate into the cold region, resulting in higher deuterium density in the cold region.

  8. High-frequency plasma-heating apparatus

    DOE Patents [OSTI]

    Brambilla, Marco; Lallia, Pascal

    1978-01-01

    An array of adjacent wave guides feed high-frequency energy into a vacuum chamber in which a toroidal plasma is confined by a magnetic field, the wave guide array being located between two toroidal current windings. Waves are excited in the wave guide at a frequency substantially equal to the lower frequency hybrid wave of the plasma and a substantially equal phase shift is provided from one guide to the next between the waves therein. For plasmas of low peripheral density gradient, the guides are excited in the TE.sub.01 mode and the output electric field is parallel to the direction of the toroidal magnetic field. For exciting waves in plasmas of high peripheral density gradient, the guides are excited in the TM.sub.01 mode and the magnetic field at the wave guide outlets is parallel to the direction of the toroidal magnetic field. The wave excited at the outlet of the wave guide array is a progressive wave propagating in the direction opposite to that of the toroidal current and is, therefore, not absorbed by so-called "runaway" electrons.

  9. SU-C-BRA-02: Gradient Based Method of Target Delineation On PET/MR Image of Head and Neck Cancer Patients

    SciTech Connect (OSTI)

    Dance, M; Chera, B; Falchook, A; Das, S; Lian, J

    2015-06-15

    Purpose: Validate the consistency of a gradient-based segmentation tool to facilitate accurate delineation of PET/CT-based GTVs in head and neck cancers by comparing against hybrid PET/MR-derived GTV contours. Materials and Methods: A total of 18 head and neck target volumes (10 primary and 8 nodal) were retrospectively contoured using a gradient-based segmentation tool by two observers. Each observer independently contoured each target five times. Inter-observer variability was evaluated via absolute percent differences. Intra-observer variability was examined by percentage uncertainty. All target volumes were also contoured using the SUV percent threshold method. The thresholds were explored case by case so its derived volume matched with the gradient-based volume. Dice similarity coefficients (DSC) were calculated to determine overlap of PET/CT GTVs and PET/MR GTVs. Results: The Levene’s test showed there was no statistically significant difference of the variances between the observer’s gradient-derived contours. However, the absolute difference between the observer’s volumes was 10.83%, with a range from 0.39% up to 42.89%. PET-avid regions with qualitatively non-uniform shapes and intensity levels had a higher absolute percent difference near 25%, while regions with uniform shapes and intensity levels had an absolute percent difference of 2% between observers. The average percentage uncertainty between observers was 4.83% and 7%. As the volume of the gradient-derived contours increased, the SUV threshold percent needed to match the volume decreased. Dice coefficients showed good agreement of the PET/CT and PET/MR GTVs with an average DSC value across all volumes at 0.69. Conclusion: Gradient-based segmentation of PET volume showed good consistency in general but can vary considerably for non-uniform target shapes and intensity levels. PET/CT-derived GTV contours stemming from the gradient-based tool show good agreement with the anatomically and

  10. Mapping the genome of meta-generalized gradient approximation density functionals: The search for B97M-V

    SciTech Connect (OSTI)

    Mardirossian, Narbe; Head-Gordon, Martin

    2015-02-21

    A meta-generalized gradient approximation density functional paired with the VV10 nonlocal correlation functional is presented. The functional form is selected from more than 10{sup 10} choices carved out of a functional space of almost 10{sup 40} possibilities. Raw data come from training a vast number of candidate functional forms on a comprehensive training set of 1095 data points and testing the resulting fits on a comprehensive primary test set of 1153 data points. Functional forms are ranked based on their ability to reproduce the data in both the training and primary test sets with minimum empiricism, and filtered based on a set of physical constraints and an often-overlooked condition of satisfactory numerical precision with medium-sized integration grids. The resulting optimal functional form has 4 linear exchange parameters, 4 linear same-spin correlation parameters, and 4 linear opposite-spin correlation parameters, for a total of 12 fitted parameters. The final density functional, B97M-V, is further assessed on a secondary test set of 212 data points, applied to several large systems including the coronene dimer and water clusters, tested for the accurate prediction of intramolecular and intermolecular geometries, verified to have a readily attainable basis set limit, and checked for grid sensitivity. Compared to existing density functionals, B97M-V is remarkably accurate for non-bonded interactions and very satisfactory for thermochemical quantities such as atomization energies, but inherits the demonstrable limitations of existing local density functionals for barrier heights.

