Science.gov

Sample records for advanced high-current particle

  1. A new method of rapid power measurement for MW-scale high-current particle beams

    NASA Astrophysics Data System (ADS)

    Xu, Yongjian; Hu, Chundong; Xie, Yuanlai; Liu, Zhimin; Xie, Yahong; Liu, Sheng; Liang, Lizheng; Jiang, Caichao; Sheng, Peng; Yu, Ling

    2015-09-01

    MW-scale high current particle beams are widely applied for plasma heating in the magnetic confinement fusion devices, in which beam power is an important indicator for efficient heating. Generally, power measurement of MW-scale high current particle beam adopts water flow calorimetry (WFC). Limited by the principles of WFC, the beam power given by WFC is an averaged value. In this article a new method of beam power for MW-scale high-current particle beams is introduced: (1) the temperature data of thermocouples embedded in the beam stopping elements were obtained using high data acquire system, (2) the surface heat flux of the beam stopping elements are calculated using heat transfer, (3) the relationships between positions and heat flux were acquired using numerical simulation, (4) the real-time power deposited on the beam stopping elements can be calculated using surface integral. The principle of measurement was described in detail and applied to the EAST neutral beam injector for demonstration. The result is compared with that measured by WFC. Comparison of the results shows good accuracy and applicability of this measuring method.

  2. Investigation of nonthermal particle effects on ionization dynamics in high current density ion beam transport experiments

    NASA Astrophysics Data System (ADS)

    Chung, H. K.; MacFarlane, J. J.; Wang, P.; Moses, G. A.; Bailey, J. E.; Olson, C. L.; Welch, D. R.

    1997-01-01

    Light ion inertial fusion experiments require the presence of a moderate density background gas in the transport region to provide charge and current neutralization for a high current density ion beam. In this article, we investigate the effects of nonthermal particles such as beam ions or non-Maxwellian electron distributions on the ionization dynamics of the background gas. In particular, we focus on the case of Li beams being transported in an argon gas. Nonthermal particles as well as thermal electrons are included in time-dependent collisional-radiative calculations to determine time-dependent atomic level populations and charge state distributions in a beam-produced plasma. We also briefly discuss the effects of beam ions and energetic electrons on the visible and vacuum ultraviolet (VUV) spectral regions. It is found that the mean charge state of the gas, and hence the electron density, is significantly increased by collisions with energetic particles. This higher ionization significantly impacts the VUV spectral region, where numerous resonance lines occur. On the other hand, the visible spectrum tends to be less affected because the closely spaced excited states are populated by lower energy thermal electrons.

  3. High Current ESD Test of Advanced Triple Junction Solar Array Coupon

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H., Jr.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Wong, Frankie

    2014-01-01

    Testing was conducted on an Advanced Triple Junction (ATJ) coupon that was part of a risk reduction effort in the development of a high-powered solar array design by Space Systems Loral, LLC (SSL). The ATJ coupon was a small, 4-cell, two-string configuration of flight-type design that has served as the basic test coupon design used in previous SSL environmental aging campaigns. The objective of the present test was to evaluate the performance of the coupon after being subjected to induced electrostatic discharge (ESD) testing at two string voltages (100 V, 150 V) and four string currents (1.65 A, 2.0 A, 2.475 A, and 3.3 A). An ESD test circuit, unique to SSL solar array design, was built that simulates the effect of missing cells and strings in a full solar panel with special primary arc flashover circuitry. A total of 73 primary arcs were obtained that included 7 temporary sustained arcs (TSA) events. The durations of the TSAs ranged from 50 micro-seconds to 2.75 milli-seconds. All TSAs occurred at a string voltage of 150 V. Post-ESD functional testing showed that no degradation occurred due to the TSA events. These test results point to a robust design for application to a high-current, high-power mission.

  4. High Current ESD Test of Advanced Triple Junction Solar Array Coupon

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H., Jr.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Wong, Frankie

    2015-01-01

    A test was conducted on an Advanced Triple Junction (ATJ) coupon that was part of a risk reduction effort in the development of a high-powered solar array design by SSL. The ATJ coupon was a small, 4-cell, two-string configuration that has served as the basic test coupon design used in previous SSL environmental aging campaigns. The coupon has many attributes of the flight design; e.g., substrate structure with graphite face sheets, integrated by-pass diodes, cell interconnects, RTV grout, wire routing, etc. The objective of the present test was to evaluate the performance of the coupon after being subjected to induced electrostatic discharge testing at two string voltages (100 V, 150 V) and four array current (1.65 A, 2.0 A, 2.475 A, and 3.3 A). An ESD test circuit, unique to SSL solar array design, was built that simulates the effect of missing cells and strings in a full solar panel with special primary arc flashover circuitry. A total of 73 primary arcs were obtained that included 7 temporary sustained arcs (TSA) events. The durations of the TSAs ranged from 50 micros to 2.9 ms. All TSAs occurred at a string voltage of 150 V. Post-test Large Area Pulsed Solar Simulator (LAPSS), Dark I-V, and By-Pass Diode tests showed that no degradation occurred due to the TSA events. In addition, the post-test insulation resistance measured was > 50 G-ohms between cells and substrate. These test results indicate a robust design for application to a high-current, high-power mission application.

  5. High Current ESD Test of Advanced Triple Junction Solar Array Coupon

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H., Jr.; Schneider, Todd A.; Vaughn, Jason A.; Hoang, Bao; Wong, Frankie

    2014-01-01

    Testing was conducted on an Advanced Triple Junction (ATJ) coupon that was part of a risk reduction effort in the development of a high-powered solar array design by Space Systems/Loral, LLC (SSL). The ATJ coupon was a small, 4-cell, two-string configuration that has served as the basic test coupon design used in previous SSL environmental aging campaigns. The coupon has many attributes of the flight design; e.g., substrate structure with graphite face sheets, integrated by-pass diodes, cell interconnects, RTV grout, wire routing, etc. The objective of the present test was to evaluate the performance of the coupon after being subjected to induced electrostatic discharge (ESD) testing at two string voltages (100 V, 150 V) and four array currents (1.65 A, 2.0 A, 2.475 A, and 3.3 A). An ESD test circuit, unique to SSL solar array design, was built that simulates the effect of missing cells and strings in a full solar panel with special primary arc flashover circuitry. A total of 73 primary arcs were obtained that included 7 temporary sustained arcs (TSA) events. The durations of the TSAs ranged from 50 micro-seconds to 2.75 milli-seconds. All TSAs occurred at a string voltage of 150 V. Post-test Large Area Pulsed Solar Simulator (LAPSS), Dark I-V, and By-Pass Diode tests showed that no degradation occurred due to the TSA events. In addition, the post-test insulation resistance measured was > 50 G-ohms between cells and substrate. These test results indicate a robust design for application to a high-current, high-power mission.

  6. High Current ESD Test of Advanced Triple Junction Solar Array Coupon

    NASA Technical Reports Server (NTRS)

    Wright, K. H.; Schneider, T. A.; Vaughn, J. A.; Hoang, B.; Wong, F.

    2014-01-01

    A test was conducted on an Advanced Triple Junction (ATJ) coupon that was part of a risk reduction effort in the development of a high-powered solar array design by SSL. The ATJ coupon was a small, 4-cell, two-string configuration that has served as the basic test coupon design used in previous SSL environmental aging campaigns. The coupon has many attributes of the flight design; e.g., substrate structure with graphite face sheets, integrated by-pass diodes, cell interconnects, RTV grout, wire routing, etc. The objective of the present test was to evaluate the performance of the coupon after being subjected to induced electrostatic discharge testing at two string voltages (100 V, 150 V) and four array current (1.65 A, 2.0 A, 2.475 A, and 3.3 A). An ESD test circuit, unique to SSL solar array design, was built that simulates the effect of missing cells and strings in a full solar panel with special primary arc flashover circuitry. A total of 73 primary arcs were obtained that included 7 temporary sustained arcs (TSA) events. The durations of the TSAs ranged from 50 µs to 2.9 ms. All TSAs occurred at a string voltage of 150 V. Post-test Large Area Pulsed Solar Simulator (LAPSS), Dark I-V, and By-Pass Diode tests showed that no degradation occurred due to the TSA events. In addition, the post-test insulation resistance measured was > 50 G-ohms between cells and substrate. These test results indicate a robust design for application to a high-current, high-power mission application.

  7. Magnetohydrodynamic modes analysis and control of Fusion Advanced Studies Torus high-current scenarios

    SciTech Connect

    Villone, F.; Mastrostefano, S.; Calabrò, G.; Vlad, G.; Crisanti, F.; Fusco, V.; Marchiori, G.; Bolzonella, T.; Marrelli, L.; Martin, P.; Liu, Y. Q.

    2014-08-15

    One of the main FAST (Fusion Advanced Studies Torus) goals is to have a flexible experiment capable to test tools and scenarios for safe and reliable tokamak operation, in order to support ITER and help the final DEMO design. In particular, in this paper, we focus on operation close to a possible border of stability related to low-q operation. To this purpose, a new FAST scenario has then been designed at I{sub p} = 10 MA, B{sub T} = 8.5 T, q{sub 95} ≈ 2.3. Transport simulations, carried out by using the code JETTO and the first principle transport model GLF23, indicate that, under these conditions, FAST could achieve an equivalent Q ≈ 3.5. FAST will be equipped with a set of internal active coils for feedback control, which will produce magnetic perturbation with toroidal number n = 1 or n = 2. Magnetohydrodynamic (MHD) mode analysis and feedback control simulations performed with the codes MARS, MARS-F, CarMa (both assuming the presence of a perfect conductive wall and using the exact 3D resistive wall structure) show the possibility of the FAST conductive structures to stabilize n = 1 ideal modes. This leaves therefore room for active mitigation of the resistive mode (down to a characteristic time of 1 ms) for safety purposes, i.e., to avoid dangerous MHD-driven plasma disruption, when working close to the machine limits and magnetic and kinetic energy density not far from reactor values.

  8. Westinghouse Advanced Particle Filter System

    SciTech Connect

    Lippert, T.E.; Bruck, G.J.; Sanjana, Z.N.; Newby, R.A.; Bachovchin, D.M.

    1996-12-31

    Integrated Gasification Combined Cycles (IGCC) and Pressurized Fluidized Bed Combustion (PFBC) are being developed and demonstrated for commercial, power generation application. Hot gas particulate filters are key components for the successful implementation of IGCC and PFBC in power generation gas turbine cycles. The objective of this work is to develop and qualify through analysis and testing a practical hot gas ceramic barrier filter system that meets the performance and operational requirements of PFBC and IGCC systems. This paper reports on the development and status of testing of the Westinghouse Advanced Hot Gas Particle Filter (W-APF) including: W-APF integrated operation with the American Electric Power, 70 MW PFBC clean coal facility--approximately 6000 test hours completed; approximately 2500 hours of testing at the Hans Ahlstrom 10 MW PCFB facility located in Karhula, Finland; over 700 hours of operation at the Foster Wheeler 2 MW 2nd generation PFBC facility located in Livingston, New Jersey; status of Westinghouse HGF supply for the DOE Southern Company Services Power System Development Facility (PSDF) located in Wilsonville, Alabama; the status of the Westinghouse development and testing of HGF`s for Biomass Power Generation; and the status of the design and supply of the HGF unit for the 95 MW Pinon Pine IGCC Clean Coal Demonstration.

  9. Westinghouse advanced particle filter system

    SciTech Connect

    Lippert, T.E.; Bruck, G.J.; Sanjana, Z.N.; Newby, R.A.

    1995-11-01

    Integrated Gasification Combined Cycles (IGCC), Pressurized Fluidized Bed Combustion (PFBC) and Advanced PFBC (APFB) are being developed and demonstrated for commercial power generation application. Hot gas particulate filters are key components for the successful implementation of IGCC, PFBC and APFB in power generation gas turbine cycles. The objective of this work is to develop and qualify through analysis and testing a practical hot gas ceramic barrier filter system that meets the performance and operational requirements of these advanced, solid fuel power generation cycles.

  10. Advances in holographic particle velocimetry

    NASA Astrophysics Data System (ADS)

    Simmons, Scott; Meng, Hui; Hussain, Fazle; Liu, David

    1993-12-01

    Holographic particle velocimetry (HPV) is a promising technique for 3D flow velocity and hence vorticity measurements to study turbulence, coherent structures and vortex interactions. We discuss various aspects in the development of this technique ranging from hologram recording configurations such as in-line, off-axis and multibeam to data processing. Difficulties in implementation are analyzed and solutions are discussed. We also present preliminary measurement results in a 3D vortex flow using one of our prototype HPV systems.

  11. Advanced analysis methods in particle physics

    SciTech Connect

    Bhat, Pushpalatha C.; /Fermilab

    2010-10-01

    Each generation of high energy physics experiments is grander in scale than the previous - more powerful, more complex and more demanding in terms of data handling and analysis. The spectacular performance of the Tevatron and the beginning of operations of the Large Hadron Collider, have placed us at the threshold of a new era in particle physics. The discovery of the Higgs boson or another agent of electroweak symmetry breaking and evidence of new physics may be just around the corner. The greatest challenge in these pursuits is to extract the extremely rare signals, if any, from huge backgrounds arising from known physics processes. The use of advanced analysis techniques is crucial in achieving this goal. In this review, I discuss the concepts of optimal analysis, some important advanced analysis methods and a few examples. The judicious use of these advanced methods should enable new discoveries and produce results with better precision, robustness and clarity.

  12. ELECTROMIGRATION ISSUES IN HIGH CURRENT HORN.

    SciTech Connect

    ZHANG, S.Y.; BELLAVIA, S.; SANDBERG, J.; ET AL.

    2005-05-16

    The secondary particle focusing horn for the AGS neutrino experiment proposal is a high current and high current density device. The peak current of horn is 300 kA. At the smallest area of horn, the current density is near 8 kA/mm{sup 2}. At very high current density, a few kA/mm{sup 2}, the electromigration phenomena will occur. Momentum transfer between electrons and metal atoms at high current density causes electromigration. The reliability and lifetime of focusing horn can be severely reduced by electromigration. In this paper, we discuss issues such as device reliability model, incubation time of electromigration, and lifetime of horn.

  13. Advance particle and Doppler measurement methods

    NASA Technical Reports Server (NTRS)

    Busch, C.

    1985-01-01

    Particle environments, i.e., rain, ice, and snow particles are discussed. Two types of particles addressed are: (1) the natural environment in which airplanes fly and conduct test flights; and (2) simulation environments that are encountered in ground-test facilities such as wind tunnels, ranges, etc. There are characteristics of the natural environment that one wishes to measure. The liquid water content (LWC) is the one that seems to be of most importance; size distribution may be of importance in some applications. Like snow, the shape of the particle may be an important parameter to measure. As one goes on to environment in simulated tests, additional parameters may be required such as velocity distribution, the velocity lag of the particle relative to the aerodynamic flow, and the trajectory of the particle as it goes through the aerodynamic flow and impacts on the test object.

  14. Workshop on advances in smooth particle hydrodynamics

    SciTech Connect

    Wingate, C.A.; Miller, W.A.

    1993-12-31

    This proceedings contains viewgraphs presented at the 1993 workshop held at Los Alamos National Laboratory. Discussed topics include: negative stress, reactive flow calculations, interface problems, boundaries and interfaces, energy conservation in viscous flows, linked penetration calculations, stability and consistency of the SPH method, instabilities, wall heating and conservative smoothing, tensors, tidal disruption of stars, breaking the 10,000,000 particle limit, modelling relativistic collapse, SPH without H, relativistic KSPH avoidance of velocity based kernels, tidal compression and disruption of stars near a supermassive rotation black hole, and finally relativistic SPH viscosity and energy.

  15. Recent Advances in Understanding Particle Acceleration Processes in Solar Flares

    NASA Astrophysics Data System (ADS)

    Zharkova, V. V.; Arzner, K.; Benz, A. O.; Browning, P.; Dauphin, C.; Emslie, A. G.; Fletcher, L.; Kontar, E. P.; Mann, G.; Onofri, M.; Petrosian, V.; Turkmani, R.; Vilmer, N.; Vlahos, L.

    2011-09-01

    We review basic theoretical concepts in particle acceleration, with particular emphasis on processes likely to occur in regions of magnetic reconnection. Several new developments are discussed, including detailed studies of reconnection in three-dimensional magnetic field configurations (e.g., current sheets, collapsing traps, separatrix regions) and stochastic acceleration in a turbulent environment. Fluid, test-particle, and particle-in-cell approaches are used and results compared. While these studies show considerable promise in accounting for the various observational manifestations of solar flares, they are limited by a number of factors, mostly relating to available computational power. Not the least of these issues is the need to explicitly incorporate the electrodynamic feedback of the accelerated particles themselves on the environment in which they are accelerated. A brief prognosis for future advancement is offered.

  16. Advanced visualization technology for terascale particle accelerator simulations

    SciTech Connect

    Ma, K-L; Schussman, G.; Wilson, B.; Ko, K.; Qiang, J.; Ryne, R.

    2002-11-16

    This paper presents two new hardware-assisted rendering techniques developed for interactive visualization of the terascale data generated from numerical modeling of next generation accelerator designs. The first technique, based on a hybrid rendering approach, makes possible interactive exploration of large-scale particle data from particle beam dynamics modeling. The second technique, based on a compact texture-enhanced representation, exploits the advanced features of commodity graphics cards to achieve perceptually effective visualization of the very dense and complex electromagnetic fields produced from the modeling of reflection and transmission properties of open structures in an accelerator design. Because of the collaborative nature of the overall accelerator modeling project, the visualization technology developed is for both desktop and remote visualization settings. We have tested the techniques using both time varying particle data sets containing up to one billion particle s per time step and electromagnetic field data sets with millions of mesh elements.

  17. Fabrication of advanced particles and particle-based materials assisted by droplet-based microfluidics.

    PubMed

    Wang, Jing-Tao; Wang, Juan; Han, Jun-Jie

    2011-07-01

    Recent advances in the fabrication of complex particles and particle-based materials assisted by droplet-based microfluidics are reviewed. Monodisperse particles with expected internal structures, morphologies, and sizes in the range of nanometers to hundreds of micrometers have received a good deal of attention in recent years. Due to the capability of generating monodisperse emulsions and of executing precise control and operations on the suspended droplets inside the microchannels, droplet-based microfluidic devices have become powerful tools for fabricating complex particles with desired properties. Emulsions and multiple-emulsions generated in the microfluidic devices can be composed of a variety of materials including aqueous solutions, gels, polymers and solutions containing functional nanoparticles. They are ideal microreactors or fine templates for synthesizing advanced particles, such as polymer particles, microcapsules, nanocrystals, and photonic crystal clusters or beads by further chemical or physical operations. These particles are promising materials that may be applicable for many fields, such as photonic materials, drug delivery systems, and bio-analysis. From simple to complex, from spherical to nonspherical, from polymerization and reaction crystallization to self-assembly, this review aims to help readers be aware of the many aspects of this field.

  18. Recent advances in the Mercury Monte Carlo particle transport code

    SciTech Connect

    Brantley, P. S.; Dawson, S. A.; McKinley, M. S.; O'Brien, M. J.; Stevens, D. E.; Beck, B. R.; Jurgenson, E. D.; Ebbers, C. A.; Hall, J. M.

    2013-07-01

    We review recent physics and computational science advances in the Mercury Monte Carlo particle transport code under development at Lawrence Livermore National Laboratory. We describe recent efforts to enable a nuclear resonance fluorescence capability in the Mercury photon transport. We also describe recent work to implement a probability of extinction capability into Mercury. We review the results of current parallel scaling and threading efforts that enable the code to run on millions of MPI processes. (authors)

  19. High PRF high current switch

    DOEpatents

    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. Characterization of the interactions within fine particle mixtures in highly concentrated suspensions for advanced particle processing.

    PubMed

    Otsuki, Akira; Bryant, Gary

    2015-12-01

    This paper aims to summarize recent investigations into the dispersion of fine particles, and the characterization of their interactions, in concentrated suspensions. This summary will provide a better understanding of the current status of this research, and will provide useful feedback for advanced particle processing. Such processes include the fabrication of functional nanostructures and the sustainable beneficiation of complex ores. For example, there has been increasing demand for complex ore utilization due to the noticeable decrease in the accessibility of high grade and easily extractable ores. In order to maintain the sustainable use of mineral resources, the effective beneficiation of complex ores is urgently required. It can be successfully achieved only with selective particle/mineral dispersion/liberation and the assistance of mineralogical and particle characterization. PMID:26298173

  1. Characterization of the interactions within fine particle mixtures in highly concentrated suspensions for advanced particle processing.

    PubMed

    Otsuki, Akira; Bryant, Gary

    2015-12-01

    This paper aims to summarize recent investigations into the dispersion of fine particles, and the characterization of their interactions, in concentrated suspensions. This summary will provide a better understanding of the current status of this research, and will provide useful feedback for advanced particle processing. Such processes include the fabrication of functional nanostructures and the sustainable beneficiation of complex ores. For example, there has been increasing demand for complex ore utilization due to the noticeable decrease in the accessibility of high grade and easily extractable ores. In order to maintain the sustainable use of mineral resources, the effective beneficiation of complex ores is urgently required. It can be successfully achieved only with selective particle/mineral dispersion/liberation and the assistance of mineralogical and particle characterization.

  2. Recent advances in neutral particle transport methods and codes

    NASA Astrophysics Data System (ADS)

    Azmy, Yousry Y.

    1997-02-01

    An overview of Oak Ridge National Laboratory's (ORNL) 3D neural particle transport code, TORT, is presented. Special features of the code that make it invaluable for large applications are summarized for the prospective user. Advanced capabilities currently under development and installation in the production release of TORT are discussed in some detail. These include: multitasking on Cray platforms running the UNICOS operating system; adjacent-cell preconditioning acceleration scheme; and graphics codes for displaying computed quantities such as the flux. Further developments for TORT and its companion codes to enhance its present capabilities, as well as expand its range of applications will be discussed. Speculation on the next generation of neutral particle transport codes at ORNL, especially regarding unstructured grids and high order spatial approximations, will also be mentioned.

  3. Recent advances in neutral particle transport methods and codes

    SciTech Connect

    Azmy, Y.Y.

    1996-06-01

    An overview of ORNL`s three-dimensional neutral particle transport code, TORT, is presented. Special features of the code that make it invaluable for large applications are summarized for the prospective user. Advanced capabilities currently under development and installation in the production release of TORT are discussed; they include: multitasking on Cray platforms running the UNICOS operating system; Adjacent cell Preconditioning acceleration scheme; and graphics codes for displaying computed quantities such as the flux. Further developments for TORT and its companion codes to enhance its present capabilities, as well as expand its range of applications are disucssed. Speculation on the next generation of neutron particle transport codes at ORNL, especially regarding unstructured grids and high order spatial approximations, are also mentioned.

  4. High current capacity electrical connector

    DOEpatents

    Bettis, Edward S.; Watts, Harry L.

    1976-01-13

    An electrical connector is provided for coupling high current capacity electrical conductors such as copper busses or the like. The connector is arranged in a "sandwiched" configuration in which a conductor plate contacts the busses along major surfaces thereof clamped between two stainless steel backing plates. The conductor plate is provided with a plurality of contact buttons affixed therein in a spaced array such that the caps of the buttons extend above the conductor plate surface to contact the busses. When clamping bolts provided through openings in the sandwiched arrangement are tightened, Belleville springs provided under the rim of each button cap are compressed and resiliently force the caps into contact with the busses' contacting surfaces to maintain a predetermined electrical contact area provided by the button cap tops. The contact area does not change with changing thermal or mechanical stresses applied to the coupled conductors.

  5. HIGH CURRENT COAXIAL PHOTOMULTIPLIER TUBE

    DOEpatents

    Glass, N.W.

    1960-01-19

    A medium-gain photomultiplier tube having high current output, fast rise- time, and matched output impedance was developed. The photomultiplier tube comprises an elongated cylindrical envelope, a cylindrical anode supported at the axis of the envelope, a plurality of elongated spaced opaque areas on the envelope, and a plurality of light admitting windows. A photo-cathode is supported adjacent to each of the windows, and a plurality of secondary emissive dynodes are arranged in two types of radial arrays which are alternately positioned to fill the annular space between the anode and the envelope. The dynodes are in an array being radially staggered with respect to the dynodes in the adjacent array, the dynodes each having a portion arranged at an angle with respect to the electron path, such that electrons emitted by each cathode undergo multiplication upon impingement on a dynode and redirected flight to the next adjacent dynode.

  6. Performance of Advanced Light Source particle beam diagnostics

    SciTech Connect

    Hinkson, J.

    1993-05-01

    The Advanced Light Source (ALS), a third-generation synchrotron radiation facility, is complete. The particle beam diagnostics have been installed and tested. The beam injection systems have been running for two years. We have performance data on beam position monitors, beam intensity monitors, scintillators, beam collimators, a 50 {Omega} Faraday cup, and broad-band striplines and kickers used in the linac, transport lines, and the booster synchrotron. The single-turn monitoring capability of the booster beam position monitoring system has been particularly useful for studying beam dynamics. Beam diagnostics for the storage ring are being commissioned. In this paper we describe each instrument, show its performance, and outline how the instruments are controlled and their output data displayed.

  7. Recent advances in UHV techniques for particle accelerators

    SciTech Connect

    M. G. Rao

    1995-01-01

    The ultrahigh vacuum (UHV) requirements for storage rings and accelerators, and the development of the science and technology of UHV for particle accelerators and magnetic fusion devices have been recently reviewed by N.B. Mistry and H.F. Dylla respectively. In this paper, the latest developments in the advancement of UHV techniques for the vacuum integrity of Continuous Electron Beam Accelerator Facility (CEBAF) and for successfully dealing with the synchrotron radiation related beam line vacuum problem encountered in the design of the SSC are reviewed: the review includes developments in extreme sensitivity He leak detection technique based on the dynamic adsorption and desorption of He, operation of ionization gauges at Lhe temperatures, metal sponges for the effective cryopumping of H{sup 2} and He to pressures better than 10{sup -14} torr, and low cost and high He sensitivity RGA's. The details of a new extreme sensitivity He leak detector system are also discussed here.

  8. Study of nanoscale structural biology using advanced particle beam microscopy

    NASA Astrophysics Data System (ADS)

    Boseman, Adam J.

    This work investigates developmental and structural biology at the nanoscale using current advancements in particle beam microscopy. Typically the examination of micro- and nanoscale features is performed using scanning electron microscopy (SEM), but in order to decrease surface charging, and increase resolution, an obscuring conductive layer is applied to the sample surface. As magnification increases, this layer begins to limit the ability to identify nanoscale surface structures. A new technology, Helium Ion Microscopy (HIM), is used to examine uncoated surface structures on the cuticle of wild type and mutant fruit flies. Corneal nanostructures observed with HIM are further investigated by FIB/SEM to provide detailed three dimensional information about internal events occurring during early structural development. These techniques are also used to reconstruct a mosquito germarium in order to characterize unknown events in early oogenesis. Findings from these studies, and many more like them, will soon unravel many of the mysteries surrounding the world of developmental biology.

  9. Mismatch Oscillations in High Current Accelerators

    SciTech Connect

    Anderson, O.A.

    2005-05-03

    When planning the design of high-current FODO transport for accelerators, it is useful to have simple, accurate tools for calculating quantities such as the phase advances {sigma}{sub 0} and !given the lattice and beam parameters. Along with the KV beam model, the smooth approximation is often used. It is simple but not very accurate in many cases. Although Struckmeier and Reiser [1] showed that the stable oscillation frequencies of mismatched beams could be obtained accurately, they actually used a hybrid approach where {sigma}{sub 0} and {sigma} were already known precisely. When starting instead with basic quantities such as quadrupole dimensions, field strength, beam line charge density and emittance, the smooth approximation gives substantial errors. Here we derive a simple modification of the smooth approximation formula that improves the accuracy of the predicted frequencies by a factor of five at {sigma}{sub 0} = 83{sup o}.

  10. Charged-particle beam diagnostics for the advanced photon source

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Decker, G.; Kahana, E.; Patterson, D.; Sellyey, W.; Wang, X.; Chung, Y.

    1993-07-01

    Plans, prototypes, and initial test results for the charged-particle beam (e -, e +) diagnostic systems on the injector rings, their transport lines, and the storage ring for the Advanced Photon Source (APS) are presented. The APS will be a synchrotron radiation user facility with one of the world's brightest X-ray sources in the 10-keV regime. Its 200-MeV electron linac, 450-MeV positron linac, positron accumulator ring, 7-GeV injector synchrotron (IS), 7-GeV storage ring (SR), and undulator test lines will also demand the development and demonstration of key particle-beam characterization techniques over a wide range of parameter space. Some of these parameter values overlap or approach those projected for fourth generation light sources (linac-driven FELs and high brightness storage rings) as described at a recent workshop. Initial results from the diagnostics prototypes on the linac test stand operating at 45-MeV include current monitor data, beam loss monitor data, and video digitization using VME architecture.

  11. The "Puck" energetic charged particle detector: Design, heritage, and advancements

    NASA Astrophysics Data System (ADS)

    Clark, G.; Cohen, I.; Westlake, J. H.; Andrews, G. B.; Brandt, P.; Gold, R. E.; Gkioulidou, M. A.; Hacala, R.; Haggerty, D.; Hill, M. E.; Ho, G. C.; Jaskulek, S. E.; Kollmann, P.; Mauk, B. H.; McNutt, R. L.; Mitchell, D. G.; Nelson, K. S.; Paranicas, C.; Paschalidis, N.; Schlemm, C. E.

    2016-08-01

    Energetic charged particle detectors characterize a portion of the plasma distribution function that plays critical roles in some physical processes, from carrying the currents in planetary ring currents to weathering the surfaces of planetary objects. For several low-resource missions in the past, the need was recognized for a low-resource but highly capable, mass-species-discriminating energetic particle sensor that could also obtain angular distributions without motors or mechanical articulation. This need led to the development of a compact Energetic Particle Detector (EPD), known as the "Puck" EPD (short for hockey puck), that is capable of determining the flux, angular distribution, and composition of incident ions between an energy range of ~10 keV to several MeV. This sensor makes simultaneous angular measurements of electron fluxes from the tens of keV to about 1 MeV. The same measurements can be extended down to approximately 1 keV/nucleon, with some composition ambiguity. These sensors have a proven flight heritage record that includes missions such as MErcury Surface, Space ENvironment, GEochemistry, and Ranging and New Horizons, with multiple sensors on each of Juno, Van Allen Probes, and Magnetospheric Multiscale. In this review paper we discuss the Puck EPD design, its heritage, unexpected results from these past missions and future advancements. We also discuss high-voltage anomalies that are thought to be associated with the use of curved foils, which is a new foil manufacturing processes utilized on recent Puck EPD designs. Finally, we discuss the important role Puck EPDs can potentially play in upcoming missions.

  12. Novel particle and radiation sources and advanced materials

    NASA Astrophysics Data System (ADS)

    Mako, Frederick

    2016-03-01

    The influence Norman Rostoker had on the lives of those who had the pleasure of knowing him is profound. The skills and knowledge I gained as a graduate student researching collective ion acceleration has fueled a career that has evolved from particle beam physics to include particle and radiation source development and advanced materials research, among many other exciting projects. The graduate research performed on collective ion acceleration was extended by others to form the backbone for laser driven plasma ion acceleration. Several years after graduate school I formed FM Technologies, Inc., (FMT), and later Electron Technologies, Inc. (ETI). Currently, as the founder and president of both FMT and ETI, the Rostoker influence can still be felt. One technology that we developed is a self-bunching RF fed electron gun, called the Micro-Pulse Gun (MPG). The MPG has important applications for RF accelerators and microwave tube technology, specifically clinically improved medical linacs and "green" klystrons. In addition to electron beam and RF source research, knowledge of materials and material interactions gained indirectly in graduate school has blossomed into breakthroughs in materials joining technologies. Most recently, silicon carbide joining technology has been developed that gives robust helium leak tight, high temperature and high strength joints between ceramic-to-ceramic and ceramic-to-metal. This joining technology has the potential to revolutionize the ethylene production, nuclear fuel and solar receiver industries by finally allowing for the practical use of silicon carbide as furnace coils, fuel rods and solar receptors, respectively, which are applications that have been needed for decades.

  13. Advances in sublimation studies for particles of explosives

    NASA Astrophysics Data System (ADS)

    Furstenberg, Robert; Nguyen, Viet; Fischer, Thomas; Abrishami, Tara; Papantonakis, Michael; Kendziora, Chris; Mott, David R.; McGill, R. Andrew

    2015-05-01

    When handling explosives, or related surfaces, the hands routinely become contaminated with particles of explosives and related materials. Subsequent contact with a solid surface results in particle crushing and deposition. These particles provide an evidentiary trail which is useful for security applications. As such, the opto-physico-chemical characteristics of these particles are critical to trace explosives detection applications in DOD or DHS arenas. As the persistence of these particles is vital to their forensic exploitation, it is important to understand which factors influence their persistence. The longevity or stability of explosives particles on a substrate is a function of several environmental parameters or particle properties including: Vapor pressure, particle geometry, airflow, particle field size, substrate topography, humidity, reactivity, adlayers, admixtures, particle areal density, and temperature. In this work we deposited particles of 2,4-dinitrotoluene on standard microscopy glass slides by particle sieving and studied their sublimation as a function of airflow velocity, areal particle density and particle field size. Analysis of 2D microscopic images was used to compute and track particle size and geometrical characteristics. The humidity, temperature and substrate type were kept constant for each experiment. A custom airflow cell, using standard microscopy glass slide, allowed in-situ photomicroscopy. Areal particle densities and airflow velocities were selected to provide relevant loadings and flow velocities for a range of potential applications. For a chemical of interest, we define the radial sublimation velocity (RSV) for the equivalent sphere of a particle as the parameter to characterize the sublimation rate. The RSV is a useful parameter because it is independent of particle size. The sublimation rate for an ensemble of particles was found to significantly depend on airflow velocity, the areal density of the particles, and the

  14. Advance in Vertical Buffered Electropolishing on Niobium for Particle Accelerators*

    SciTech Connect

    A.T. Wu, S. Jin, J.D. Mammosser, C.E. Reece, R.A. Rimmer,L. Lin, X.Y. Lu, K. Zhao

    2011-09-01

    Niobium (Nb) is the most popular material that has been employed for making superconducting radio frequency (SRF) cavities to be used in various particle accelerators over the last couple of decades. One of the most important steps in fabricating Nb SRF cavities is the final chemical removal of 150 {mu}m of Nb from the inner surfaces of the SRF cavities. This is usually done by either buffered chemical polishing (BCP) or electropolishing (EP). Recently a new Nb surface treatment technique called buffered electropolishing (BEP) has been developed at Jefferson Lab. It has been demonstrated that BEP can produce the smoothest surface finish on Nb ever reported in the literature while realizing a Nb removal rate as high as 10 {mu}m/min that is more than 25 and 5 times quicker than those of EP and BCP(112) respectively. In this contribution, recent advance in optimizing and understanding BEP treatment technique is reviewed. Latest results from RF measurements on BEP treated Nb single cell cavities by our unique vertical polishing system will be reported.

  15. SEPServer advances overview on Solar Energetic Particle events

    NASA Astrophysics Data System (ADS)

    Malandraki, O.

    2013-09-01

    SEPServer hosted activities related to the scientific analysis of SEP event observations, including data analysis using both data-driven and simulation-based methods. The scientific conclusions of this effort are drawn with the implementation and release to the SEP community of multiple SEP event catalogs based on different spacecrafts and instruments, covering a broad timescale from 1975 to 2013 as well as a variety of distances from 0.3 to ~5 AU in the heliosphere. SEP events from Helios A & B missions, going back to 1975, at distances 0.3-1 AU, together with their Electromagnetic (EM) counterpart from OSRA data are being released for the first time. A catalog covering solar cycle 23 based upon the Solar and Heliospheric Observatory (SOHO)/ Energetic and Relativistic Nuclei and Electron (ERNE) highenergy (~68 MeV) protons at 1 AU with parallel analysis of SOHO/ Electron Proton Helium Instrument (EPHIN) and Advanced Composition Explorer (ACE) / Electron, Proton and Alpha Monitor (EPAM) data, including the relevant EM associations has also been delivered. Furthermore, the first complete Solar TErrestrial RElations Observatory (STEREO) SEP catalog based on the Low Energy Telescope (LET) protons (610 MeV) and the Solar Electron Proton Telescope (SEPT) electrons (65-105 keV) covering the rising phase of solar cycle 24 has been implemented. Moreover, the Cosmic Ray and Solar Particle Investigation (COSPIN) Kiel Electron Telescope (KET) data of 38-125 MeV has been used to identify a new catalog of SEP events observed in and out of the ecliptic plane over solar cycle 23, with simultaneous analysis of electrons recorded by the Heliosphere Instrument for Spectra, Composition and Anisotropy at Low Energies (HISCALE). For selected cases simulation based analysis has been applied in order to identify the timing of the injection history and to provide a cross reference to the EM emissions, leading to a comprehensive treatment of these events and to the corresponding testing of

  16. The High Current Experiment: First Results

    SciTech Connect

    Seidl, P; Baca, D; Bieniosek, F; Faltens, A; Lund, S; Molvik, A; Prost, L

    2004-05-10

    The High Current Experiment (HCX) is being assembled at Lawrence Berkeley National Laboratory as part of the U.S. program to explore heavy ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge dominated heavy ion beams at high space-charge intensity (line-charge density {approx}0.2{micro}C/m) over long pulse durations (>4 {micro}s). This machine will test transport issues at a driver-relevant scale resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and beam steering, matching, image charges, halo, lost-particle induced electron effects, and longitudinal bunch control. We present the first experimental results carried out with the coasting K{sup +} ion beam transported through the first 10 electrostatic transport quadrupoles and associated diagnostics. Later phases of the experiment will include more electrostatic lattice periods to allow more sensitive tests of emittance growth, and also magnetic quadrupoles to explore similar issues in magnetic channels with a full driver scale beam.

  17. The high current experiment: First results

    SciTech Connect

    Seidl, Peter A.; Baca, D.; Bieniosek, F.M.; Faltens, A.; Lund, S.M.; Molvik, A.W.; Prost, L.R.; Waldron, W.L.

    2002-05-26

    The High Current Experiment (HCX) is being assembled at Lawrence Berkeley National Laboratory as part of the US program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge dominated heavy-ion beams at high spacecharge intensity (line-charge density {approx} 0.2 {micro}C/m) over long pulse durations (>4 {micro}s). This machine will test transport issues at a driver-relevant scale resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and beam steering, matching, image charges, halo, lost-particle induced electron effects, and longitudinal bunch control. We present the first experimental results carried out with the coasting K{sup +} ion beam transported through the first 10 electrostatic transport quadrupoles and associated diagnostics. Later phases of the experiment will include more electrostatic lattice periods to allow more sensitive tests of emittance growth, and also magnetic quadrupoles to explore similar issues in magnetic channels with a full driver scale beam.

  18. Recent advances in the simulation of particle-laden flows

    NASA Astrophysics Data System (ADS)

    Harting, J.; Frijters, S.; Ramaioli, M.; Robinson, M.; Wolf, D. E.; Luding, S.