  11. A direct numerical simulation-based investigation and modeling of pressure Hessian effects on compressible velocity gradient dynamics

    SciTech Connect (OSTI)

    Danish, Mohammad Suman, Sawan Srinivasan, Balaji

    2014-12-15

    The pressure Hessian tensor plays a key role in shaping the behavior of the velocity gradient tensor, and in turn, that of many incumbent non-linear processes in a turbulent flow field. In compressible flows, the role of pressure Hessian is even more important because it represents the level of fluid-thermodynamic coupling existing in the flow field. In this work, we first perform a direct numerical simulation-based study to clearly identify, isolate, and understand various important inviscid mechanisms that govern the evolution of the pressure Hessian tensor in compressible turbulence. The ensuing understanding is then employed to introduce major improvements to the existing Lagrangian model of the pressure Hessian tensor (the enhanced Homogenized Euler equation or EHEE) in terms of (i) non-symmetric, non-isentropic effects and (ii) improved representation of the anisotropic portion of the pressure Hessian tensor. Finally, we evaluate the new model extensively by comparing the new model results against known turbulence behavior over a range of Reynolds and Mach numbers. Indeed, the new model shows much improved performance as compared to the EHEE model.

  12. Road Map for Studies to Produce Consistent and High Performance SRF Accelerator Structures

    SciTech Connect (OSTI)

    Ganapati Rao Myneni; John F. OHanlon

    2007-06-20

    Superconducting Radio Frequency (SRF) accelerator structures made from high purity niobium are becoming the technological choice for a large number of future accelerators and energy recovery LINACs (ERL). Most of the presently planned accelerators and ERL requirements will be met with some effort by the current SRF technology where accelerating gradients of about 20 MV/m can be produced on a routine basis with an acceptable yield. However, the XFEL at DESY and the planned ILC require acceleration gradients more than 28 MV/m and 35 MV/m respectively. At the recent ILC meeting at Snowmass (2005) concern was expressed regarding the wide spread in the achieved accelerator gradients and the relatively low yields. For obtaining accelerating gradients of 35 MV/m in SRF accelerator structures consistently, a deeper understanding of the causes for the spread has to be gained and advances have to be made in many scientific and high technology fields, including materials, surface and vacuum sciences, application of reliable processes and procedures, which provide contamination free surfaces and avoid recontamination and cryogenics related technologies. In this contribution a road map for studies needed to produce consistent and high performance SRF accelerator structures from the needed materials development to clean and non-recontaminating processes and procedures will be presented.

  13. Alpha channeling with high-field launch of lower hybrid waves

    SciTech Connect (OSTI)

    Ochs, I. E.; Bertelli, N.; Fisch, N. J.

    2015-11-04

    Although lower hybrid waves are effective at driving currents in present-day tokamaks, they are expected to interact strongly with high-energy particles in extrapolating to reactors. In the presence of a radial alpha particle birth gradient, this interaction can take the form of wave amplification rather than damping. While it is known that this amplification more easily occurs when launching from the tokamak high-field side, the extent of this amplification has not been made quantitative. Here, by tracing rays launched from the high- field-side of a tokamak, the required radial gradients to achieve amplification are calculated for a temperature and density regime consistent with a hot-ion-mode fusion reactor. As a result, these simulations, while valid only in the linear regime of wave amplification, nonetheless illustrate the possibilities for wave amplification using high-field launch of the lower hybrid wave.

  14. Alpha channeling with high-field launch of lower hybrid waves

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

    Ochs, I. E.; Bertelli, N.; Fisch, N. J.

    2015-11-04

    Although lower hybrid waves are effective at driving currents in present-day tokamaks, they are expected to interact strongly with high-energy particles in extrapolating to reactors. In the presence of a radial alpha particle birth gradient, this interaction can take the form of wave amplification rather than damping. While it is known that this amplification more easily occurs when launching from the tokamak high-field side, the extent of this amplification has not been made quantitative. Here, by tracing rays launched from the high- field-side of a tokamak, the required radial gradients to achieve amplification are calculated for a temperature and densitymore » regime consistent with a hot-ion-mode fusion reactor. As a result, these simulations, while valid only in the linear regime of wave amplification, nonetheless illustrate the possibilities for wave amplification using high-field launch of the lower hybrid wave.« less

  15. Gas and RRR distribution in high purity Niobium EB welded in Ultra-High Vacuum

    SciTech Connect (OSTI)

    Anakhov, S.; Singer, X.; Singer, W.; Wen, H.

    2006-05-24

    Electron beam (EB) welding in UHV (ultra-high vacuum, 10-5 divide 10-8 mbar) is applied in the standard fabrication of high gradient niobium superconducting radio frequency (SRF) cavities of TESLA design. The quality of EB welding is critical for cavity performance. Experimental data of gas content (H2, O2, N2) and RRR (residual resistivity ratio) measurements in niobium (Nb) welding seams are presented. EB welding in UHV conditions allow to preserve low gas content (1 divide 3 wt. ppm hydrogen and 5 divide 7 ppm oxygen and nitrogen), essential for high values of RRR - 350 divide 400 units. Gas content redistribution in the electron beam welded and heat affected region take place in the welding process. Correlation between gas solubility parameters, RRR and thermal conductivity are presented. Mechanisms of gas solubility in EB welding process are discussed.

  16. Gradient descent algorithm applied to wavefront retrieval from through-focus images by an extreme ultraviolet microscope with partially coherent source

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

    Yamazoe, Kenji; Mochi, Iacopo; Goldberg, Kenneth A.

    2014-12-01

    The wavefront retrieval by gradient descent algorithm that is typically applied to coherent or incoherent imaging is extended to retrieve a wavefront from a series of through-focus images by partially coherent illumination. For accurate retrieval, we modeled partial coherence as well as object transmittance into the gradient descent algorithm. However, this modeling increases the computation time due to the complexity of partially coherent imaging simulation that is repeatedly used in the optimization loop. To accelerate the computation, we incorporate not only the Fourier transform but also an eigenfunction decomposition of the image. As a demonstration, the extended algorithm is appliedmore » to retrieve a field-dependent wavefront of a microscope operated at extreme ultraviolet wavelength (13.4 nm). The retrieved wavefront qualitatively matches the expected characteristics of the lens design.« less

  17. Gradient descent algorithm applied to wavefront retrieval from through-focus images by an extreme ultraviolet microscope with partially coherent source

    SciTech Connect (OSTI)

    Yamazoe, Kenji; Mochi, Iacopo; Goldberg, Kenneth A.

    2014-12-01

    The wavefront retrieval by gradient descent algorithm that is typically applied to coherent or incoherent imaging is extended to retrieve a wavefront from a series of through-focus images by partially coherent illumination. For accurate retrieval, we modeled partial coherence as well as object transmittance into the gradient descent algorithm. However, this modeling increases the computation time due to the complexity of partially coherent imaging simulation that is repeatedly used in the optimization loop. To accelerate the computation, we incorporate not only the Fourier transform but also an eigenfunction decomposition of the image. As a demonstration, the extended algorithm is applied to retrieve a field-dependent wavefront of a microscope operated at extreme ultraviolet wavelength (13.4 nm). The retrieved wavefront qualitatively matches the expected characteristics of the lens design.

  18. Giant optical enhancement of strain gradient in ferroelectric BiFeO3 thin films and its physical origin

    SciTech Connect (OSTI)

    Li, Yuelin; Adamo, C.; Chen, Pice; Evans, Paul G.; Nakhmanson, Serge M.; Parker, William; Rowland, Clare E.; Schaller, Richard D.; Schlom, Darrell G.; Walko, Donald A.; Wen, Haidan; Zhang, Qingteng

    2015-11-20

    Through mapping of the spatiotemporal strain profile in ferroelectric BiFeO3 epitaxial thin films, we report an optically initiated dynamic enhancement of the strain gradient of 105–106 m-1 that lasts up to a few ns depending on the film thickness. Correlating with transient optical absorption measurements, the enhancement of the strain gradient is attributed to a piezoelectric effect driven by a transient screening field mediated by excitons. In conclusion, these findings not only demonstrate a new possible way of controlling the flexoelectric effect, but also reveal the important role of exciton dynamics in photostriction and photovoltaic effects in ferroelectrics.