    2014-10-01

    A substantial number of algorithms exists for the simulation of moving particles suspended in fluids. However, finding the best method to address a particular physical problem is often highly non-trivial and depends on the properties of the particles and the involved fluid(s) together. In this report, we provide a short overview on a number of existing simulation methods and provide two state of the art examples in more detail. In both cases, the particles are described using a Discrete Element Method (DEM). The DEM solver is usually coupled to a fluid-solver, which can be classified as grid-based or mesh-free (one example for each is given). Fluid solvers feature different resolutions relative to the particle size and separation. First, a multicomponent lattice Boltzmann algorithm (mesh-based and with rather fine resolution) is presented to study the behavior of particle stabilized fluid interfaces and second, a Smoothed Particle Hydrodynamics implementation (mesh-free, meso-scale resolution, similar to the particle size) is introduced to highlight a new player in the field, which is expected to be particularly suited for flows including free surfaces.

  19. High current ion beam transport using solenoids

    SciTech Connect

    Hollinger, R.; Spaedtke, P.

    2008-02-15

    In the framework of the future project FAIR several upgrade programs and construction of new facilities are in progress such as the U{sup 4+} upgrade for the existing high current injector and the new 70 MeV proton injector. For both injectors solenoids in the low energy beam transport section are foreseen to inject the beam into the following rf accelerator. The paper presents beam quality measurements of high current ion beams behind a solenoid using a slit-grid emittance measurement device, viewing targets, and a pepper pot measurement device at the high current test bench at GSI.

  20. Advances in Bayesian Model Based Clustering Using Particle Learning

    SciTech Connect

    Merl, D M

    2009-11-19

    Recent work by Carvalho, Johannes, Lopes and Polson and Carvalho, Lopes, Polson and Taddy introduced a sequential Monte Carlo (SMC) alternative to traditional iterative Monte Carlo strategies (e.g. MCMC and EM) for Bayesian inference for a large class of dynamic models. The basis of SMC techniques involves representing the underlying inference problem as one of state space estimation, thus giving way to inference via particle filtering. The key insight of Carvalho et al was to construct the sequence of filtering distributions so as to make use of the posterior predictive distribution of the observable, a distribution usually only accessible in certain Bayesian settings. Access to this distribution allows a reversal of the usual propagate and resample steps characteristic of many SMC methods, thereby alleviating to a large extent many problems associated with particle degeneration. Furthermore, Carvalho et al point out that for many conjugate models the posterior distribution of the static variables can be parametrized in terms of [recursively defined] sufficient statistics of the previously observed data. For models where such sufficient statistics exist, particle learning as it is being called, is especially well suited for the analysis of streaming data do to the relative invariance of its algorithmic complexity with the number of data observations. Through a particle learning approach, a statistical model can be fit to data as the data is arriving, allowing at any instant during the observation process direct quantification of uncertainty surrounding underlying model parameters. Here we describe the use of a particle learning approach for fitting a standard Bayesian semiparametric mixture model as described in Carvalho, Lopes, Polson and Taddy. In Section 2 we briefly review the previously presented particle learning algorithm for the case of a Dirichlet process mixture of multivariate normals. In Section 3 we describe several novel extensions to the original

  1. Individual Particle Analysis of Ambient PM 2.5 Using Advanced Electron Microscopy Techniques

    SciTech Connect

    Gerald J. Keeler; Masako Morishita

    2006-12-31

    The overall goal of this project was to demonstrate a combination of advanced electron microscopy techniques that can be effectively used to identify and characterize individual particles and their sources. Specific techniques to be used include high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), STEM energy dispersive X-ray spectrometry (EDX), and energy-filtered TEM (EFTEM). A series of ambient PM{sub 2.5} samples were collected in communities in southwestern Detroit, MI (close to multiple combustion sources) and Steubenville, OH (close to several coal fired utility boilers). High-resolution TEM (HRTEM) -imaging showed a series of nano-metal particles including transition metals and elemental composition of individual particles in detail. Submicron and nano-particles with Al, Fe, Ti, Ca, U, V, Cr, Si, Ba, Mn, Ni, K and S were observed and characterized from the samples. Among the identified nano-particles, combinations of Al, Fe, Si, Ca and Ti nano-particles embedded in carbonaceous particles were observed most frequently. These particles showed very similar characteristics of ultrafine coal fly ash particles that were previously reported. By utilizing HAADF-STEM, STEM-EDX, and EF-TEM, this investigation was able to gain information on the size, morphology, structure, and elemental composition of individual nano-particles collected in Detroit and Steubenville. The results showed that the contributions of local combustion sources - including coal fired utilities - to ultrafine particle levels were significant. Although this combination of advanced electron microscopy techniques by itself can not identify source categories, these techniques can be utilized as complementary analytical tools that are capable of providing detailed information on individual particles.

  2. A New High-Current Proton Accelerator

    NASA Astrophysics Data System (ADS)

    Cleland, M. R.; Galloway, R. A.; DeSanto, L.; Jongen, Y.

    2009-03-01

    A high-current (>20 mA) dc proton accelerator is being developed for applications such as boron neutron capture therapy (BNCT) and the detection of explosive materials by nuclear resonance absorption (NRA) of gamma radiation. The high-voltage dc accelerator (adjustable between 1.4 and 2.8 MeV) will be a single-ended industrial Dynamitron® system equipped with a compact high-current, microwave-driven proton source. A magnetic mass analyzer inserted between the ion source and the acceleration tube will select the protons and reject heavier ions. A sorption pump near the ion source will minimize the flow of neutral hydrogen gas into the acceleration tube. For BNCT, a lithium target for generating epithermal neutrons is being developed that will be capable of dissipating the high power (>40 kW) of the proton beam. For NRA, special targets will be used to generate gamma rays with suitable energies for exciting nuclides typically present in explosive materials. Proton accelerators with such high-current and high-power capabilities in this energy range have not been developed previously.

  3. Innovative experimental particle physics through technological advances: Past, present and future

    SciTech Connect

    Cheung, Harry W.K.; /Fermilab

    2005-01-01

    This mini-course gives an introduction to the techniques used in experimental particle physics with an emphasis on the impact of technological advances. The basic detector types and particle accelerator facilities will be briefly covered with examples of their use and with comparisons. The mini-course ends with what can be expected in the near future from current technology advances. The mini-course is intended for graduate students and post-docs and as an introduction to experimental techniques for theorists.

  4. Advanced analysis of polymer emulsions: Particle size and particle size distribution by field-flow fractionation and dynamic light scattering.

    PubMed

    Makan, Ashwell C; Spallek, Markus J; du Toit, Madeleine; Klein, Thorsten; Pasch, Harald

    2016-04-15

    Field flow fractionation (FFF) is an advanced fractionation technique for the analyses of very sensitive particles. In this study, different FFF techniques were used for the fractionation and analysis of polymer emulsions/latexes. As model systems, a pure acrylic emulsion and emulsions containing titanium dioxide were prepared and analyzed. An acrylic emulsion polymerization was conducted, continuously sampled from the reactor and subsequently analyzed to determine the particle size, radius of gyration in specific, of the latex particles throughout the polymerization reaction. Asymmetrical flow field-flow fractionation (AF4) and sedimentation field-flow fractionation (SdFFF), coupled to a multidetector system, multi-angle laser light scattering (MALLS), ultraviolet (UV) and refractive index (RI), respectively, were used to investigate the evolution of particle sizes and particle size distributions (PSDs) as the polymerization progressed. The obtained particle sizes were compared against batch-mode dynamic light scattering (DLS). Results indicated differences between AF4 and DLS results due to DLS taking hydration layers into account, whereas both AF4 and SdFFF were coupled to MALLS detection, hence not taking the hydration layer into account for size determination. SdFFF has additional separation capabilities with a much higher resolution compared to AF4. The calculated radii values were 5 nm larger for SdFFF measurements for each analyzed sample against the corresponding AF4 values. Additionally a low particle size shoulder was observed for SdFFF indicating bimodality in the reactor very early during the polymerization reaction. Furthermore, different emulsions were mixed with inorganic species used as additives in cosmetics and coatings such as TiO2. These complex mixtures of species were analyzed to investigate the retention and particle interaction behavior under different AF4 experimental conditions, such as the mobile phase. The AF4 system was coupled online

  5. HIGH CURRENT RADIO FREQUENCY ION SOURCE

    DOEpatents

    Abdelaziz, M.E.

    1963-04-01

    This patent relates to a high current radio frequency ion source. A cylindrical plasma container has a coil disposed around the exterior surface thereof along the longitudinal axis. Means are provided for the injection of an unionized gas into the container and for applying a radio frequency signal to the coil whereby a radio frequency field is generated within the container parallel to the longitudinal axis thereof to ionize the injected gas. Cathode and anode means are provided for extracting transverse to the radio frequency field from an area midway between the ends of the container along the longitudinal axis thereof the ions created by said radio frequency field. (AEC)

  6. Development of an integrated energetic neutral particle measurement system on experimental advanced full superconducting tokamak

    SciTech Connect

    Zhu, Y. B. Liu, D.; Heidbrink, W. W.; Zhang, J. Z.; Qi, M. Z.; Xia, S. B.; Wan, B. N.; Li, J. G.

    2014-11-15

    Full function integrated, compact silicon photodiode based solid state neutral particle analyzers (ssNPA) have been developed for energetic particle (EP) relevant studies on the Experimental Advanced Superconducting Tokamak (EAST). The ssNPAs will be mostly operated in advanced current mode with a few channels to be operated in conventional pulse-counting mode, aiming to simultaneously achieve individually proved ultra-fast temporal, spatial, and spectral resolution capabilities. The design details together with considerations on EAST specific engineering realities and physics requirements are presented. The system, including a group of single detectors on two vertical ports and two 16-channel arrays on a horizontal port, can provide both active and passive charge exchange measurements. ssNPA detectors, with variable thickness of ultra thin tungsten dominated foils directly deposited on the front surface, are specially fabricated and utilized to achieve about 22 keV energy resolution for deuterium particle detection.

  7. Development of an integrated energetic neutral particle measurement system on experimental advanced full superconducting tokamak

    NASA Astrophysics Data System (ADS)

    Zhu, Y. B.; Zhang, J. Z.; Qi, M. Z.; Xia, S. B.; Liu, D.; Heidbrink, W. W.; Wan, B. N.; Li, J. G.

    2014-11-01

    Full function integrated, compact silicon photodiode based solid state neutral particle analyzers (ssNPA) have been developed for energetic particle (EP) relevant studies on the Experimental Advanced Superconducting Tokamak (EAST). The ssNPAs will be mostly operated in advanced current mode with a few channels to be operated in conventional pulse-counting mode, aiming to simultaneously achieve individually proved ultra-fast temporal, spatial, and spectral resolution capabilities. The design details together with considerations on EAST specific engineering realities and physics requirements are presented. The system, including a group of single detectors on two vertical ports and two 16-channel arrays on a horizontal port, can provide both active and passive charge exchange measurements. ssNPA detectors, with variable thickness of ultra thin tungsten dominated foils directly deposited on the front surface, are specially fabricated and utilized to achieve about 22 keV energy resolution for deuterium particle detection.

  8. Development of an integrated energetic neutral particle measurement system on experimental advanced full superconducting tokamak.

    PubMed

    Zhu, Y B; Zhang, J Z; Qi, M Z; Xia, S B; Liu, D; Heidbrink, W W; Wan, B N; Li, J G

    2014-11-01

    Full function integrated, compact silicon photodiode based solid state neutral particle analyzers (ssNPA) have been developed for energetic particle (EP) relevant studies on the Experimental Advanced Superconducting Tokamak (EAST). The ssNPAs will be mostly operated in advanced current mode with a few channels to be operated in conventional pulse-counting mode, aiming to simultaneously achieve individually proved ultra-fast temporal, spatial, and spectral resolution capabilities. The design details together with considerations on EAST specific engineering realities and physics requirements are presented. The system, including a group of single detectors on two vertical ports and two 16-channel arrays on a horizontal port, can provide both active and passive charge exchange measurements. ssNPA detectors, with variable thickness of ultra thin tungsten dominated foils directly deposited on the front surface, are specially fabricated and utilized to achieve about 22 keV energy resolution for deuterium particle detection.

  9. Single Particle ICP-MS: Advances toward routine analysis of nanomaterials.

    PubMed

    Montaño, Manuel D; Olesik, John W; Barber, Angela G; Challis, Katie; Ranville, James F

    2016-07-01

    From its early beginnings in characterizing aerosol particles to its recent applications for investigating natural waters and waste streams, single particle inductively coupled plasma-mass spectrometry (spICP-MS) has proven to be a powerful technique for the detection and characterization of aqueous dispersions of metal-containing nanomaterials. Combining the high-throughput of an ensemble technique with the specificity of a single particle counting technique and the elemental specificity of ICP-MS, spICP-MS is capable of rapidly providing researchers with information pertaining to size, size distribution, particle number concentration, and major elemental composition with minimal sample perturbation. Recently, advances in data acquisition, signal processing, and the implementation of alternative mass analyzers (e.g., time-of-flight) has resulted in a wider breadth of particle analyses and made significant progress toward overcoming many of the challenges in the quantitative analysis of nanoparticles. This review provides an overview of spICP-MS development from a niche technique to application for routine analysis, a discussion of the key issues for quantitative analysis, and examples of its further advancement for analysis of increasingly complex environmental and biological samples. Graphical Abstract Single particle ICP-MS workflow for the analysis of suspended nanoparticles.

  10. Space charge templates for high-current beam modeling

    SciTech Connect

    Vorobiev, Leonid G.; /Fermilab

    2008-07-01

    A computational method to evaluate space charge potential and gradients of charged particle beam in the presence of conducting boundaries, has been introduced. The three-dimensional (3D) field of the beam can be derived as a convolution of macro Green's functions (template fields), satisfying the same boundary conditions, as the original beam. Numerical experiments gave a confidence that space charge effects can be modeled by templates with enough accuracy and generality within dramatically faster computational times than standard combination: a grid density + Poisson solvers, realized in the most of Particle in Cell codes. The achieved rapidity may significantly broaden the high-current beam design space, making the optimization in automatic mode possible, which so far was only feasible for simplest self-field formulations such as rms envelope equations. The template technique may be used as a standalone program, or as an optional field solver in existing beam dynamics codes both in one-passage structures and in rings.

  11. High-current, high-frequency capacitors

    NASA Technical Reports Server (NTRS)

    Renz, D. D.

    1983-01-01

    The NASA Lewis high-current, high-frequency capacitor development program was conducted under a contract with Maxwell Laboratories, Inc., San Diego, California. The program was started to develop power components for space power systems. One of the components lacking was a high-power, high-frequency capacitor. Some of the technology developed in this program may be directly usable in an all-electric airplane. The materials used in the capacitor included the following: the film is polypropylene, the impregnant is monoisopropyl biphenyl, the conductive epoxy is Emerson and Cuming Stycast 2850 KT, the foil is aluminum, the case is stainless steel (304), and the electrode is a modified copper-ceramic.

  12. Quench properties of high current superconductors

    SciTech Connect

    Garber, M; Sampson, W B

    1980-01-01

    A technique has been developed which allows the simultaneous determination of most of the important parameters of a high current superconductor. The critical current, propagation velocity, normal state resistivity, magnetoresistance, and enthalpy are determined as a function of current and applied field. The measurements are made on non-inductive samples which simulate conditions in full scale magnets. For wide, braided conductors the propagation velocity was found to vary approximately quadratically with current in the 2 to 5 kA region. A number of conductors have been tested including some Nb/sub 3/Sn braids which have critical currents in excess of 10 kA at 5 T, 4.2 K.

  13. High current high accuracy IGBT pulse generator

    SciTech Connect

    Nesterov, V.V.; Donaldson, A.R.

    1995-05-01

    A solid state pulse generator capable of delivering high current triangular or trapezoidal pulses into an inductive load has been developed at SLAC. Energy stored in a capacitor bank of the pulse generator is switched to the load through a pair of insulated gate bipolar transistors (IGBT). The circuit can then recover the remaining energy and transfer it back to the capacitor bank without reversing the capacitor voltage. A third IGBT device is employed to control the initial charge to the capacitor bank, a command charging technique, and to compensate for pulse to pulse power losses. The rack mounted pulse generator contains a 525 {mu}F capacitor bank. It can deliver 500 A at 900V into inductive loads up to 3 mH. The current amplitude and discharge time are controlled to 0.02% accuracy by a precision controller through the SLAC central computer system. This pulse generator drives a series pair of extraction dipoles.

  14. Comparison of Electron Cloud Simulation and Experiments in the High-Current Experiment

    SciTech Connect

    Cohen, R H; Friedman, A; Covo, M K; Lund, S M; Molvik, A W; Bieniosek, F M; Seidl, P A; Vay, J; Stoltz, P; Veitzer, S

    2004-11-11

    Contaminating clouds of electrons are a common concern for accelerators of positive-charged particles, but there are some unique aspects of heavy-ion accelerators for fusion and high-energy density physics which make modeling such clouds especially challenging. In particular, self-consistent electron and ion simulation is required, including a particle advance scheme which can follow electrons in regions where electrons are strongly, weakly, and un-magnetized. We describe our approach to such self-consistency, and in particular a scheme for interpolating between full-orbit (Boris) and drift-kinetic particle pushes that enables electron time steps long compared to the typical gyro period in the magnets. We present tests and applications: simulation of electron clouds produced by three different kinds of sources indicates the sensitivity of the cloud shape to the nature of the source; first-of-a-kind self-consistent simulation of electron-cloud experiments on the High-Current Experiment (HCX) at LBNL, in which the machine can be flooded with electrons released by impact of the ion beam on an end plate, demonstrate the ability to reproduce key features of the ion-beam phase space; and simulation of a two-stream instability of thin beams in a magnetic field demonstrate the ability of the large-timestep mover to accurately calculate the instability.

  15. Delta-doped hybrid advanced detector for low energy particle detection

    NASA Technical Reports Server (NTRS)

    Cunningham, Thomas J. (Inventor); Fossum, Eric R. (Inventor); Nikzad, Shouleh (Inventor); Pain, Bedabrata (Inventor); Soli, George A. (Inventor)

    2000-01-01

    A delta-doped hybrid advanced detector (HAD) is provided which combines at least four types of technologies to create a detector for energetic particles ranging in energy from hundreds of electron volts (eV) to beyond several million eV. The detector is sensitive to photons from visible light to X-rays. The detector is highly energy-sensitive from approximately 10 keV down to hundreds of eV. The detector operates with milliwatt power dissipation, and allows non-sequential readout of the array, enabling various advanced readout schemes.

  16. Delta-doped hybrid advanced detector for low energy particle detection

    NASA Technical Reports Server (NTRS)

    Cunningham, Thomas J. (Inventor); Fossum, Eric R. (Inventor); Nikzad, Shouleh (Inventor); Pain, Bedabrata (Inventor); Soli, George A. (Inventor)

    2002-01-01

    A delta-doped hybrid advanced detector (HAD) is provided which combines at least four types of technologies to create a detector for energetic particles ranging in energy from hundreds of electron volts (eV) to beyond several million eV. The detector is sensitive to photons from visible light to X-rays. The detector is highly energy-sensitive from approximately 10 keV down to hundreds of eV. The detector operates with milliwatt power dissipation, and allows non-sequential readout of the array, enabling various advanced readout schemes.

  17. First results from solid state neutral particle analyzer on experimental advanced superconducting tokamak

    NASA Astrophysics Data System (ADS)

    Zhang, J. Z.; Zhu, Y. B.; Zhao, J. L.; Wan, B. N.; Li, J. G.; Heidbrink, W. W.

    2016-11-01

    Full function integrated, compact solid state neutral particle analyzers (ssNPA) based on absolute extreme ultraviolet silicon photodiode have been successfully implemented on the experimental advanced superconducting tokamak to measure energetic particle. The ssNPA system has been operated in advanced current mode with fast temporal and spatial resolution capabilities, with both active and passive charge exchange measurements. It is found that the ssNPA flux signals are increased substantially with neutral beam injection (NBI). The horizontal active array responds to modulated NBI beam promptly, while weaker change is presented on passive array. Compared to near-perpendicular beam, near-tangential beam brings more passive ssNPA flux and a broader profile, while no clear difference is observed on active ssNPA flux and its profile. Significantly enhanced intensities on some ssNPA channels have been observed during ion cyclotron resonant heating.

  18. Particle trapping at an advancing solidification front with interfacial-curvature effects

    NASA Astrophysics Data System (ADS)

    Rempel, A. W.; Worster, M. G.

    2001-03-01

    We predict the maximum solidification rate, or critical velocity, Vc at which an insoluble particle suspended in a melt is pushed ahead of an advancing solidification front by intermolecular forces. At higher solidification rates the particle is incorporated within the solid. The net intermolecular force pushing the particle and the viscous resistance opposing it are both significantly influenced by the shape of the front as it conforms to the particle in response to interfacial pre-melting. We predict the entire shape of the front, within a thin-film approximation, accounting for the freezing-point depression due to curvature. We show how the interface shape varies with the magnitude of the surface energy and the closeness of the particle, and compare these to previous, ad hoc representations of the interface. We confirm the scaling results of previous, more approximate, analyses for the case in which the intermolecular forces are dominated by non-retarded van der Waals interactions, and provide new results for other power-law interactions. We examine how the particle behaviour changes as its radius increases so that the effect of interfacial curvature is diminished.

  19. Advanced In-Situ Detection and Chemical Analysis of Interstellar Dust Particles

    NASA Astrophysics Data System (ADS)

    Sternovsky, Z.; Gemer, A.; Gruen, E.; Horanyi, M.; Kempf, S.; Maute, K.; Postberg, F.; Srama, R.; Williams, E.; O'brien, L.; Rocha, J. R. R.

    2015-12-01

    The Ulysses dust detector discovered that interstellar dust particles pass through the solar system. The Hyperdsut instrument is developed for the in-situ detection and analysis of these particles to determine the elemental, chemical and isotopic compositions. Hyperdust builds on the heritage of previous successful instruments, e.g. the Cosmic Dust Analyzer (CDA) on Cassini. Hyperdust combines a highly sensitive Dust Trajectory Sensor (DTS) and the high mass resolution Chemical Analyzer (CA). The DTS will detect dust particles as small as 0.3 μm in radius, and the velocity vector information is used to confirm the interstellar origin and/or reveal the dynamics from the interactions within the solar system. The effective target area of the CA is > 600 cm2 achieves mass resolution in excess of 200, which is considerably higher than that of CDA, and is acheved by advanced ion optics design. The Hyperdust instrument is in the final phases of development to TRL 6.

  20. Achromatic beam transport of High Current Injector

    NASA Astrophysics Data System (ADS)

    Kumar, Sarvesh; Mandal, A.

    2016-02-01

    The high current injector (HCI) provides intense ion beams of high charge state using a high temperature superconducting ECR ion source. The ion beam is accelerated upto a final energy of 1.8 MeV/u due to an electrostatic potential, a radio frequency quadrupole (RFQ) and a drift tube linac (DTL). The ion beam has to be transported to superconducting LINAC which is around 50 m away from DTL. This section is termed as high energy beam transport section (HEBT) and is used to match the beam both in transverse and longitudinal phase space to the entrance of LINAC. The HEBT section is made up of four 90 deg. achromatic bends and interconnecting magnetic quadrupole triplets. Two RF bunchers have been used for longitudinal phase matching to the LINAC. The ion optical design of HEBT section has been simulated using different beam dynamics codes like TRACEWIN, GICOSY and TRACE 3D. The field computation code OPERA 3D has been utilized for hardware design of all the magnets. All the dipole and quadrupole magnets have been field mapped and their test results such as edge angles measurements, homogeneity and harmonic analysis etc. are reported. The whole design of HEBT section has been performed such that the most of the beam optical components share same hardware design and there is ample space for beam diagnostics as per geometry of the building. Many combination of achromatic bends have been simulated to transport the beam in HEBT section but finally the four 90 deg. achromatic bend configuration is found to be the best satisfying all the geometrical constraints with simplified beam tuning process in real time.

  1. Settleability and characteristics of ferrate(VI)-induced particles in advanced wastewater treatment.

    PubMed

    Zheng, Lei; Deng, Yang

    2016-04-15

    Ferrate(VI) as an emerging water treatment agent has recently recaptured interests for advanced wastewater treatment. A large number of studies were published to report ferrate(VI)-driven oxidation for various water contaminants. In contrast, very few efforts were made to characterize ferrate(VI) resultant particles in water and wastewater. In this study, jar tests were performed to examine the settleability and characteristics of ferrate(VI)-induced iron oxide particles, particularly the non-settable fraction of these particles, after ferrate(VI) reduction in a biologically treated municipal wastewater. The particle settleability was evaluated through the measurement of turbidity and particulate iron concentration in the supernatant with the settling time. Results showed that a majority of ferrate(VI)-induced iron oxide aggregates remained suspended and caused an increased turbidity. For example, at a Fe(VI) dose of 5.0 mg/L and pH 7.50, 82% of the added iron remained in the supernatant and the turbidity was 8.97 NTU against the untreated sample turbidity (2.33 NTU) after 72-h settling. The poor settling property of these particles suggested that coagulation and flocculation did not perform well in the ferrate(VI) treatment. Particle size analysis and transmission electron microscopy (TEM) revealed that nano-scale particles were produced after ferrate(VI) decomposition, and gradually aggregated to form micro-scale larger particles in the secondary effluent. Zeta potentials of the non-settable ferrate(VI) resultant aggregates varied between -7.36 and -8.01 mV at pH 7.50 during the 72-h settling. The negative surface charges made the aggregates to be relatively stable in the wastewater matrix. PMID:26900976

  2. Settleability and characteristics of ferrate(VI)-induced particles in advanced wastewater treatment.

    PubMed

    Zheng, Lei; Deng, Yang

    2016-04-15

    Ferrate(VI) as an emerging water treatment agent has recently recaptured interests for advanced wastewater treatment. A large number of studies were published to report ferrate(VI)-driven oxidation for various water contaminants. In contrast, very few efforts were made to characterize ferrate(VI) resultant particles in water and wastewater. In this study, jar tests were performed to examine the settleability and characteristics of ferrate(VI)-induced iron oxide particles, particularly the non-settable fraction of these particles, after ferrate(VI) reduction in a biologically treated municipal wastewater. The particle settleability was evaluated through the measurement of turbidity and particulate iron concentration in the supernatant with the settling time. Results showed that a majority of ferrate(VI)-induced iron oxide aggregates remained suspended and caused an increased turbidity. For example, at a Fe(VI) dose of 5.0 mg/L and pH 7.50, 82% of the added iron remained in the supernatant and the turbidity was 8.97 NTU against the untreated sample turbidity (2.33 NTU) after 72-h settling. The poor settling property of these particles suggested that coagulation and flocculation did not perform well in the ferrate(VI) treatment. Particle size analysis and transmission electron microscopy (TEM) revealed that nano-scale particles were produced after ferrate(VI) decomposition, and gradually aggregated to form micro-scale larger particles in the secondary effluent. Zeta potentials of the non-settable ferrate(VI) resultant aggregates varied between -7.36 and -8.01 mV at pH 7.50 during the 72-h settling. The negative surface charges made the aggregates to be relatively stable in the wastewater matrix.

  3. PENETRATION AND DEFECT FORMATION IN HIGH CURRENT ARC WELDING

    SciTech Connect

    MENDEZ,P.F.; EAGAR, T.W.

    2003-01-01

    The work performed during the three previous years can be roughly divided into two main categories: (1) development of advanced modeling techniques; and (2) modeling of arc welding process. The work in the first category comprised the development of the Order of Magnitude Scaling (OMS) technique, which is complementary to numerical modeling techniques such as finite elements, but it provides approximate formulas instead of just numerical results. Borrowing concepts from OMS, another modeling technique based on empirical data was also developed. During this stage special software was also developed. The second category comprised the application of OMS to the three main subsystems of arc welding: the weld pool, the arc, and the electrode. For each of these subsystems they found scaling laws and regimes. With this knowledge, they analyzed the generation of weld pool defects during high current arc welding, proposed a mechanistic description of the process, and possible solutions.

  4. Advances and future needs in particle production and transport code developments

    SciTech Connect

    Mokhov, N.V.; /Fermilab

    2009-12-01

    The next generation of accelerators and ever expanding needs of existing accelerators demand new developments and additions to Monte-Carlo codes, with an emphasis on enhanced modeling of elementary particle and heavy-ion interactions and transport. Challenges arise from extremely high beam energies and beam power, increasing complexity of accelerators and experimental setups, as well as design, engineering and performance constraints. All these put unprecedented requirements on the accuracy of particle production predictions, the capability and reliability of the codes used in planning new accelerator facilities and experiments, the design of machine, target and collimation systems, detectors and radiation shielding and minimization of their impact on environment. Recent advances in widely-used general-purpose all-particle codes are described for the most critical modules such as particle production event generators, elementary particle and heavy ion transport in an energy range which spans up to 17 decades, nuclide inventory and macroscopic impact on materials, and dealing with complex geometry of accelerator and detector structures. Future requirements for developing physics models and Monte-Carlo codes are discussed.

  5. Advances in associated-particle sealed-tube neutron probe diagnostics for substance detection

    SciTech Connect

    Rhodes, E.; Dickerman, C.E.; Frey, M.

    1995-07-01

    The development and investigation of a small associated-particle sealed-tube neutron generator (APSTNG) shows potential to allow the associated-particle diagnostic method to be moved out of the laboratory into field applications. The APSTNG interrogates the inspected object with 14-MeV neutrons generated from the deuterium-tritium reaction and detects the alpha-particle associated with each neutron inside a cone encompassing the region of interest. Gamma-ray spectra of resulting neutron reactions identify many nuclides. Flight-times determined from detection times of the gamma-rays and alpha-particles can yield a separate coarse tomographic image of each identified nuclide, from a single orientation. Chemical substances are identified by comparing relative spectral line intensities with ratios of elements in reference compounds. The high-energy neutrons and gamma-rays penetrate large objects and dense materials. Generally no collimators or radiation shielding are needed. Proof-of-concept laboratory experiments have been successfully performed for simulated nuclear, chemical warfare, and conventional munitions. Most recently, inspection applications have been investigated for radioactive waste characterization, presence of cocaine in propane tanks, and uranium and plutonium smuggling. Based on lessons learned with the present APSTNG system, an advanced APSTNG tube (along with improved high voltage supply and control units) is being designed and fabricated that will be transportable and rugged, yield a substantial neutron output increase, and provide sufficiently improved lifetime to allow operation at more than an order of magnitude increase in neutron flux.

  6. Particles, waves and storms in geospace: Recent advances and persistent gaps in our comprehension

    NASA Astrophysics Data System (ADS)

    Daglis, Ioannis A.

    2016-07-01

    The terrestrial magnetosphere features plasma populations with a wide dynamic range of energies, spanning more than 8 orders of magnitude -- from ≃V in the plasmasphere to tens of MeV in the outer Van Allen belt and hundreds of MeV in the inner Van Allen belt. A wealth of in-situ measurements of particles and waves, and ground-based measurements of waves, has shaped a comprehensive understanding of the interactions of the various plasma populations with electromagnetic waves during geospace magnetic storms and magnetospheric substorms. We shall discuss recent advances and persistent gaps in our comprehension of inner magnetosphere dynamics.

  7. Advanced laser particle accelerator development at LANL: from fast ignition to radiation oncology

    SciTech Connect

    Flippo, Kirk A; Gaillard, Sandrine A; Offermann, D T; Cobble, J A; Schmitt, M J; Gautier, D C; Kwan, T J T; Montgomery, D S; Kluge, Thomas; Bussmann, Micheal; Bartal, T; Beg, F N; Gall, B; Geissel, M; Korgan, G; Kovaleski, S; Lockard, T; Malekos, S; Schollmeier, M; Sentoku, Y; Cowan, T E

    2010-01-01

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, SN M detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high current and high energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology in conjunction with our partners at the ForschungsZentrum Dresden-Rossendorf (FZD). Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent etliciencies of >5% from flat foils, on Trident using only a 5th of the intensity and energy of the Nova Petawatt. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  8. Advanced Laser Particle Accelerator Development at LANL: From Fast Ignition to Radiation Oncology

    SciTech Connect

    Flippo, K. A.; Offermann, D. T.; Cobble, J. A.; Schmitt, M. J.; Gautier, D. C.; Kwan, T. J.; Montgomery, D. S.; Gaillard, S. A.; Kluge, T.; Bussmann, M.; Cowan, T. E.; Bartal, T.; Beg, F. N.; Gall, B.; Kovaleski, S.; Geissel, M.; Schollmeier, M.; Korgan, G.; Malekos, S.; Lockard, T.

    2010-11-04

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, Special Nuclear Material (SNM) detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high-current and high-energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology. Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent efficiencies of >5% from flat foils, on Trident using only a 5th of the intensity and energy of the Nova Petawatt laser. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world [3]. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  9. Advanced Laser Particle Accelerator Development at LANL: From Fast Ignition to Radiation Oncology

    NASA Astrophysics Data System (ADS)

    Flippo, K. A.; Gaillard, S. A.; Kluge, T.; Bussmann, M.; Offermann, D. T.; Cobble, J. A.; Schmitt, M. J.; Bartal, T.; Beg, F. N.; Cowan, T. E.; Gall, B.; Gautier, D. C.; Geissel, M.; Kwan, T. J.; Korgan, G.; Kovaleski, S.; Lockard, T.; Malekos, S.; Montgomery, D. S.; Schollmeier, M.; Sentoku, Y.

    2010-11-01

    Laser-plasma accelerated ion and electron beam sources are an emerging field with vast prospects, and promise many superior applications in a variety of fields such as hadron cancer therapy, compact radioisotope generation, table-top nuclear physics, laboratory astrophysics, nuclear forensics, waste transmutation, Special Nuclear Material (SNM) detection, and inertial fusion energy. LANL is engaged in several projects seeking to develop compact high-current and high-energy ion and electron sources. We are especially interested in two specific applications: ion fast ignition/capsule perturbation and radiation oncology. Laser-to-beam conversion efficiencies of over 10% are needed for practical applications, and we have already shown inherent efficiencies of >5% from flat foils, on Trident using only a 5th of the intensity [1] and energy of the Nova Petawatt laser [2]. With clever target designs, like structured curved cone targets, we have also been able to achieve major ion energy gains, leading to the highest energy laser-accelerated proton beams in the world [3]. These new target designs promise to help usher in the next generation of particle sources realizing the potential of laser-accelerated beams.

  10. Advances in Single-Particle Electron Cryomicroscopy Structure Determination applied to Sub-tomogram Averaging.

    PubMed

    Bharat, Tanmay A M; Russo, Christopher J; Löwe, Jan; Passmore, Lori A; Scheres, Sjors H W

    2015-09-01

    Recent innovations in specimen preparation, data collection, and image processing have led to improved structure determination using single-particle electron cryomicroscopy (cryo-EM). Here we explore some of these advances to improve structures determined using electron cryotomography (cryo-ET) and sub-tomogram averaging. We implement a new three-dimensional model for the contrast transfer function, and use this in a regularized likelihood optimization algorithm as implemented in the RELION program. Using direct electron detector data, we apply both single-particle analysis and sub-tomogram averaging to analyze radiation-induced movements of the specimen. As in single-particle cryo-EM, we find that significant sample movements occur during tomographic data acquisition, and that these movements are substantially reduced through the use of ultrastable gold substrates. We obtain a sub-nanometer resolution structure of the hepatitis B capsid, and show that reducing radiation-induced specimen movement may be central to attempts at further improving tomogram quality and resolution.

  11. On the behaviour of foreign particles at an advancing solid-liquid interface

    NASA Astrophysics Data System (ADS)

    Pötschke, Jürgen; Rogge, Volker

    1989-03-01

    The present paper describes a theoretical approach to the behaviour at advancing solid-liquid interfaces of foreign particles present in the melt as a separate phase. The temperature field and the influence of a contaminant in the melt were taken into account. The equations which arose were solved numerically. The numerical data can be described with satisfactory accuracy by a function, so that the result can be communicated in the form of a self-contained expression. The use of this equation is found to be in good agreement with recent measurements of latex particles in water: the model gives the critical solidification velocity at which the latex particles of a specific size are only just pushed along by the ice front. An assessment of other measured values given in the literature is not possible since the material values and experimental parameters are not completely known. To consolidate the theory, therefore, further quantitative measurements of systems with known material values, interfacial free energies in particular, are required.

  12. Advancements in the Coupling of State-of-the-Art Energetic Particle and Magnetohydrodynamic Simulations

    NASA Astrophysics Data System (ADS)

    Gorby, M.

    2015-12-01

    Recent advancements in coupling the Earth Moon Mars Radiation Environment Module (EMMREM) and two MHD models, Magnetohydrodynamics Around a Sphere (MAS) and ENLIL, have yielded promising results for predicting differential energy flux and radiation doses at 1AU. The EMMREM+MAS coupling focuses on the details of particle acceleration due to CMEs initiated low in the corona (1Rs - 20Rs). The EMMREM+ENLIL coupling gives results for CMEs initiated at ~20Rs and is part of a predictive capability being developed in conjunction with the CCMC. The challenge in forming large solar energetic particle events in both the prompt scenario lower down or for a gradual CME further out is to have enhanced scattering within the acceleration regions while also allowing for efficient escape of accelerated particles downstream. We present here details of the MHD parameters and topology of a CME around the acceleration regions in the early evolution (below 2Rs), dose and flux predictions at 1AU, and how compression regions vs. shocks affect the evolution and spectrum of an SEP event.

  13. Advances in Single-Particle Electron Cryomicroscopy Structure Determination applied to Sub-tomogram Averaging.

    PubMed

    Bharat, Tanmay A M; Russo, Christopher J; Löwe, Jan; Passmore, Lori A; Scheres, Sjors H W

    2015-09-01

    Recent innovations in specimen preparation, data collection, and image processing have led to improved structure determination using single-particle electron cryomicroscopy (cryo-EM). Here we explore some of these advances to improve structures determined using electron cryotomography (cryo-ET) and sub-tomogram averaging. We implement a new three-dimensional model for the contrast transfer function, and use this in a regularized likelihood optimization algorithm as implemented in the RELION program. Using direct electron detector data, we apply both single-particle analysis and sub-tomogram averaging to analyze radiation-induced movements of the specimen. As in single-particle cryo-EM, we find that significant sample movements occur during tomographic data acquisition, and that these movements are substantially reduced through the use of ultrastable gold substrates. We obtain a sub-nanometer resolution structure of the hepatitis B capsid, and show that reducing radiation-induced specimen movement may be central to attempts at further improving tomogram quality and resolution. PMID:26256537

  14. The movement of particles in liquid metals under gravity forces and the interaction of particles with advancing solid-liquid interface

    NASA Technical Reports Server (NTRS)

    Weinberg, F.

    1984-01-01

    The problems of shrinkage and gas porosity are discussed. Gravity forces enhance the removal of gas bubbles from a metal melt and contribute to the feeding of shrinkage porosity in castings. Experiments are reviewed which determine how large a density difference is required for metal particles to float or sink in a metal melt and to what extent do factors not considered in Stokes Law influence particle movement in a real system. As to the interaction of particles with an advancing solid-liquid interface, the results indicate that the metal particles are not rejected in a metal melt, and that concentrations of particles in a metal following solidification are due to other factors.

  15. High-Current Experiments for Accelerator-Based Neutron Capture Therapy Applications

    SciTech Connect

    Gierga, D.P.; Klinkowstein, R.E.; Hughey, B.H.; Shefer, R.E.; Yanch, J.C.; Blackburn, B.W.

    1999-06-06

    Several accelerator-based neutron capture therapy applications are under development. These applications include boron neutron capture therapy for glioblastoma multiform and boron neutron capture synovectomy (BNCS) for rheumatoid arthritis. These modalities use accelerator-based charged-particle reactions to create a suitable neutron source. Neutrons are produced using a high-current, 2-MV terminal tandem accelerator. For these applications to be feasible, high accelerator beam currents must be routinely achievable. An effort was undertaken to explore the operating regime of the accelerator in the milliampere range. In preparation for high-current operation of the accelerator, computer simulations of charged-particle beam optics were performed to establish high-current operating conditions. Herein we describe high beam current simulations and high beam current operation of the accelerator.

  16. Comparison of electron cloud simulation and experiments in the high-current experiment

    SciTech Connect

    Cohen, R.H.; Friedman, A.; Covo, M. Kireeff; Lund, S.M.; Molvik, A.W.; Bieniosek, F.M.; Seidl, P.A.; Vay, J.-L.; Verboncoeur, J.; Stoltz, P.; Veitzer, S.

    2004-08-27

    A set of experiments has been performed on the High-Current Experiment (HCX) facility at LBNL, in which the ion beam is allowed to collide with an end plate and thereby induce a copious supply of desorbed electrons. Through the use of combinations of biased and grounded electrodes positioned in between and downstream of the quadrupole magnets, the flow of electrons upstream into the magnets can be turned on or off. Properties of the resultant ion beam are measured under each condition. The experiment is modeled via a full three-dimensional, two species (electron and ion) particle simulation, as well as via reduced simulations (ions with appropriately chosen model electron cloud distributions, and a high-resolution simulation of the region adjacent to the end plate). The three-dimensional simulations are the first of their kind and the first to make use of a timestep-acceleration scheme that allows the electrons to be advanced with a timestep that is not small compared to the highest electron cyclotron period. The simulations reproduce qualitative aspects of the experiments, illustrate some unanticipated physical effects, and serve as an important demonstration of a developing simulation capability.

  17. Comparison of Electron Cloud Simulation and Experiments in the High-Current Experiment

    SciTech Connect

    Cohen, R; Friedman, A; Covo, M K; Lund, S; Molvik, A; Bieniosek, F; Seidl, P; Vay, J; Verboncoeur, J; Stoltz, P; Veitzer, S

    2004-10-07

    A set of experiments has been performed on the High-Current Experiment (HCX) facility at LBNL, in which the ion beam is allowed to collide with an end plate and thereby induce a copious supply of desorbed electrons. Through the use of combinations of biased and grounded electrodes positioned in between and downstream of the quadrupole magnets, the flow of electrons upstream into the magnets can be turned on or off. Properties of the resultant ion beam are measured under each condition. The experiment is modeled via a full three-dimensional, two species (electron and ion) particle simulation, as well as via reduced simulations (ions with appropriately chosen model electron cloud distributions, and a high-resolution simulation of the region adjacent to the end plate). The three-dimensional simulations are the first of their kind and the first to make use of a timestep-acceleration scheme that allows the electrons to be advanced with a timestep that is not small compared to the highest electron cyclotron period. The simulations reproduce qualitative aspects of the experiments, illustrate some unanticipated physical effects, and serve as an important demonstration of a developing simulation capability.

  18. A high current, short pulse electron source for wakefield accelerators

    SciTech Connect

    Ho, Ching-Hung

    1992-12-31

    Design studies for the generation of a high current, short pulse electron source for the Argonne Wakefield Accelerator are presented. An L-band laser photocathode rf gun cavity is designed using the computer code URMEL to maximize the electric field on the cathode surface for fixed frequency and rf input power. A new technique using a curved incoming laser wavefront to minimize the space charge effect near the photocathode is studied. A preaccelerator with large iris to minimize wakefield effects is used to boost the drive beam to a useful energy of around 20 MeV for wakefield acceleration experiments. Focusing in the photocathode gun and the preaccelerator is accomplished with solenoids. Beam dynamics simulations throughout the preaccelerator are performed using particle simulation codes TBCI-SF and PARMELA. An example providing a useful set of operation parameters for the Argonne Wakefield Accelerator is given. The effects of the sagitta of the curved beam and laser amplitude and timing jitter effects are discussed. Measurement results of low rf power level bench tests and a high power test for the gun cavity are presented and discussed.

  19. A high current, short pulse electron source for wakefield accelerators

    SciTech Connect

    Ho, Ching-Hung.

    1992-01-01

    Design studies for the generation of a high current, short pulse electron source for the Argonne Wakefield Accelerator are presented. An L-band laser photocathode rf gun cavity is designed using the computer code URMEL to maximize the electric field on the cathode surface for fixed frequency and rf input power. A new technique using a curved incoming laser wavefront to minimize the space charge effect near the photocathode is studied. A preaccelerator with large iris to minimize wakefield effects is used to boost the drive beam to a useful energy of around 20 MeV for wakefield acceleration experiments. Focusing in the photocathode gun and the preaccelerator is accomplished with solenoids. Beam dynamics simulations throughout the preaccelerator are performed using particle simulation codes TBCI-SF and PARMELA. An example providing a useful set of operation parameters for the Argonne Wakefield Accelerator is given. The effects of the sagitta of the curved beam and laser amplitude and timing jitter effects are discussed. Measurement results of low rf power level bench tests and a high power test for the gun cavity are presented and discussed.

  20. MHD Modeling of Conductors at Ultra-High Current Density

    SciTech Connect

    ROSENTHAL,STEPHEN E.; DESJARLAIS,MICHAEL P.; SPIELMAN,RICK B.; STYGAR,WILLIAM A.; ASAY,JAMES R.; DOUGLAS,M.R.; HALL,C.A.; FRESE,M.H.; MORSE,R.L.; REISMAN,D.B.

    2000-08-29

    In conjunction with ongoing high-current experiments on Sandia National Laboratories' Z accelerator, the authors have revisited a problem first described in detail by Heinz Knoepfel. Unlike the 1-Tesla MITLs of pulsed power accelerators used to produce intense particle beams, Z's disc transmission line (downstream of the current addition) is in a 100--1,200 Tesla regime, so its conductors cannot be modeled simply as static infinite conductivity boundaries. Using the MHD code MACH2 they have been investigating the conductor hydrodynamics, characterizing the joule heating, magnetic field diffusion, and material deformation, pressure, and velocity over a range of current densities, current rise-times, and conductor materials. Three purposes of this work are (1) to quantify power flow losses owing to ultra-high magnetic fields, (2) to model the response of VISAR diagnostic samples in various configurations on Z, and (3) to incorporate the most appropriate equation of state and conductivity models into the MHD computations. Certain features are strongly dependent on the details of the conductivity model.

  1. High-Current Energy-Recovering Electron Linacs

    SciTech Connect

    Nikolitsa Merminga; David Douglas; Geoffrey Krafft

    2003-12-01

    The use of energy recovery provides a potentially powerful new paradigm for generation of the charged particle beams used in synchrotron radiation sources, high-energy electron cooling devices, electron-ion colliders, and other applications in photon science and nuclear and high-energy physics. Energy-recovering electron linear accelerators (called energy-recovering linacs, or ERLs) share many characteristics with ordinary linacs, as their six-dimensional beam phase space is largely determined by electron source properties. However, in common with classic storage rings, ERLs possess a high average-current-carrying capability enabled by the energy recovery process, and thus promise similar efficiencies. The authors discuss the concept of energy recovery and its technical challenges and describe the Jefferson Lab (JLab) Infrared Demonstration Free-Electron Laser (IR Demo FEL), originally driven by a 3548-MeV, 5-mA superconducting radiofrequency (srf) ERL, which provided the most substantial demonstration of energy recovery to date: a beam of 250 kW average power. They present an overview of envisioned ERL applications and a development path to achieving the required performance. They use experimental data obtained at the JLab IR Demo FEL and recent experimental results from CEBAF-ERL GeV-scale, comparatively low-current energy-recovery demonstration at JLab to evaluate the feasibility of the new applications of high-current ERLs, as well as ERLs' limitations and ultimate performance.

  2. Stable superconducting magnet. [high current levels below critical temperature

    NASA Technical Reports Server (NTRS)

    Boom, R. W. (Inventor)

    1967-01-01

    Operation of a superconducting magnet is considered. A method is described for; (1) obtaining a relatively high current in a superconducting magnet positioned in a bath of a gas refrigerant; (2) operating a superconducting magnet at a relatively high current level without training; and (3) operating a superconducting magnet containing a plurality of turns of a niobium zirconium wire at a relatively high current level without training.

  3. High current density cathode for electrorefining in molten electrolyte

    DOEpatents

    Li, Shelly X.

    2010-06-29

    A high current density cathode for electrorefining in a molten electrolyte for the continuous production and collection of loose dendritic or powdery deposits. The high current density cathode eliminates the requirement for mechanical scraping and electrochemical stripping of the deposits from the cathode in an anode/cathode module. The high current density cathode comprises a perforated electrical insulated material coating such that the current density is up to 3 A/cm.sup.2.

  4. Results of prototype particle-beam diagnostics tests for the Advanced Photon Source (APS)

    SciTech Connect

    Lumpkin, A.H.; Chung, Y.; Kahana, E.; Patterson, D.; Sellyey, W.; Votaw, A.; Wang, X.

    1993-07-01

    The Advanced Photon Source (APS) will be a third-generation synchrotron radiation source (hard x-rays) based on 7-GeV positrons circulating in a 1,104-m circumference storage ring. In the past year a number of the diagnostic prototypes for the measurement of the charged-particle beam parameters throughout the subsystems of the facility (ranging from 450-MeV to 7-GeV positrons and with different pulse formats) have been built and tested. Results are summarized for the beam position monitor (BPM), current monitor (CM), loss monitor (LM), and imaging systems (ISYS). The test facilities ranged from the 40-MeV APS linac test stand to the existing storage rings at SSRL and NSLS.

  5. Observation of Energetic Particle Driven Modes Relevant to Advanced Tokamak Regimes

    SciTech Connect

    R. Nazikian; B. Alper; H.L. Berk; D. Borba; C. Boswell; R.V. Budny; K.H. Burrell; C.Z. Cheng; E.J. Doyle; E. Edlund; R.J. Fonck; A. Fukuyama; N.N. Gorelenkov; C.M. Greenfield; D.J. Gupta; M. Ishikawa; R.J. Jayakumar; G.J. Kramer; Y. Kusama; R.J. La Haye; G.R. McKee; W.A. Peebles; S.D. Pinches; M. Porkolab; J. Rapp; T.L. Rhodes; S.E. Sharapov; K. Shinohara; J.A. Snipes; W.M. Solomon; E.J. Strait; M. Takechi; M.A. Van Zeeland; W.P. West; K.L. Wong; S. Wukitch; L. Zeng

    2004-10-21

    Measurements of high-frequency oscillations in JET [Joint European Torus], JT-60U, Alcator C-Mod, DIII-D, and TFTR [Tokamak Fusion Test Reactor] plasmas are contributing to a new understanding of fast ion-driven instabilities relevant to Advanced Tokamak (AT) regimes. A model based on the transition from a cylindrical-like frequency-chirping mode to the Toroidal Alfven Eigenmode (TAE) has successfully encompassed many of the characteristics seen in experiments. In a surprising development, the use of internal density fluctuation diagnostics has revealed many more modes than has been detected on edge magnetic probes. A corollary discovery is the observation of modes excited by fast particles traveling well below the Alfven velocity. These observations open up new opportunities for investigating a ''sea of Alfven Eigenmodes'' in present-scale experiments, and highlight the need for core fluctuation and fast ion measurements in a future burning-plasma experiment.

  6. Coated Particles Fuel Compact-General Purpose Heat Source for Advanced Radioisotope Power Systems

    NASA Astrophysics Data System (ADS)

    El-Genk, Mohamed S.; Tournier, Jean-Michel

    2003-01-01

    Coated Particles Fuel Compacts (CPFC) have recently been shown to offer performance advantage for use in Radioisotope Heater Units (RHUs) and design flexibility for integrating at high thermal efficiency with Stirling Engine converters, currently being considered for 100 We. Advanced Radioisotope Power Systems (ARPS). The particles in the compact consist of 238PuO2 fuel kernels with 5-μm thick PyC inner coating and a strong ZrC outer coating, whose thickness depends on the maximum fuel temperature during reentry, the fuel kernel diameter, and the fraction of helium gas released from the kernels and fully contained by the ZrC coating. In addition to containing the helium generated by radioactive decay of 238Pu for up to 10 years before launch and 10-15 years mission lifetime, the kernels are intentionally sized (>= 300 μm in diameter) to prevent any adverse radiological effects on reentry. This paper investigates the advantage of replacing the four iridium-clad 238PuO2 fuel pellets, the two floating graphite membranes, and the two graphite impact shells in current State-Of-The-Art (SOA) General Purpose Heat Source (GPHS) with CPFC. The total mass, thermal power, and specific power of the CPFC-GPHS are calculated as functions of the helium release fraction from the fuel kernels and maximum fuel temperature during reentry from 1500 K to 2400 K. For the same total mass and volume as SOA GPHS, the generated thermal power by single-size particles CPFC-GPHS is 260 W at Beginning-Of-Mission (BOM), versus 231 W for the GPHS. For an additional 10% increase in total mass, the CPFC-GPHS could generate 340 W BOM; 48% higher than SOA GPHS. The corresponding specific thermal power is 214 W/kg, versus 160 W/kg for SOA GPHS; a 34% increase. Therefore, for the same thermal power, the CPFC-GPHS is lighter than SOA GPHS, while it uses the same amount of 238PuO2 fuel and same aeroshell. For the same helium release fraction and fuel temperature, binary-size particles CPFC-GPHS could

  7. Overview of charged-particle beam diagnostics for the Advanced Photon Source (APS)

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Decker, G.; Kahana, E.; Patterson, D.; Sellyey, W.; Votaw, A.; Wang, X.; Chung, Y.

    Plans, prototypes, and initial test results for the charged-particle beam (e-,e+) diagnostic systems on the injector rings, their transport lines, and the storage ring for the Advanced Photon Source (APS) are presented. The APS will be a synchrotron radiation user facility with one of the world's brightest x-ray sources in the 10-keV to 100-keV regime. Its 200-MeV electron linac, 450-MeV positron linac, positron accumulator ring, 7-GeV booster synchrotron, 7-GeV storage ring, and undulator test lines will also demand the development and demonstration of key particle-beam characterization techniques over a wide range of parameter space. Some of these parameter values overlap or approach those projected for fourth generation light sources (linac-driven FEL's and high brightness storage rings) as described at a recent workshop. Initial results from the diagnostics prototypes on the linac test stand operating at 45-MeV include current monitor data, beam loss monitor data, and video digitization using VME architecture.

  8. Charged-particle beam diagnostics for the Advanced Photon Source (APS)

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Decker, G.; Kahana, E.; Patterson, D.; Sellyey, W.; Wang, X.; Chung, Y.

    1992-08-01

    Plans, prototypes, and initial test results for the charged-particle beam (e-), e(+) diagnostic systems on the injector rings, their transport lines, and the storage ring for the Advanced Photon Source (APS) are presented. The APS will be a synchrotron radiation user facility with one of the world's brightest x-ray sources in the 10-keV to 100-keV regime. Its 200-MeV electron linac, 450-MeV positron linac, positron accumulator ring, 7-GeV booster synchrotron, 7-GeV storage ring, and undulator test lines will also demand the development and demonstration of key particle-beam characterization techniques over a wide range of parameter space. Some of these parameter values overlap or approach those projected for fourth generation light sources (linac-driven FELs and high brightness storage rings) as described at a recent workshop. Initial results from the diagnostics prototypes on the linac test stand operating at 45-MeV include current monitor data, beam loss monitor data, and video digitization using VME architecture.

  9. Overview of charged-particle beam diagnostics for the advanced photon source (APS)

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Decker, G.; Kahana, E.; Patterson, D.; Sellyey, W.; Votaw, A.; Wang, X.; Chung, Y.

    1992-07-01

    Plans, prototypes, and initial test results for the charged-particle beam (e-,e+) diagnostic systems on the injector rings, their transport lines, and the storage ring for the Advanced Photon Source (APS) are presented. The APS will be a synchrotron radiation user facility with one of the world's brightest x-ray sources in the 10-keV to 100-keV regime. Its 200-MeV electron linac, 450-MeV positron linac, positron accumulator ring, 7-GeV booster synchrotron, 7-GeV storage ring, and undulator test lines will also demand the development and demonstration of key particle-beam characterization techniques over a wide range of parameter space. Some of these parameter values overlap or approach those projected for fourth generation light sources (linac-driven FELs and high brightness storage rings) as described at a recent workshop. Initial results from the diagnostics prototypes on the linac test stand operating at 45-MeV include current monitor data, beam loss monitor data, and video digitization using VME architecture.

  10. Rational design and optimization of downstream processes of virus particles for biopharmaceutical applications: current advances.

    PubMed

    Vicente, Tiago; Mota, José P B; Peixoto, Cristina; Alves, Paula M; Carrondo, Manuel J T

    2011-01-01

    The advent of advanced therapies in the pharmaceutical industry has moved the spotlight into virus-like particles and viral vectors produced in cell culture holding great promise in a myriad of clinical targets, including cancer prophylaxis and treatment. Even though a couple of cases have reached the clinic, these products have yet to overcome a number of biological and technological challenges before broad utilization. Concerning the manufacturing processes, there is significant research focusing on the optimization of current cell culture systems and, more recently, on developing scalable downstream processes to generate material for pre-clinical and clinical trials. We review the current options for downstream processing of these complex biopharmaceuticals and underline current advances on knowledge-based toolboxes proposed for rational optimization of their processing. Rational tools developed to increase the yet scarce knowledge on the purification processes of complex biologicals are discussed as alternative to empirical, "black-boxed" based strategies classically used for process development. Innovative methodologies based on surface plasmon resonance, dynamic light scattering, scale-down high-throughput screening and mathematical modeling for supporting ion-exchange chromatography show great potential for a more efficient and cost-effective process design, optimization and equipment prototyping.

  11. Advances in 4D Treatment Planning for Scanned Particle Beam Therapy — Report of Dedicated Workshops

    PubMed Central

    Bert, Christoph; Graeff, Christian; Riboldi, Marco; Nill, Simeon; Baroni, Guido; Knopf, Antje-Christin

    2014-01-01

    We report on recent progress in the field of mobile tumor treatment with scanned particle beams, as discussed in the latest editions of the 4D treatment planning workshop. The workshop series started in 2009, with about 20 people from 4 research institutes involved, all actively working on particle therapy delivery and development. The first workshop resulted in a summary of recommendations for the treatment of mobile targets, along with a list of requirements to apply these guidelines clinically. The increased interest in the treatment of mobile tumors led to a continuously growing number of attendees: the 2012 edition counted more than 60 participants from 20 institutions and commercial vendors. The focus of research discussions among workshop participants progressively moved from 4D treatment planning to complete 4D treatments, aiming at effective and safe treatment delivery. Current research perspectives on 4D treatments include all critical aspects of time resolved delivery, such as in-room imaging, motion detection, beam application, and quality assurance techniques. This was motivated by the start of first clinical treatments of hepato cellular tumors with a scanned particle beam, relying on gating or abdominal compression for motion mitigation. Up to date research activities emphasize significant efforts in investigating advanced motion mitigation techniques, with a specific interest in the development of dedicated tools for experimental validation. Potential improvements will be made possible in the near future through 4D optimized treatment plans that require upgrades of the currently established therapy control systems for time resolved delivery. But since also these novel optimization techniques rely on the validity of the 4DCT, research focusing on alternative 4D imaging technique, such as MRI based 4DCT generation will continue. PMID:24354749

  12. The Advanced Composition Explorer Shock Database and Application to Particle Acceleration Theory

    NASA Technical Reports Server (NTRS)

    Parker, L. Neergaard; Zank, G. P.

    2015-01-01

    The theory of particle acceleration via diffusive shock acceleration (DSA) has been studied in depth by Gosling et al. (1981), van Nes et al. (1984), Mason (2000), Desai et al. (2003), Zank et al. (2006), among many others. Recently, Parker and Zank (2012, 2014) and Parker et al. (2014) using the Advanced Composition Explorer (ACE) shock database at 1 AU explored two questions: does the upstream distribution alone have enough particles to account for the accelerated downstream distribution and can the slope of the downstream accelerated spectrum be explained using DSA? As was shown in this research, diffusive shock acceleration can account for a large population of the shocks. However, Parker and Zank (2012, 2014) and Parker et al. (2014) used a subset of the larger ACE database. Recently, work has successfully been completed that allows for the entire ACE database to be considered in a larger statistical analysis. We explain DSA as it applies to single and multiple shocks and the shock criteria used in this statistical analysis. We calculate the expected injection energy via diffusive shock acceleration given upstream parameters defined from the ACE Solar Wind Electron, Proton, and Alpha Monitor (SWEPAM) data to construct the theoretical upstream distribution. We show the comparison of shock strength derived from diffusive shock acceleration theory to observations in the 50 keV to 5 MeV range from an instrument on ACE. Parameters such as shock velocity, shock obliquity, particle number, and time between shocks are considered. This study is further divided into single and multiple shock categories, with an additional emphasis on forward-forward multiple shock pairs. Finally with regard to forward-forward shock pairs, results comparing injection energies of the first shock, second shock, and second shock with previous energetic population will be given.

  13. The Advanced Composition Explorer Shock Database and Application to Particle Acceleration Theory

    NASA Technical Reports Server (NTRS)

    Parker, L. Neergaard; Zank, G. P.

    2015-01-01

    The theory of particle acceleration via diffusive shock acceleration (DSA) has been studied in depth by Gosling et al. (1981), van Nes et al. (1984), Mason (2000), Desai et al. (2003), Zank et al. (2006), among many others. Recently, Parker and Zank (2012, 2014) and Parker et al. (2014) using the Advanced Composition Explorer (ACE) shock database at 1 AU explored two questions: does the upstream distribution alone have enough particles to account for the accelerated downstream distribution and can the slope of the downstream accelerated spectrum be explained using DSA? As was shown in this research, diffusive shock acceleration can account for a large population of the shocks. However, Parker and Zank (2012, 2014) and Parker et al. (2014) used a subset of the larger ACE database. Recently, work has successfully been completed that allows for the entire ACE database to be considered in a larger statistical analysis. We explain DSA as it applies to single and multiple shocks and the shock criteria used in this statistical analysis. We calculate the expected injection energy via diffusive shock acceleration given upstream parameters defined from the ACE Solar Wind Electron, Proton, and Alpha Monitor (SWEPAM) data to construct the theoretical upstream distribution. We show the comparison of shock strength derived from diffusive shock acceleration theory to observations in the 50 keV to 5 MeV range from an instrument on ACE. Parameters such as shock velocity, shock obliquity, particle number, and time between shocks are considered. This study is further divided into single and multiple shock categories, with an additional emphasis on forward-forward multiple shock pairs. Finally with regard to forwardforward shock pairs, results comparing injection energies of the first shock, second shock, and second shock with previous energetic population will be given.

  14. The development of optical microscopy techniques for the advancement of single-particle studies

    SciTech Connect

    Marchuk, Kyle

    2013-05-15

    Single particle orientation and rotational tracking (SPORT) has recently become a powerful optical microscopy tool that can expose many molecular motions. Unfortunately, there is not yet a single microscopy technique that can decipher all particle motions in all environmental conditions, thus there are limitations to current technologies. Within, the two powerful microscopy tools of total internal reflection and interferometry are advanced to determine the position, orientation, and optical properties of metallic nanoparticles in a variety of environments. Total internal reflection is an optical phenomenon that has been applied to microscopy to produce either fluorescent or scattered light. The non-invasive far-field imaging technique is coupled with a near-field illumination scheme that allows for better axial resolution than confocal microscopy and epi-fluorescence microscopy. By controlling the incident illumination angle using total internal reflection fluorescence (TIRF) microscopy, a new type of imaging probe called “non-blinking” quantum dots (NBQDs) were super-localized in the axial direction to sub-10-nm precision. These particles were also used to study the rotational motion of microtubules being propelled by the motor protein kinesin across the substrate surface. The same instrument was modified to function under total internal reflection scattering (TIRS) microscopy to study metallic anisotropic nanoparticles and their dynamic interactions with synthetic lipid bilayers. Utilizing two illumination lasers with opposite polarization directions at wavelengths corresponding to the short and long axis surface plasmon resonance (SPR) of the nanoparticles, both the in-plane and out-of-plane movements of many particles could be tracked simultaneously. When combined with Gaussian point spread function (PSF) fitting for particle super-localization, the binding status and rotational movement could be resolved without degeneracy. TIRS microscopy was also used to

  15. The development of optical microscopy techniques for the advancement of single-particle studies

    NASA Astrophysics Data System (ADS)

    Marchuk, Kyle

    Single particle orientation and rotational tracking (SPORT) has recently become a powerful optical microscopy tool that can expose many molecular motions. Unfortunately, there is not yet a single microscopy technique that can decipher all particle motions in all environmental conditions, thus there are limitations to current technologies. Within, the two powerful microscopy tools of total internal reflection and interferometry are advanced to determine the position, orientation, and optical properties of metallic nanoparticles in a variety of environments. Total internal reflection is an optical phenomenon that has been applied to microscopy to produce either fluorescent or scattered light. The non-invasive far-field imaging technique is coupled with a near-field illumination scheme that allows for better axial resolution than confocal microscopy and epi-fluorescence microscopy. By controlling the incident illumination angle using total internal reflection fluorescence (TIRF) microscopy, a new type of imaging probe called "non-blinking" quantum dots (NBQDs) were super-localized in the axial direction to sub-10-nm precision. These particles were also used to study the rotational motion of microtubules being propelled by the motor protein kinesin across the substrate surface. The same instrument was modified to function under total internal reflection scattering (TIRS) microscopy to study metallic anisotropic nanoparticles and their dynamic interactions with synthetic lipid bilayers. Utilizing two illumination lasers with opposite polarization directions at wavelengths corresponding to the short and long axis surface plasmon resonance (SPR) of the nanoparticles, both the in-plane and out-of-plane movements of many particles could be tracked simultaneously. When combined with Gaussian point spread function (PSF) fitting for particle super-localization, the binding status and rotational movement could be resolved without degeneracy. TIRS microscopy was also used to

  16. Recent advances in the modeling of plasmas with the Particle-In-Cell methods

    NASA Astrophysics Data System (ADS)

    Vay, Jean-Luc; Lehe, Remi; Vincenti, Henri; Godfrey, Brendan; Lee, Patrick; Haber, Irv

    2015-11-01

    The Particle-In-Cell (PIC) approach is the method of choice for self-consistent simulations of plasmas from first principles. The fundamentals of the PIC method were established decades ago but improvements or variations are continuously being proposed. We report on several recent advances in PIC related algorithms, including: (a) detailed analysis of the numerical Cherenkov instability and its remediation, (b) analytic pseudo-spectral electromagnetic solvers in Cartesian and cylindrical (with azimuthal modes decomposition) geometries, (c) arbitrary-order finite-difference and generalized pseudo-spectral Maxwell solvers, (d) novel analysis of Maxwell's solvers' stencil variation and truncation, in application to domain decomposition strategies and implementation of Perfectly Matched Layers in high-order and pseudo-spectral solvers. Work supported by US-DOE Contracts DE-AC02-05CH11231 and the US-DOE SciDAC program ComPASS. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.

  17. Advanced multi-frequency radar: Design, preliminary measurements and particle size distribution retrieval

    NASA Astrophysics Data System (ADS)

    Majurec, Ninoslav

    In the spring of 2001 the Microwave Remote Sensing Laboratory (MIRSL) at the University of Massachusetts began the development of an advanced Multi-Frequency Radar (AMFR) system for studying clouds and precipitation. This mobile radar was designed to consist of three polarimetric Doppler subsystems operating at Ku-band (13.4 GHz), Ka-band (35.6 GHz) and W-band (94.92 GHz). This combination of frequency bands allows a measurement of a wide range of atmospheric targets ranging from weakly reflecting clouds to strong precipitation. The antenna beamwidths at each frequency were intentionally matched, ensuring consistent sampling volume. Multi-frequency radar remote sensing techniques are not widely used because few multi-frequency radars are available to the science community. One exception is the 33 GHz/95 GHz UMass Cloud Profiling Radar System (CPRS), which AMFR is intended to replace. AMFR's multi-parameter capabilities are designed for characterizing the complex microphysics of layer clouds and precipitation processes in winter storms. AMFR will also play an important role in developing algorithms and validating measurements for an upcoming generation of space-borne radars. The frequency bands selected for AMFR match those of several sensors that have been deployed or are under development. These include the Japanese Aerospace Exploration Agencies (JAXA's) Tropical Rainfall Measuring Mission (TRMM) satellite Ku-band (13 GHz) radar, the CloudSat W-band (95 GHz) radar, and the Global Precipitation Mission (GPM) satellite radars at Ku-band and Ka-band. This dissertation describes the AMFR hardware design and development. Compared to CPRS, the addition of one extra frequency band (Ku) will extend AMFR's measurement capabilities towards the larger particle sizes (precipitation). AMFR's design is based around high-power klystron amplifiers. This ensures complete coherency (CPRS uses magnetrons and coherent-on-receive technique). The partial loss in sensitivity due to

  18. On-sun testing of an advanced falling particle receiver system

    NASA Astrophysics Data System (ADS)

    Ho, Clifford K.; Christian, Joshua M.; Yellowhair, Julius; Siegel, Nathan; Jeter, Sheldon; Golob, Matthew; Abdel-Khalik, Said I.; Nguyen, Clayton; Al-Ansary, Hany

    2016-05-01

    A 1 MWth high-temperature falling particle receiver was constructed and tested at the National Solar Thermal Test Facility at Sandia National Laboratories. The continuously recirculating system included a particle elevator, top and bottom hoppers, and a cavity receiver that comprised a staggered array of porous chevron-shaped mesh structures that slowed the particle flow through the concentrated solar flux. Initial tests were performed with a peak irradiance of ~300 kW/m2 and a particle mass flow rate of 3.3 kg/s. Peak particle temperatures reached over 700 °C near the center of the receiver, but the particle temperature increase near the sides was lower due to a non-uniform irradiance distribution. At a particle inlet temperature of ~440 °C, the particle temperature increase was 27 °C per meter of drop length, and the thermal efficiency was ~60% for an average irradiance of 110 kW/m2. At an average irradiance of 211 kW/m2, the particle temperature increase was 57.1 °C per meter of drop length, and the thermal efficiency was ~65%. Tests with higher irradiances are being performed and are expected to yield greater particle temperature increases and efficiencies.

  19. Use of advanced particle methods in modeling space propulsion and its supersonic expansions

    NASA Astrophysics Data System (ADS)

    Borner, Arnaud

    This research discusses the use of advanced kinetic particle methods such as Molecular Dynamics (MD) and direct simulation Monte Carlo (DSMC) to model space propulsion systems such as electrospray thrusters and their supersonic expansions. MD simulations are performed to model an electrospray thruster for the ionic liquid (IL) EMIM--BF4 using coarse-grained (CG) potentials. The model is initially featuring a constant electric field applied in the longitudinal direction. Two coarse-grained potentials are compared, and the effective-force CG (EFCG) potential is found to predict the formation of the Taylor cone, the cone-jet, and other extrusion modes for similar electric fields and mass flow rates observed in experiments of a IL fed capillary-tip-extractor system better than the simple CG potential. Later, one-dimensional and fully transient three-dimensional electric fields, the latter solving Poisson's equation to take into account the electric field due to space charge at each timestep, are computed by coupling the MD model to a Poisson solver. It is found that the inhomogeneous electric field as well as that of the IL space-charge improve agreement between modeling and experiment. The boundary conditions (BCs) are found to have a substantial impact on the potential and electric field, and the tip BC is introduced and compared to the two previous BCs, named plate and needle, showing good improvement by reducing unrealistically high radial electric fields generated in the vicinity of the capillary tip. The influence of the different boundary condition models on charged species currents as a function of the mass flow rate is studied, and it is found that a constant electric field model gives similar agreement to the more rigorous and computationally expensive tip boundary condition at lower flow rates. However, at higher mass flow rates the MD simulations with the constant electric field produces extruded particles with higher Coulomb energy per ion, consistent with

  20. Heavy charged particle radiobiology: using enhanced biological effectiveness and improved beam focusing to advance cancer therapy.

    PubMed

    Allen, Christopher; Borak, Thomas B; Tsujii, Hirohiko; Nickoloff, Jac A

    2011-06-01

    Ionizing radiation causes many types of DNA damage, including base damage and single- and double-strand breaks. Photons, including X-rays and γ-rays, are the most widely used type of ionizing radiation in radiobiology experiments, and in radiation cancer therapy. Charged particles, including protons and carbon ions, are seeing increased use as an alternative therapeutic modality. Although the facilities needed to produce high energy charged particle beams are more costly than photon facilities, particle therapy has shown improved cancer survival rates, reflecting more highly focused dose distributions and more severe DNA damage to tumor cells. Despite early successes of charged particle radiotherapy, there is room for further improvement, and much remains to be learned about normal and cancer cell responses to charged particle radiation.

  1. Heavy Charged Particle Radiobiology: Using Enhanced Biological Effectiveness and Improved Beam Focusing to Advance Cancer Therapy

    PubMed Central

    Allen, Christopher; Borak, Thomas B.; Tsujii, Hirohiko; Nickoloff, Jac A.

    2011-01-01

    Ionizing radiation causes many types of DNA damage, including base damage and single- and double-strand breaks. Photons, including X-rays and γ-rays, are the most widely used type of ionizing radiation in radiobiology experiments, and in radiation cancer therapy. Charged particles, including protons and carbon ions, are seeing increased use as an alternative therapeutic modality. Although the facilities needed to produce high energy charged particle beams are more costly than photon facilities, particle therapy has shown improved cancer survival rates, reflecting more highly focused dose distributions and more severe DNA damage to tumor cells. Despite early successes of charged particle radiotherapy, there is room for further improvement, and much remains to be learned about normal and cancer cell responses to charged particle radiation. PMID:21376738

  2. Heavy charged particle radiobiology: using enhanced biological effectiveness and improved beam focusing to advance cancer therapy.

    PubMed

    Allen, Christopher; Borak, Thomas B; Tsujii, Hirohiko; Nickoloff, Jac A

    2011-06-01

    Ionizing radiation causes many types of DNA damage, including base damage and single- and double-strand breaks. Photons, including X-rays and γ-rays, are the most widely used type of ionizing radiation in radiobiology experiments, and in radiation cancer therapy. Charged particles, including protons and carbon ions, are seeing increased use as an alternative therapeutic modality. Although the facilities needed to produce high energy charged particle beams are more costly than photon facilities, particle therapy has shown improved cancer survival rates, reflecting more highly focused dose distributions and more severe DNA damage to tumor cells. Despite early successes of charged particle radiotherapy, there is room for further improvement, and much remains to be learned about normal and cancer cell responses to charged particle radiation. PMID:21376738

  3. The Interaction Between an Insoluble Particle and an Advancing Solid/Liquid Interface: Micro-Gravity Experiments and Theoretical Developments

    NASA Technical Reports Server (NTRS)

    Catalina, Adrian V.; Ssen, Subhayu; Stefanescu, Doru M.

    2003-01-01

    The interaction of an insoluble particle with an advancing solid/liquid interface (SLI) has been a subject of investigation for the past four decades. While the original interest stemmed from geology applications (e.g., frost heaving in soil), researchers soon realized that the complex science associated with such an interaction is relevant to many other scientific fields encompassing metal matrix composites (MMCs), high temperature superconductors, inclusion management in steel, growth of monotectics, and preservation of biological cells. During solidification of a liquid containing an insoluble particle, three distinct interaction phenomena have been experimentally observed: instantaneous engulfment of the particle, continuous pushing, and particle pushing followed by engulfment. It was also observed that for given experimental conditions and particle size there is a critical solidification velocity, V(sub cr), above which a particle is engulfed. During solidification of MMCs pushing leads to particle agglomeration at the grain boundaries and this has detrimental effects on mechanical properties of the casting. Consequently, the process must be designed for instantaneous engulfment to occur. This implies the development of accurate theoretical models to predict V(sub cr), and perform benchmark experiments to test the validity of such models. Although considerable progress has been made in understanding the pushing/engulfment phenomenon (PEP), its quantification in terms of the material and processing parameters remains a focus of research. Since natural convection currents occurring during terrestrial solidification experiments complicate the study of PEP, execution of experiments on the International Space Station (ISS) has been approved and funded by NASA. Extensive terrestrial (1g) experiments and preliminary micro-gravity (mu g) experiments on two space shuttle missions have been conducted in preparation for future experiments on the ISS. The investigated

  4. Design considerations for high-current superconducting ion linacs

    SciTech Connect

    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.

  5. High-current, fast-switching transistor development

    NASA Technical Reports Server (NTRS)

    Hower, P. L.

    1981-01-01

    The design, wafer-processing techniques, and various measurements which include forward safe operating area, dc characteristics, and switching times are described for a larger-diameter (33) transistor. An improved base contact for equalizing the base-emitter voltage at high currents was developed along with an improved emitter contact preform which increases the silicon area available for current conduction. The electrical performance achieved is consistent with the proposed optimum design.

  6. Rarefied flow diagnostics using pulsed high-current electron beams

    NASA Technical Reports Server (NTRS)

    Wojcik, Radoslaw M.; Schilling, John H.; Erwin, Daniel A.

    1990-01-01

    The use of high-current short-pulse electron beams in low-density gas flow diagnostics is introduced. Efficient beam propagation is demonstrated for pressure up to 300 microns. The beams, generated by low-pressure pseudospark discharges in helium, provide extremely high fluorescence levels, allowing time-resolved visualization in high-background environments. The fluorescence signal frequency is species-dependent, allowing instantaneous visualization of mixing flowfields.

  7. A merging preaccelerator for high current H - ion beams

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Miyamoto, K.; Mizuno, M.; Okumura, Y.; Ohara, Y.; Ackerman, G. D.; Chan, C. F.; Cooper, W. S.; Kwan, J. W.; Vella, M. C.

    1995-07-01

    The high power ion beams used in the next generation thermonuclear fusion reactors require high current negative ion beams accelerated to high energy, with high efficiency. One way to meet these requirements is to merge multiple low current density H- beamlets into a single high current beam. The feasibility of a high current merging preaccelerator was demonstrated in this experiment by merging 19 beamlets of H- ions distributed over a circular area 80 mm in diameter from a Japan Atomic Energy Research Institute negative ion source. H- ions were extracted at a current density exceeding 10 mA/cm2 at the ion source which operates at 0.13 Pa (1 mTorr), with a low arc power density (70 V×250 A). Spherically curved grids (with built-in magnetic electron suppression) were used in the preaccelerator to focus the extracted beamlets into a single 104 mA, 100 keV beam. The merged beam has a diameter of 23 mm and a converging angle of ±30 mrad at the beam envelope. The rms emittance of the 104 mA merging beam was 1.00 π mrad cm, which is a condition acceptable to the electrostatic quadropole accelerator for further acceleration.

  8. Regression modeling of particle size distributions in urban storm water: advancements through improved sample collection methods

    USGS Publications Warehouse

    Fienen, Michael N.; Selbig, William R.