  19. Effects of diffusion and surface interactions on the line shape of electron paramagnetic resonances in the presence of a magnetic field gradient

    SciTech Connect (OSTI)

    Schaden, M.; Zhao, K. F.; Wu, Z.

    2007-12-15

    In an evanescent wave magnetometer the Zeeman polarization is probed at micrometer to submicrometer distances from the cell surface. The electron paramagnetic resonance lines of an evanescent wave magnetometer in the presence of a magnetic field gradient exhibit edge enhancement seen previously in nuclear magnetic resonance lines. We present a theoretical model that describes quantitatively the shape of the magnetic resonance lines of an evanescent wave magnetometer under a wide range of experimental conditions. It accounts for diffusion broadening in the presence of a magnetic field gradient as well as interactions of spin polarized Rb atoms with the coated Pyrex glass surfaces. Depending on the field gradient, cell thickness, and buffer gas pressure, the resonance line may have the form of a single asymmetric peak or two peaks localized near the front and back surfaces in frequency space. The double-peaked response depends on average characteristics of the surface interactions. Its shape is sensitive to the dwell time, relaxation probability, and average phase shift of adsorbed spin polarized Rb atoms.

  20. COAXIAL TWO-CHANNEL DIELECTRIC WAKE FIELD ACCELERATOR

    SciTech Connect (OSTI)

    Hirshfield, Jay L.

    2013-04-30

    Theory, computations, and experimental apparatus are presented that describe and are intended to confirm novel properties of a coaxial two-channel dielectric wake field accelerator. In this configuration, an annular drive beam in the outer coaxial channel excites multimode wakefields which, in the inner channel, can accelerate a test beam to an energy much higher than the energy of the drive beam. This high transformer ratio is the result of judicious choice of the dielectric structure parameters, and of the phase separation between drive bunches and test bunches. A structure with cm-scale wakefields has been build for tests at the Argonne Wakefield Accelerator Laboratory, and a structure with mm-scale wakefields has been built for tests at the SLAC FACET facility. Both tests await scheduling by the respective facilities.

  1. High-pressure microhydraulic actuator

    DOE Patents [OSTI]

    Mosier, Bruce P. [San Francisco, CA; Crocker, Robert W. [Fremont, CA; Patel, Kamlesh D. [Dublin, CA

    2008-06-10

    Electrokinetic ("EK") pumps convert electric to mechanical work when an electric field exerts a body force on ions in the Debye layer of a fluid in a packed bed, which then viscously drags the fluid. Porous silica and polymer monoliths (2.5-mm O.D., and 6-mm to 10-mm length) having a narrow pore size distribution have been developed that are capable of large pressure gradients (250-500 psi/mm) when large electric fields (1000-1500 V/cm) are applied. Flowrates up to 200 .mu.L/min and delivery pressures up to 1200 psi have been demonstrated. Forces up to 5 lb-force at 0.5 mm/s (12 mW) have been demonstrated with a battery-powered DC-DC converter. Hydraulic power of 17 mW (900 psi@ 180 uL/min) has been demonstrated with wall-powered high voltage supplies. The force and stroke delivered by an actuator utilizing an EK pump are shown to exceed the output of solenoids, stepper motors, and DC motors of similar size, despite the low thermodynamic efficiency.

  2. High e

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

    e ne rgy data s am ple ● NuMI beam events provide an useful calibration sample ● Collected over 70K candidates before shutdown The highest energy events are prim arily from kaon decays. Two sam ples at high energy provide normalization and shape inform ation for kaon backgrounds to oscillation analysis: ● ν e events passing oscillation event selection cuts ● ν µ induced CCQE, CCπ+events Reconstructed neutrino energy EνQE(GeV) ν from other particles ν from pions ν from Kaons -

  3. Experimental study of layer mixing, relative ionic escape velocity, and electron temperature gradients in spherical multilayered targets by XUV spectroscopy

    SciTech Connect (OSTI)

    Griem, H.R.