    2012-01-01

    A new sample collection system was developed to improve the representation of sediment entrained in urban storm water by integrating water quality samples from the entire water column. The depth-integrated sampler arm (DISA) was able to mitigate sediment stratification bias in storm water, thereby improving the characterization of suspended-sediment concentration and particle size distribution at three independent study locations. Use of the DISA decreased variability, which improved statistical regression to predict particle size distribution using surrogate environmental parameters, such as precipitation depth and intensity. The performance of this statistical modeling technique was compared to results using traditional fixed-point sampling methods and was found to perform better. When environmental parameters can be used to predict particle size distributions, environmental managers have more options when characterizing concentrations, loads, and particle size distributions in urban runoff.

  9. ADVANCED METHODS FOR THE COMPUTATION OF PARTICLE BEAM TRANSPORT AND THE COMPUTATION OF ELECTROMAGNETIC FIELDS AND MULTIPARTICLE PHENOMENA

    SciTech Connect

    Alex J. Dragt

    2012-08-31

    Since 1980, under the grant DEFG02-96ER40949, the Department of Energy has supported the educational and research work of the University of Maryland Dynamical Systems and Accelerator Theory (DSAT) Group. The primary focus of this educational/research group has been on the computation and analysis of charged-particle beam transport using Lie algebraic methods, and on advanced methods for the computation of electromagnetic fields and multiparticle phenomena. This Final Report summarizes the accomplishments of the DSAT Group from its inception in 1980 through its end in 2011.

  10. Characterizing the distribution of particles in urban stormwater: advancements through improved sampling technology

    USGS Publications Warehouse

    Selbig, William R.

    2014-01-01

    A new sample collection system was developed to improve the representation of sediment in stormwater by integrating the entire water column. The depth-integrated sampler arm (DISA) was able to mitigate sediment stratification bias in storm water, thereby improving the characterization of particle size distribution from urban source areas. Collector streets had the lowest median particle diameter of 8 μm, followed by parking lots, arterial streets, feeder streets, and residential and mixed land use (32, 43, 50, 80 and 95 μm, respectively). Results from this study suggest there is no single distribution of particles that can be applied uniformly to runoff in urban environments; however, integrating more of the entire water column during the sample collection can address some of the shortcomings of a fixed-point sampler by reducing variability and bias caused by the stratification of solids in a water column.

  11. Modeling Combined Chemotherapy and Particle Therapy for Locally Advanced Pancreatic Cancer

    PubMed Central

    Durante, Marco; Tommasino, Francesco; Yamada, Shigeru

    2015-01-01

    Pancreatic ductal adenocarcinoma is the only cancer for which deaths are predicted to increase in 2014 and beyond. Combined radiochemotherapy protocols using gemcitabine and hypofractionated X-rays are ongoing in several clinical trials. Recent results indicate that charged particle therapy substantially increases local control of resectable and unresectable pancreas cancer, as predicted from previous radiobiology studies considering the high tumor hypoxia. Combination with chemotherapy improves the overall survival (OS). We compared published data on X-ray and charged particle clinical results with or without adjuvant chemotherapy calculating the biological effective dose. We show that chemoradiotherapy with protons or carbon ions results in 1 year OS significantly higher than those obtained with other treatment schedules. Further hypofractionation using charged particles may result in improved local control and survival. A comparative clinical trial using the standard X-ray scheme vs. the best current standard with carbon ions is crucial and may open new opportunities for this deadly disease. PMID:26217585

  12. Study on metal foil explosion using high current

    NASA Astrophysics Data System (ADS)

    Mihara, Takayuki; Matsuo, N.; Otsuka, M.; Itoh, S.

    2009-12-01

    In the high energy processing using explosive, there are variety of application examples which is explosion welding of differential metallic plate and powder compaction of diamond. However a rule legal to explosives is severe and needs many efforts for handling qualification acquisition, maintenance, and security. In this research, the metallic foil explosion using high current is paid my attention to the method to obtain linear or planate explosive initiation easily, and the main evaluation of metallic foil explosion was conducted. The explosion power was evaluated by observing optically the underwater shock wave generated from the metallic foil explosion.

  13. Study on metal foil explosion using high current

    NASA Astrophysics Data System (ADS)

    Mihara, Takayuki; Matsuo, N.; Otsuka, M.; Itoh, S.

    2010-03-01

    In the high energy processing using explosive, there are variety of application examples which is explosion welding of differential metallic plate and powder compaction of diamond. However a rule legal to explosives is severe and needs many efforts for handling qualification acquisition, maintenance, and security. In this research, the metallic foil explosion using high current is paid my attention to the method to obtain linear or planate explosive initiation easily, and the main evaluation of metallic foil explosion was conducted. The explosion power was evaluated by observing optically the underwater shock wave generated from the metallic foil explosion.

  14. High Current Ion Sources and Injectors for Heavy Ion Fusion

    SciTech Connect

    Kwan, Joe W.

    2005-02-15

    Heavy ion beam driven inertial fusion requires short ion beam pulses with high current and high brightness. Depending on the beam current and the number of beams in the driver system, the injector can use a large diameter surface ionization source or merge an array of small beamlets from a plasma source. In this paper, we review the scaling laws that govern the injector design and the various ion source options including the contact ionizer, the aluminosilicate source, the multicusp plasma source, and the MEVVA source.

  15. Fast high-temperature superconductor switch for high current applications

    NASA Astrophysics Data System (ADS)

    Solovyov, Vyacheslav F.; Li, Qiang

    2013-07-01

    Reversible operation of a high current superconductor switch based on the quench of high-resistance second generation high temperature superconducting wire is demonstrated. The quench is induced by a burst of an ac field generated by an inductively coupled radio-frequency coil. The switch makes a superconducting-to-normal transition within 5 ms and also has a rapid recovery to the superconducting state. The device has potential applications as an active current limiter or as a storage switch for superconducting magnetic energy storage systems. Operation in a full flux penetration/flow regime can effectively minimize the detrimental effects of the intrinsic conductor non-uniformity.

  16. Astro-E2 Magnesium Diboride High Current Leads

    NASA Technical Reports Server (NTRS)

    Panek, J. S.; Tuttle, J. G.; Riall, S.; Mustafi, S.; Gray, A.; Edmonds, R.; Marrero, V.

    2003-01-01

    The recent discovery of superconducting properties in MgB_2 and rapid development of small diameter steel-clad wires has opened up the possibility of enhancing the design of the baseline Astro-E2 high current lead assembly. Replacing YBCO filaments with MgB_2 wires and modifying the heat sink location can give much higher margins against quench from temperature oscillations of the 4 K heat sink, although wih some overall thermal penalty. The design and performance of a new lead assembly during flight qualification is discussed, with emphasis on thermal, structural, and electrical test results.

  17. Hard carbon coatings deposited by pulsed high current magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Oskomov, K. V.; Solov'ev, A. A.; Rabotkin, S. V.

    2014-12-01

    Hard (up to 17 GPa) carbon coatings are deposited onto face SiC bearings used in liquid pumps by pulsed high-current magnetron sputtering of graphite. As a result, the friction coefficient is decreased from 0.43 to 0.11 and the wear rate is decreased from 26 to 0.307 μm3 N-1 m-1, which increases the service life of the bearings by approximately three times. The deposited carbon coatings have a high hardness and wear resistance due to the generation of high-density (up to 1013 cm-3) plasma.

  18. Electromagnetic field interactions with micro channels, particles and cells: Application to advanced cytometry

    NASA Astrophysics Data System (ADS)

    Venkatapathi, Murugesan

    This thesis involves a study of the interaction of laser beams with micro channels and micro particles/cells using the electromagnetic field approach. This problem is relevant to the next generation cytometry, in particular to model based design of flow cytometers. The field approach is applied to study light scatter from particles/cells and also internal and scattered fields of cylindrical micro channels that are important for optical interrogation of particles and cells flowing through. Though current flow cytometers use qualitative fluorescence measurements for biological analysis, other viable optical interrogation techniques like light scatter, quantitative fluorescence and Coherent anti-stokes Raman scatter (CARS) are being studied for application to flow cytometry. The light scatter from particles and cells in a flow cytometer has been studied with the objective of extracting useful information about the particles using scatter measurements. First, the correlation between the size of particles and the current forward scatter measurements was both analytically modeled and experimentally determined. These results indicated that integrated scatter measurements currently used in flow cytometry (forward and side scatter) cannot be used to unambiguously estimate size, shape or refractive index of particles for classification. It is shown that multi-angle scatter measurements can be used to classify micro spheres of different sizes/refractive indices and different bacteria species, provided the scatter measurements are designed based on numerical scatter models. The numerical scatter models were then also used to do a preliminary study of correlation of scatter with internal structure of simple cells like stem cells. A few multivariate statistical methods have been applied for the classification of such particles in flow cytometry using scatter and multi-spectral fluorescence measurements. Typically the micro channels used in flow cytometry have square or circular

  19. The R and D progress of 4 MW EAST-NBI high current ion source

    SciTech Connect

    Xie, Yahong Hu, Chundong; Liu, Sheng; Xu, Yongjian; Liang, Lizhen; Xie, Yuanlai; Sheng, Peng; Jiang, Caichao; Liu, Zhimin

    2014-02-15

    A high current ion source, which consists of the multi-cusp bucket plasma generator and tetrode accelerator with multi-slot apertures, is developed and tested for the Experimental Advanced Superconducting Tokamak neutral beam injector. Three ion sources are tested on the test bed with arc power of 80 kW, beam voltage of 80 keV, and beam power of 4 MW. The arc regulation technology with Langmuir probes is employed for the long pulse operation of ion source, and the long pulse beam of 50 keV @ 15.5 A @ 100 s and 80 keV @ 52A @ 1s are extracted, respectively.

  20. High Current Systems for HyperV and PLX Plasma Railguns

    NASA Astrophysics Data System (ADS)

    Brockington, S.; Case, A.; Messer, S.; Elton, R.; Witherspoon, F. D.

    2011-10-01

    HyperV is developing gas fed, pulsed, plasma railgun accelerators for PLX and other high momentum plasma applications. The present 2.5 cm square-bore plasma railgun forms plasma armatures from high density neutral gas (argon), preionizes it electrothermally, and accelerates the armature with 30 cm long parallel-plate railgun electrodes driven by a pulse forming network (PFN). Recent experiments have successfully formed and accelerated plasma armatures of ~4 mg at 40 km/s, with PFN currents of ~400 kA. In order to further increase railgun performance to the PLX design goal of 8 mg at 50 km/s, the PFN was upgraded to support currents of up to ~750 kA. A high voltage, high current linear array spark-gap switch and flexible, low-inductance transmission line were designed and constructed to handle the increased current load. We will describe these systems and present initial performance data from high current operation of the plasma rail gun from spectroscopy, interferometry, and imaging systems as well as pressure, magnetic field, and optical diagnostics. High current performance of railgun bore materials for electrodes and insulators will also be discussed as well as plans for upcoming experimentation with advanced materials. Supported by the U.S. DOE Joint Program in HEDLP.

  1. Eddy Current, Magnetic Particle and Hardness Testing, Aviation Quality Control (Advanced): 9227.04.

    ERIC Educational Resources Information Center

    Dade County Public Schools, Miami, FL.

    This unit of instruction includes the principles of eddy current, magnetic particle and hardness testing; standards used for analyzing test results; techniques of operating equipment; interpretation of indications; advantages and limitations of these methods of testing; care and calibration of equipment; and safety and work precautions. Motion…

  2. RF Input Power Couplers for High Current SRF Applications

    SciTech Connect

    Khan, V. F.; Anders, W.; Burrill, Andrew; Knobloch, Jens; Kugeler, Oliver; Neumann, Axel; Wang, Haipeng

    2014-12-01

    High current SRF technology is being explored in present day accelerator science. The bERLinPro project is presently being built at HZB to address the challenges involved in high current SRF machines with the goal of generating and accelerating a 100 mA electron beam to 50 MeV in continuous wave (cw) mode at 1.3 GHz. One of the main challenges in this project is that of handling the high input RF power required for the photo-injector as well as booster cavities where there is no energy recovery process. A high power co-axial input power coupler is being developed to be used for the photo-injector and booster cavities at the nominal beam current. The coupler is based on the KEK–cERL design and has been modified to minimise the penetration of the coupler tip in the beam pipe without compromising on beam-power coupling (Qext ~105). Herein we report on the RF design of the high power (115 kW per coupler, dual couplers per cavity) bERLinPro (BP) coupler along with initial results on thermal calculations. We summarise the RF conditioning of the TTF-III couplers (modified for cw operation) performed in the past at BESSY/HZB. A similar conditioning is envisaged in the near future for the low current SRF photo-injector and the bERLinPro main linac cryomodule.

  3. High current pulse testing for ground rod integrity

    NASA Technical Reports Server (NTRS)

    Walko, Lawrence C.

    1991-01-01

    A test technique was developed to assess various grounding system concepts used for mobile facilities. The test technique involves applying a high current pulse to the grounding system with the proper waveshape and magnitude to simulate a lightning return stroke. Of concern were the step voltages present along the ground near the point of lightning strike. Step voltage is equated to how fast the current pulse is dissipated by the grounding system. The applied current pulse was produced by a high current capacitor bank with a total energy content of 80 kilojoules. A series of pulse tests were performed on two types of mobile facility grounding systems. One system consisted of an array of four 10 foot copper clad steel ground rods connected by 1/0 gauge wire. The other system was an array of 10 inch long tapered ground rods, strung on stainless steel cable. The focus here is on the pulse test technique used and its relevance to actual lightning strike conditions.

  4. A double output pulsed high current thyratron driver

    NASA Astrophysics Data System (ADS)

    Reghu, T.; Kumar, Manoj; Verma, Abrat; Mandloi, Vagesh; Kukreja, L. M.; Shrivastava, P.

    2012-11-01

    The design and development of a double output pulsed high current driver for high power multi-grid thyratron is reported. The driver generates a 100 A current pulse of 2 μs duration with a compliance voltage of 1000 V for driving grid-1. A voltage pulse of 1200 V and 1.2 μs duration, superimposed with -150 V bias has been generated for driving grid-2. A delay of 1 μs between the two drive pulses is achieved with the use of a simple circuit. The rate of rise of voltage better than 10 kV/μs and jitter of ±3 ns is achieved for grid-2 pulse. This driver module has been successfully used in a 50 kV, CX1575C thyratron switched pulsed power supply to drive a multi-joule transversely excited atmospheric CO2 laser at 100 Hz. The grid driver module can also be used for driving any high current thyratrons with minor external changes.

  5. A double output pulsed high current thyratron driver.

    PubMed

    Reghu, T; Kumar, Manoj; Verma, Abrat; Mandloi, Vagesh; Kukreja, L M; Shrivastava, P

    2012-11-01

    The design and development of a double output pulsed high current driver for high power multi-grid thyratron is reported. The driver generates a 100 A current pulse of 2 μs duration with a compliance voltage of 1000 V for driving grid-1. A voltage pulse of 1200 V and 1.2 μs duration, superimposed with -150 V bias has been generated for driving grid-2. A delay of 1 μs between the two drive pulses is achieved with the use of a simple circuit. The rate of rise of voltage better than 10 kV/μs and jitter of ±3 ns is achieved for grid-2 pulse. This driver module has been successfully used in a 50 kV, CX1575C thyratron switched pulsed power supply to drive a multi-joule transversely excited atmospheric CO(2) laser at 100 Hz. The grid driver module can also be used for driving any high current thyratrons with minor external changes.

  6. Broad-beam, high current, metal ion implantation facility

    SciTech Connect

    Brown, I.G.; Dickinson, M.R.; Galvin, J.E.; Godechot, X.; MacGill, R.A.

    1990-07-01

    We have developed a high current metal ion implantation facility with which high current beams of virtually all the solid metals of the Periodic Table can be produced. The facility makes use of a metal vapor vacuum arc ion source which is operated in a pulsed mode, with pulse width 0.25 ms and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge state multiplicity; beam current is up to several Amperes peak and around 10 mA time averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the seeding' of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III-V compounds. 16 refs., 6 figs.

  7. PHYSICS OF THE HIGH CURRENT DENSITY ELECTRON BEAM ION SOURCE (EBIS).

    SciTech Connect

    Vella, M.C.

    1980-02-01

    Interest in upgrading present heavy particle accelerators has led to study of EBIS as a possible source of high Z ions, e.g,, Ar{sup +18}. The present work has been motivated primarily by the results reported by CRYEBIS, which indicate that a space charge neutralized, external electron gun can achieve current densities of 10{sup 5} A/cm{sup 2}. Scaling relationships are developed as a basis for understanding CRYEBIS operation. The relevance of collective effects to beam equilibrium and stability is pointed out, Single electron impact ionization scaling and beam neutralization scaling indicate that higher beam voltage may be the easiest way of increasing both ionization rate and particle intensity. Consideration of radial ion confinement suggests that beam collapse to high current density may be related to the highest charge state which is energetically accessible.

  8. The Frontier of Modern Calorimetry: Hardware Advances and Application in Particle Physics Analysis

    NASA Astrophysics Data System (ADS)

    Medvedeva, Tatiana

    While the last missing components of the SM puzzle seem to be successfully found, particle physicists remain hungry for what might be there, beyond the cosy boundaries of the well studies elementary particle world. However, the sophisticated technique of data analysis and acute Monte Carlo simulations remain fruitless. It appears that the successful intrusion into the realm, in which we were not welcome so far, may require a very different implication of effort. All those results might suggest, though banal, that we need an improvement on the hardware side. Indeed, the hadronic calorimeter of CMS is no competitor to its other state-of-art components. This obstacle in many cases significantly complicates the flow of the physics analysis. Besides, the era of high luminosity LHC operation in the offing is calling for the same. After exploration of the analysis debri with 8TeV collision data, we investigate various approaches for better calorimetry for the CMS detector.

  9. Advanced methods in global gyrokinetic full f particle simulation of tokamak transport

    SciTech Connect

    Ogando, F.; Heikkinen, J. A.; Henriksson, S.; Janhunen, S. J.; Kiviniemi, T. P.; Leerink, S.

    2006-11-30

    A new full f nonlinear gyrokinetic simulation code, named ELMFIRE, has been developed for simulating transport phenomena in tokamak plasmas. The code is based on a gyrokinetic particle-in-cell algorithm, which can consider electrons and ions jointly or separately, as well as arbitrary impurities. The implicit treatment of the ion polarization drift and the use of full f methods allow for simulations of strongly perturbed plasmas including wide orbit effects, steep gradients and rapid dynamic changes. This article presents in more detail the algorithms incorporated into ELMFIRE, as well as benchmarking comparisons to both neoclassical theory and other codes.Code ELMFIRE calculates plasma dynamics by following the evolution of a number of sample particles. Because of using an stochastic algorithm its results are influenced by statistical noise. The effect of noise on relevant magnitudes is analyzed.Turbulence spectra of FT-2 plasma has been calculated with ELMFIRE, obtaining results consistent with experimental data.

  10. ADVANCING THE ION BEAM THIN FILM PLANARIZATION PROCESS FOR THE SMOOTHING OF SUBSTRATE PARTICLES

    SciTech Connect

    Mirkarimi, P B; Spiller, E; Baker, S L; Robinson, J C; Stearns, D G; Liddle, J A; Salmassi, F; Liang, T; Stivers, A R

    2004-10-19

    For a number of technologies small substrate contaminants are undesirable, and for one technology in particular, extreme ultraviolet lithography (EUVL), they can be a very serious issue. We have demonstrated that the Ion Beam Thin Film Planarization Process, a coating process designed to planarize substrate asperities, can be extended to smooth {approx}70 nm and {approx}80 nm diameter particles on EUVL reticle substrates to a height of {approx}0.5 nm, which will render them noncritical in an EUVL printing process. We demonstrate this smoothing process using controlled nanoscale substrate particles and lines fabricated with an e-beam lithography process. The above smoothing process was also modified to yield an excellent reflectance/wavelength uniformity and a good EUV reflectivity for the multilayer, which is required for EUVL reticles. Cross-sectional TEM on a smoothed substrate line defect shows excellent agreement with results obtained from our multilayer growth model.

  11. Current Advances in Virus-Like Particles as a Vaccination Approach against HIV Infection

    PubMed Central

    Zhao, Chongbo; Ao, Zhujun; Yao, Xiaojian

    2016-01-01

    HIV-1 virus-like particles (VLPs) are promising vaccine candidates against HIV-1 infection. They are capable of preserving the native conformation of HIV-1 antigens and priming CD4+ and CD8+ T cell responses efficiently via cross presentation by both major histocompatibility complex (MHC) class I and II molecules. Progress has been achieved in the preclinical research of HIV-1 VLPs as prophylactic vaccines that induce broadly neutralizing antibodies and potent T cell responses. Moreover, the progress in HIV-1 dendritic cells (DC)-based immunotherapy provides us with a new vision for HIV-1 vaccine development. In this review, we describe updates from the past 5 years on the development of HIV-1 VLPs as a vaccine candidate and on the combined use of HIV particles with HIV-1 DC-based immunotherapy as efficient prophylactic and therapeutic vaccination strategies. PMID:26805898

  12. Remediating radium contaminated legacy sites: Advances made through machine learning in routine monitoring of "hot" particles.

    PubMed

    Varley, Adam; Tyler, Andrew; Smith, Leslie; Dale, Paul; Davies, Mike

    2015-07-15

    The extensive use of radium during the 20th century for industrial, military and pharmaceutical purposes has led to a large number of contaminated legacy sites across Europe and North America. Sites that pose a high risk to the general public can present expensive and long-term remediation projects. Often the most pragmatic remediation approach is through routine monitoring operating gamma-ray detectors to identify, in real-time, the signal from the most hazardous heterogeneous contamination (hot particles); thus facilitating their removal and safe disposal. However, current detection systems do not fully utilise all spectral information resulting in low detection rates and ultimately an increased risk to the human health. The aim of this study was to establish an optimised detector-algorithm combination. To achieve this, field data was collected using two handheld detectors (sodium iodide and lanthanum bromide) and a number of Monte Carlo simulated hot particles were randomly injected into the field data. This allowed for the detection rate of conventional deterministic (gross counts) and machine learning (neural networks and support vector machines) algorithms to be assessed. The results demonstrated that a Neural Network operated on a sodium iodide detector provided the best detection capability. Compared to deterministic approaches, this optimised detection system could detect a hot particle on average 10cm deeper into the soil column or with half of the activity at the same depth. It was also found that noise presented by internal contamination restricted lanthanum bromide for this application.

  13. Generation of multi-charged high current ion beams using the SMIS 37 gas-dynamic electron cyclotron resonance (ECR) ion source

    SciTech Connect

    Dorf, M. A.; Zorin, V. G.; Sidorov, A. V.; Bokhanov, A. F.; Izotov, I. V.; Razin, S. V.; Skalyga, V. A.

    2013-06-02

    A gas-dynamic ECR ion source (GaDIS) is distinguished by its ability to produce high current and high brightness beams of moderately charged ions. Contrary to a classical ECR ion source where the plasma confinement is determined by the slow electron scattering into an empty loss-cone, the higher density and lower electron temperature in a GaDIS plasma lead to an isotropic electron distribution with the confinement time determined by the prompt gas-dynamic flow losses. As a result, much higher ion fluxes are available, however a decrease in the confinement time of the GaDIS plasma lowers the ion charge state. The gas-dynamic ECR ion source concept has been successfully realized in the SMIS 37 experimental facility operated at the Institute of Applied Physics, Russia. The use of high-power (~100 kW) microwave (37.5 GHz) radiation provides a dense plasma (~1013 cm-3) with a relatively low electron temperature (~50- 100 eV) and allows for the generation of high current (~1 A/cm2) beams of multi-charged ions. In this work we report on the present status of the SMIS 37 ion source and discuss the advanced numerical modeling of ion beam extraction using the particle-in-cell code WARP

  14. Advanced 3D Poisson solvers and particle-in-cell methods for accelerator modeling

    NASA Astrophysics Data System (ADS)

    Serafini, David B.; McCorquodale, Peter; Colella, Phillip

    2005-01-01

    We seek to improve on the conventional FFT-based algorithms for solving the Poisson equation with infinite-domain (open) boundary conditions for large problems in accelerator modeling and related areas. In particular, improvements in both accuracy and performance are possible by combining several technologies: the method of local corrections (MLC); the James algorithm; and adaptive mesh refinement (AMR). The MLC enables the parallelization (by domain decomposition) of problems with large domains and many grid points. This improves on the FFT-based Poisson solvers typically used as it doesn't require the all-to-all communication pattern that parallel 3d FFT algorithms require, which tends to be a performance bottleneck on current (and foreseeable) parallel computers. In initial tests, good scalability up to 1000 processors has been demonstrated for our new MLC solver. An essential component of our approach is a new version of the James algorithm for infinite-domain boundary conditions for the case of three dimensions. By using a simplified version of the fast multipole method in the boundary-to-boundary potential calculation, we improve on the performance of the Hockney algorithm typically used by reducing the number of grid points by a factor of 8, and the CPU costs by a factor of 3. This is particularly important for large problems where computer memory limits are a consideration. The MLC allows for the use of adaptive mesh refinement, which reduces the number of grid points and increases the accuracy in the Poisson solution. This improves on the uniform grid methods typically used in PIC codes, particularly in beam problems where the halo is large. Also, the number of particles per cell can be controlled more closely with adaptivity than with a uniform grid. To use AMR with particles is more complicated than using uniform grids. It affects depositing particles on the non-uniform grid, reassigning particles when the adaptive grid changes and maintaining the load

  15. Ultra-high current density thin-film Si diode

    DOEpatents

    Wang, Qi

    2008-04-22

    A combination of a thin-film .mu.c-Si and a-Si:H containing diode structure characterized by an ultra-high current density that exceeds 1000 A/cm.sup.2, comprising: a substrate; a bottom metal layer disposed on the substrate; an n-layer of .mu.c-Si deposited the bottom metal layer; an i-layer of .mu.c-Si deposited on the n-layer; a buffer layer of a-Si:H deposited on the i-layer, a p-layer of .mu.c-Si deposited on the buffer layer; and a top metal layer deposited on the p-layer.

  16. High pressure, high current, low inductance, high reliability sealed terminals

    DOEpatents

    Hsu, John S [Oak Ridge, TN; McKeever, John W [Oak Ridge, TN

    2010-03-23

    The invention is a terminal assembly having a casing with at least one delivery tapered-cone conductor and at least one return tapered-cone conductor routed there-through. The delivery and return tapered-cone conductors are electrically isolated from each other and positioned in the annuluses of ordered concentric cones at an off-normal angle. The tapered cone conductor service can be AC phase conductors and DC link conductors. The center core has at least one service conduit of gate signal leads, diagnostic signal wires, and refrigerant tubing routed there-through. A seal material is in direct contact with the casing inner surface, the tapered-cone conductors, and the service conduits thereby hermetically filling the interstitial space in the casing interior core and center core. The assembly provides simultaneous high-current, high-pressure, low-inductance, and high-reliability service.

  17. Recent Progress on High-Current SRF Cavities at Jlab

    SciTech Connect

    Robert Rimmer, William Clemens, James Henry, Peter Kneisel, Kurt Macha, Frank Marhauser, Larry Turlington, Haipeng Wang, Daniel Forehand

    2010-05-01

    JLab has designed and fabricated several prototype SRF cavities with cell shapes optimized for high current beams and with strong damping of unwanted higher order modes. We report on the latest test results of these cavities and on developments of concepts for new variants optimized for particular applications such as light sources and high-power proton accelerators, including betas less than one. We also report on progress towards a first beam test of this design in the recirculation loop of the JLab ERL based FEL. With growing interest worldwide in applications of SRF for high-average power electron and hadron machines, a practical test of these concepts is highly desirable. We plan to package two prototype cavities in a de-mountable cryomodule for temporary installation into the JLab FEL for testing with RF and beam. This will allow verification of all critical design and operational parameters paving the way to a full-scale prototype cryomodule.

  18. Design of a proof of principle high current transport experiment

    SciTech Connect

    Lund, S.M.; Bangerter, R.O.; Barnard, J.J.; Celata, C.M.; Faltens, A.; Friedman, A.; Kwan, J.W.; Lee, E.P.; Seidl, P.A.

    2000-01-15

    Preliminary designs of an intense heavy-ion beam transport experiment to test issues for Heavy Ion Fusion (HIF) are presented. This transport channel will represent a single high current density beam at full driver scale and will evaluate practical issues such as aperture filling factors, electrons, halo, imperfect vacuum, etc., that cannot be fully tested using scaled experiments. Various machine configurations are evaluated in the context of the range of physics and technology issues that can be explored in a manner relevant to a full scale driver. it is anticipated that results from this experiment will allow confident construction of next generation ''Integrated Research Experiments'' leading to a full scale driver for energy production.

  19. Energetic ion production in high current hollow cathodes

    NASA Astrophysics Data System (ADS)

    Foster, John; Kovach, Yao; Arthur, Neil; Viges, Eric; Davis, Chris

    2015-09-01

    High power Hall and gridded ion thrusters are being considered as a propulsion option supporting human operations (cargo or tug) to Mars. These engines utilize hollow cathodes for plasma production and beam neutralization. It has now been well documented that these cathodes produce energetic ions when operated at high current densities. Such ions are observed with peak energies approaching 100 eV. Because these ions can drive erosion of the cathode assembly, they represent a credible failure mode. An understanding of energetic ion production and approaches to mitigation is therefore desired. Presented here are data documenting the presence of energetic ions for both a barium oxide and a lanthanum hexaboride cathode as measured using a retarding potential analyzer. Also presented are energetic ion mitigation approaches, which are designed to eliminate the ion energy transfer mechanism. NASA SBIR Contract NNX15CP62P.

  20. Fast high-temperature superconductor switch for high current applications

    SciTech Connect

    Solovyov, VF; Li, Q

    2013-07-15

    Reversible operation of a high current superconductor switch based on the quench of high-resistance second generation high temperature superconducting wire is demonstrated. The quench is induced by a burst of an ac field generated by an inductively coupled radio-frequency coil. The switch makes a superconducting-to-normal transition within 5 ms and also has a rapid recovery to the superconducting state. The device has potential applications as an active current limiter or as a storage switch for superconducting magnetic energy storage systems. Operation in a full flux penetration/flow regime can effectively minimize the detrimental effects of the intrinsic conductor non-uniformity. (C) 2013 AIP Publishing LLC.

  1. Rf Gun with High-Current Density Field Emission Cathode

    SciTech Connect

    Jay L. Hirshfield

    2005-12-19

    High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes

  2. Drift distance survey in DPIS for high current beam production

    SciTech Connect

    Kanesue,T.; Okamura, M.; Kondo, K.; Tamura, J.; Kashiwagi, H.; Zhang, Z.

    2009-09-20

    In a laser ion source, plasma drift distance is one of the most important design parameters. Ion current density and beam pulse width are defined by plasma drift distance between laser target and beam extraction position. In direct plasma injection scheme (DPIS), which uses a laser ion source and Radio Frequency Quadrupole (RFQ) linac, we can apply relatively higher electric field at the beam extraction due to the unique shape of a positively biased electrode. However, when we aim at very high current acceleration like several tens of mA, we observed mismatched beam extraction conditions. We tested three different ion current at ion extraction region by changing plasma drift distance to study better extraction condition. In this experiment, C{sup 6+} beam was accelerated. We confirmed that the matching condition can be improved by controlling plasma drift distance.

  3. FEL POTENTIAL OF THE HIGH CURRENT ERLs AT BNL.

    SciTech Connect

    KAYRAN,D.; BEN-ZVI, I.; LITVINENKO, V.; POZDEYEV, E.; MATVEENKO, A.; SHEVCHENKO, O.; VINOKUROV, N.

    2007-08-26

    An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is under construction at Brookhaven National Laboratory (BNL) for testing concepts for high-energy electron cooling and electron-ion colliders. This ERL prototype will be used as a test bed to study issues relevant for very high current ERLs. High average current and high performance of electron beam with some additional components make this ERL an excellent driver for high power far infrared Free Electron Laser (FEL). A possibility for future up-grade to a two-pass ERL is considered. We present the status and our plans for construction and commissioning of the ERL. We discus a FEL potential based on electron beam provided by BNL ERL.

  4. New HOM coupler design for high current SRF cavity

    SciTech Connect

    Xu, W.; Ben-Zvi, I.; Belomestnykh, S.; Hahn, H.; Johnson, E.

    2011-03-28

    Damping higher order modes (HOMs) significantly to avoid beam instability is a challenge for the high current Energy Recovery Linac-based eRHIC at BNL. To avoid the overheating effect and high tuning sensitivity, current, a new band-stop HOM coupler is being designed at BNL. The new HOM coupler has a bandwidth of tens of MHz to reject the fundamental mode, which will avoid overheating due to fundamental frequency shifting because of cooling down. In addition, the S21 parameter of the band-pass filter is nearly flat from first higher order mode to 5 times the fundamental frequency. The simulation results showed that the new couplers effectively damp HOMs for the eRHIC cavity with enlarged beam tube diameter and 2 120{sup o} HOM couplers at each side of cavity. This paper presents the design of HOM coupler, HOM damping capacity for eRHIC cavity and prototype test results.

  5. MHz repetition rate solid-state driver for high current induction accelerators

    SciTech Connect

    Brooksby, C; Caporaso, G; Goerz, D; Hanks, R; Hickman, B; Kirbie, H; Lee, B; Saethre, R

    1999-03-01

    A research team from the Lawrence Livermore National Laboratory and Bechtel Nevada Corporation is developing an all solid-state power source for high current induction accelerators. The original power system design, developed for heavy-ion fusion accelerators, is based on the simple idea of using an array of field effect transistors to switch energy from a pre-charged capacitor bank to an induction accelerator cell. Recently, that idea has been expanded to accommodate the greater power needs of a new class of high-current electron accelerators for advanced radiography. For this purpose, we developed a 3-stage induction adder that uses over 4,000 field effect transistors to switch peak voltages of 45 kV at currents up to 4.8 kA with pulse repetition rates of up to 2 MHz. This radically advanced power system can generate a burst of five or more pulses that vary from 200 ns to 2 µs at a duty cycle of up to 25%. Our new source is precise, robust, flexible, and exceeds all previous drivers for induction machines by a factor of 400 in repetition rate and a factor of 1000 in duty cycle.

  6. High current heavy ion beam transport experiment at LBL

    SciTech Connect

    Chupp, W.; Faltens, A.; Hartwig, E.C.; Keefe, D.; Kim, C.H.; Pike, C.; Rosenblum, S.S.; Tiefenback, M.; Vanecek, D.; Warwick, A.I.

    1984-01-01

    Information on the current limit in a long quadrupole transport channel is required in designing an accelerator driver for an inertial confinement fusion system. Although a current transport limit was proposed by Maschke, quantitative estimates require a detailed knowledge of the stability of the beam. Analytic calculations based on the Kapchinskij-Vladimirskij (K-V) distribution function have identified transversely unstable modes, but particle simulations have shown that some of the K-V instabilities are benign, i.e., particles redistribute themselves in the 4-D transverse phase space, but the rms emittances do not grow. Some preliminary results of beam transport experiments were reported in the 1983 Particle Accelerator Conference in Santa Fe.

  7. Advanced oxidation of natural organic matter using hydrogen peroxide and iron-coated pumice particles.

    PubMed

    Kitis, M; Kaplan, S S

    2007-08-01

    The oxidative removal of natural organic matter (NOM) from waters using hydrogen peroxide and iron-coated pumice particles as heterogeneous catalysts was investigated. Two NOM sources were tested: humic acid solution and a natural source water. Iron coated pumice removed about half of the dissolved organic carbon (DOC) concentration at a dose of 3000 mg l(-1) in 24 h by adsorption only. Original pumice and peroxide dosed together provided UV absorbance reductions as high as 49%, mainly due to the presence of metal oxides including Al(2)O(3), Fe(2)O(3) and TiO(2) in the natural pumice, which are known to catalyze the decomposition of peroxide forming strong oxidants. Coating the original pumice particles with iron oxides significantly enhanced the removal of NOM with peroxide. A strong linear correlation was found between iron contents of coated pumices and UV absorbance reductions. Peroxide consumption also correlated with UV absorbance reduction. Control experiments proved the effective coating and the stability of iron oxide species bound on pumice surfaces. Results overall indicated that in addition to adsorptive removal of NOM by metal oxides on pumice surfaces, surface reactions between iron oxides and peroxide result in the formation of strong oxidants, probably like hydroxyl radicals, which further oxidize both adsorbed NOM and remaining NOM in solution, similar to those in Fenton-like reactions.

  8. An advanced stochastic model for mucociliary particle clearance in cystic fibrosis lungs

    PubMed Central

    Sturm, Robert

    2012-01-01

    Background A mathematical model describing mucociliary clearance in cystic fibrosis (CF) patients and its development with progressing course of the disease was developed. The approach should support the prediction of the disease state on the basis of measured bronchial clearance efficiencies. Methods The approach is based on the assumption of a steady-state steady-flow mucus transport through the tracheobronchial tree which enables the determination of airway generation-specific mucus velocities by using a measured tracheal mucus velocity and a realistic morphometric dataset of the human lung. Architecture of the tracheobronchial tree was approximated by a stochastic model, reflecting the intra-subject variability of geometric parameters within a given lung generation. Results As predicted by the appropriately validated mathematical approach, mucociliary clearance efficiency in CF patients is partly significantly decreased with respect to healthy controls. 24-h retention of patients with mild CF (FEV1 >70% of predicted) is reduced by 10% compared to healthy subjects, whilst 24-h retention of patients with moderate to severe CF (FEV1 <70% of predicted) differs by 25% from that of the healthy controls. These discrepancies are further enhanced with continuation of the clearance process. Conclusions The theoretical results lead to the conclusion that CF patients have a higher risk of inhaled particle accumulation and related particle overload in specific lung compartments than healthy subjects. PMID:22295167

  9. Superstructure for high current applications in superconducting linear accelerators

    DOEpatents

    Sekutowicz, Jacek; Kneisel, Peter

    2008-03-18

    A superstructure for accelerating charged particles at relativistic speeds. The superstructure consists of two weakly coupled multi-cell subunits equipped with HOM couplers. A beam pipe connects the subunits and an HOM damper is included at the entrance and the exit of each of the subunits. A coupling device feeds rf power into the subunits. The subunits are constructed of niobium and maintained at cryogenic temperatures. The length of the beam pipe between the subunits is selected to provide synchronism between particles and rf fields in both subunits.

  10. Particle exhaust schemes in the DIII-D advanced divertor configuration

    SciTech Connect

    Menon, M.M.; Mioduszewski, P.K.

    1989-01-01

    For density control in long-pulse operation, the open divertor on the DIII-D tokamak will be equipped with a baffled chamber and a pumping system. The throat of the baffle chamber is sized to provide optimal pumping for the typical plasma equilibrium configuration. Severe limitations on the toroidal conductance of this baffle chamber require the use of in-vessel pumping to achieve the desired particle exhaust of about 25 Torr{center dot}l/s. Two separate pumping schemes are considered: an array of titanium getter modules based on the design developed by the Tore Supra team and a cryocondensation pump. The merits and demerits of each scheme are analyzed, and the design considerations introduced by the tokamak environment are brought out. 3 refs., 5 figs.

  11. Advanced cell therapies: targeting, tracking and actuation of cells with magnetic particles.

    PubMed

    Connell, John J; Patrick, P Stephen; Yu, Yichao; Lythgoe, Mark F; Kalber, Tammy L

    2015-01-01

    Regenerative medicine would greatly benefit from a new platform technology that enabled measurable, controllable and targeting of stem cells to a site of disease or injury in the body. Superparamagnetic iron-oxide nanoparticles offer attractive possibilities in biomedicine and can be incorporated into cells, affording a safe and reliable means of tagging. This review describes three current and emerging methods to enhance regenerative medicine using magnetic particles to guide therapeutic cells to a target organ; track the cells using MRI and assess their spatial localization with high precision and influence the behavior of the cell using magnetic actuation. This approach is complementary to the systemic injection of cell therapies, thus expanding the horizon of stem cell therapeutics.

  12. Characterization of a High Current, Long Life Hollow Cathode

    NASA Technical Reports Server (NTRS)

    VanNoord, Jonathan L.; Kamhawi, Hani; McEwen, Heather K.

    2006-01-01

    The advent of higher power spacecraft makes it desirable to use higher power electric propulsion thrusters such as ion thrusters or Hall thrusters. Higher power thrusters require cathodes that are capable of producing higher currents. One application of these higher power spacecraft is deep-space missions that require tens of thousands of hours of operation. This paper presents the approach used to design a high current, long life hollow cathode assembly for that application, along with test results from the corresponding hollow cathode. The design approach used for the candidate hollow cathode was to reduce the temperature gradient in the insert, yielding a lower peak temperature and allowing current to be produced more uniformly along the insert. The lower temperatures result in a hollow cathode with increased life. The hollow cathode designed was successfully operated at currents from 10 to 60 A with flow rates of 5 to 19 sccm with a maximum orifice temperature measured of 1100 C. Data including discharge voltage, keeper voltage, discharge current, flow rates, and orifice plate temperatures are presented.

  13. High Current Cathodes Fabricated by KrF Laser Ablation

    SciTech Connect

    Gilgenbach, Ronald M.; Lau, Y. Y.; Jones, M. C.; Johnston, M. D.; Jordan, N. M.; Hoff, B. W.

    2010-10-08

    In this paper we review several high power laser ablation techniques that have been utilized to fabricate high current (1-80 kA) electron beam cathodes for accelerators and microwave sources: 1) Projection Ablation Lithography (PAL) cathodes, 2) Ablation Line Focus (ALF) cathodes, and 3) Metal-Oxide-Junction (MOJ) cathodes. Laser-ablative micromachining techniques (PAL and ALF) have been utilized to generate micron-scale features on metal substrates that provide electric field (beta) enhancement for Fowler-Nordheim emission and plasma cathodes. Since these laser-ablated patterns are directly, laser-written on the substrate metal they exhibit much higher thermal conductivity for higher current capability and increased damage thresholds. Metal-Oxide-Junction (MOJ) cathodes exploit the triple-point electron emission that occurs at the interface between metal, insulator and vacuum.The ablation laser is a KrF excimer laser with a pulse energy of 600 mJ and pulselength of 20 ns. Cathode experiments were performed on the MELBA-C accelerator: V = -300 kV, pulselength = 0.5 microsecond. Data will be presented for PAL, ALF and MOJ cathodes.

  14. Dynamics of a high-current relativistic electron beam

    SciTech Connect

    Strelkov, P. S.; Tarakanov, V. P.; Ivanov, I. E. Shumeiko, D. V.

    2015-06-15

    The dynamics of a high-current relativistic electron beam is studied experimentally and by numerical simulation. The beam is formed in a magnetically insulated diode with a transverse-blade explosive-emission cathode. It is found experimentally that the radius of a 500-keV beam with a current of 2 kA and duration of 500 ns decreases with time during the beam current pulse. The same effect was observed in numerical simulations. This effect is explained by a change in the shape of the cathode plasma during the current pulse, which, according to calculations, leads to a change in the beam parameters, such as the electron pitch angle and the spread over the longitudinal electron momentum. These parameters are hard to measure experimentally; however, the time evolution of the radial profile of the beam current density, which can be measured reliably, coincides with the simulation results. This allows one to expect that the behavior of the other beam parameters also agrees with numerical simulations.

  15. Interdigitated back contact solar cell with high-current collection

    SciTech Connect

    Garner, C. M.; Nasby, R. D.; Sexton, F. W.; Rodriguez, J. L.; Norwood, D. P.

    1981-01-01

    Internal current-collection efficiencies greater than 90 percent and energy-conversion efficiencies of 18 percent at 30 suns have been measured on a laboratory version of the interdigitated back contact (IBC) solar cell. The quantum efficiency at 600 nm was greater than 90 percent which implies a minority carrier lifetime of greater than 350 ..mu..sec and a front surface recombination velocity of less than 30 cm/sec on the better devices. To achieve these high-current collection efficiencies, a phosphorous gettering diffusion was performed on the front surface and then etched off. Also, thermal oxides were grown on the front and back of the cell to passivate the silicon surfaces. Although the internal collection efficiencies of the cell were high, series resistance caused the fill factor (FF) to decrease at concentrations above 30 suns. Dark current measurements on cells with a new grid spacing indicate that the series resistance is much lower than in the previous cell design. This should result in higher efficiencies at high concentration.

  16. Testing of a high current dc ESQ accelerator

    SciTech Connect

    Kwan, J.W.; Ackerman, G.D.; Ackerman, O.A.; Chan, C.F.; Cooper, W.S.; deVries, G.J.; Kunkel, W.B.; Soroka, L.; Steele, W.F.; Wells, R.P.

    1991-05-01

    A high current dc electrostatic quadrupole (ESQ) accelerator is being developed for negative-ion-based neutral beam heating and current drive on the next generation tokamak. Beam energy and current will eventually be in the MeV and multiampere range.l This CCVV (constant- current variable-voltage) accelerator uses a series of identical ESQ modules. We have successfully tested a prototype CCVV accelerator up to 200 keV with a 100 mA He{sub +} beam (with space charge equivalence of 140 mA of D{sup {minus}}) for a pulse length of 1 s. Testing was also done with a 42 mA H{sup {minus}} beam (H{sup {minus}} beam current was limited by source performance). There was almost no beam loss in the ESQ accelerator. no emittance growth was found in the beam injected from the preaccelerator into the ESQ accelerator had low aberration. We are presently designing a proof-of- principle one-channel CCVV accelerator that would accelerate 1.0 A of D{sup {minus}} 1.3 MeV energy. 4 refs., 7 figs.

  17. A neutron diagnostic for high current deuterium beams

    SciTech Connect

    Rebai, M.; Perelli Cippo, E.; Cavenago, M.; Dalla Palma, M.; Pasqualotto, R.; Tollin, M.; Croci, G.; Gervasini, G.; Ghezzi, F.; Grosso, G.; Tardocchi, M.; Murtas, F.; Gorini, G.

    2012-02-15

    A neutron diagnostic for high current deuterium beams is proposed for installation on the spectral shear interferometry for direct electric field reconstruction (SPIDER, Source for Production of Ion of Deuterium Extracted from RF plasma) test beam facility. The proposed detection system is called Close-contact Neutron Emission Surface Mapping (CNESM). The diagnostic aims at providing the map of the neutron emission on the beam dump surface by placing a detector in close contact, right behind the dump. CNESM uses gas electron multiplier detectors equipped with a cathode that also serves as neutron-proton converter foil. The cathode is made of a thin polythene film and an aluminium film; it is designed for detection of neutrons of energy >2.2 MeV with an incidence angle < 45 deg. CNESM was designed on the basis of simulations of the different steps from the deuteron beam interaction with the beam dump to the neutron detection in the nGEM. Neutron scattering was simulated with the MCNPX code. CNESM on SPIDER is a first step towards the application of this diagnostic technique to the MITICA beam test facility, where it will be used to resolve the horizontal profile of the beam intensity.

  18. A Superconducting transformer system for high current cable testing

    SciTech Connect

    Godeke, A.; Dietderich, D. R.; Joseph, J. M.; Lizarazo, J.; Prestemon, S. O.; Miller, G.; Weijers, H. W.

    2010-02-15

    This article describes the development of a direct-current (dc) superconducting transformer system for the high current test of superconducting cables. The transformer consists of a core-free 10 464 turn primary solenoid which is enclosed by a 6.5 turn secondary. The transformer is designed to deliver a 50 kA dc secondary current at a dc primary current of about 50 A. The secondary current is measured inductively using two toroidal-wound Rogowski coils. The Rogowski coil signal is digitally integrated, resulting in a voltage signal that is proportional to the secondary current. This voltage signal is used to control the secondary current using a feedback loop which automatically compensates for resistive losses in the splices to the superconducting cable samples that are connected to the secondary. The system has been commissioned up to 28 kA secondary current. The reproducibility in the secondary current measurement is better than 0.05% for the relevant current range up to 25 kA. The drift in the secondary current, which results from drift in the digital integrator, is estimated to be below 0.5 A/min. The system's performance is further demonstrated through a voltage-current measurement on a superconducting cable sample at 11 T background magnetic field. The superconducting transformer system enables fast, high resolution, economic, and safe tests of the critical current of superconducting cable samples.

  19. Mevva development for the new GSI high-current injector

    SciTech Connect

    Wolf, B.H.; Emig, H.; Spaedtke, P.

    1996-08-01

    To increase the intensity of the heavy ion synchrotron SIS for heavy elements by a factor of {approximately}50, a new prestripper accelerator is planned for Unilac and the heavy ion synchrotron SIS. It is designed to accept ions with mass/charge {le} 65 and an injection energy of 2.2 keV/u. A vacuum arc ion source with a strong axial magnetic field will deliver 15 mA of U{sup 4+} as heaviest element at a repetition rate of 1 Hz and a pulse length of 300 {mu}s. The investigation of the Mevva ion source with pulsed magnetic field of several kGauss have shown that ion currents of 8 mA U{sup 4+} can be measured at the authors test bench after 5m of transport and charge analysis (transmission at the test bench 25% only). The noise on the extracted ion beam was already {le}25%, a value similar to the Pig ion source in the sputter mode, but efficient high current beam transport probably requests further improvements.

  20. Some Physical and Engineering Aspects of High Current EBIS

    SciTech Connect

    Pikin, A; Prelec, K.

    1999-05-21

    Some applications of an Electron Beam Ion Source (EBIS) require intensities of highly charged ions significantly greater than those which have been achieved in present EBIS sources. For example, the ion source for the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) must be capable of generating 3 x 10{sup 9} ions of Au{sup 35+} or 2 x 10{sup 9} ions of U{sup 45+} per pulse. In this case, if the fraction of ions of interest is 20% of the total ion space charge, the total extracted charge is {approximately} 5 x 10{sup 11}. It is also desirable to extract these ions in a 10 {micro}s pulse to allow single turn injection into the first synchrotrons. Requirements for an EBIS which could meet the needs of the LHC at CERN are similar ({approximately} 1.5 x 10{sup 9} ions of Pb{sup 54+} in 5.5 {micro}s). This charge yield is about an order of magnitude greater than that achieved in existing EBIS sources, and is what is meant here by high current. This also implies, then, an EBIS with a high electron beam current.

  1. Flux pinning in high-current-density superconductors

    SciTech Connect

    Freyhardt, H.

    1983-05-01

    A major application of superconducting wire materials is the generation of magnetic fields, often in large volumes, with particular strenth, homogeneity, and field gradients. To fabricate superconductors which can carry high current densities at high temperatures and fields, flux pinning, by crystal inhomogeneities, must be understood. This paper attempts to answer two questions about flux pinning. The first addresses the nature and strenght of the elementary interaction force (f) between one flux line (FL) and one obstacle; the second, the correct summation of these elementary interactions between the obstacles in a unit volume and the FL to the (total) volume pinning force F /SUB v/ = B X J /SUB c/ . The discussion is confined to NbTi and A15 superconductors such as Nb/sub 3/Sn and V/sub 3/Ga. Important pinning sites in these superconductors are dislocation walls, precipitates, small inclusions, voids, grain boundaries, and bubbles. A series of mathematical models which have been used in the past are presented and synthesized into a more sophisticated explanation of pinning.

  2. Advanced methods for the computation of particle beam transport and the computation of electromagnetic fields and beam-cavity interactions

    SciTech Connect

    Dragt, A.J.; Gluckstern, R.L.

    1990-11-01

    The University of Maryland Dynamical Systems and Accelerator Theory Group carries out research in two broad areas: the computation of charged particle beam transport using Lie algebraic methods and advanced methods for the computation of electromagnetic fields and beam-cavity interactions. Important improvements in the state of the art are believed to be possible in both of these areas. In addition, applications of these methods are made to problems of current interest in accelerator physics including the theoretical performance of present and proposed high energy machines. The Lie algebraic method of computing and analyzing beam transport handles both linear and nonlinear beam elements. Tests show this method to be superior to the earlier matrix or numerical integration methods. It has wide application to many areas including accelerator physics, intense particle beams, ion microprobes, high resolution electron microscopy, and light optics. With regard to the area of electromagnetic fields and beam cavity interactions, work is carried out on the theory of beam breakup in single pulses. Work is also done on the analysis of the high behavior of longitudinal and transverse coupling impendances, including the examination of methods which may be used to measure these impedances. Finally, work is performed on the electromagnetic analysis of coupled cavities and on the coupling of cavities to waveguides.

  3. Time-resolved ion energy distribution measurements using an advanced neutral particle analyzer on the MST reversed-field pinch.

    PubMed

    Eilerman, S; Anderson, J K; Reusch, J A; Liu, D; Fiksel, G; Polosatkin, S; Belykh, V

    2012-10-01

    An advanced neutral particle analyzer (ANPA) capable of simultaneously measuring hydrogen and deuterium ions of energies up to 45 keV has recently been developed for use on the Madison Symmetric Torus. The charge-to-mass separation allows for separate analysis of bulk deuterium ions and hydrogen ions injected with a 1 MW, 25 keV neutral beam. Orientation of the ANPA allows sampling of different regions of ion velocity space; a radial viewport favors collection of ions with high v(perpendicular)∕|v| while a recently installed tangential viewport favors ions with high v(||)∕|v|, such as those from the core-localized fast ion population created by the neutral beam. Signals are observed in the ANPA's highest energy channels during periodic magnetic reconnection events, which are drivers of anisotropic, non-Maxwellian ion energization in the reversed-field pinch. ANPA signal strength is dependent on the background neutral density, which also increases during magnetic reconnection events, so careful analysis must be performed to identify the true change in the ion distribution. A Monte Carlo neutral particle tracing code (NENE) is used to reconstruct neutral density profiles based on D(α) line emission, which is measured using a 16-chord filtered photodiode array.

  4. Incorporating advanced language models into the P300 speller using particle filtering

    NASA Astrophysics Data System (ADS)

    Speier, W.; Arnold, C. W.; Deshpande, A.; Knall, J.; Pouratian, N.

    2015-08-01

    Objective. The P300 speller is a common brain-computer interface (BCI) application designed to communicate language by detecting event related potentials in a subject’s electroencephalogram signal. Information about the structure of natural language can be valuable for BCI communication, but attempts to use this information have thus far been limited to rudimentary n-gram models. While more sophisticated language models are prevalent in natural language processing literature, current BCI analysis methods based on dynamic programming cannot handle their complexity. Approach. Sampling methods can overcome this complexity by estimating the posterior distribution without searching the entire state space of the model. In this study, we implement sequential importance resampling, a commonly used particle filtering (PF) algorithm, to integrate a probabilistic automaton language model. Main result. This method was first evaluated offline on a dataset of 15 healthy subjects, which showed significant increases in speed and accuracy when compared to standard classification methods as well as a recently published approach using a hidden Markov model (HMM). An online pilot study verified these results as the average speed and accuracy achieved using the PF method was significantly higher than that using the HMM method. Significance. These findings strongly support the integration of domain-specific knowledge into BCI classification to improve system performance.

  5. Advanced antigen delivery of murine survivin: chimeric virus-like particles in cancer vaccine research.

    PubMed

    Schumacher, Thomas; Ruehland, Claus; Schultheiss, Christine; Brinkman, Marc; Roedel, Franz; Reiser, Christian O A; Hess, Juergen; Reichel, Christoph

    2007-09-01

    Success in cancer immunotherapy depends on the identification and efficient targeting of specific tumor-associated antigens. Two pivotal strategies to prime patients' immune system against malignant cells are tumor-specific adoptive T-cell therapy and tumor-specific vaccination. Here, we will focus on immunotherapeutic vaccination and discuss the advantages and disadvantages of different strategies to deliver tumor-specific T-cell epitopes. A particular focus will be put on virus-like particles (VLPs) as vehicle to deliver tumor-specific epitopes in the context of full-length proteins, as multi-epitope constructs or as individual tumor-associated T-cell epitopes. VLPs represent non-infectious and non-replicating antigen delivery systems devoid of any nucleic acid. They constitute innovative immunotherapeutic agents against cancer due to their superior, adjuvant-like antigenicity. We will present various tumor-associated antigens currently in different stages of development including survivin, as promising candidates for targeted tumor therapies. PMID:23675044

  6. Advanced Antigen Delivery of Murine Survivin: Chimeric Virus-Like Particles in Cancer Vaccine Research

    PubMed Central

    Schumacher, Thomas; Ruehland, Claus; Schultheiss, Christine; Brinkman, Marc; Roedel, Franz; Reiser, Christian O. A.; Hess, Juergen; Reichel, Christoph

    2007-01-01

    Success in cancer immunotherapy depends on the identification and efficient targeting of specific tumor-associated antigens. Two pivotal strategies to prime patients’ immune system against malignant cells are tumor-specific adoptive T-cell therapy and tumor-specific vaccination. Here, we will focus on immunotherapeutic vaccination and discuss the advantages and disadvantages of different strategies to deliver tumor-specific T-cell epitopes. A particular focus will be put on virus-like particles (VLPs) as vehicle to deliver tumor-specific epitopes in the context of full-length proteins, as multi-epitope constructs or as individual tumor-associated T-cell epitopes. VLPs represent non-infectious and non-replicating antigen delivery systems devoid of any nucleic acid. They constitute innovative immunotherapeutic agents against cancer due to their superior, adjuvant-like antigenicity. We will present various tumor-associated antigens currently in different stages of development including survivin, as promising candidates for targeted tumor therapies. PMID:23675044

  7. Advanced antigen delivery of murine survivin: chimeric virus-like particles in cancer vaccine research.

    PubMed

    Schumacher, Thomas; Ruehland, Claus; Schultheiss, Christine; Brinkman, Marc; Roedel, Franz; Reiser, Christian O A; Hess, Juergen; Reichel, Christoph

    2007-09-01

    Success in cancer immunotherapy depends on the identification and efficient targeting of specific tumor-associated antigens. Two pivotal strategies to prime patients' immune system against malignant cells are tumor-specific adoptive T-cell therapy and tumor-specific vaccination. Here, we will focus on immunotherapeutic vaccination and discuss the advantages and disadvantages of different strategies to deliver tumor-specific T-cell epitopes. A particular focus will be put on virus-like particles (VLPs) as vehicle to deliver tumor-specific epitopes in the context of full-length proteins, as multi-epitope constructs or as individual tumor-associated T-cell epitopes. VLPs represent non-infectious and non-replicating antigen delivery systems devoid of any nucleic acid. They constitute innovative immunotherapeutic agents against cancer due to their superior, adjuvant-like antigenicity. We will present various tumor-associated antigens currently in different stages of development including survivin, as promising candidates for targeted tumor therapies.

  8. Characterization techniques for the high-brightness particle beams of the Advanced Photon Source (APS)

    SciTech Connect

    Lumpkin, A.H.

    1993-08-01

    The Advanced Photon Source (APS) will be a third-generation synchrotron radiation (SR) user facility in the hard x-ray regime (10--100 keV). The design objectives for the 7-GeV storage ring include a positron beam natural emittance of 8 {times} 10{sup {minus}9} m-rad at an average current of 100 mA. Proposed methods for measuring the transverse and longitudinal profiles will be described. Additionally, a research and development effort using an rf gun as a low-emittance source of electrons for injection into the 200- to 650-MeV linac subsystem is underway. This latter system is projected to produce electron beams with a normalized, rms emittance of {approximately}2 {pi} mm-mrad at peak currents of near one hundred amps. This interesting characterization problem will also be briefly discussed. The combination of both source types within one laboratory facility will stimulate the development of diagnostic techniques in these parameter spaces.

  9. New progress of high current gasdynamic ion source (invited).

    PubMed

    Skalyga, V; Izotov, I; Golubev, S; Sidorov, A; Razin, S; Vodopyanov, A; Tarvainen, O; Koivisto, H; Kalvas, T

    2016-02-01

    The experimental and theoretical research carried out at the Institute of Applied Physics resulted in development of a new type of electron cyclotron resonance ion sources (ECRISs)-the gasdynamic ECRIS. The gasdynamic ECRIS features a confinement mechanism in a magnetic trap that is different from Geller's ECRIS confinement, i.e., the quasi-gasdynamic one similar to that in fusion mirror traps. Experimental studies of gasdynamic ECRIS were performed at Simple Mirror Ion Source (SMIS) 37 facility. The plasma was created by 37.5 and 75 GHz gyrotron radiation with power up to 100 kW. High frequency microwaves allowed to create and sustain plasma with significant density (up to 8 × 10(13) cm(-3)) and to maintain the main advantages of conventional ECRIS such as high ionization degree and low ion energy. Reaching such high plasma density relies on the fact that the critical density grows with the microwave frequency squared. High microwave power provided the average electron energy on a level of 50-300 eV enough for efficient ionization even at neutral gas pressure range of 10(-4)-10(-3) mbar. Gasdynamic ECRIS has demonstrated a good performance producing high current (100-300 mA) multi-charged ion beams with moderate average charge (Z = 4-5 for argon). Gasdynamic ECRIS has appeared to be especially effective in low emittance hydrogen and deuterium beams formation. Proton beams with current up to 500 emA and RMS emittance below 0.07 π ⋅ mm ⋅ mrad have been demonstrated in recent experiments. PMID:26931934

  10. Electrical and hydrodynamic characterization of a high current pulsed arc

    NASA Astrophysics Data System (ADS)

    Sousa Martins, R.; Chemartin, L.; Zaepffel, C.; Lalande, Ph; Soufiani, A.

    2016-05-01

    High current pulsed arcs are of significant industrial interest and, aiming to reduce time and cost, there is progressively more and more need for computation tools that describe and predict the behaviour of these arcs. These simulation codes need inputs and validations by experimental databases, but accurate data is missing for this category of electric discharges. The principal lack of understanding is with respect to the transient phase of the current, which can reach thousands of amperes in a few microseconds. In this paper, we present the work realized on an experimental setup that simulates in the laboratory an arc column subjected to five levels of high pulsed current, ranging from 10 kA to 100 kA, with the last one corresponding to the standard lightning current waveform used in aircraft certification processes. This device was instrumented by high speed video cameras to assess the characteristic sizes of the arc channel and to characterize the shock wave generated by the arc expansion. The arc channel radius was measured over time during the axisymmetric phase and reached 3.2 cm. The position and velocity of the shock wave was determined during the first 140 μs. The background-oriented schlieren method was used to study the shock wave and a model for the light deflection inside the shock wave was developed. The mass density profile of the shock wave was estimated and showed good agreement with Rankine-Hugoniot relations at the wave front. Electrical measurements were also used to estimate the time-dependent resistance and conductivity of the arc for times lasting up to 50 μs.

  11. The high current transport experiment for heavy ion inertial fusion

    SciTech Connect

    Prost, L.R.; Baca, D.; Bieniosek, F.M.; Celata, C.M.; Faltens, A.; Henestroza, E.; Kwan, J.W.; Leitner, M.; Seidl, P.A.; Waldron, W.L.; Cohen, R.; Friedman, A.; Grote, D.; Lund, S.M.; Molvik, A.W.; Morse, E.

    2004-05-01

    The High Current Experiment (HCX) at Lawrence Berkeley National Laboratory is part of the US program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density {approx} 0.2 {micro}C/m) over long pulse durations (4 {micro}s) in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo and, electron and gas cloud effects. We present the results for a coasting 1 MeV K{sup +} ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius) for which the transverse phase-space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor ({approx}80%) is achieved with acceptable emittance growth and beam loss, even though the initial beam distribution is not ideal (but the emittance is low) nor in thermal equilibrium. We achieved good envelope control, and rematching may only be needed every ten lattice periods (at 80% fill factor) in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics.

  12. New progress of high current gasdynamic ion source (invited)

    NASA Astrophysics Data System (ADS)

    Skalyga, V.; Izotov, I.; Golubev, S.; Sidorov, A.; Razin, S.; Vodopyanov, A.; Tarvainen, O.; Koivisto, H.; Kalvas, T.

    2016-02-01

    The experimental and theoretical research carried out at the Institute of Applied Physics resulted in development of a new type of electron cyclotron resonance ion sources (ECRISs)—the gasdynamic ECRIS. The gasdynamic ECRIS features a confinement mechanism in a magnetic trap that is different from Geller's ECRIS confinement, i.e., the quasi-gasdynamic one similar to that in fusion mirror traps. Experimental studies of gasdynamic ECRIS were performed at Simple Mirror Ion Source (SMIS) 37 facility. The plasma was created by 37.5 and 75 GHz gyrotron radiation with power up to 100 kW. High frequency microwaves allowed to create and sustain plasma with significant density (up to 8 × 1013 cm-3) and to maintain the main advantages of conventional ECRIS such as high ionization degree and low ion energy. Reaching such high plasma density relies on the fact that the critical density grows with the microwave frequency squared. High microwave power provided the average electron energy on a level of 50-300 eV enough for efficient ionization even at neutral gas pressure range of 10-4-10-3 mbar. Gasdynamic ECRIS has demonstrated a good performance producing high current (100-300 mA) multi-charged ion beams with moderate average charge (Z = 4-5 for argon). Gasdynamic ECRIS has appeared to be especially effective in low emittance hydrogen and deuterium beams formation. Proton beams with current up to 500 emA and RMS emittance below 0.07 π ṡ mm ṡ mrad have been demonstrated in recent experiments.

  13. Large dynamic range diagnostics for high current electron LINACs

    SciTech Connect

    Evtushenko, P.

    2013-11-07

    The Jefferson Lab FEL driver accelerator - Energy Recovery Linac has provided a beam with average current of up to 9 mA and beam energy of 135 MeV. The high power beam operations have allowed developing and testing methods and approaches required to set up and tune such a facility simultaneously for the high beam power and high beam quality required for high performance FEL operations. In this contribution we briefly review this experience and outline problems that are specific to high current - high power non-equilibrium linac beams. While the original strategy for beam diagnostics and tuning have proven to be quite successful, some shortcomings and unresolved issues were also observed. The most important issues are the non-equilibrium (non-Gaussian) nature of the linac beam and the presence of small intensity - large amplitude fraction of the beam a.k.a. beam halo. Thus we also present a list of the possible beam halo sources and discuss possible mitigations means. We argue that for proper understanding and management of the beam halo large dynamic range (>10{sup 6}) transverse and longitudinal beam diagnostics can be used. We also present results of transverse beam profile measurements with the dynamic range approaching 10{sup 5} and demonstrate the effect the increased dynamic range has on the beam characterization, i.e., emittance and Twiss parameters measurements. We also discuss near future work planned in this field and where the JLab FEL facility will be used for beam tests of the developed of new diagnostics.

  14. Large dynamic range diagnostics for high current electron LINACs

    SciTech Connect

    Evtushenko, Pavel

    2013-11-01

    The Jefferson Lab FEL driver accelerator - Energy Recovery Linac has provided a beam with average current of up to 9 mA and beam energy of 135 MeV. The high power beam operations have allowed developing and testing methods and approaches required to set up and tune such a facility simultaneously for the high beam power and high beam quality required for high performance FEL operations. In this contribution we briefly review this experience and outline problems that are specific to high current - high power non-equilibrium linac beams. While the original strategy for beam diagnostics and tuning have proven to be quite successful, some shortcomings and unresolved issues were also observed. The most important issues are the non-equilibrium (non-Gaussian) nature of the linac beam and the presence of small intensity - large amplitude fraction of the beam a.k.a. beam halo. Thus we also present a list of the possible beam halo sources and discuss possible mitigations means. We argue that for proper understanding and management of the beam halo large dynamic range (>10{sup 6}) transverse and longitudinal beam diagnostics can be used. We also present results of transverse beam profile measurements with the dynamic range approaching 10{sup 5} and demonstrate the effect the increased dynamic range has on the beam characterization, i.e., emittance and Twiss parameters measurements. We also discuss near future work planned in this field and where the JLab FEL facility will be used for beam tests of the developed of new diagnostics.

  15. High-current fast electron beam propagation in a dielectric target

    SciTech Connect

    Klimo, Ondrej; Tikhonchuk, V. T.; Debayle, A.

    2007-01-15

    Recent experiments demonstrate an efficient transformation of high intensity laser pulse into a relativistic electron beam with a very high current density exceeding 10{sup 12} A cm{sup -2}. The propagation of such a beam inside the target is possible if its current is neutralized. This phenomenon is not well understood, especially in dielectric targets. In this paper, we study the propagation of high current density electron beam in a plastic target using a particle-in-cell simulation code. The code includes both ionization of the plastic and collisions of newborn electrons. The numerical results are compared with a relatively simple analytical model and a reasonable agreement is found. The temporal evolution of the beam velocity distribution, the spatial density profile, and the propagation velocity of the ionization front are analyzed and their dependencies on the beam density and energy are discussed. The beam energy losses are mainly due to the target ionization induced by the self-generated electric field and the return current. For the highest beam density, a two-stream instability is observed to develop in the plasma behind the ionization front and it contributes to the beam energy losses.

  16. High-current fast electron beam propagation in a dielectric target.

    PubMed

    Klimo, Ondrej; Tikhonchuk, V T; Debayle, A

    2007-01-01

    Recent experiments demonstrate an efficient transformation of high intensity laser pulse into a relativistic electron beam with a very high current density exceeding 10(12) A cm(-2). The propagation of such a beam inside the target is possible if its current is neutralized. This phenomenon is not well understood, especially in dielectric targets. In this paper, we study the propagation of high current density electron beam in a plastic target using a particle-in-cell simulation code. The code includes both ionization of the plastic and collisions of newborn electrons. The numerical results are compared with a relatively simple analytical model and a reasonable agreement is found. The temporal evolution of the beam velocity distribution, the spatial density profile, and the propagation velocity of the ionization front are analyzed and their dependencies on the beam density and energy are discussed. The beam energy losses are mainly due to the target ionization induced by the self-generated electric field and the return current. For the highest beam density, a two-stream instability is observed to develop in the plasma behind the ionization front and it contributes to the beam energy losses.

  17. Design and study of a high-current 5-cell superconducting rf cavity.

    SciTech Connect

    Liu, Z.; Nassiri, A.; Waldschmidt, G. )

    2010-01-01

    The Advanced Photon Source (APS) at Argonne National Laboratory is considering the development of a superconducting linac-based fourth-generation hard X-ray source to meet future scientific needs of the hard X-ray user community. This work specifically focuses on the design of an optimized 5-cell superconducting radio-frequency structure well suited for a high-energy, high-beam-current energy recovery linac. The cavity design parameters are based on the APS storage ring nominal 7 GeV and 100 mA beam operation. A high-current 5-cell cw superconducting cavity operating at 1.4 GHz has been designed. In order to achieve a high current, the accelerating cavity shape has been optimized and large end-cell beam pipes have been adopted. The beam break-up threshold of the cavity has been estimated using the code TDBBU, which predicts a high threshold beam current for a 7 GeV energy recovery linac model. A copper prototype cavity has been fabricated that uses half-cell modules, initially assembled by clamping the cells together.

  18. Low Impedance Bellows for High-current Beam Operations

    SciTech Connect

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

    2012-07-01

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

  19. Plasma Emission Characteristics from a High Current Hollow Cathode in an Ion Thruster Discharge Chamber

    NASA Technical Reports Server (NTRS)

    Foster, John E.; Patterson, Michael J.

    2002-01-01

    The presence of energetic ions produced by a hollow cathodes operating at high emission currents (greater than 5A) has been documented in the literature. In order to further elucidate these findings, an investigation of a high current cathode operating in an ion thruster discharge chamber has been undertaken. Using Langmuir probes, a low energy charged particle analyzer and emission spectroscopy, the behavior of the near-cathode plasma and the emitted ion energy distribution was characterized. The presence of energetic ions was confirmed. It was observed that these ions had energies in excess of the discharge voltage and thus cannot be simply explained by ions falling out of plasma through a potential difference of this order. Additionally, evidence provided by Langmuir probes suggests the existence of a double layer essentially separating the hollow cathode plasma column from the main discharge. The radial potential difference associated with this double layer was measured to be of order the ionization potential.

  20. Advancement of Shock-wave Induced Spraying Process through the Study of Gas and Particle Flow Fields

    NASA Astrophysics Data System (ADS)

    Karimi Esfahani, Mohammad

    This research advances the knowledge of the working principles of the Shock-wave Induced Spraying Process (SISP), a thermal spray material deposition technique. Pulses created by a fast acting valve pass through a heated line increasing energy content and interacting with metered batches of heated or non-heated powder introduced into the line. The powder is accelerated to high velocities before bonding to the substrate upon impact. Advantages over other cold spray processes include cost savings and a more effective transfer of thermal energy to the powder. The shock-wave occurring near the substrate in other cold spray processes is avoided. The SISP flow field is resolved by using a computational model. The two-dimensional model accounts for the valve, gas heater, a tapered nozzle at the tip of the device, and preheating of the powder. It is implemented with a commercial computational fluid dynamics code. Comparisons are made with one-dimensional predictions, and measurements of pressure and temperature. Particle flow predictions are validated using particle velocity and adhesion measurements. A flow region of both high temperature and velocity gas, favorable to material deposition, forms which is not present in comparable steady-state cold spray processes. Increasing gas pressure increases the gas speed, while increasing temperature increases speed and temperature of this region. Using helium results in greater energy levels but for shorter periods of time. This indicates the need for a powder feeder which places particles in the flow at correct instants and durations of time. The effects of particle flow parameters on system performance are examined. It is found that the device must be operated at very high main heater and powder heater temperatures: 900 °C and 700 °C respectively to achieve a coating with stainless steel using nitrogen as the driving gas. It is also shown that a heater length range of 0.9 m to 1.4 m results in the greatest likelihood of

  1. Recent advances in high current vacuum arc ion sources for heavy ion fusion

    NASA Astrophysics Data System (ADS)

    Qi, Niansheng; Schein, Jochen; Prasad, Rahul R.; Krishnan, Mahadevan; Anders, Andre; Kwan, Joe; Brown, Ian

    2001-05-01

    For a heavy ion fusion induction linac driver, a source of heavy ions with charge states 1+-3+, ≈0.5 A current beams, ≈20 μs pulse widths and ˜10 Hz repetition rates is required. Thermionic sources have been the workhorse for the Heavy Ion Fusion (HIF) program to date, but suffer from heating problems for large areas and contamination. They are limited to low (contact) ionization potential elements and offer relatively low ion fluxes with a charge state limited to 1+. Gas injection sources suffer from partial ionization and deleterious neutral gas effects. The above shortcomings of the thermionic ion sources can be overcome by a vacuum arc ion source. The vacuum arc ion source is a good candidate for HIF applications. It is capable of providing ions of various elements and different charge states in short and long pulse bursts and high beam current density. Under a Phase-I STTR from DOE, the feasibility of the vacuum arc ion source for the HIF applications was investigated. We have modified an existing vacuum arc ion source at LBNL to produce a gadolinium ( A≈158) ion beam with >0.5 A beam current, 120 keV beam energy, ≈6 cm diameter extraction aperture and ≈20 μs pulse width. The average beam current density at the extraction grids was ≈17 mA/cm 2. We have measured that >85% Gd ions were in the 3+ charge state, the beam current fluctuation level (rms) was ≈3%, pulse-to-pulse variation of the beam (rms) was about 3%, the uniformity of the beam density over its 6 cm diameter was ⩾98% and the ion longitudinal energy spread was ⩽1%. Additional measurements were made to improve charge state purity by using other materials and employing an axial magnetic field close to the cathode. Yttrium ( A≈89), lead ( A≈207), and Ba ( A≈137) were tested at similar current parameters with Ba delivering nearly a pure charge state with >95% being in 2+ state. The results of the experiments indicate that the vacuum arc ion source is a good candidate for HIF applications.

  2. Compact high current generator for x-ray radiography

    NASA Astrophysics Data System (ADS)

    Kharlov, A. V.; Kovalchuk, B. M.; Zorin, V. B.

    2006-12-01

    We report here a design of the portable high current generator, which can be used for a row of experiments and applications, including, but not limited to, X pinch, plasma focus, vacuum spark, etc. The X generator consists of the capacitor bank, multigap spark switch, load chamber, and built-in high voltage triggering generator. The capacitor bank consists of 12 General Atomics 35404 type capacitors (20nF, 25nH, 0.2Ω, 100kV). It stores ˜0.8kJ at 80kV charging voltage. Each three capacitors are commuted to a load by the multigap spark switch, which is able to commute by eight parallel channels. Switches operate in ambient air at atmospheric pressure. At 76kV charging voltage the generator provides ˜260kA with 120ns rise time and 5nH inductive load and ˜220kA with 145ns rise time and 10nH. Delay of output pulse relative to high voltage triggering pulse is ˜65ns with 5ns jitter. The dimensions of the generator are 1240×1240×225mm3 and the weight is ˜250kg, and only one high voltage power supply is required as additional equipment for the generator. The generator with a pumping system is placed on area about 0.5m2. Operation and handling are very simple, because no oil nor purified gases are required for the generator. The X generator has been successfully employed for experiments on the Ni X pinch load. X-ray pulse duration (full width at half maximum above 1keV) was about 5ns. Radiation yield Wr⩾500mJ was observed in the 1.2-1.5KeV range and Wr⩾20mJ in the 3-5keV energy range, which is comparable to results, obtained on the nanosecond accelerators. Clearly resolved images of 6μm wire indicate micron level size of hot spot. These results demonstrate possibility of this generator for application for x-ray backlighting.

  3. Compact high current generator for x-ray radiography

    SciTech Connect

    Kharlov, A. V.; Kovalchuk, B. M.; Zorin, V. B.

    2006-12-15

    We report here a design of the portable high current generator, which can be used for a row of experiments and applications, including, but not limited to, X pinch, plasma focus, vacuum spark, etc. The X generator consists of the capacitor bank, multigap spark switch, load chamber, and built-in high voltage triggering generator. The capacitor bank consists of 12 General Atomics 35404 type capacitors (20 nF, 25 nH, 0.2 {omega}, 100 kV). It stores {approx}0.8 kJ at 80 kV charging voltage. Each three capacitors are commuted to a load by the multigap spark switch, which is able to commute by eight parallel channels. Switches operate in ambient air at atmospheric pressure. At 76 kV charging voltage the generator provides {approx}260 kA with 120 ns rise time and 5 nH inductive load and {approx}220 kA with 145 ns rise time and 10 nH. Delay of output pulse relative to high voltage triggering pulse is {approx}65 ns with 5 ns jitter. The dimensions of the generator are 1240x1240x225 mm{sup 3} and the weight is {approx}250 kg, and only one high voltage power supply is required as additional equipment for the generator. The generator with a pumping system is placed on area about 0.5 m{sup 2}. Operation and handling are very simple, because no oil nor purified gases are required for the generator. The X generator has been successfully employed for experiments on the Ni X pinch load. X-ray pulse duration (full width at half maximum above 1 keV) was about 5 ns. Radiation yield W{sub r}{>=}500 mJ was observed in the 1.2-1.5 KeV range and W{sub r}{>=}20 mJ in the 3-5 keV energy range, which is comparable to results, obtained on the nanosecond accelerators. Clearly resolved images of 6 {mu}m wire indicate micron level size of hot spot. These results demonstrate possibility of this generator for application for x-ray backlighting.