    1990-07-01

    This past year we have undertaken experiments at the University of Rochester's Laboratory for Laser Energetics investigating layer mixing and expansion velocities of spherical targets uniformly irradiated by high intensity laser light. We performed high resolution spectroscopic measurements of spherical plasmas, produced using the Omega laser, and have observed enhanced broadening of XUV emission lines due to the expansion velocities.

  4. A compact high-performance low-field NMR apparatus for measurements on fluids at very high pressures and temperatures

    SciTech Connect (OSTI)

    Freedman, R.; Anand, V. Ganesan, K.; Tabrizi, P.; Torres, R.; Grant, B.; Catina, D.; Ryan, D.; Borman, C.; Krueckl, C.

    2014-02-15

    We discuss an innovative new high-performance apparatus for performing low-field Nuclear Magnetic Resonance (NMR) relaxation times and diffusion measurements on fluids at very high pressures and high temperatures. The apparatus sensor design and electronics specifications allow for dual deployment either in a fluid sampling well logging tool or in a laboratory. The sensor and electronics were designed to function in both environments. This paper discusses the use of the apparatus in a laboratory environment. The operating temperature and pressure limits, and the signal-to-noise ratio (SNR) of the new system exceed by a very wide margin what is currently possible. This major breakthrough was made possible by a revolutionary new sensor design that breaks many of the rules of conventional high pressure NMR sensor design. A metallic sample holder capable of operating at high pressures and temperatures is provided to contain the fluid under study. The sample holder has been successfully tested for operation up to 36 Kpsi. A solenoid coil wound on a slotted titanium frame sits inside the metallic sample holder and serves as an antenna to transmit RF pulses and receive NMR signals. The metal sample holder is sandwiched between a pair of gradient coils which provide a linear field gradient for pulsed field gradient diffusion measurements. The assembly sits in the bore of a low-gradient permanent magnet. The system can operate over a wide frequency range without the need for tuning the antenna to the Larmor frequency. The SNR measured on a water sample at room temperature is more than 15 times greater than that of the commercial low-field system in our laboratory. Thus, the new system provides for data acquisition more than 200 times faster than was previously possible. Laboratory NMR measurements of relaxations times and diffusion coefficients performed at pressures up to 25 Kpsi and at temperatures up to 175?C with crude oils enlivened with dissolved hydrocarbon gases

  5. Reproducibility of High-Q SRF Cavities by High Temperature Heat Treatment

    SciTech Connect (OSTI)

    Dhakal, Pashupati; Ciovati, Gianluigi; Kneisel, Peter; Myneni, Ganapati Rao

    2014-07-01

    Recent work on high-temperature (> 600 °C) heat treatment of ingot Nb cavities in a customized vacuum furnace for several hours showed the possibility of achieving Q0-values of up to ~5×1010 at 2.0 K, 1.5 GHz and accelerating gradients of ~20 MV/m. This contribution presents results on further studies of the heat treatment process to produce cavities with high Q0 values for continuous-wave accelerator application. Single-cell cavities of different Nb purity have been processed through few cycles of heat-treatments and chemical etching. Measurements of Q0 as a function of temperature at low RF field and of Q0 as a function of the RF field at or below 2.0 K have been made after each treatment. Measurements by TOF-SIMS of the impurities depth profiles were made on samples heat treated with the cavities.

  6. Merging of high speed argon plasma jets

    SciTech Connect (OSTI)

    Case, A.; Messer, S.; Brockington, S.; Wu, L.; Witherspoon, F. D.; Elton, R.