  4. Heavy ion linac as a high current proton beam injector

    NASA Astrophysics Data System (ADS)

    Barth, Winfried; Adonin, Aleksey; Appel, Sabrina; Gerhard, Peter; Heilmann, Manuel; Heymach, Frank; Hollinger, Ralph; Vinzenz, Wolfgang; Vormann, Hartmut; Yaramyshev, Stepan

    2015-05-01

    A significant part of the experimental program at Facility for Antiproton and Ion Research (FAIR) is dedicated to pbar physics requiring a high number of cooled pbars per hour. The primary proton beam has to be provided by a 70 MeV proton linac followed by two synchrotrons. The new FAIR proton linac will deliver a pulsed proton beam of up to 35 mA of 36 μ s duration at a repetition rate of 4 Hz (maximum). The GSI heavy ion linac (UNILAC) is able to deliver world record uranium beam intensities for injection into the synchrotrons, but it is not suitable for FAIR relevant proton beam operation. In an advanced machine investigation program it could be shown that the UNILAC is able to provide for sufficient high intensities of CH3 beam, cracked (and stripped) in a supersonic nitrogen gas jet into protons and carbon ions. This advanced operational approach will result in up to 3 mA of proton intensity at a maximum beam energy of 20 MeV, 1 0 0 μ s pulse duration and a repetition rate of up to 2.7 Hz delivered to the synchrotron SIS18. Recent linac beam measurements will be presented, showing that the UNILAC is able to serve as a proton FAIR injector for the first time, while the performance is limited to 25% of the FAIR requirements.

  5. Using advanced dispersion models and mobile monitoring to characterize spatial patterns of ultrafine particles in an urban area

    NASA Astrophysics Data System (ADS)

    Zwack, Leonard M.; Hanna, Steven R.; Spengler, John D.; Levy, Jonathan I.

    2011-09-01

    In urban settings with elevated bridges, buildings, and other complex terrain, the relationship between traffic and air pollution can be highly variable and difficult to accurately characterize. Atmospheric dispersion models are often used in this context, but incorporating background concentrations and characterizing emissions at high spatiotemporal resolution is challenging, especially for ultrafine particles (UFPs). Ambient pollutant monitoring can characterize this relationship, especially when using continuous real-time monitoring. However, it is challenging to quantify local source contributions over background or to characterize spatial patterns across a neighborhood. The goal of this study is to evaluate contributions of traffic to neighborhood-scale air pollution using a combination of regression models derived from mobile UFP monitoring observations collected in Brooklyn, NY and outputs from the Quick Urban & Industrial Complex (QUIC) model. QUIC is a dispersion model that can explicitly take into account the three-dimensional shapes of buildings. The monitoring-based regression model characterized concentration gradients from a major elevated roadway, controlling for real-time traffic volume, meteorological variables, and other local sources. QUIC was applied to simulate dispersion from this same major roadway. The relative concentration decreases with distance from the roadway estimated by the monitoring-based regression model after removal of background and by QUIC were similar. Horizontal contour plots with both models demonstrated non-uniform patterns related to building configuration and source heights. We used the best-fit relationship between the monitoring-based regression model after removal of background and the QUIC outputs ( R2 = 0.80) to estimate a UFP emissions factor of 5.7 × 10 14 particles/vehicle-km, which was relatively consistent across key model assumptions. Our joint applications of novel techniques for analyzing mobile monitoring

  6. Low temperature high current ion beams and laminar flows

    NASA Astrophysics Data System (ADS)

    Cavenago, Marco

    2014-07-01

    Self-consistent Vlasov-Poisson equilibria for the extraction of ions with low temperature Ti are discussed, with comparison to the laminar flow case Ti = 0, in two dimensional diodes. Curvilinear coordinates aligned with laminar beam flow lines are extended to the low ion temperature case, with a reduced current density jd, expressed with cathode integrals. This generalizes one-dimensional interpolation between rays along the cathode coordinate to multidimensional integrations, including also the momentum components, so that jd is free from the granularity defect and noise, typical of standard ray tracing approach. A robust numerical solution procedure is developed, which allows studying current saturated extraction and drift tube effects. A discussion of particle initial conditions determines the emission angles and shows that temperature effect at beam edge is partly balanced by the focus electrode inclination. Results for a typical diode are described, with detail about normalized emittance, here taken strictly proportional to the x - px phase space area, for a beam with non uniform velocities. Contribution to the Topical Issue "Theory and Applications of the Vlasov Equation", edited by Francesco Pegoraro, Francesco Califano, Giovanni Manfredi and Philip J. Morrison.

  7. Magnetic particle imaging: advancements and perspectives for real-time in vivo monitoring and image-guided therapy

    NASA Astrophysics Data System (ADS)

    Pablico-Lansigan, Michele H.; Situ, Shu F.; Samia, Anna Cristina S.

    2013-05-01

    Magnetic particle imaging (MPI) is an emerging biomedical imaging technology that allows the direct quantitative mapping of the spatial distribution of superparamagnetic iron oxide nanoparticles. MPI's increased sensitivity and short image acquisition times foster the creation of tomographic images with high temporal and spatial resolution. The contrast and sensitivity of MPI is envisioned to transcend those of other medical imaging modalities presently used, such as magnetic resonance imaging (MRI), X-ray scans, ultrasound, computed tomography (CT), positron emission tomography (PET) and single photon emission computed tomography (SPECT). In this review, we present an overview of the recent advances in the rapidly developing field of MPI. We begin with a basic introduction of the fundamentals of MPI, followed by some highlights over the past decade of the evolution of strategies and approaches used to improve this new imaging technique. We also examine the optimization of iron oxide nanoparticle tracers used for imaging, underscoring the importance of size homogeneity and surface engineering. Finally, we present some future research directions for MPI, emphasizing the novel and exciting opportunities that it offers as an important tool for real-time in vivo monitoring. All these opportunities and capabilities that MPI presents are now seen as potential breakthrough innovations in timely disease diagnosis, implant monitoring, and image-guided therapeutics.

  8. Simulation of System Error Tolerances of a High Current Transport Experiment for Heavy-Ion Fusion

    NASA Astrophysics Data System (ADS)

    Lund, Steven M.; Bangerter, Roger O.; Freidman, Alex; Grote, Dave P.; Seidl, Peter A.

    2000-10-01

    A driver-scale, intense ion beam transport experiment (HCX) is being designed to test issues for Heavy Ion Fusion (HIF) [1]. Here we present detailed, Particle in Cell simulations of HCX to parametrically explore how various system errors can impact machine performance. The simulations are transverse and include the full 3D fields of the quadrupole focusing magnets, spreads in axial momentum, conducting pipe boundary conditions, etc. System imperfections such as applied focusing field errors (magnet strength, field nonlinearities, etc.), alignment errors (magnet offsets and rotations), beam envelope mismatches to the focusing lattice, induced beam image charges, and beam distribution errors (beam nonuniformities, collective modes, and other distortions) are all analyzed in turn and in combination. The influence of these errors on the degradation of beam quality (emittance growth), halo production, and loss of beam control are evaluated. Evaluations of practical machine apertures and centroid steering corrections that can mitigate particle loss and degradation of beam quality are carried out. 1. P.A. Seidl, L.E. Ahle, R.O. Bangerter, V.P. Karpenko, S.M. Lund, A Faltens, R.M. Franks, D.B. Shuman, and H.K. Springer, Design of a Proof of Principal High Current Transport Experiment for Heavy-Ion Fusion, these proceedings.

  9. Stretchable electronics for wearable and high-current applications

    NASA Astrophysics Data System (ADS)

    Hilbich, Daniel; Shannon, Lesley; Gray, Bonnie L.

    2016-04-01

    Advances in the development of novel materials and fabrication processes are resulting in an increased number of flexible and stretchable electronics applications. This evolving technology enables new devices that are not readily fabricated using traditional silicon processes, and has the potential to transform many industries, including personalized healthcare, consumer electronics, and communication. Fabrication of stretchable devices is typically achieved through the use of stretchable polymer-based conductors, or more rigid conductors, such as metals, with patterned geometries that can accommodate stretching. Although the application space for stretchable electronics is extensive, the practicality of these devices can be severely limited by power consumption and cost. Moreover, strict process flows can impede innovation that would otherwise enable new applications. In an effort to overcome these impediments, we present two modified approaches and applications based on a newly developed process for stretchable and flexible electronics fabrication. This includes the development of a metallization pattern stamping process allowing for 1) stretchable interconnects to be directly integrated with stretchable/wearable fabrics, and 2) a process variation enabling aligned multi-layer devices with integrated ferromagnetic nanocomposite polymer components enabling a fully-flexible electromagnetic microactuator for large-magnitude magnetic field generation. The wearable interconnects are measured, showing high conductivity, and can accommodate over 20% strain before experiencing conductive failure. The electromagnetic actuators have been fabricated and initial measurements show well-aligned, highly conductive, isolated metal layers. These two applications demonstrate the versatility of the newly developed process and suggest potential for its furthered use in stretchable electronics and MEMS applications.

  10. Studies in High Current Density Ion Sources for Heavy Ion FusionApplications

    SciTech Connect

    Chacon-Golcher, E.

    2002-06-01

    This dissertation develops diverse research on small (diameter {approx} few mm), high current density (J {approx} several tens of mA/cm{sup 2}) heavy ion sources. The research has been developed in the context of a programmatic interest within the Heavy Ion Fusion (HIF) Program to explore alternative architectures in the beam injection systems that use the merging of small, bright beams. An ion gun was designed and built for these experiments. Results of average current density yield () at different operating conditions are presented for K{sup +} and Cs{sup +} contact ionization sources and potassium aluminum silicate sources. Maximum values for a K{sup +} beam of {approx}90 mA/cm{sup 2} were observed in 2.3 {micro}s pulses. Measurements of beam intensity profiles and emittances are included. Measurements of neutral particle desorption are presented at different operating conditions which lead to a better understanding of the underlying atomic diffusion processes that determine the lifetime of the emitter. Estimates of diffusion times consistent with measurements are presented, as well as estimates of maximum repetition rates achievable. Diverse studies performed on the composition and preparation of alkali aluminosilicate ion sources are also presented. In addition, this work includes preliminary work carried out exploring the viability of an argon plasma ion source and a bismuth metal vapor vacuum arc (MEVVA) ion source. For the former ion source, fast rise-times ({approx} 1 {micro}s), high current densities ({approx} 100 mA/cm{sup 2}) and low operating pressures (< 2 mtorr) were verified. For the latter, high but acceptable levels of beam emittance were measured ({var_epsilon}{sub n} {le} 0.006 {pi} mm {center_dot} mrad) although measured currents differed from the desired ones (I {approx} 5mA) by about a factor of 10.

  11. RESULTS OF TESTS TO DEMONSTRATE A SIX-INCH DIAMETER COATER FOR PRODUCTION OF TRISO-COATED PARTICLES FOR ADVANCED GAS REACTOR EXPERIMENTS

    SciTech Connect

    Douglas W. Marshall

    2008-09-01

    The Next Generation Nuclear Plant (NGNP)/Advanced Gas Reactor (AGR) Fuel Development and Qualification Program includes a series of irradiation experiments in Idaho National Laboratory's (INL's) Advanced Test Reactor. TRISOcoated particles for the first AGR experiment, AGR-1, were produced at Oak Ridge National Laboratory (ORNL) in a twoinch diameter coater. A requirement of the NGNP/AGR Program is to produce coated particles for later experiments in coaters more representative of industrial scale. Toward this end, tests have been performed by Babcock and Wilcox (B&W) in a six-inch diameter coater. These tests are expected to lead to successful fabrication of particles for the second AGR experiment, AGR-2. While a thorough study of how coating parameters affect particle properties was not the goal of these tests, the test data obtained provides insight into process parameter/coated particle property relationships. Most relationships for the six-inch diameter coater followed trends found with the ORNL two-inch coater, in spite of differences in coater design and bed hydrodynamics. For example the key coating parameters affecting pyrocarbon anisotropy were coater temperature, coating gas fraction, total gas flow rate and kernel charge size. Anisotropy of the outer pyrolytic carbon (OPyC) layer also strongly correlates with coater differential pressure. In an effort to reduce the total particle fabrication run time, silicon carbide (SiC) was deposited with methyltrichlorosilane (MTS) concentrations up to 3 mol %. Using only hydrogen as the fluidizing gas, the high concentration MTS tests resulted in particles with lower than desired SiC densities. However when hydrogen was partially replaced with argon, high SiC densities were achieved with the high MTS gas fraction.

  12. RESULTS OF TESTS TO DEMONSTRATE A SIX-INCH-DIAMETER COATER FOR PRODUCTION OF TRISO-COATED PARTICLES FOR ADVANCED GAS REACTOR EXPERIMENTS

    SciTech Connect

    Charles M Barnes

    2008-09-01

    The Next Generation Nuclear Plant (NGNP)/Advanced Gas Reactor (AGR) Fuel Development and Qualification Program includes a series of irradiation experiments in Idaho National Laboratory’s (INL’s) Advanced Test Reactor. TRISOcoated particles for the first AGR experiment, AGR-1, were produced at Oak Ridge National Laboratory (ORNL) in a two inch diameter coater. A requirement of the NGNP/AGR Program is to produce coated particles for later experiments in coaters more representative of industrial scale. Toward this end, tests have been performed by Babcock and Wilcox (B&W) in a six-inch diameter coater. These tests are expected to lead to successful fabrication of particles for the second AGR experiment, AGR-2. While a thorough study of how coating parameters affect particle properties was not the goal of these tests, the test data obtained provides insight into process parameter/coated particle property relationships. Most relationships for the six-inch diameter coater followed trends found with the ORNL two-inch coater, in spite of differences in coater design and bed hydrodynamics. For example the key coating parameters affecting pyrocarbon anisotropy were coater temperature, coating gas fraction, total gas flow rate and kernel charge size. Anisotropy of the outer pyrolytic carbon (OPyC) layer also strongly correlates with coater differential pressure. In an effort to reduce the total particle fabrication run time, silicon carbide (SiC) was deposited with methyltrichlorosilane (MTS) concentrations up to 3 mol %. Using only hydrogen as the fluidizing gas, the high concentration MTS tests resulted in particles with lower than desired SiC densities. However when hydrogen was partially replaced with argon, high SiC densities were achieved with the high MTS gas fraction.

  13. Recent advances in particle and droplet manipulation for lab-on-a-chip devices based on surface acoustic waves.

    PubMed

    Wang, Zhuochen; Zhe, Jiang

    2011-04-01

    Manipulation of microscale particles and fluid liquid droplets is an important task for lab-on-a-chip devices for numerous biological researches and applications, such as cell detection and tissue engineering. Particle manipulation techniques based on surface acoustic waves (SAWs) appear effective for lab-on-a-chip devices because they are non-invasive, compatible with soft lithography micromachining, have high energy density, and work for nearly any type of microscale particles. Here we review the most recent research and development of the past two years in SAW based particle and liquid droplet manipulation for lab-on-a-chip devices including particle focusing and separation, particle alignment and patterning, particle directing, and liquid droplet delivery.

  14. Experimental study of a high-current FEM with a broadband microwave system

    SciTech Connect

    Denisov, G.G.; Bratman, V.L.; Ginzburg, N.S.

    1995-12-31

    One of the main features of FELs and FEMs is the possibility of fast and wideband tuning of the resonant frequency of active media, which can be provided by changing the particle energy. For a frequency adjustable FEM-oscillator, a broadband microwave system, which is simply combined with an electron-optical FEM system and consists of an oversized waveguide and reflectors based on the microwave beams multiplication effect has been proposed and studied successfully in {open_quotes}cold{close_quotes} measurements. Here, the operating ability of a cavity, that includes some key elements of the broadband microwave system, was tested in the presence of an electron beam. To provide large particle oscillation velocities in a moderate undulator field and the presence of a guide magnetic field, the FEM operating regime of double resonance was chosen. In this regime the cyclotron as well as undulator resonance conditions were satisfied. The FEM-oscillator was investigated experimentally on a high-current accelerator {open_quotes}Sinus-6{close_quotes} that forms an electron beam with particle energy 500keV and pulse duration 25ns. The aperture with a diameter 2.5mm at the center of the anode allows to pass through only the central fraction of the electron beam with a current about 100A and a small spread of longitudinal velocities of the particles. Operating transverse velocity was pumped into the electron beam in the pulse plane undulator of a 2.4cm period. The cavity with a frequency near 45GHz consists of a square waveguide and two reflectors. The broadband up-stream reflector based on the multiplication effect had the power reflectivity coefficient more than 90% in the frequency band 10% for the H{sup 10} wave of the square waveguide with the maximum about 100% at a frequency 45GHz. The down-stream narrow-band Bragg reflector had the power reflection coefficient approximately 80% in the frequency band of 4% near 45GHz for the operating mode.

  15. Simulative research on the expansion of cathode plasma in high-current electron beam diode

    SciTech Connect

    Xu Qifu; Liu Lie

    2012-09-15

    The expansion of cathode plasma has long been recognized as a limiting factor in the impedance lifetime of high-current electron beam diode. Realistic modeling of such plasma is of great necessity in order to discuss the dynamics of cathode plasma. Using the method of particle-in-cell, the expansion of cathode plasma is simulated in this paper by a scaled-down diode model. It is found that the formation of cathode plasma increases the current density in the diode. This consequently leads to the decrease of the potential at plasma front. Once the current density has been increased to a certain value, the potential at plasma front would then be equal to or lower than the plasma potential. Then the ions would move towards the anode, and the expansion of cathode plasma is thereby formed. Different factors affecting the plasma expansion velocity are discussed in this paper. It is shown that the decrease of proton genatation rate has the benefit of reducing the plasma expansion velocity.

  16. Investigation of various equations of state for high current, pulsed power load modeling

    NASA Astrophysics Data System (ADS)

    Luginsland, John; Parkinson, Roland; Rigby, Fred; Toepfer, Alan

    2002-08-01

    A number of technologies utilize the increasing availability of modern pulsed power systems to produce high currents to resistively drive solid, metallic loads into the plasma state. Examples include ablation plasma deposition, circuit breakers, fuses, exploding and imploding wires, and high velocity jet disruption. One important feature in any computational model of these phenomena is the equation of state (EOS). The equations of state used in these models are typically as varied as the range of applications. In this work, using a segmented wire experiment performed at the Army Research Laboratory [1] as a benchmark, we investigate three equations of state [2-4]. We assess the merits of the EOS for both their physical accuracy and easy of use computationally. Finally, we comment on the availability of the information necessary to build the EOS, given the wide variety of materials that are used in this applied field. [1] C.E. Hollandsworth et al., J. Appl. Phys., vol. 84, no. 9, 4992-5000, 1998. [2] SESAME tables, LANL T-1 Division, Equation of State and Strength of Materials. [3] Zhukov, Demidov, and Ryabenko, Fiz. Metal. Metalloved., vol. 57, no. 2, 224-229, 1984. [4] Chittenden et al., Laser and Particle Beams, vol. 19, issue 3, 323-343, 2001, and references therein.

  17. High-Current Gain Two-Dimensional MoS₂-Base Hot-Electron Transistors.

    PubMed

    Torres, Carlos M; Lan, Yann-Wen; Zeng, Caifu; Chen, Jyun-Hong; Kou, Xufeng; Navabi, Aryan; Tang, Jianshi; Montazeri, Mohammad; Adleman, James R; Lerner, Mitchell B; Zhong, Yuan-Liang; Li, Lain-Jong; Chen, Chii-Dong; Wang, Kang L

    2015-12-01

    The vertical transport of nonequilibrium charge carriers through semiconductor heterostructures has led to milestones in electronics with the development of the hot-electron transistor. Recently, significant advances have been made with atomically sharp heterostructures implementing various two-dimensional materials. Although graphene-base hot-electron transistors show great promise for electronic switching at high frequencies, they are limited by their low current gain. Here we show that, by choosing MoS2 and HfO2 for the filter barrier interface and using a noncrystalline semiconductor such as ITO for the collector, we can achieve an unprecedentedly high-current gain (α ∼ 0.95) in our hot-electron transistors operating at room temperature. Furthermore, the current gain can be tuned over 2 orders of magnitude with the collector-base voltage albeit this feature currently presents a drawback in the transistor performance metrics such as poor output resistance and poor intrinsic voltage gain. We anticipate our transistors will pave the way toward the realization of novel flexible 2D material-based high-density, low-energy, and high-frequency hot-carrier electronic applications. PMID:26524388

  18. High Current Density, Long Life Cathodes for High Power RF Sources

    SciTech Connect

    Ives, Robert Lawrence; Collins, George; Falce, Lou; Schwartzkopf, Steve; Busbaher, Daniel

    2014-01-22

    This program was tasked with improving the quality and expanding applications for Controlled Porosity Reservoir (CPR) cathodes. Calabazas Creek Research, Inc. (CCR) initially developed CPR cathodes on a DOE-funded SBIR program to improve cathodes for magnetron injection guns. Subsequent funding was received from the Defense Advanced Research Projects Agency. The program developed design requirements for implementation of the technology into high current density cathodes for high frequency applications. During Phase I of this program, CCR was awarded the prestigious 2011 R&D100 award for this technology. Subsequently, the technology was presented at numerous technical conferences. A patent was issued for the technology in 2009. These cathodes are now marketed by Semicon Associates, Inc. in Lexington, KY. They are the world’s largest producer of cathodes for vacuum electron devices. During this program, CCR teamed with Semicon Associates, Inc. and Ron Witherspoon, Inc. to improve the fabrication processes and expand applications for the cathodes. Specific fabrications issues included the quality of the wire winding that provides the basic structure and the sintering to bond the wires into a robust, cohesive structure. The program also developed improved techniques for integrating the resulting material into cathodes for electron guns.

  19. Microstructural analysis of mass transport phenomena in gas diffusion media for high current density operation in PEM fuel cells

    NASA Astrophysics Data System (ADS)

    Kotaka, Toshikazu; Tabuchi, Yuichiro; Mukherjee, Partha P.

    2015-04-01

    Cost reduction is a key issue for commercialization of fuel cell electric vehicles (FCEV). High current density operation is a solution pathway. In order to realize high current density operation, it is necessary to reduce mass transport resistance in the gas diffusion media commonly consisted of gas diffusion layer (GDL) and micro porous layer (MPL). However, fundamental understanding of the underlying mass transport phenomena in the porous components is not only critical but also not fully understood yet due to the inherent microstructural complexity. In this study, a comprehensive analysis of electron and oxygen transport in the GDL and MPL is conducted experimentally and numerically with three-dimensional (3D) microstructural data to reveal the structure-transport relationship. The results reveal that the mass transport in the GDL is strongly dependent on the local microstructural variations, such as local pore/solid volume fractions and connectivity. However, especially in the case of the electrical conductivity of MPL, the contact resistance between carbon particles is the dominant factor. This suggests that reducing the contact resistance between carbon particles and/or the number of contact points along the transport pathway can improve the electrical conductivity of MPL.

  20. Advances in measurements and simulation of gas-particle flows and coal combustion in burners/combustors

    NASA Astrophysics Data System (ADS)

    Zhou, L. X.

    2009-02-01

    Innovative coal combustors were developed, and measurement and simulation of gas-particle flows and coal combustion in such combustors were done in the Department of Engineering Mechanics, Tsinghua University. LDV/PDPA measurements are made to understand the behavior of turbulent gas-particle flows in coal combustors. Coal combustion test was done for the non-slagging cyclone coal combustor. The full two-fluid model developed by the present author was used to simulate turbulent gas-particle flows, coal combustion and NOx formation. It is found by measurements and simulation that the optimum design can give large-size recirculation zones for improving the combustion performance for all the combustors. The combustion test shows that the nonslagging coal combustor can burn 3-5mm coal particles with good combustion efficiency and low NO emission. Simulation in comparison with experiments indicates that the swirl number can significantly affect the NO formation in the swirl coal combustor.

  1. PREFACE: Advanced Science Research Symposium 2009 Positron, Muon and other exotic particle beams for materials and atomic/molecular sciences (ASR2009)

    NASA Astrophysics Data System (ADS)

    Higemoto, Wataru; Kawasuso, Atsuo

    2010-05-01

    It is our great pleasure to deliver the proceedings of ASR2009, the Advanced Science Research International Symposium 2009. ASR2009 is part of a series of symposia which is hosted by the Japan Atomic Energy Agency, Advanced Science Research Center (JAEA-ASRC), and held every year with different scientific topics. ASR2009 was held at Tokai in Japan from 10-12 November 2009. In total, 102 participants, including 29 overseas scientists, made 44 oral presentations and 64 poster presentations. In ASR2009 we have focused on material and atomic/molecular science research using positrons, muons and other exotic particle beams. The symposium covered all the fields of materials science which use such exotic particle beams. Positrons, muons and other beams have similar and different features. For example, although positrons and muons are both leptons having charge and spin, they give quite different information about materials. A muon mainly detects the local magnetic state of the solid, while a positron detects crystal imperfections and electron momenta in solids. Other exotic particle beams also provide useful information about materials which is not able to be obtained with muons or positrons. Therefore, the complementary use of particle beams, coupled with an understanding of their relative advantages, leads to greater excellence in materials research. This symposium crossed the fields of muon science, positron science, unstable-nuclei science, and other exotic particle-beam science. We therefore believe that ASR2009 became an especially important meeting for finding new science with exotic particle beams. Finally, we would like to extend our appreciation to all the participants, committee members, and support staff for their great efforts to make ASR2009 a fruitful symposium. ASR2009 Chairs Wataru Higemoto and Atsuo Kawasuso Advanced Science Research Center, Japan Atomic Energy Agency Organizing committee Y Hatano, JAEA (Director of ASRC) M Fujinami, Chiba Univ. R H

  2. Particle Beam Radiography

    NASA Astrophysics Data System (ADS)

    Peach, Ken; Ekdahl, Carl

    2014-02-01

    Particle beam radiography, which uses a variety of particle probes (neutrons, protons, electrons, gammas and potentially other particles) to study the structure of materials and objects noninvasively, is reviewed, largely from an accelerator perspective, although the use of cosmic rays (mainly muons but potentially also high-energy neutrinos) is briefly reviewed. Tomography is a form of radiography which uses multiple views to reconstruct a three-dimensional density map of an object. There is a very wide range of applications of radiography and tomography, from medicine to engineering and security, and advances in instrumentation, specifically the development of electronic detectors, allow rapid analysis of the resultant radiographs. Flash radiography is a diagnostic technique for large high-explosive-driven hydrodynamic experiments that is used at many laboratories. The bremsstrahlung radiation pulse from an intense relativistic electron beam incident onto a high-Z target is the source of these radiographs. The challenge is to provide radiation sources intense enough to penetrate hundreds of g/cm2 of material, in pulses short enough to stop the motion of high-speed hydrodynamic shocks, and with source spots small enough to resolve fine details. The challenge has been met with a wide variety of accelerator technologies, including pulsed-power-driven diodes, air-core pulsed betatrons and high-current linear induction accelerators. Accelerator technology has also evolved to accommodate the experimenters' continuing quest for multiple images in time and space. Linear induction accelerators have had a major role in these advances, especially in providing multiple-time radiographs of the largest hydrodynamic experiments.

  3. Advances in the simulation and automated measurement of well-sorted granular material: 2. Direct measures of particle properties

    USGS Publications Warehouse

    Buscombe, Daniel D.; Rubin, David M.

    2012-01-01

    1. In this, the second of a pair of papers on the structure of well-sorted natural granular material (sediment), new methods are described for automated measurements from images of sediment, of: 1) particle-size standard deviation (arithmetic sorting) with and without apparent void fraction; and 2) mean particle size in material with void fraction. A variety of simulations of granular material are used for testing purposes, in addition to images of natural sediment. Simulations are also used to establish that the effects on automated particle sizing of grains visible through the interstices of the grains at the very surface of a granular material continue to a depth of approximately 4 grain diameters and that this is independent of mean particle size. Ensemble root-mean squared error between observed and estimated arithmetic sorting coefficients for 262 images of natural silts, sands and gravels (drawn from 8 populations) is 31%, which reduces to 27% if adjusted for bias (slope correction between observed and estimated values). These methods allow non-intrusive and fully automated measurements of surfaces of unconsolidated granular material. With no tunable parameters or empirically derived coefficients, they should be broadly universal in appropriate applications. However, empirical corrections may need to be applied for the most accurate results. Finally, analytical formulas are derived for the one-step pore-particle transition probability matrix, estimated from the image's autocorrelogram, from which void fraction of a section of granular material can be estimated directly. This model gives excellent predictions of bulk void fraction yet imperfect predictions of pore-particle transitions.

  4. Bowl-like SnO2 @carbon hollow particles as an advanced anode material for lithium-ion batteries.

    PubMed

    Liang, Jin; Yu, Xin-Yao; Zhou, Han; Wu, Hao Bin; Ding, Shujiang; Lou, Xiong Wen David

    2014-11-17

    Despite the great advantages of hollow structures as electrodes for lithium-ion batteries, one apparent common drawback which is often criticized is their compromised volumetric energy density due to the introduced hollow interior. Here, we design and synthesize bowl-like SnO2 @carbon hollow particles to reduce the excessive hollow interior space while retaining the general advantages of hollow structures. As a result, the tap density can be increased about 30 %. The as-prepared bowl-like SnO2 @carbon hollow particles with conformal carbon support exhibit excellent lithium storage properties in terms of high capacity, stable cyclability and excellent rate capability.

  5. Advances in understanding the genesis and evolution solar energetic particle events over the last two solar cycles

    NASA Astrophysics Data System (ADS)

    Vainio, Rami

    2016-04-01

    I will review the observational and modeling efforts related to solar energetic particle (SEP) events over the 23rd and 24th solar cycles. I will concentrate on large SEP events related to coronal mass ejections (CMEs), but discuss observations related to the possible role of flares in the acceleration of particles in those events, as well. The possible roles of various acceleration and transport processes in understanding the characteristics of the events will be discussed. This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324 (HESPERIA).

  6. Bowl-like SnO2 @carbon hollow particles as an advanced anode material for lithium-ion batteries.

    PubMed

    Liang, Jin; Yu, Xin-Yao; Zhou, Han; Wu, Hao Bin; Ding, Shujiang; Lou, Xiong Wen David

    2014-11-17

    Despite the great advantages of hollow structures as electrodes for lithium-ion batteries, one apparent common drawback which is often criticized is their compromised volumetric energy density due to the introduced hollow interior. Here, we design and synthesize bowl-like SnO2 @carbon hollow particles to reduce the excessive hollow interior space while retaining the general advantages of hollow structures. As a result, the tap density can be increased about 30 %. The as-prepared bowl-like SnO2 @carbon hollow particles with conformal carbon support exhibit excellent lithium storage properties in terms of high capacity, stable cyclability and excellent rate capability. PMID:25251871

  7. Advanced Petroleum-Based Fuels - Diesel Emissions Project (APBF-DEC): 2,000-Hour Performance of a NOx Adsorber Catalyst and Diesel Particle Filter System for a Medium-Duty, Pick-Up Diesel Engine Platform; Final Report

    SciTech Connect

    Not Available

    2007-03-01

    Presents the results of a 2,000-hour test of an emissions control system consisting of a nitrogen oxides adsorber catalyst in combination with a diesel particle filter, advanced fuels, and advanced engine controls in an SUV/pick-up truck vehicle platform.

  8. Characterization and control of wafer charging effects during high-current ion implantation

    SciTech Connect

    Current, M.I.; Lukaszek, W.; Dixon, W.; Vella, M.C.; Messick, C.; Shideler, J.; Reno, S.

    1994-02-01

    EEPROM-based sense and memory devices provide direct measures of the charge flow and potentials occurring on the surface of wafers during ion beam processing. Sensor design and applications for high current ion implantation are discussed.

  9. Delivery of Differentiation Factors by Mesoporous Silica Particles Assists Advanced Differentiation of Transplanted Murine Embryonic Stem Cells

    PubMed Central

    Kozhevnikova, Mariya; König, Niclas; Zhou, Chunfang; Leao, Richardson; Knöpfel, Thomas; Pankratova, Stanislava; Trolle, Carl; Berezin, Vladimir; Bock, Elisabeth; Aldskogius, Håkan

    2013-01-01

    Stem cell transplantation holds great hope for the replacement of damaged cells in the nervous system. However, poor long-term survival after transplantation and insufficiently robust differentiation of stem cells into specialized cell types in vivo remain major obstacles for clinical application. Here, we report the development of a novel technological approach for the local delivery of exogenous trophic factor mimetics to transplanted cells using specifically designed silica nanoporous particles. We demonstrated that delivering Cintrofin and Gliafin, established peptide mimetics of the ciliary neurotrophic factor and glial cell line-derived neurotrophic factor, respectively, with these particles enabled not only robust functional differentiation of motor neurons from transplanted embryonic stem cells but also their long-term survival in vivo. We propose that the delivery of growth factors by mesoporous nanoparticles is a potentially versatile and widely applicable strategy for efficient differentiation and functional integration of stem cell derivatives upon transplantation. PMID:24089415

  10. New Insights Into the Surface / Atmosphere Exchange of Particles Based on Recent Advances in Measurement Technology (Invited)

    NASA Astrophysics Data System (ADS)

    Nemitz, E.; Phillips, G. J.; Thomas, R.; di Marco, C. F.; Fowler, D.

    2009-12-01

    Dry deposition velocities of particles govern the deposition and atmospheric lifetime of aerosols and their constituents and need to be parameterised in chemical transport models to predict air quality, climate change and ecosystem impacts. The same micrometeorological flux measurement approaches used to measure deposition rates can be used to quantify emissions from area sources such as urban emissions and resuspension. This paper reviews recent measurements of fluxes of particle number and, importantly, individual aerosol chemical compounds, made with wet-chemistry gradient systems and eddy-covariance using aerosol mass spectrometry. The results indicate that aerosol exchange tends to be bi-directional and is modulated by particle dynamics due to evaporation and condensation growth. Often, some aerosol components are emitted or chemically formed below the measurement height, while other components deposit or evaporate. This has important implications on the use of field measurements of number fluxes for the development of model parameterisations. For example, measurements over a range of surfaces show that ammonium nitrate volatilises during the deposition to semi-natural vegetation, forming associated gaseous precursors, which deposit faster than the aerosol species. This evaporation therefore enhances total nitrogen deposition, and models need to use enhanced effective deposition rates to account for the effect. Conversely, the effect of particle dynamics on fluxes can be used to study aerosol processing, such as the in-situ formation of inorganic and organic secondary aerosol and the volatilisation of primary combustion aerosol. Examples will be shown from agricultural, natural and urban environments. Finally, the paper will discuss future research priorities to help improve parameterisations of dry deposition velocities further.

  11. Mixed sulfur-iron particles packed reactor for simultaneous advanced removal of nitrogen and phosphorus from secondary effluent.

    PubMed

    Wang, Shenghui; Liang, Peng; Wu, Zhongqin; Su, Fengfeng; Yuan, Lulu; Sun, Yanmei; Wu, Qing; Huang, Xia

    2015-01-01

    A mixed sulfur-iron particles packed reactor (SFe reactor) was developed to simultaneously remove total nitrogen (TN) and total phosphorus (TP) of the secondary effluent from municipal wastewater treatment plants. Low effluent TN (<1.5 mg/L) and TP (<0.3 mg/L) concentrations were simultaneously obtained, and high TN removal rate [1.03 g N/(L·d)] and TP removal rate [0.29 g P/(L·d)] were achieved at the hydraulic retention time (HRT) of 0.13 h. Kinetic models describing denitrification were experimentally obtained, which predicted a higher denitrification rate [1.98 g N/(L·d)] of SFe reactor than that [1.58 g N/(L·d)] of sulfur alone packed reactor due to the mutual enhancement between sulfur-based autotrophic denitrification and iron-based chemical denitrification. A high TP removal obtained in SFe reactor was attributed to chemical precipitation of iron particles. Microbial community analysis based on 16S rRNA revealed that autotrophic denitrifying bacteria Thiobacillus and Sulfuricella were the dominant genus, indicating that autotrophic denitrification played important role in nitrate removal. These results indicate that sulfur and iron particles can be packed together in a single reactor to effectively remove nitrate and phosphorus.

  12. Airborne Particles: What We Have Learned About Their Role in Climate from Remote Sensing, and Prospects for Future Advances

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.

    2013-01-01

    Desert dust, wildfire smoke, volcanic ash, biogenic and urban pollution particles, all affect the regional-scale climate of Earth in places and at times; some have global-scale impacts on the column radiation balance, cloud properties, atmospheric stability structure, and circulation patterns. Remote sensing has played a central role in identifying the sources and transports of airborne particles, mapping their three-dimensional distribution and variability, quantifying their amount, and constraining aerosol air mass type. The measurements obtained from remote sensing have strengths and limitations, and their value for characterizing Earths environment is enhanced immensely when they are combined with direct, in situ observations, and used to constrain aerosol transport and climate models. A similar approach has been taken to study the role particles play in determining the climate of Mars, though based on far fewer observations. This presentation will focus what we have learned from remote sensing about the impacts aerosol have on Earths climate; a few points about how aerosols affect the climate of Mars will also be introduced, in the context of how we might assess aerosol-climate impacts more generally on other worlds.

  13. Advanced zirconia-coated carbonyl-iron particles for acidic magnetorheological finishing of chemical-vapor-deposited ZnS and other IR materials

    NASA Astrophysics Data System (ADS)

    Salzman, S.; Giannechini, L. J.; Romanofsky, H. J.; Golini, N.; Taylor, B.; Jacobs, S. D.; Lambropoulos, J. C.

    2015-10-01

    We present a modified version of zirconia-coated carbonyl-iron (CI) particles that were invented at the University of Rochester in 2008. The amount of zirconia on the coating is increased to further protect the iron particles from corrosion when introduced to an acidic environment. Five low-pH, magnetorheological (MR) fluids were made with five acids: acetic, hydrochloric, nitric, phosphoric, and hydrofluoric. All fluids were based on the modified zirconia-coated CI particles. Off-line viscosity and pH stability were measured for all acidic MR fluids to determine the ideal fluid composition for acidic MR finishing of chemical-vapor-deposited (CVD) zinc sulfide (ZnS) and other infrared (IR) optical materials, such as hot-isostatic-pressed (HIP) ZnS, CVD zinc selenide (ZnSe), and magnesium fluoride (MgF2). Results show significant reduction in surface artifacts (millimeter-size, pebble-like structures on the finished surface) for several standard-grade CVD ZnS substrates and good surface roughness for the non-CVD MgF2 substrate when MR finished with our advanced acidic MR fluid.

  14. On the performance of the HVE high-current light-ion 3 MV Tandetron™ accelerator system

    NASA Astrophysics Data System (ADS)

    Podaru, Nicolae C.; Gottdang, A.; Mous, D. J. W.; Frena Group

    2012-02-01

    High Voltage Engineering has successfully completed the factory tests of a 3 MV Tandetron™ based accelerator system, fulfilling the rigorous requirements of the Facility for Research in Experimental Nuclear Astrophysics, part of the Saha Institute of Nuclear Physics, Kolkata, India. To satisfy requirements, High Voltage Engineering has developed a unique high-current light-ion injector. The injector includes two multicusp ion sources, one for H - and one for He +, and a Na charge exchange canal. Extensive measurements yield routine production of about 70 μA analyzed He - and 1 mA H -. The Tandetron™ designed and tested at 3 kW of beam power features low ripple (27 V RMS at 3 MV), a particle transmission of at least 60% over the entire terminal voltage range, 200 kV up to 3 MV. In addition, the dual slit stabilization system ensures long term terminal voltage stability, ±30 V per hour at 3 MV.

  15. Analysis of uranium-zirconium-carbon-oxygen quaternary system for applications in advanced zirconium carbide coated TRISO particles

    NASA Astrophysics Data System (ADS)

    Degange, Jonathan Lee

    The implementation of ZrC for use in oxide TRISO particles for Very High Temperature Reactor (VHTR) conditions to prevent kernel overpressurization and kernel migration has been proposed by several researchers. Analysis is performed incorporating first-principles thermodynamics along with out-of-pile experimental work. UO2+x-U4O9 powders are created and used for in-vacuo thermogravimetric testing with both carbon and zirconium carbide powders to evaluate the efficiency of ZrC for usage as an oxygen getter in oxide TRISO fuels.

  16. Advances in colloid and biocolloid transport in porous media: particle size-dependent dispersivity and gravity effects

    NASA Astrophysics Data System (ADS)

    Chrysikopoulos, Constantinos V.; Manariotis, Ioannis D.; Syngouna, Vasiliki I.

    2014-05-01

    Accurate prediction of colloid and biocolloid transport in porous media relies heavily on usage of suitable dispersion coefficients. The widespread procedure for dispersion coefficient determination consists of conducting conservative tracer experiments and subsequently fitting the collected breakthrough data with a selected advection-dispersion transport model. The fitted dispersion coefficient is assumed to characterize the porous medium and is often used thereafter to analyze experimental results obtained from the same porous medium with other solutes, colloids, and biocolloids. The classical advection-dispersion equation implies that Fick's first law of diffusion adequately describes the dispersion process, or that the dispersive flux is proportional to the concentration gradient. Therefore, the above-described procedure inherently assumes that the dispersive flux of all solutes, colloids and biocolloids under the same flow field conditions is exactly the same. Furthermore, the available mathematical models for colloid and biocoloid transport in porous media do not adequately account for gravity effects. Here an extensive laboratory study was undertaken in order to assess whether the dispersivity, which traditionally has been considered to be a property of the porous medium, is dependent on colloid particle size, interstitial velocity and length scale. The breakthrough curves were successfully simulated with a mathematical model describing colloid and biocolloid transport in homogeneous, water saturated porous media. The results demonstrated that the dispersivity increases very slowly with increasing interstitial velocity, and increases with column length. Furthermore, contrary to earlier results, which were based either on just a few experimental observations or experimental conditions leading to low mass recoveries, dispersivity was positively correlated with colloid particle size. Also, transport experiments were performed with biocolloids (bacteriophages:

  17. [Advances in Understanding Carcinogenetic Mechanisms of the Human Papillomavirus and Vaccines Based on Virus-like Particles].

    PubMed

    Zhao, Zhihong; Wang, Lili; Ma, Bo

    2015-03-01

    Prevention of infection by the human papillomavirus (HPV) has become a hot research topic since the relationship between the HPV and cervical cancer was confirmed. Persistent infection with HPV and early expression of proteins has an important role in the pathogenesis of cervical cancer. Vaccines that protect against four high-risk types of HPV (-6, -11, -16, -18) have been used worldwide. A bivalent vaccine (HPV-16 and -18) developed by Walvax is in clinical trials. This study reviews progress in ascertainment of the structure and function of the HPV genome, the molecular mechanism of carcinogenesis, and vaccines based on virus-like particles.

  18. SRRC/ANL high current l-band single cell photocathode rf gun.

    SciTech Connect

    Ho, C. H.

    1998-07-16

    A high current L-band photocathode rf gun is under development at SRRC (Synchrotron Radiation Research Center, Taiwan) in collaboration with ANL (Argonne National Laboratory, USA). The goal is to produce up to 100 nC charge with the surface field gradient of over 90 MV/m at the center of the photocathode. In this report, they present the detailed design and initial test results. If successful, this gun will be used as the future AWA (Argonne Wakefield Accelerator)[1] high current gun.

  19. Graphene electron cannon: High-current edge emission from aligned graphene sheets

    SciTech Connect

    Liu, Jianlong; Li, Nannan; Guo, Jing; Fang, Yong; Deng, Jiang; Zeng, Baoqing; Wang, Wenzhong; Li, Jiangnan; Hao, Chenchun

    2014-01-13

    High-current field emitters are made by graphene paper consist of aligned graphene sheets. Field emission luminance pattern shows that their electron beams can be controlled by rolling the graphene paper from sheet to cylinder. These specific electron beams would be useful to vacuum devices and electron beam lithograph. To get high-current emission, the graphene paper is rolled to array and form graphene cannon. Due to aligned emission array, graphene cannon have high emission current. Besides high emission current, the graphene cannon is also tolerable with excellent emission stability. With good field emission properties, these aligned graphene emitters bring application insight.

  20. Advanced electron microscopic techniques applied to the characterization of irradiation effects and fission product identification of irradiated TRISO coated particles from the AGR-1 experiment

    SciTech Connect

    Rooyen, I.J. van; Lillo, T.M.; Trowbridge, T.L.; Madden, J.M.; Wu, Y.Q.; Goran, D.

    2013-07-01

    Preliminary electron microscopy of coated fuel particles from the AGR-1 experiment was conducted using characterization techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and wavelength dispersive spectroscopy (WDS). Microscopic quantification of fission-product precipitates was performed. Although numerous micro- and nano-sized precipitates observed in the coating layers during initial SEM characterization of the cross-sections, and in subsequent TEM diffraction patterns, were indexed as UPd{sub 2}Si{sub 2}, no Ag was conclusively found. Additionally, characterization of these precipitates highlighted the difficulty of measuring low concentrations of Ag in precipitates in the presence of significantly higher concentrations of Pd and U. The electron microscopy team followed a multi-directional and phased approach in the identification of fission products in irradiated TRISO fuel. The advanced electron microscopy techniques discussed in this paper, not only demonstrate the usefulness of the equipment (methods) as relevant research tools, but also provide relevant scientific results which increase the knowledge about TRISO fuel particles microstructure and fission products transport.

  1. Study of recovery phenomena in a high-current pulse-triggered vacuum switch

    SciTech Connect

    Bauville, G.; Delmas, A.; Haddad, N.; Rioux, C. , Batiment 214, 91405 Orsay )

    1989-10-01

    This paper relates to the recovery capacities of a triggered vacuum switch after the crossing of a 25-{mu}s high-current pulse. The recovery time is less than 100 {mu}s. The authors experiment with several electrodes with different gaps, and study the influence of an axial magnetic field on the switch.

  2. Development and characterization of diamond film and compound metal surface high current photocathodes

    SciTech Connect

    Shurter, R.P.; Moir, D.C.; Devlin, D.J.; Springer, R.W.; Archuleta, T.A.

    1997-09-01

    High current photocathodes operating in vacuum environments as high as 8xE-5 torr are being developed at Los Alamos for use in a new generation of linear induction accelerators. We report quantum efficiencies in wide bandgap semiconductors, pure metals, and compound metal surfaces photocathode materials illuminated by ultraviolet laser radiation.

  3. An annular high-current electron beam with an energy spread in a coaxial magnetically insulated diode

    SciTech Connect

    Grishkov, A. A. Pegel, I. V.

    2013-11-15

    An elementary theory of an annular high-current electron beam in a uniform transport channel and a coaxial magnetically insulated diode is generalized to the case of counterpropagating electron beams with a spread over kinetic energies. Expressions for the sum of the absolute values of the forward and backward currents in a uniform transport channel and for the flux of the longitudinal component of the generalized momentum in a coaxial magnetically insulated diode as functions of the maximum electron kinetic energy are derived for different values of the relative width of the energy distribution function. It is shown that, in a diode with an expanding transport channel and a virtual cathode limiting the extracted current, counterpropagating particle flows are established between the cathode and the virtual cathode within a certain time interval after the beginning of electron emission. The accumulation of electrons in these flows is accompanied by an increase in their spread over kinetic energies and the simultaneous decrease in the maximum kinetic energy. The developed model agrees with the results of particle-in-cell simulations performed using the KARAT and OOPIC-Pro codes.

  4. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

    SciTech Connect

    Hirano, Y. E-mail: hirano.yoichi@phys.cst.nihon-u.ac.jp; Kiyama, S.; Koguchi, H.; Fujiwara, Y.; Sakakita, H.

    2015-11-15

    A high current density (≈3 mA/cm{sup 2}) hydrogen ion beam source operating in an extremely low-energy region (E{sub ib} ≈ 150–200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E{sub ib} is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

  5. High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region.

    PubMed

    Hirano, Y; Kiyama, S; Fujiwara, Y; Koguchi, H; Sakakita, H

    2015-11-01

    A high current density (≈3 mA/cm(2)) hydrogen ion beam source operating in an extremely low-energy region (E(ib) ≈ 150-200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E(ib) is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

  6. Advanced spray-dried design, physicochemical characterization, and aerosol dispersion performance of vancomycin and clarithromycin multifunctional controlled release particles for targeted respiratory delivery as dry powder inhalation aerosols.

    PubMed

    Park, Chun-Woong; Li, Xiaojian; Vogt, Frederick G; Hayes, Don; Zwischenberger, Joseph B; Park, Eun-Seok; Mansour, Heidi M

    2013-10-15

    Respirable microparticles/nanoparticles of the antibiotics vancomycin (VCM) and clarithromycin (CLM) were successfully designed and developed by novel organic solution advanced spray drying from methanol solution. Formulation optimization was achieved through statistical experimental design of pump feeding rates of 25% (Low P), 50% (Medium P) and 75% (High P). Systematic and comprehensive physicochemical characterization and imaging were carried out using scanning electron microscopy (SEM), hot-stage microscopy (HSM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), Karl Fischer titration (KFT), laser size diffraction (LSD), gravimetric vapor sorption (GVS), confocal Raman microscopy (CRM) and spectroscopy for chemical imaging mapping. These novel spray-dried (SD) microparticulate/nanoparticulate dry powders displayed excellent aerosol dispersion performance as dry powder inhalers (DPIs) with high values in emitted dose (ED), respirable fraction (RF), and fine particle fraction (FPF). VCM DPIs displayed better aerosol dispersion performance compared to CLM DPIs which was related to differences in the physicochemical and particle properties of VCM and CLM. In addition, organic solution advanced co-spray drying particle engineering design was employed to successfully produce co-spray-dried (co-SD) multifunctional microparticulate/nanoparticulate aerosol powder formulations of VCM and CLM with the essential lung surfactant phospholipid, dipalmitoylphosphatidylcholine (DPPC), for controlled release pulmonary nanomedicine delivery as inhalable dry powder aerosols. Formulation optimization was achieved through statistical experimental design of molar ratios of co-SD VCM:DPPC and co-SD CLM:DPPC. XRPD and DSC confirmed that the phospholipid bilayer structure in the solid-state was preserved following spray drying. Co-SD VCM:DPPC and co-SD CLM:DPPC dry powder aerosols demonstrated controlled release of antibiotic drug that was fitted to various

  7. Li(+)-conductive polymer-embedded nano-Si particles as anode material for advanced Li-ion batteries.

    PubMed

    Chen, Yao; Zeng, Shi; Qian, Jianfeng; Wang, Yadong; Cao, Yuliang; Yang, Hanxi; Ai, Xinping

    2014-03-12

    Si has been considered as a promising alternative anode for next-generation lithium ion batteries (LIBs), but the commercial application of Si anodes is still limited due to their poor cyclability. In this paper, we propose a new strategy to enhance the long-term cyclability of Si anode by embedding nano-Si particles into a Li(+)-conductive polymer to form a Si/polymer composite with core-shell structure, in which nano-Si cores act as active Li-storage phase and the polymeric matrix serves not only as a strong buffer to accommodate the volume change, but also as a protection barrier to prevent the direct contact of Si surface with electrolyte, so as to maintain the mechanical integrity of Si anode and suppress the repeated destruction and construction of solid electrolyte interphase (SEI) on the Si surface. To realize this strategy, we synthesize a Si/PPP (polyparaphenylene) composite simply by ball-milling the Si nanoparticles with PPP polymer that has n-doping activity. Our experimental results demonstrate that the thus-prepared Si/PPP composite exhibits a high capacity of 3184 mA h g(-1) with an initial coulombic efficiency of 78%, an excellent rate capability with a considerably high capacity of 1670 mA h g(-1) even at a very high rate of 16 A g(-1), and a long-term cyclability with 60% capacity retention over 400 cycles, showing a great prospect for battery application. In addition, this structural design could be adopted to other Li-storable metals or alloys for developing cycle-stable anode materials for Li-ion batteries.

  8. Analysis of particle size and interface effects on the strength and ductility of advanced high strength steels

    NASA Astrophysics Data System (ADS)

    Ettehad, Mahmood

    This thesis is devoted to the numerical investigation of mechanical behavior of Dual phase (DP) steels. Such grade of advanced high strength steels (AHSS) is favorable to the automotive industry due the unique properties such as high strength and ductility with low finished cost. Many experimental and numerical studies have been done to achieve the optimized behavior of DP steels by controlling their microstructure. Experiments are costly and time consuming so in recent years numerical tools are utilized to help the metallurgist before doing experiments. Most of the numerical studies are based on classical (local) constitutive models where no material length scale parameters are incorporated in the model. Although these models are proved to be very effective in modeling the material behavior in the large scales but they fail to address some critical phenomena which are important for our goals. First, they fail to address the size effect phenomena which materials show at microstructural scale. This means that materials show stronger behavior at small scales compared to large scales. Another issue with classical models is the mesh size dependency in modeling the softening behavior of materials. This means that in the finite element context (FEM) the results will be mesh size dependent and no converged solution exist upon mesh refinement. Thereby by applying the classical (local) models one my loose the accuracy on measuring the strength and ductility of DP steels. Among the non-classical (nonlocal) models, gradient-enhanced plasticity models which consider the effect of neighboring point on the behavior of one specific point are proved to be numerically effective and versatile tools to accomplish the two concerns mentioned above. So in this thesis a gradient-enhanced plasticity model which incorporates both the energetic and dissipative material length scales is derived based on the laws of thermodynamics. This model also has a consistent yield-like function for the

  9. Application of radiofrequency superconductivity to accelerators for high-current ion beams

    SciTech Connect

    Delayen, J.R.; Bohn, C.L.; Kennedy, W.L.; Roche, C.T.; Sagalovsky, L.

    1992-01-01

    A development program is underway to apply rf superconductivity to the design of continuous-wave (cw) linear accelerators for high-current, high-brightness ion beam. During the last few years, considerable progress has been made both experimentally and theoretically toward this application. Recent tests of niobium resonators for ion acceleration have yielded average accelerating gradients as high as 18 MV/m. In an experiment with a radio-frequency quadrupole geometry, niobium was found to sustain cw peak surface electric fields as high as 128 MV/m over large (10 cm) surface areas. Theoretical studies of beam halo, cumulative beam breakup and alternating-phase focusing have also yielded important results. This paper su-summarizes the recent progress and identifies current and future work in the areas of superconducting accelerator technology for high-current ion beams.

  10. Application of radiofrequency superconductivity to accelerators for high-current ion beams

    SciTech Connect

    Delayen, J.R.; Bohn, C.L.; Kennedy, W.L.; Roche, C.T.; Sagalovsky, L.

    1992-12-31

    A development program is underway to apply rf superconductivity to the design of continuous-wave (cw) linear accelerators for high-current, high-brightness ion beam. During the last few years, considerable progress has been made both experimentally and theoretically toward this application. Recent tests of niobium resonators for ion acceleration have yielded average accelerating gradients as high as 18 MV/m. In an experiment with a radio-frequency quadrupole geometry, niobium was found to sustain cw peak surface electric fields as high as 128 MV/m over large (10 cm) surface areas. Theoretical studies of beam halo, cumulative beam breakup and alternating-phase focusing have also yielded important results. This paper su-summarizes the recent progress and identifies current and future work in the areas of superconducting accelerator technology for high-current ion beams.

  11. Composite carbon-based ionic liquid supercapacitor for high-current micro devices

    NASA Astrophysics Data System (ADS)

    Cowell, M.; Winslow, R.; Zhang, Q.; Ju, J.; Evans, J.; Wright, P.

    2014-11-01

    Manufacture and performance of a composite carbon-based supercapacitor that employs a gel polymer ionic liquid electrolyte to achieve stable, long cycle life, high-current draw energy storage is discussed in this paper. This supercapacitor when cycled galvanostatically can achieve a discharge capacitance of 43.0 mF per square centimeter of substrate by leveraging the strengths of a composite electrode composition. The printed manufacturing process takes place in ambient conditions at room temperature enabling high-current, rechargeable energy storage to be built onto many substrates. Single-cell discharge power densities have reached 404 μW/cm2 which could enable many technologies when paired with a MEMS energy harvester.

  12. The use of a high-current electron beam in plasma relativistic microwave oscillators

    SciTech Connect

    Bekhovskaya, K. S. Bogdankevich, I. L.; Strelkov, P. S.; Tarakanov, V. P.; Ul'yanov, D. K.

    2011-12-15

    Relativistic microwave electronics faces the problem of using high currents of relativistic electron beams; i.e., it is possible to use beams the current of which is lower than that of actually existing high-current accelerators. We show the possibility of increasing the power of radiation generated in a plasma relativistic microwave oscillator (PRMO) due to an increase in the absolute value of current. For the beam currents close to the value of limiting vacuum current, the efficiency of microwave generation decreases; therefore, we study PRMO schemes with a high value of limiting vacuum current, i.e., schemes with a small gap between a hollow relativistic electron beam and the waveguide wall. The results of the experiment and numerical simulation are discussed.

  13. Investigations of a high current linear aperture radial multichannel pseudospark switch

    NASA Astrophysics Data System (ADS)

    Lamba, R. P.; Pathania, V.; Meena, B. L.; Rahaman, H.; Pal, U. N.; Prakash, Ram

    2015-10-01

    In this paper, a high current linear aperture radial multichannel Pseudospark switch (LARM-PSS) is reported which has been analyzed for its high current characteristics. In order to enhance hold-off voltage and support hollow cathode effect for the ignition of the discharge in this configuration, the field penetration analysis through circular and linear apertures of the electrodes has been carried out. The linear apertures in the electrodes increase the current handling capacity than that of circular aperture electrodes without significant compromise of the hold-off capacity. The developed LARM-PSS switch is capable to hold voltage up to 25 kV at gas pressure between 10 and 50 Pa for hydrogen. The switch has been operated using a 800 nF capacitor bank and conducted an effective charge up to 1.5 C with peak switch current ˜20 kA at applied voltage 19 kV.

  14. Investigations of a high current linear aperture radial multichannel pseudospark switch.

    PubMed

    Lamba, R P; Pathania, V; Meena, B L; Rahaman, H; Pal, U N; Prakash, Ram

    2015-10-01

    In this paper, a high current linear aperture radial multichannel Pseudospark switch (LARM-PSS) is reported which has been analyzed for its high current characteristics. In order to enhance hold-off voltage and support hollow cathode effect for the ignition of the discharge in this configuration, the field penetration analysis through circular and linear apertures of the electrodes has been carried out. The linear apertures in the electrodes increase the current handling capacity than that of circular aperture electrodes without significant compromise of the hold-off capacity. The developed LARM-PSS switch is capable to hold voltage up to 25 kV at gas pressure between 10 and 50 Pa for hydrogen. The switch has been operated using a 800 nF capacitor bank and conducted an effective charge up to 1.5 C with peak switch current ∼20 kA at applied voltage 19 kV. PMID:26520956

  15. Progress on the high-current 704 MHz superconducting RF cavity at BNL

    SciTech Connect

    Xu W.; Astefanous, C.; Belomestnykh, S.; Ben-Zvi, I.; et al

    2012-05-20

    The 704 MHz high current superconducting cavity has been designed with consideration of both performance of fundamental mode and damping of higher order modes. A copper prototype cavity was fabricated by AES and delivered to BNL. RF measurements were carried out on this prototype cavity, including fundamental pass-band and HOM spectrum measurements, HOM studies using bead-pull setup, prototyping of antenna-type HOM couplers. The measurements show that the cavity has very good damping for the higher-order modes, which was one of the main goals for the high current cavity design. 3D cavity models were simulated with Omega3P code developed by SLAC to compare with the measurements. The paper describes the cavity design, RF measurement setups and results for the copper prototype. The progress with the niobium cavity fabrication will also be described.

  16. Microplastic deformation of polycrystalline iron and molybdenum subjected to high-current electron-beam irradiation

    NASA Astrophysics Data System (ADS)

    Dudarev, E. F.; Pochivalova, G. P.; Proskurovskii, D. I.; Rotshtein, V. P.; Markov, A. B.

    1996-03-01

    A technique for determination of residual stresses at various distances from the irradiated surface is proposed. It is established for iron and molybdenum that compressive stresses are set up under irradiation by low-energy high-current electron beams and that their values decrease sharply with increasing distance from the surface. The residual stresses are much smaller in absolute magnitude than those operating during irradiation. It is shown that the change in resistance to microplastic deformation on irradiation with low-energy high-current electron beams is governed not only by formation of a gradient dislocation substructure in the surface layer, but also by the residual stresses and the appearance of the Bauschinger effect.

  17. Conversion of high explosive chemical energy into energy of powerful nanosecond high-current pulses

    NASA Astrophysics Data System (ADS)

    Gorbachev, K. V.; Mikhaylov, V. M.; Nesterov, E. V.; Stroganov, V. A.; Chernykh, E. V.

    2015-01-01

    This study is a contribution into the development of physicotechnical foundations for generation of powerful nanosecond high-current pulses on the basis of explosively driven magnetic flux compression generators. This problem is solved by using inductive storage of energy for matching comparatively low-voltage explosively driven magnetic flux compression generators and high-impedance loads; short forming lines and vacuum diodes. Experimental data of charging of forming lines are given.

  18. Surface modification of structural materials by low-energy high-current pulsed electron beam treatment

    SciTech Connect

    Panin, A. V. E-mail: kms@ms.tsc.ru; Kazachenok, M. S. E-mail: kms@ms.tsc.ru; Sinyakova, E. A.; Borodovitsina, O. M.; Ivanov, Yu. F.; Leontieva-Smirnova, M. V.

    2014-11-14

    Microstructure formation in surface layers of pure titanium and ferritic-martensitic steel subjected to electron beam treatment is studied. It is shown that low energy high-current pulsed electron beam irradiation leads to the martensite structure within the surface layer of pure titanium. Contrary, the columnar ferrite grains grow during solidification of ferritic-martensitic steel. The effect of electron beam energy density on the surface morphology and microstructure of the irradiated metals is demonstrated.

  19. Enhanced D-T supershot performance at high current using extensive lithium conditioning in TFTR

    SciTech Connect

    Mansfield, D.K.; Strachan, J.D.; Bell, M.G.; Scott, S.D.; Budny, R.; Bell, R.E.; Bitter, M.; Darrow, D.S.; Fredrickson, E.; Grek, B.

    1995-05-01

    A substantial improvement in supershot fusion plasma performance has been realized by combining the enhanced confinement due to tritium fueling with the enhanced confinement due to extensive Li conditioning of the TFTR limiter. This combination has resulted in not only significantly higher global energy confinement times than had previously been obtained in high current supershots, but also the highest ratio of central fusion output power to input power observed to date.

  20. High Current Systems for HyperV and PLX Plasma Railguns

    NASA Astrophysics Data System (ADS)

    Brockington, Samuel; Case, Andrew; Messer, Sarah; Bomgardner, Richard; Wu, Linchun; Elton, Raymond; Witherspoon, F. Douglas

    2010-11-01

    HyperV has been developing coaxial pulsed, plasma railgun accelerators for PLX and other high momentum plasma experiments. The full scale HyperV coaxial gun accelerates plasma armatures using a contoured electrode gap designed to mitigate the blow-by instability. Previous experiments with the full scale gun successfully formed and accelerated annular plasma armatures, but were limited to currents of up to only ˜400 kA. In order to increase full scale gun performance to the design goal of 200 μg at 200 km/s, the pulse forming networks required upgrading to support currents up to ˜1 MA. A high voltage, high current field-effect sparkgap switch and low inductance transmission line were designed and constructed to handle the increased current pulse. We will describe these systems and present initial test data from high current operation of the full-scale coax gun along with plans for future testing. Similar high current accelerator banks, switches, and TM lines will also be required to power PLX railguns which are planned to operate at 8000 μg at 50 km/s. The design of that experiment may require the capacitor banks to be located as much as 10 feet from the gun. We discuss the available options for low inductance connections for these systems.

  1. High-power Čerenkov microwave oscillators utilizing High-Current nanosecond Electron beams

    NASA Astrophysics Data System (ADS)

    Korovin, S. D.; Polevin, S. D.; Rostov, V. V.

    1996-12-01

    A short review is given of results obtained at the Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences on generating high-power microwave radiation. Most of the research was devoted to a study of stimulated Čerenkov radiation from relativistic electron beams. It is shown that the efficiency of a relativistic 3-cm backward wave tube with a nonuniform coupling resistance can reach 35%. High-frequency radiation was discovered in the emission spectrum of the Čerenkov oscillators and it was shown that the nature of the radiation was associated with the stimulated scattering of low-frequency radiation by the relativistic electrons. Radiation with a power of 500 MW was obtained in the 8-mm wavelength range using a two-beam Čerenkov oscillator. High-current pulse-periodic nanosecond accelerators with a charging device utilizing a Tesla transformer were used in the experiments. The possibility was demonstrated of generating high-power microwave radiation with a pulse-repetition frequency of up to 100 Hz. An average power of ˜500 W was achieved from the relativistic oscillators. A relativistic backward wave tube with a high-current electron beam was used to make a prototype nanosecond radar device. Some of the results presented were obtained jointly with the Russian Academy of Sciences Institute of Applied Physics. Questions concerning multiwave Čerenkov interaction are not considered in this paper.

  2. A merging preaccelerator for high current H{sup {minus}} ion beams

    SciTech Connect

    Inoue, T.; Miyamoto, K.; Mizuno, M.; Okumura, Y.; Ohara, Y.; Ackerman, G.D.; Chan, C.F.; Cooper, W.S.; Kwan, J.W.; Vella, M.C.

    1995-07-01

    The high power ion beams used in the next generation thermonuclear fusion reactors require high current negative ion beams accelerated to high energy, with high efficiency. One way to meet these requirements is to merge multiple low current density H{sup {minus}} beamlets into a single high current beam. The feasibility of a high current merging preaccelerator was demonstrated in this experiment by merging 19 beamlets of H{sup {minus}} ions distributed over a circular area 80 mm in diameter from a Japan Atomic Energy Research Institute negative ion source. H{sup {minus}} ions were extracted at a current density exceeding 10 mA/cm{sup 2} at the ion source which operates at 0.13 Pa (1 mTorr), with a low arc power density (70 V{times}250 A). Spherically curved grids (with built-in magnetic electron suppression) were used in the preaccelerator to focus the extracted beamlets into a single 104 mA, 100 keV beam. The merged beam has a diameter of 23 mm and a converging angle of {plus_minus}30 mrad at the beam envelope. The rms emittance of the 104 mA merging beam was 1.00 {pi} mrad cm, which is a condition acceptable to the electrostatic quadropole accelerator for further acceleration. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  3. Fluid-particle hybrid simulation on the transports of plasma, recycling neutrals, and carbon impurities in the Korea Superconducting Tokamak Advanced Research divertor region

    NASA Astrophysics Data System (ADS)

    Kim, Deok-Kyu; Hong, Sang Hee

    2005-06-01

    A two-dimensional simulation modeling that has been performed in a self-consistent way for analysis on the fully coupled transports of plasma, recycling neutrals, and intrinsic carbon impurities in the divertor domain of tokamaks is presented. The numerical model coupling the three major species transports in the tokamak edge is based on a fluid-particle hybrid approach where the plasma is described as a single magnetohydrodynamic fluid while the neutrals and impurities are treated as kinetic particles using the Monte Carlo technique. This simulation code is applied to the KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak [G. S. Lee, J. Kim, S. M. Hwang et al., Nucl. Fusion 40, 575 (2000)] to calculate the peak heat flux on the divertor plate and to explore the divertor plasma behavior depending on the upstream conditions in its base line operation mode for various values of input heating power and separatrix plasma density. The numerical modeling for the KSTAR tokamak shows that its full-powered operation is subject to the peak heat loads on the divertor plate exceeding an engineering limit, and reveals that the recycling zone is formed in front of the divertor by increasing plasma density and by reducing power flow into the scrape-off layer. Compared with other researchers' work, the present hybrid simulation more rigorously reproduces severe electron pressure losses along field lines by the presence of recycling zone accounting for the transitions between the sheath limited and the detached divertor regimes. The substantial profile changes in carbon impurity population and ionic composition also represent the key features of this divertor regime transition.

  4. Paramagnetic ultrasmall gadolinium oxide nanoparticles as advanced T1 MRI contrast agent: account for large longitudinal relaxivity, optimal particle diameter, and in vivo T1 MR images.

    PubMed

    Park, Ja Young; Baek, Myung Ju; Choi, Eun Sook; Woo, Seungtae; Kim, Joo Hyun; Kim, Tae Jeong; Jung, Jae Chang; Chae, Kwon Seok; Chang, Yongmin; Lee, Gang Ho

    2009-11-24

    Paramagnetic ultrasmall gadolinium oxide (Gd(2)O(3)) nanoparticles with particle diameters (d) of approximately 1 nm were synthesized by using three kinds of Gd(III) ion precursors and by refluxing each of them in tripropylene glycol under an O(2) flow. A large longitudinal relaxivity (r(1)) of water proton of 9.9 s(-1) mM(-1) was estimated. As a result, high contrast in vivo T(1) MR images of the brain tumor of a rat were observed. This large r(1) is discussed in terms of the huge surface to volume ratio (S/V) of the ultrasmall gadolinium oxide nanoparticles coupled with the cooperative induction of surface Gd(III) ions for the longitudinal relaxation of a water proton. It is found from the d dependence of r(1) that the optimal range of d for the maximal r(1), which may be used as an advanced T(1) MRI contrast agent, is 1-2.5 nm.

  5. Productivity Improvement for the SHX--SEN's Single-Wafer High-Current Ion Implanter

    SciTech Connect

    Ninomiya, Shiro; Ochi, Akihiro; Kimura, Yasuhiko; Yumiyama, Toshio; Kudo, Tetsuya; Kurose, Takeshi; Kariya, Hiroyuki; Tsukihara, Mitsukuni; Ishikawa, Koji; Ueno, Kazuyoshi

    2011-01-07

    Equipment productivity is a critical issue for device fabrication. For ion implantation, productivity is determined both by ion current at the wafer and by utilization efficiency of the ion beam. Such improvements not only result in higher fabrication efficiency but also reduce consumption of both electrical power and process gases. For high-current ion implanters, reduction of implant area is a key factor to increase efficiency. SEN has developed the SAVING system (Scanning Area Variation Implantation with Narrower Geometrical pattern) to address this opportunity. In this paper, three variations of the SAVING system are introduced along with discussion of their effects on fab productivity.

  6. Methods of high current magnetic field generator for transcranial magnetic stimulation application

    SciTech Connect

    Bouda, N. R. Pritchard, J.; Weber, R. J.; Mina, M.

    2015-05-07

    This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ±1200 A can be generated with inputs of +/−20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG{sub 1}) and MOSFET circuits (HCMFG{sub 2}) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed.

  7. High-current density, high-brightness electron beams from large-area lanthanum hexaboride cathodes

    NASA Astrophysics Data System (ADS)

    Loschialpo, P.; Kapetanakos, C. A.

    1987-12-01

    Large (approx. 5 cm) diameter lanthanum hexaboride (LaB6) cathodes operated at 10 kV have produced 1 to 5 micro electron pulses with current density between 10 and 20 A/sq cm. Normalized beam brightness, has been consistently measured. To obtain this high current density, the LaB6 cathodes have been heated to temperatures between approximately 1600 to 1800 C. Very uniform temperature profiles are obtained by applying a carefully tailored electron bombardment heating power distribution. These measurements have been made between pressure .000001 to .00001 Torr, i.e., under much less demanding vacuum conditions than that required by conventional dispenser type cathodes.

  8. Beam brilliance investigation of high current ion beams at GSI heavy ion accelerator facility

    SciTech Connect

    Adonin, A. A. Hollinger, R.

    2014-02-15

    In this work the emittance measurements of high current Ta-beam provided by VARIS (Vacuum Arc Ion Source) ion source are presented. Beam brilliance as a function of beam aperture at various extraction conditions is investigated. Influence of electrostatic ion beam compression in post acceleration gap on the beam quality is discussed. Use of different extraction systems (single aperture, 7 holes, and 13 holes) in order to achieve more peaked beam core is considered. The possible ways to increase the beam brilliance are discussed.

  9. Methods of high current magnetic field generator for transcranial magnetic stimulation application

    NASA Astrophysics Data System (ADS)

    Bouda, N. R.; Pritchard, J.; Weber, R. J.; Mina, M.

    2015-05-01

    This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ±1200 A can be generated with inputs of +/-20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG1) and MOSFET circuits (HCMFG2) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed.

  10. High-current lanthanum-hexaboride electron emitter for a quasi-stationary arc plasma generator

    SciTech Connect

    Davydenko, V. I. Ivanov, A. A. Shul’zhenko, G. I.

    2015-11-15

    A high-current electron emitter on the basis of lanthanum hexaboride is developed for quasi-stationary arc plasma generators of ion sources. The emitter consists of a set of LaB{sub 6} washers interleaved with washers made of thermally extended graphite. The emitter is heated by the current flowing through the graphite washers. The thermal regime of emitter operation during plasma generation is considered. The emitter has been successfully used in the ion sources of the diagnostic injectors of fast hydrogen atomic beams.

  11. High-current quasi-square-wave millisecond light source for high-speed photography

    NASA Astrophysics Data System (ADS)

    Lin, Wenzheng; Jiang, Aibao; Zhuo, Meizhen

    1993-01-01

    A novel powerful strobe for high-speed photography is described which can replace the high power cw light source, to save energy and synchroflash with the camera. In this strobe, three- phase transformerless direct rectifier, high current SCR switch and pre-ionization technique are used so that the energy consumption goes down greatly, and its total weight is less than 25 Kg. Its principal parameters are as follows: average power, 50 KW; light emitting pulse width, 1 - 100 ms; pulse rise time, less than 0.05 ms; pulse fall time, less than 0.1 ms.

  12. Efficiency of pulse high-current generator energy transfer into plasma liner energy

    NASA Astrophysics Data System (ADS)

    Oreshkin, V. I.

    2013-08-01

    The efficiency of capacitor-bank energy transfer from a high-current pulse generator into kinetic energy of a plasma liner has been analyzed. The analysis was performed using a model including the circuit equations and equations of the cylindrical shell motion. High efficiency of the energy transfer into kinetic energy of the liner is shown to be achieved only by a low-inductance generator. We considered an "ideal" liner load in which the load current is close to zero in the final of the shell compression. This load provides a high (up to 80%) efficiency of energy transfer and higher stability when compressing the liner.

  13. Beam brilliance investigation of high current ion beams at GSI heavy ion accelerator facility.

    PubMed

    Adonin, A A; Hollinger, R

    2014-02-01

    In this work the emittance measurements of high current Ta-beam provided by VARIS (Vacuum Arc Ion Source) ion source are presented. Beam brilliance as a function of beam aperture at various extraction conditions is investigated. Influence of electrostatic ion beam compression in post acceleration gap on the beam quality is discussed. Use of different extraction systems (single aperture, 7 holes, and 13 holes) in order to achieve more peaked beam core is considered. The possible ways to increase the beam brilliance are discussed.

  14. Optimization of the epitaxial design of high current density resonant tunneling diodes for terahertz emitters

    NASA Astrophysics Data System (ADS)

    Baba, Razvan; Stevens, Benjamin J.; Mukai, Toshikazu; Hogg, Richard A.

    2016-02-01

    We discuss the numerical simulation of high current density InGaAs/AlAs/InP resonant tunneling diodes with a view to their optimization for application as THz emitters. We introduce a figure of merit based upon the ratio of maximum extractable THz power and the electrical power developed in the chip. The aim being to develop high efficiency emitters as output power is presently limited by catastrophic failure. A description of the interplay of key parameters follows, with constraints on strained layer epitaxy introduced. We propose an optimized structure utilizing thin barriers paired with a comparatively wide quantum well that satisfies strained layer epitaxy constraints.

  15. High-current lanthanum-hexaboride electron emitter for a quasi-stationary arc plasma generator

    NASA Astrophysics Data System (ADS)

    Davydenko, V. I.; Ivanov, A. A.; Shul'zhenko, G. I.

    2015-11-01

    A high-current electron emitter on the basis of lanthanum hexaboride is developed for quasi-stationary arc plasma generators of ion sources. The emitter consists of a set of LaB6 washers interleaved with washers made of thermally extended graphite. The emitter is heated by the current flowing through the graphite washers. The thermal regime of emitter operation during plasma generation is considered. The emitter has been successfully used in the ion sources of the diagnostic injectors of fast hydrogen atomic beams.

  16. Switching of YBCO thin films into the dissipative state at high current densities

    NASA Astrophysics Data System (ADS)

    Villard, Catherine; Devismes, Marie-Françoise; Carbone, Laurent; Bourgault, Daniel

    We report on the switching properties at high current densities of YBCO thin films shunted by an Ag layer. These experiments are performed either in liquid nitrogen or liquid argon (87.3K). Different transition regimes associated to specific electric field thresholds are observed. The nature of the thermal exchange with the bath and the role of the silver shunt and substrate are discussed. While only two regimes in the current-voltage characteristics are observed in liquid nitrogen, successively reversible and hysteretic, an intermediate behaviour appears at 87.3K associated with a total current diversion by the silver layer.

  17. High Current Ionic Diode Using Homogeneously Charged Asymmetric Nanochannel Network Membrane.

    PubMed

    Choi, Eunpyo; Wang, Cong; Chang, Gyu Tae; Park, Jungyul

    2016-04-13

    A high current ionic diode is achieved using an asymmetric nanochannel network membrane (NCNM) constructed by soft lithography and in situ self-assembly of nanoparticles with uniform surface charge. The asymmetric NCNM exhibits high rectified currents without losing a rectification ratio because of its ionic selectivity gradient and differentiated electrical conductance. Asymmetric ionic transport is analyzed with diode-like I-V curves and visualized via fluorescent dyes, which is closely correlated with ionic selectivity and ion distribution according to variation of NCNM geometries.

  18. Coherent Effects of High Current Beam in Project-X Linac

    SciTech Connect

    Sukhanov, A.; Lunin, A.; Yakovlev, V.; Gonin, I.; Khabiboulline, T.; Saini, A.; Solyak, N.; Yostrikov, A.