    2013-01-15

    Formation of an imploding plasma liner for the plasma liner experiment (PLX) requires individual plasma jets to merge into a quasi-spherical shell of plasma converging on the origin. Understanding dynamics of the merging process requires knowledge of the plasma phenomena involved. We present results from the study of the merging of three plasma jets in three dimensional geometry. The experiments were performed using HyperV Technologies Corp. 1 cm Minirailguns with a preionized argon plasma armature. The vacuum chamber partially reproduces the port geometry of the PLX chamber. Diagnostics include fast imaging, spectroscopy, interferometry, fast pressure probes, B-dot probes, and high speed spatially resolved photodiodes, permitting measurements of plasma density, temperature, velocity, stagnation pressure, magnetic field, and density gradients. These experimental results are compared with simulation results from the LSP 3D hybrid PIC code.

  7. The role of composition and microstructure gradients on weld metal properties and behavior: Progress report for the period of June 1, 1987 to December 31, 1987. [Fe-Al-Cr-Mn-Ni weld metals

    SciTech Connect (OSTI)

    Matlock, D.K.; Olson, D.L.

    1988-01-01

    The effects of weld metal compositional and microstructural gradients on phase transformations, microstructural stability, and mechanical properties are considered from a fundamental basis in weld metal alloys which are primarily austenitic (e.g., stainless steels). Models which incorporate compositional gradients are developed to predict the resulting weld metal properties. The mechanical properties of weld metals are modeled based on composite theory in which individual weld metal zones are considered as discrete elements within a composite structure. 23 figs.

  8. Beam-driven acceleration in ultra-dense plasma media

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

    Shin, Young-Min

    2014-09-15

    Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 1025 m-3 and 1.6 x 1028 m-3 plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers 20 % higher acceleration gradient by enlarging the channel radius (r)more » from 0.2 Ap to 0.6 .Ap in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g. nanotubes) of high electron plasma density.« less

  9. INTEGRAL FIELD SPECTROSCOPY AND MULTI-WAVELENGTH IMAGING OF THE NEARBY SPIRAL GALAXY NGC 5668 : AN UNUSUAL FLATTENING IN METALLICITY GRADIENT

    SciTech Connect (OSTI)

    Marino, R. A.; Gil de Paz, A.; Castillo-Morales, A.; Perez-Gonzalez, P. G.; Gallego, J.; Zamorano, J.; Sanchez, S. F.

    2012-07-20

    We present an analysis of the full bidimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the Pmas fiber PAcK Integral Field Unit (IFU) at the Calar Alto observatory 3.5 m telescope. We make use of broadband imaging to provide further constraints on the evolutionary history of the galaxy. This data set will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that while inward of r {approx}36'' {approx} 4.4 kpc {approx} 0.36 (D{sub 25}/2) the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r {approx} 36'' flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and circular velocity of {lambda} = 0.053 and v{sub c} = 167 km s{sup -1}, respectively. The metallicity gradient and rotation curve predicted by this best-fitting galaxy model nicely match the values derived from the IFU observations, especially within r {approx}36''. The same is true for the colors despite some small offsets and a reddening in the bluest colors beyond that radius. On the other hand, deviations of some of these properties in the outer disk indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC 5668.

  10. A Non-scaling Fixed Field Alternating Gradient Accelerator for the Final Acceleration Stage of the International Design Study of the Neutrino Factory.

    SciTech Connect (OSTI)

    Berg, J.S.; Aslaninejad, M.; Pasternak, J.; Witte, H.; Bliss, N. Cordwell M.; Jones, T.; Muir, A., Kelliher, D.; Machida, S.

    2011-09-04

    The International Design Study of the Neutrino Factory (IDS-NF) has recently completed its Interim Design Report (IDR), which presents our current baseline design of the neutrino factory. To increase the efficiency and reduce the cost of acceleration, the IDR design uses a linear non-scaling fixed field alternating gradient accelerator (FFAG) for its final acceleration stage. We present the current lattice design of that FFAG, including the main ring plus its injection and extraction systems. We describe parameters for the main ring magnets, kickers, and septa, as well as the power supplies for the kickers. We present a first pass at an engineering layout for the ring and its subsystems.

  11. Beam-halo measurements in high-current proton beams

    SciTech Connect (OSTI)

    Allen, C.K.; Chan, K.C.D.; Colestock, P.L.; Crandall, K.R.; Garnett, R.W.; Gilpatrick, J.D.; Lysenko, W.; Qiang, J.; Schneider, J.D.; Schulze, M.E.; Sheffield, R.L.; Smith, H.V.; Wangler, T.P.

    2002-01-11

    We present results from an experimental study of the beam halo in a high-current 6.7-MeV proton beam propagating through a 52-quadrupole periodic-focusing channel. The gradients of the first four quadrupoles were independently adjusted to match or mismatch the injected beam. Emittances and beamwidths were obtained from measured profiles for comparisons with maximum emittance-growth predictions of a free-energy model and maximum halo-amplitude predictions of a particle-core model. The experimental results support both models and the present theoretical picture of halo formation.

  12. High-voltage R-F feedthrough bushing

    DOE Patents [OSTI]

    Grotz, G.F.

    1982-09-03

    Described is a multi-element, high voltage radio frequency bushing for transmitting rf energy to an antenna located in a vacuum container. The bushing includes a center conductor of complex geometrical shape, an outer coaxial shield conductor, and a thin-walled hollow truncated cone insulator disposed between central and outer conductors. The shape of the center conductor, which includes a reverse curvature portion formed of a radially inwardly directed shoulder and a convex portion, controls the uniformity of the axial surface gradient on the insulator cone. The outer shield has a first substantially cylindrical portion and a second radially inwardly extending truncated cone portion.

  13. Design considerations for high-current superconducting ion linacs

    SciTech Connect (OSTI)

    Delayen, J.R.; Bohn, C.L.; Micklich, B.J.; Roche, C.T.; Sagalovsky, L.

    1993-08-01

    Superconducting linacs may be a viable option for high-current applications such as fusion materials irradiation testing, spallation neutron source, transmutation of radioactive waste, tritium production, and energy production. These linacs must run reliably for many years and allow easy routine maintenance. Superconducting cavities operate efficiently with high cw gradients, properties which help to reduce operating and capital costs, respectively. However, cost-effectiveness is not the sole consideration in these applications. For example, beam impingement must be essentially eliminated to prevent unsafe radioactivation of the accelerating structures, and thus large apertures are needed through which to pass the beam. Because of their high efficiency, superconducting cavities can be designed with very large bore apertures, thereby reducing the effect of beam impingement. Key aspects of high-current cw superconducting linac designs are explored in this context.

  14. Overview of High Power Vacuum Dry RF Load Designs

    SciTech Connect (OSTI)

    Krasnykh, Anatoly

    2015-08-27

    A specific feature of RF linacs based on the pulsed traveling wave (TW) mode of operation is that only a portion of the RF energy is used for the beam acceleration. The residual RF energy has to be terminated into an RF load. Higher accelerating gradients require higher RF sources and RF loads, which can stably terminate the residual RF power. RF feeders (from the RF source though the accelerating section to the load) are vacuumed to transmit multi-megawatt high power RF. This overview will outline vacuumed RF loads only. A common method to terminate multi-MW RF power is to use circulated water (or other liquid) as an absorbing medium. A solid dielectric interface (a high quality ceramic) is required to separate vacuum and liquid RF absorber mediums. Using such RF load approaches in TW linacs is troubling because there is a fragile ceramic window barrier and a failure could become catastrophic for linac vacuum and RF systems. Traditional loads comprising of a ceramic disk have limited peak and average power handling capability and are therefore not suitable for high gradient TW linacs. This overview will focus on ''vacuum dry'' or ''all-metal'' loads that do not employ any dielectric interface between vacuum and absorber. The first prototype is an original design of RF loads for the Stanford Two-Mile Accelerator.

  15. Method for producing ceramic composition having low friction coefficient at high operating temperatures

    DOE Patents [OSTI]

    Lankford, Jr., James

    1988-01-01

    A method for producing a stable ceramic composition having a surface with a low friction coefficient and high wear resistance at high operating temperatures. A first deposition of a thin film of a metal ion is made upon the surface of the ceramic composition and then a first ion implantation of at least a portion of the metal ion is made into the near surface region of the composition. The implantation mixes the metal ion and the ceramic composition to form a near surface composite. The near surface composite is then oxidized sufficiently at high oxidizing temperatures to form an oxide gradient layer in the surface of the ceramic composition.

  16. High Energy Physics

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

    High Energy Physics High Energy Physics Investigating the field of high energy physics ... Through the Office of High Energy Physics (HEP), Los Alamos conducts research in particle ...

  17. High-Power Ka-Band Window and Resonant Ring

    SciTech Connect (OSTI)

    Jay L. Hirshfield

    2006-11-29

    A stand-alone 200 MW rf test station is needed for carrying out development of accelerator structures and components for a future high-gradient multi-TeV collider, such as CLIC. A high-power rf window is needed to isolate the test station from a structure element under test. This project aimed to develop such a window for use at a frequency in the range 30-35 GHz, and to also develop a high-power resonant ring for testing the window. During Phase I, successful conceptual designs were completed for the window and the resonant ring, and cold tests of each were carried out that confirmed the designs.

  18. Progress with high-field superconducting magnets for high-energy colliders

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

    Apollinari, Giorgio; Prestemon, Soren; Zlobin, Alexander V.

    2015-10-01

    One of the possible next steps for high-energy physics research relies on a high-energy hadron or muon collider. The energy of a circular collider is limited by the strength of bending dipoles, and its maximum luminosity is determined by the strength of final focus quadrupoles. For this reason, the high-energy physics and accelerator communities have shown much interest in higher-field and higher-gradient superconducting accelerator magnets. The maximum field of NbTi magnets used in all present high-energy machines, including the LHC, is limited to ~10 T at 1.9 K. Fields above 10 T became possible with the use of Nb$_3$Sn superconductors.more » Nb$_3$Sn accelerator magnets can provide operating fields up to ~15 T and can significantly increase the coil temperature margin. Accelerator magnets with operating fields above 15 T require high-temperature superconductors. Furthermore, this review discusses the status and main results of Nb$_3$Sn accelerator magnet research and development and work toward 20-T magnets.« less

  19. Progress with high-field superconducting magnets for high-energy colliders

    SciTech Connect (OSTI)

    Apollinari, Giorgio; Prestemon, Soren; Zlobin, Alexander V.

    2015-10-01

    One of the possible next steps for high-energy physics research relies on a high-energy hadron or muon collider. The energy of a circular collider is limited by the strength of bending dipoles, and its maximum luminosity is determined by the strength of final focus quadrupoles. For this reason, the high-energy physics and accelerator communities have shown much interest in higher-field and higher-gradient superconducting accelerator magnets. The maximum field of NbTi magnets used in all present high-energy machines, including the LHC, is limited to ~10 T at 1.9 K. Fields above 10 T became possible with the use of Nb$_3$Sn superconductors. Nb$_3$Sn accelerator magnets can provide operating fields up to ~15 T and can significantly increase the coil temperature margin. Accelerator magnets with operating fields above 15 T require high-temperature superconductors. Furthermore, this review discusses the status and main results of Nb$_3$Sn accelerator magnet research and development and work toward 20-T magnets.

  20. Method and system for producing sputtered thin films with sub-angstrom thickness uniformity or custom thickness gradients

    DOE Patents [OSTI]

    Folta, James A.; Montcalm, Claude; Walton, Christopher

    2003-01-01

    A method and system for producing a thin film with highly uniform (or highly accurate custom graded) thickness on a flat or graded substrate (such as concave or convex optics), by sweeping the substrate across a vapor deposition source with controlled (and generally, time-varying) velocity. In preferred embodiments, the method includes the steps of measuring the source flux distribution (using a test piece that is held stationary while exposed to the source), calculating a set of predicted film thickness profiles, each film thickness profile assuming the measured flux distribution and a different one of a set of sweep velocity modulation recipes, and determining from the predicted film thickness profiles a sweep velocity modulation recipe which is adequate to achieve a predetermined thickness profile. Aspects of the invention include a practical method of accurately measuring source flux distribution, and a computer-implemented method employing a graphical user interface to facilitate convenient selection of an optimal or nearly optimal sweep velocity modulation recipe to achieve a desired thickness profile on a substrate. Preferably, the computer implements an algorithm in which many sweep velocity function parameters (for example, the speed at which each substrate spins about its center as it sweeps across the source) can be varied or set to zero.