    2012-09-01

    Resonance excitation of longitudinal high order modes in superconducting RF structures of Project-X continuous wave linac is studied. We analyze regimes of operation of the linac with high beam current, which can be used to provide an intense muon source for the future Neutrino Factory or Muon Collider, and also important for the Accelerator-Driven Subcritical systems. We calculate power loss and associated heat load to the cryogenic system. Longitudinal emittance growth is estimated. We consider an alternative design of the elliptical cavity for the high energy part of the linac, which is more suitable for high current operation.

  19. Coherent Effects of High Current Beam in Project-X Linac

    SciTech Connect

    Sukhanov, Alexander; Yakovlev, Vyacheslav; Gonin, Ivan; Khabiboulline, Timergali; Lunin, Andrei; Saini, Arun; Solyak, Nikolay; Vostrikov, Alexander

    2013-04-01

    Resonance excitation of longitudinal high order modes in superconducting RF structures of Project-X continuous wave linac is studied. We analyze regimes of operation of the linac with high beam current, which can be used to provide an intense muon source for the future Neutrino Factory or Muon Collider, and also important for the Accelerator-Driven Subcritical systems. We calculate power loss and associated heat load to the cryogenic system. Longitudinal emittance growth is estimated. We consider an alternative design of the elliptical cavity for the high energy part of the linac, which is more suitable for high current operation.

  20. Westinghouse advanced particle filter system

    SciTech Connect

    Lippert, T.E.; Bruck, G.J.; Sanjana, Z.N.; Newby, R.A.

    1994-10-01

    Integrated Gasification Combined Cycles (IGCC) and Pressurized Fluidized Bed Combustion (PFBC) are being developed and demonstrated for commercial, power generation application. Hot gas particulate filters are key components for the successful implementation of IGCC and PFBC in power generation gas turbine cycles. The objective of this work is to develop and qualify through analysis and testing a practical hot gas ceramic barrier filter system that meets the performance and operational requirements of PFBC and IGCC systems. This paper updates the assessment of the Westinghouse hot gas filter design based on ongoing testing and analysis. Results are summarized from recent computational fluid dynamics modeling of the plenum flow during back pulse, analysis of candle stressing under cleaning and process transient conditions and testing and analysis to evaluate potential flow induced candle vibration.

  1. High-current-density gun with a LaB6 cathode

    NASA Astrophysics Data System (ADS)

    Ebihara, K.; Hiramatsu, S.

    1996-08-01

    To develop a high-current electron gun for an induction linac, a prototype of a Pierce-type electron gun using planar 12-mm-diam lanthanum hexaboride (LaB6) is studied as a thermionic emitter at high current densities. The cathode is heated up to temperatures of 1750 °C by electron bombardment and thermal radiation from a tungsten heater. The heater that has the highest temperature in the gun is thermally isolated from the outer vacuum chamber with heat shields. The bombardment voltage of ˜1 kV is typically applied to a gap between the cathode and the heater. The gun has been operated up to voltages of 55 kV, obtaining a maximum current density of 20 A/cm2 with a pulse width of 250 ns at a cathode temperature of 1600 °C. High-voltage pulsing results show that the gun, with applied voltages of over 40 kV, is operated in space-charge-limited region at temperatures of over 1600 °C; also it is operated in a temperature-limited region at temperatures of less than 1500 °C. An effective work function of 2.68 eV is obtained. The cathode, when heated up to 1600 °C, emits over 7 A of electrons with a ˜20% reduction after 850 h of continuous operation. These measurements were made between vacuum pressures of 10-6 and 10-7 Torr.

  2. Progress and future developments of high current ion source for neutral beam injector in the ASIPP

    SciTech Connect

    Hu, Chundong; Xie, Yahong Xie, Yuanlai; Liu, Sheng; Liu, Zhimin; Xu, Yongjian; Liang, Lizhen; Sheng, Peng; Jiang, Caichao

    2015-04-08

    A high current hot cathode bucket ion source, which based on the US long pulse ion source is developed in Institute of Plasma Physics, Chinese Academy of Sciences. The ion source consists of a bucket plasma generator with multi-pole cusp fields and a set of tetrode accelerator with slit apertures. So far, four ion sources are developed and conditioned on the ion source test bed. 4 MW hydrogen beam with beam energy of 80 keV is extracted. In Aug. 2013, EAST NBI 1 with two ion source installed on the EAST, and achieved H-mode plasma with NBI injection for the first time. In order to achieve stable long pulse operation of high current ion source and negative ion source research, the RF ion source with 200 mm diameter and 120 mm depth driver is designed and developed. The first RF plasma generated with 2 kW power of 1 MHz frequency. More of the RF plasma tests and negative source relative research need to do in the future.

  3. Tin nanoparticle-loaded porous carbon nanofiber composite anodes for high current lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Shen, Zhen; Hu, Yi; Chen, Yanli; Zhang, Xiangwu; Wang, Kehao; Chen, Renzhong

    2015-03-01

    Metallic Sn is a promising high-capacity anode material for use in lithium-ion batteries (LIBs), but its huge volume variation during lithium ion insertion/extraction typically results in poor cycling stability. To address this, we demonstrate the fabrication of Sn nanoparticle-loaded porous carbon nanofiber (Sn-PCNF) composites via the electrospinning of Sn(II) acetate/mineral oil/polyacrylonitrile precursors in N,N-dimethylformamide solvent and their subsequent carbonization at 700 °C under an argon atmosphere. This is shown to result in an even distribution of pores on the surface of the nanofibers, allowing the Sn-PCNF composite to be used directly as an anode in lithium-ion batteries without the need to add non-active materials such as polymer binders or electrical conductors. With a discharge capacity of around 774 mA h g-1 achieved at a high current of 0.8 A g-1 over 200 cycles, this material clearly has a high rate capability and excellent cyclic stability, and thanks to its unique structure and properties, is an excellent candidate for use as an anode material in high-current rechargeable lithium-ion batteries.

  4. R & D on Very-High-Current Superconducting Proton Linac, Final Report

    SciTech Connect

    Ben-Zvi, Ilan

    2013-03-31

    The aim of this R&D project was to develop a superconducting cavity for a very-­ high-current proton accelerator. The particular application motivating the proposal was a LHC upgrade called the Superconducting Proton Linac, or SPL. Under the grant awarded to Stony Brook University the cavity was designed, a prototype copper cavity, followed by the niobium cavity, were built. A new set of HOM dampers was developed. The cavity has outstanding RF performance parameters – low surface fields, low power loss and all HOMs are fully damped. In fact, it is a “universal cavity” in the sense that it is suited for the acceleration of high-­current protons and well as high current electrons. Its damping of HOM modes is so good that it can see service in a multi-pass linac or an Energy Recovery Linac in addition to the easier service in a single-pass linac. Extensive measurements were made on the cavities and couplers, with the exception of the cold test of the niobium cavity. At the time of this report the cavity has been chemically processed and is ready for vertical testing which will be carried out shortly.

  5. Aperture Test for Internal Target Operation in the JLAB High-current ERL

    SciTech Connect

    Zhang, Shukui

    2013-06-01

    A high current beam transmission test has been successfully completed at the JLAB FEL Facility, culminating in very low-loss transmission of a high current CW beam through a small aperture. The purpose of this test was to determine if an ERL is capable of meeting the stringent requirements imposed by the use of a 1018/cm3 internal gas target proposed for the DarkLight experiment*. Minimal beamline modifications were made to create a machine configuration that is substantially different from those used in routine UV or IR FEL operation. A sustained (8 hour) high power beam run was performed, with clean transmission through a 2 mm transverse aperture of 127 mm length simulating the target configuration. A beam size of 50 um (rms) was measured near the center of the aperture. Experimental data from a week-long test run consistently exhibited beam loss of only a few ppm on the aperture while running 4.5 mA current at 100 MeV -- or nearly 0.5 MW beam power. This surpassed the users? expectation and demonstrated a unique capability of an ERL for this type of experiments. This report presents a summary of the experiment, a brief overview of our activities, and outlines future plans.

  6. Development and Testing of High Current Hollow Cathodes for High Power Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Kamhawi, Hani; Van Noord, Jonathan

    2012-01-01

    NASA's Office of the Chief Technologist In-Space Propulsion project is sponsoring the testing and development of high power Hall thrusters for implementation in NASA missions. As part of the project, NASA Glenn Research Center is developing and testing new high current hollow cathode assemblies that can meet and exceed the required discharge current and life-time requirements of high power Hall thrusters. This paper presents test results of three high current hollow cathode configurations. Test results indicated that two novel emitter configurations were able to attain lower peak emitter temperatures compared to state-of-the-art emitter configurations. One hollow cathode configuration attained a cathode orifice plate tip temperature of 1132 degC at a discharge current of 100 A. More specifically, test and analysis results indicated that a novel emitter configuration had minimal temperature gradient along its length. Future work will include cathode wear tests, and internal emitter temperature and plasma properties measurements along with detailed physics based modeling.

  7. A high-resolution beam profile measuring system for high-current ion implanters

    NASA Astrophysics Data System (ADS)

    Fujishita, N.; Noguchi, K.; Sasaki, S.; Yamamoto, H.

    1991-04-01

    A high-resolution beam profile measuring system (BPM) has been developed to analyze the correlation between charging damage and the ion beam profile for high-current ion implanters. With the increase of the ion beam current, insulators such as thin oxide layers of VLSI devices are subject to charging damage during ion implantation. To obtain accurate information on the local current density of the ion beam, 125 Faraday cups are placed in the BPM. This system has two measuring modes. One is a topographic mode that can detect the ion beam current density of 12500 sampling points in 30 s. A high-resolution contour map of the current density distribution is displayed on a CRT. The other is a real-time mode in which the current density distribution (125 sampling points) of the ion beam can be monitored every half second on the CRT. In this mode, fine adjustment of the ion beam profile is easily possible by visual control. The charging damage of insulating layers in the TEG (test element group) to the beam profile was investigated using this newly developed BPM. It has been proven that the damage probability increases rapidly above some threshold level of the beam current density. It is confirmed that for high-current implantation a uniform current density distribution of the ion beam is very effective to prevent charging damage. It is concluded that this measuring system is valuable not only for quick analysis of damage phenomena, but also for evaluating machine performance.

  8. Characterisation of high current density resonant tunneling diodes for THz emission using photoluminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Jacobs, Kristof J. P.; Baba, Razvan; Stevens, Benjamin J.; Mukai, Toshikazu; Ohnishi, Dai; Hogg, Richard A.

    2016-03-01

    Resonant tunneling diodes (RTDs) provide high speed current oscillation which is applicable to THz generation when coupled to a suitably designed antenna. For this purpose, the InGaAs/AlAs/InP materials have been used, as this system offers high electron mobility, suitable band-offsets, and low resistance contacts. However for high current density operation (~MA/cm2) the epitaxial structure is challenging to characterize using conventional techniques as it consists of a single, very thin AlAs/InGaAs quantum well (QW). Here, we present a detailed low temperature photoluminescence spectroscopic study of high current density RTDs that allow the non-destructive mapping of a range of critical parameters for the device. We show how the doping level of the emitter/collector and contact layers in the RTD structure can be measured using the Moss-Burstein effect. For the full device structure, we show how emission from the QW may be identified, and detail how the emission changes with differing indium composition and well widths. We show that by studying nominally identical, un-doped structures, a type-II QW emission is observed, and explain the origin of the type-I emission in doped devices. This observation opens the way for a new characterization scheme where a "dummy" RTD active element is incorporated below the real RTD structure. This structure allows significantly greater control in the epitaxial process.

  9. Evaluating of scale-up methodologies of gas-solid spouted beds for coating TRISO nuclear fuel particles using advanced measurement techniques

    NASA Astrophysics Data System (ADS)

    Ali, Neven Y.

    The work focuses on implementing for the first time advanced non-invasive measurement techniques to evaluate the scale-up methodology of gas-solid spouted beds for hydrodynamics similarity that has been reported in the literature based on matching dimensionless groups and the new mechanistic scale up methodology that has been developed in our laboratory based on matching the radial profile of gas holdup since the gas dynamics dictate the hydrodynamics of the gas-solid spouted beds. These techniques are gamma-ray computed tomography (CT) to measure the cross-sectional distribution of the phases' holdups and their radial profiles along the bed height and radioactive particle tracking (RPT) to measure in three-dimension (3D) solids velocity and their turbulent parameters. The measured local parameters and the analysis of the results obtained in this work validate our new methodology of scale up of gas-solid spouted beds by comparing for the similarity the phases' holdups and the dimensionless solids velocities and their turbulent parameters that are non-dimensionalized using the minimum spouting superficial gas velocity. However, the scale-up methodology of gas-solid spouted beds that is based on matching dimensionless groups has not been validated for hydrodynamics similarity with respect to the local parameters such as phases' holdups and dimensionless solids velocities and their turbulent parameters. Unfortunately, this method was validated in the literature by only measuring the global parameters. Thus, this work confirms that validation of the scale-up methods of gas-solid spouted beds for hydrodynamics similarity should reside on measuring and analyzing the local hydrodynamics parameters.

  10. Field Testing of High Current Electrokinetic Nanoparticle Treatment for Corrosion Mitigation in Reinforced Concrete

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; Alexander, Joshua B.; Cardenas, Henry E.; Kupwade-Patil, Kunal

    2008-01-01

    This work examines field performance of nanoscale pozzolan treatments delivered el ctrokinetically to suppress chloride induced corrosion of concrete reinforcement. The particles are 20 nm silica spheres coated with 2 nm alumina particles that carry a net positive charge. Earlier work demonstrated that the alumina particles were stripped from the silica carriers and formed a dense phase with an interparticle spacing that is small enough to inhibit the transport of solvated chlorides. A D.C. field was used to inject the particles into the pores of concrete specimens, directly toward the mild steel bars that were embedded within each 3 inch diameter by 6 inch length concrete specimen. The voltage was held constant at 25 v per inch of concrete cover for a period of 7 days. These voltages permitted current densities as high as 3 A/sq m. During the final 3 days, a 1 molar solution of calcium nitrate tetrahydrate was used to provide a source of calcium to facilitate stronger and more densified phase formation within the pores. In a departure from prior work the particle treatments were started concurrent with chloride extraction in order to determine if particle delivery would inhibit chloride transport. Following treatment the specimens were immersed in seawater for 4 weeks. After this posttreatment exposure, the specimens were tested for tensile strength and the steel reinforcement was examined for evidence of corrosion. Scanning electron microscopy was conducted to assess impact on microstructure.

  11. Development and fabrication of low ON resistance high current vertical VMOS power FETs

    NASA Technical Reports Server (NTRS)

    Kay, S.

    1979-01-01

    The design of a VMOS Power FET exhibiting low ON resistance, high current as well as high breakdown voltage and fast switching speeds is described. The design which is based on a 1st-order device model, features a novel polysilicon-gate structure and fieldplated groove termination to achieve high packing density and high breakdown voltage, respectively. One test chip, named VNTKI, can block 180 V at an ON resistence of 2.5 ohm. A 150 mil x 200 mil (.19 sq cm) experimental chip has demonstrated a breakdown voltage of 200v, an ON resistance of 0.12 ohm, a switching time of less than 100 ns, and a pulse drain - current of 50 A with 10 V gate drive.

  12. High-current density, high-brightness electron beams from large-area lanthanum hexaboride cathodes

    NASA Astrophysics Data System (ADS)

    Loschialpo, P.; Kapetanakos, C. A.

    1988-04-01

    Large diameter lanthanum hexaboride (LaB6) cathodes operated at 10 kV have produced 1-5-microsec electron pulses with current density between 10 and 20 A/sq cm. Normalized beam brightness, approximately 300,000 A/sq cm sq rad has been consistently measured. To obtain this high-current density, the LaB6 cathodes have been heated to temperatures between about 1600 and 1800 C. Very uniform temperature profiles are obtained by applying a carefully tailored electron bombardment heating power distribution. These measurements have been made between pressure 10 to the -6th to -10 to the -5th Torr, i.e., under much less demanding vacuum conditions than that required by conventional dispenser-type cathodes.

  13. High-current-density field emission display fabricated from single-walled carbon nanotube electron sources

    NASA Astrophysics Data System (ADS)

    Zhao, P.; Shang, X. F.; Ma, Y. P.; Zhou, J. J.; Gu, Z. Q.; Li, Z. H.; Xu, Y. B.; Wang, M.

    2008-06-01

    Single-walled carbon nanotubes can be used as electron sources in the process of field emission, and have great potential for practical application of the field emission display (FED) panels with large screen size. We fabricated a FED using the single-walled carbon nanotubes (SWNTs) as the cathode by the screen-printing process. Test showed that the SWNTs emitters exhibit excellent macroscopic emission properties. It has low turn-on voltage (2.7 V/μ m) and high brightness, with a high current density of good uniformity and stability. It was observed that the field emission qualitatively follows the conventional Fowler Nordheim (F N) theory, and aging treatment played an important role in improving the image uniformity and stability. Compared to other complicated processes, the simple fabrication using screen-printing process seems to be advantageous for practical application.

  14. Emittance and proton fraction measurement in High current electron cyclotron resonance proton ion source

    NASA Astrophysics Data System (ADS)

    Roychowdhury, P.; Kewlani, H.; Mishra, L.; Gharat, S.; Rajawat, R. K.

    2015-09-01

    The beam characterization studies in terms of emittance and proton fraction have been carried out in the high current Electron Cyclotron Resonance (ECR) proton ion source developed for Low Energy High Intensity Proton Accelerator (LEHIPA). The beam emittance was measured using two slit emittance measurement units (EMU). The emittance was measured at three locations (1) after beam extraction at ion source end, (2) after focusing the beam using solenoid magnet and (3) after focusing and separating H+ using solenoid magnet and analyzing magnet. The beam emittance measured in all three cases was found to be less than 0.2π mm-mrad (rms-normalized). The proton fraction in the beam measured using analyzing magnet was found to be more than 90%. The variations of beam emittance and proton fraction have been studied as a function of microwave power and neutral gas pressure.

  15. Enabling cost-effective high-current burst-mode operation in superconducting accelerators

    SciTech Connect

    Sheffield, Richard L.

    2015-06-01

    Superconducting (SC) accelerators are very efficient for CW or long-pulse operation, and normal conducting (NC) accelerators are cost effective for short-pulse operation. The addition of a short NC linac section to a SC linac can correct for the energy droop that occurs when pulsed high-current operation is required that exceeds the capability of the klystrons to replenish the cavity RF fields due to the long field fill-times of SC structures, or a requirement to support a broad range of beam currents results in variable beam loading. This paper describes the implementation of this technique to enable microseconds of high beam-current, 90 mA or more, in a 12 GeV SC long-pulse accelerator designed for the MaRIE 42-keV XFEL proposed for Los Alamos National Laboratory.

  16. High Current Density and Low Thermal Conductivity of Atomically Thin Semimetallic WTe2.

    PubMed

    Mleczko, Michal J; Xu, Runjie Lily; Okabe, Kye; Kuo, Hsueh-Hui; Fisher, Ian R; Wong, H-S Philip; Nishi, Yoshio; Pop, Eric

    2016-08-23

    Two-dimensional (2D) semimetals beyond graphene have been relatively unexplored in the atomically thin limit. Here, we introduce a facile growth mechanism for semimetallic WTe2 crystals and then fabricate few-layer test structures while carefully avoiding degradation from exposure to air. Low-field electrical measurements of 80 nm to 2 μm long devices allow us to separate intrinsic and contact resistance, revealing metallic response in the thinnest encapsulated and stable WTe2 devices studied to date (3-20 layers thick). High-field electrical measurements and electrothermal modeling demonstrate that ultrathin WTe2 can carry remarkably high current density (approaching 50 MA/cm(2), higher than most common interconnect metals) despite a very low thermal conductivity (of the order ∼3 Wm(-1) K(-1)). These results suggest several pathways for air-stable technological viability of this layered semimetal.

  17. A high-current microwave ion source with permanent magnet and its beam emittance measurement

    SciTech Connect

    Yao Zeen; Tan Xinjian; Du Hongxin; Luo Ben; Liu Zhanwen

    2008-07-15

    The progress of a 2.45 GHz high-current microwave ion source with permanent magnet for T(d,n){sup 4}He reaction neutron generator is reported in this paper. At 600 W microwave power and 22 kV extraction voltage, 90 mA peak hydrogen ion beam is extracted from a single aperture of 6 mm diameter. The beam emittance is measured using a simplified pepper-pot method. The (x,x{sup '}) emittance and the (y,y{sup '}) emittance for 14 keV hydrogen ion beam are 55.3{pi} and 58.2{pi} mm mrad, respectively. The normalized emittances are 0.302{pi} and 0.317{pi} mm mrad, respectively.

  18. Transport and Measurements of High-Current Electron Beams from X pinches

    SciTech Connect

    Agafonov, Alexey V.; Mingaleev, Albert R.; Romanova, Vera M.; Tarakanov, Vladimir P.; Shelkovenko, Tatiana A.; Pikuz, Sergey A.; Blesener, Isaac C.; Kusse, Bruce R.; Hammer, David A.

    2009-01-21

    Generation of electron beams is an unavoidable property of X-pinches and other pulsed-power-driven pinches of different geometry. Some issues concerning high-current electron beam transport from the X pinch to the diagnostic system and measurements of the beam current by Faraday cups with different geometry's are discussed. Of particular interest is the partially neutralized nature of the beam propagating from the X-pinch to a diagnostic system. Two scenarios of electron beam propagation from X-pinch to Faraday cup are analyzed by means of computer simulation using the PIC-code KARAT. The first is longitudinal neutralization by ions extracted from plasma at an output window of the X-pinch diode; the second is the beam transport through a plasma background between the diode and a diagnostic system.

  19. Enabling cost-effective high-current burst-mode operation in superconducting accelerators

    DOE PAGESBeta

    Sheffield, Richard L.

    2015-06-01

    Superconducting (SC) accelerators are very efficient for CW or long-pulse operation, and normal conducting (NC) accelerators are cost effective for short-pulse operation. The addition of a short NC linac section to a SC linac can correct for the energy droop that occurs when pulsed high-current operation is required that exceeds the capability of the klystrons to replenish the cavity RF fields due to the long field fill-times of SC structures, or a requirement to support a broad range of beam currents results in variable beam loading. This paper describes the implementation of this technique to enable microseconds of high beam-current,more » 90 mA or more, in a 12 GeV SC long-pulse accelerator designed for the MaRIE 42-keV XFEL proposed for Los Alamos National Laboratory.« less

  20. High Current Density and Low Thermal Conductivity of Atomically Thin Semimetallic WTe2.

    PubMed

    Mleczko, Michal J; Xu, Runjie Lily; Okabe, Kye; Kuo, Hsueh-Hui; Fisher, Ian R; Wong, H-S Philip; Nishi, Yoshio; Pop, Eric

    2016-08-23

    Two-dimensional (2D) semimetals beyond graphene have been relatively unexplored in the atomically thin limit. Here, we introduce a facile growth mechanism for semimetallic WTe2 crystals and then fabricate few-layer test structures while carefully avoiding degradation from exposure to air. Low-field electrical measurements of 80 nm to 2 μm long devices allow us to separate intrinsic and contact resistance, revealing metallic response in the thinnest encapsulated and stable WTe2 devices studied to date (3-20 layers thick). High-field electrical measurements and electrothermal modeling demonstrate that ultrathin WTe2 can carry remarkably high current density (approaching 50 MA/cm(2), higher than most common interconnect metals) despite a very low thermal conductivity (of the order ∼3 Wm(-1) K(-1)). These results suggest several pathways for air-stable technological viability of this layered semimetal. PMID:27434729

  1. New methods for high current fast ion beam production by laser-driven acceleration

    SciTech Connect

    Margarone, D.; Krasa, J.; Prokupek, J.; Velyhan, A.; Laska, L.; Jungwirth, K.; Mocek, T.; Korn, G.; Rus, B.; Torrisi, L.; Gammino, S.; Cirrone, P.; Cutroneo, M.; Romano, F.; Picciotto, A.; Serra, E.; Giuffrida, L.; Mangione, A.; Rosinski, M.; Parys, P.; and others

    2012-02-15

    An overview of the last experimental campaigns on laser-driven ion acceleration performed at the PALS facility in Prague is given. Both the 2 TW, sub-nanosecond iodine laser system and the 20 TW, femtosecond Ti:sapphire laser, recently installed at PALS, are used along our experiments performed in the intensity range 10{sup 16}-10{sup 19} W/cm{sup 2}. The main goal of our studies was to generate high energy, high current ion streams at relatively low laser intensities. The discussed experimental investigations show promising results in terms of maximum ion energy and current density, which make the laser-accelerated ion beams a candidate for new-generation ion sources to be employed in medicine, nuclear physics, matter physics, and industry.

  2. Characteristics of Arc Voltage of High-Current Air Arc in Sealed Chamber

    NASA Astrophysics Data System (ADS)

    Watanabe, Shinya; Kokura, Kentaro; Minoda, Kyohei; Sato, Shinji

    Effect of arc voltage on different factor of design and control was investigated for high current in order to develop design guide of circuit breaker. In this study, dependences on these factors which are current, arc length, surface area on electrode and internal pressure of arc voltage were evaluated quantitatively. As a result of the evaluations, it was estimated that arc voltage near electrode surface rise linearly with arc current and the area on the surface to the power -0.8, and the voltage in arc column rise pressure increase to the power 0.3. We confirmed the validity of the characteristics of the estimated voltage by comparison with the generated voltage in an actual arc extinguishing chamber. The characteristics of the estimated voltage would be provided as effective guidelines to design arc extinguishing chambers.

  3. Switch contact device for interrupting high current, high voltage, AC and DC circuits

    DOEpatents

    Via, Lester C.; Witherspoon, F. Douglas; Ryan, John M.

    2005-01-04

    A high voltage switch contact structure capable of interrupting high voltage, high current AC and DC circuits. The contact structure confines the arc created when contacts open to the thin area between two insulating surfaces in intimate contact. This forces the arc into the shape of a thin sheet which loses heat energy far more rapidly than an arc column having a circular cross-section. These high heat losses require a dramatic increase in the voltage required to maintain the arc, thus extinguishing it when the required voltage exceeds the available voltage. The arc extinguishing process with this invention is not dependent on the occurrence of a current zero crossing and, consequently, is capable of rapidly interrupting both AC and DC circuits. The contact structure achieves its high performance without the use of sulfur hexafluoride.

  4. High ion charge states in a high-current, short-pulse, vacuum ARC ion sources

    SciTech Connect

    Anders, A.; Brown, I.; MacGill, R.; Dickinson, M.

    1996-08-01

    Ions of the cathode material are formed at vacuum arc cathode spots and extracted by a grid system. The ion charge states (typically 1-4) depend on the cathode material and only little on the discharge current as long as the current is low. Here the authors report on experiments with short pulses (several {mu}s) and high currents (several kA); this regime of operation is thus approaching a more vacuum spark-like regime. Mean ion charge states of up to 6.2 for tungsten and 3.7 for titanium have been measured, with the corresponding maximum charge states of up to 8+ and 6+, respectively. The results are discussed in terms of Saha calculations and freezing of the charge state distribution.

  5. Microstructure Analysis of HPb59-1 Brass Induced by High Current Pulsed Electron Beam

    NASA Astrophysics Data System (ADS)

    Lyu, Jike; Gao, Bo; Hu, Liang; Lu, Shuaidan; Tu, Ganfeng

    2016-08-01

    In this paper, the effects of high current pulsed electron beam (HCPEB) on the microstructure evolution of casting HPb59-1 (Cu 57.1 mass%, Pb 1.7 mass% and Zn balance) alloy were investigated. The results showed a "wavy" surface which was formed with Pb element existing in the forms of stacking block and microparticles on the top surface layer after treatment. Nanocrystalline structures including Pb grains and two phases (α and β) were formed on the top remelted layer and their sizes were all less than 100 nm. The disordered β phase was generated in the surface layer after HCPEB treatment, which is beneficial for the improvement of surface properties. Meanwhile, there was a large residual stress on the alloy surface, along with the appearance of microcracks, and the preferred orientations of grains also changed.

  6. Insulator and electrode mass erosion and surface voltage holdoff recovery for transient, high current surface discharges

    NASA Astrophysics Data System (ADS)

    Engel, T. G.; Dickens, J. C.; Kristiansen, M.

    1993-01-01

    Several polymeric insulator materials commonly used as sidewall insulators in EM accelerators are subjected to repetitive, high current transient surface discharges. The insulator materials tested include the thermosetting polymers G-9, G-10, and G-11 (i.e., fiberglass reinforced melamine and epoxy) and the thermoplastic polymers Lexan (i.e, polycarbonate) and Delrin (i.e., polyacetyl). Empirical scaling relationships are given that relate the total amount of insulator and electrode (i.e., molybdenum) mass erosion versus the total amount of arc energy transferred. Scaling relationships are also given that relate the 'lifetime' of the given polymer as a function of the initial discharge current. The 'lifetime' of an insulator material is defined as the number of discharges required to reduce the initial surface holdoff voltage to its half-power level for three consecutive discharges, and is a useful parameter when specifying insulator materials to be used in high power switching devices.

  7. Deposition of ultrahard Ti-Si-N coatings by pulsed high-current reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Oskomov, K. V.; Zakharov, A. N.; Rabotkin, S. V.; Solov'ev, A. A.

    2016-02-01

    We report on the results of investigation of properties of ultrahard Ti-Si-N coatings deposited by pulsed high-current magnetron reactive sputtering (discharge pulse voltage is 300-900 V, discharge pulse current is up to 200 A, pulse duration is 10-100 μs, and pulse repetition rate is 20-2000 Hz). It is shown that for a short sputtering pulse (25 μs) and a high discharge current (160 A), the films exhibit high hardness (66 GPa), wear resistance, better adhesion, and a lower sliding friction coefficient. The reason is an enhancement of ion bombardment of the growing coating due to higher plasma density in the substrate region (1013 cm-3) and a manifold increase in the degree of ionization of the plasma with increasing peak discharge current (mainly due to the material being sputtered).

  8. Neutron generator for BNCT based on high current ECR ion source with gyrotron plasma heating.

    PubMed

    Skalyga, V; Izotov, I; Golubev, S; Razin, S; Sidorov, A; Maslennikova, A; Volovecky, A; Kalvas, T; Koivisto, H; Tarvainen, O

    2015-12-01

    BNCT development nowadays is constrained by a progress in neutron sources design. Creation of a cheap and compact intense neutron source would significantly simplify trial treatments avoiding use of expensive and complicated nuclear reactors and accelerators. D-D or D-T neutron generator is one of alternative types of such sources for. A so-called high current quasi-gasdynamic ECR ion source with plasma heating by millimeter wave gyrotron radiation is suggested to be used in a scheme of D-D neutron generator in the present work. Ion source of that type was developed in the Institute of Applied Physics of Russian Academy of Sciences (Nizhny Novgorod, Russia). It can produce deuteron ion beams with current density up to 700-800 mA/cm(2). Generation of the neutron flux with density at the level of 7-8·10(10) s(-1) cm(-2) at the target surface could be obtained in case of TiD2 target bombardment with deuteron beam accelerated to 100 keV. Estimations show that it is enough for formation of epithermal neutron flux with density higher than 10(9) s(-1) cm(-2) suitable for BNCT. Important advantage of described approach is absence of Tritium in the scheme. First experiments performed in pulsed regime with 300 mA, 45 kV deuteron beam directed to D2O target demonstrated 10(9) s(-1) neutron flux. This value corresponds to theoretical estimations and proofs prospects of neutron generator development based on high current quasi-gasdynamic ECR ion source. PMID:26302662

  9. Beam extraction and high stability operation of high current electron cyclotron resonance proton ion source

    NASA Astrophysics Data System (ADS)

    Roychowdhury, P.; Mishra, L.; Kewlani, H.; Patil, D. S.; Mittal, K. C.

    2014-03-01

    A high current electron cyclotron resonance proton ion source is designed and developed for the low energy high intensity proton accelerator at Bhabha Atomic Research Centre. The plasma discharge in the ion source is stabilized by minimizing the reflected microwave power using four stub auto tuner and magnetic field. The optimization of extraction geometry is performed using PBGUNS code by varying the aperture, shape, accelerating gap, and the potential on the electrodes. While operating the source, it was found that the two layered microwave window (6 mm quartz plate and 2 mm boron nitride plate) was damaged (a fine hole was drilled) by the back-streaming electrons after continuous operation of the source for 3 h at beam current of 20-40 mA. The microwave window was then shifted from the line of sight of the back-streaming electrons and located after the water-cooled H-plane bend. In this configuration the stable operation of the high current ion source for several hours is achieved. The ion beam is extracted from the source by biasing plasma electrode, puller electrode, and ground electrode to +10 to +50 kV, -2 to -4 kV, and 0 kV, respectively. The total ion beam current of 30-40 mA is recorded on Faraday cup at 40 keV of beam energy at 600-1000 W of microwave power, 800-1000 G axial magnetic field and (1.2-3.9) × 10-3 mbar of neutral hydrogen gas pressure in the plasma chamber. The dependence of beam current on extraction voltage, microwave power, and gas pressure is investigated in the range of operation of the ion source.

  10. Beam extraction and high stability operation of high current electron cyclotron resonance proton ion source

    SciTech Connect

    Roychowdhury, P. Mishra, L.; Kewlani, H.; Mittal, K. C.; Patil, D. S.

    2014-03-15

    A high current electron cyclotron resonance proton ion source is designed and developed for the low energy high intensity proton accelerator at Bhabha Atomic Research Centre. The plasma discharge in the ion source is stabilized by minimizing the reflected microwave power using four stub auto tuner and magnetic field. The optimization of extraction geometry is performed using PBGUNS code by varying the aperture, shape, accelerating gap, and the potential on the electrodes. While operating the source, it was found that the two layered microwave window (6 mm quartz plate and 2 mm boron nitride plate) was damaged (a fine hole was drilled) by the back-streaming electrons after continuous operation of the source for 3 h at beam current of 20–40 mA. The microwave window was then shifted from the line of sight of the back-streaming electrons and located after the water-cooled H-plane bend. In this configuration the stable operation of the high current ion source for several hours is achieved. The ion beam is extracted from the source by biasing plasma electrode, puller electrode, and ground electrode to +10 to +50 kV, −2 to −4 kV, and 0 kV, respectively. The total ion beam current of 30–40 mA is recorded on Faraday cup at 40 keV of beam energy at 600–1000 W of microwave power, 800–1000 G axial magnetic field and (1.2–3.9) × 10{sup −3} mbar of neutral hydrogen gas pressure in the plasma chamber. The dependence of beam current on extraction voltage, microwave power, and gas pressure is investigated in the range of operation of the ion source.

  11. HIGH-CURRENT COLD CATHODE FIELD EMISSION ARRAY FOR ELECTRON LENS APPLICATION

    SciTech Connect

    Hirshfield, Jay L

    2012-12-28

    During Phase I, the following goals were achieved: (1) design and fabrication of a novel, nano-dimensional CNT field emitter assembly for high current density application, with high durability; (2) fabrication of a ceramic based micro channel plate (MCP) and characterization of its secondary electron emission; and (3) characterizing the CNT/MCP cathode for high field emission and durability. As a result of these achievements, a relatively high current density of ~ 1.2 A/cm2 from a CNT cathode and single channel MCP were measured. The emission current was also extremely stable with a peak-to-peak variation of only 1.8%. The emission current could be further enhanced to meet requirements for electron lens applications by increasing the number of MCP channels. A calculation for maximum possible current density with a 1200 channel/cm2 MCP, placed over a cathode with 1200 uniformly functioning CNTs, would be ~1.46 kA/cm2, neglecting space charge limitations. Clearly this level of emission is far greater than what is needed for the electron lens application, but it does offer a highly comforting margin to account for sub-standard emitters and/or to allow the lesser challenge of building a cathode with fewer channels/cm2. A satisfactory goal for the electron lens application would be a controllable emission of 2-4 mA per channel in an ensemble of 800-1200 uniformly-functioning channels/cm2, and a cathode with overall area of about 1 cm2.

  12. Neutron generator for BNCT based on high current ECR ion source with gyrotron plasma heating.

    PubMed

    Skalyga, V; Izotov, I; Golubev, S; Razin, S; Sidorov, A; Maslennikova, A; Volovecky, A; Kalvas, T; Koivisto, H; Tarvainen, O

    2015-12-01

    BNCT development nowadays is constrained by a progress in neutron sources design. Creation of a cheap and compact intense neutron source would significantly simplify trial treatments avoiding use of expensive and complicated nuclear reactors and accelerators. D-D or D-T neutron generator is one of alternative types of such sources for. A so-called high current quasi-gasdynamic ECR ion source with plasma heating by millimeter wave gyrotron radiation is suggested to be used in a scheme of D-D neutron generator in the present work. Ion source of that type was developed in the Institute of Applied Physics of Russian Academy of Sciences (Nizhny Novgorod, Russia). It can produce deuteron ion beams with current density up to 700-800 mA/cm(2). Generation of the neutron flux with density at the level of 7-8·10(10) s(-1) cm(-2) at the target surface could be obtained in case of TiD2 target bombardment with deuteron beam accelerated to 100 keV. Estimations show that it is enough for formation of epithermal neutron flux with density higher than 10(9) s(-1) cm(-2) suitable for BNCT. Important advantage of described approach is absence of Tritium in the scheme. First experiments performed in pulsed regime with 300 mA, 45 kV deuteron beam directed to D2O target demonstrated 10(9) s(-1) neutron flux. This value corresponds to theoretical estimations and proofs prospects of neutron generator development based on high current quasi-gasdynamic ECR ion source.

  13. Modeling of the anode surface deformation in high-current vacuum arcs with AMF contacts

    NASA Astrophysics Data System (ADS)

    Huang, Xiaolong; Wang, Lijun; Deng, Jie; Jia, Shenli; Qin, Kang; Shi, Zongqian

    2016-02-01

    A high-current vacuum arc subjected to an axial magnetic field is maintained in a diffuse status. With an increase in arc current, the energy carried by the arc column to the anode becomes larger and finally leads to the anode temperature exceeding the melting point of the anode material. When the anode melting pool is formed, and the rotational plasma of the arc column delivers its momentum to the melting pool, the anode melting pool starts to rotate and also flow outwards along the radial direction, which has been photographed by some researchers using high-speed cameras. In this paper, the anode temperature and melting status is calculated using the melting and solidification model. The swirl flow of the anode melting pool and deformation of the anode is calculated using the magneto-hydrodynamic (MHD) model with the volume of fraction (VOF) method. All the models are transient 2D axial-rotational symmetric models. The influence of the impaction force of the arc plasma, electromagnetic force, viscosity force, and surface tension of the liquid metal are all considered in the model. The heat flux density injected into the anode and the arc pressure are obtained from the 3D numerical simulation of the high-current vacuum arc using the MHD model, which gives more realistic parameters for the anode simulation. Simulation results show that the depth of the anode melting pool increases with an increase in the arc current. Some droplets sputter out from the anode surface, which is caused by the inertial centrifugal force of the rotational melting pool and strong plasma pressure. Compared with the previous anode melting model without consideration of anode deformation, when the deformation and swirl flow of the anode melting pool are considered, the anode temperature is relatively lower, and just a little more than the melting point of Cu. This is because of liquid droplets sputtering out of the anode surface taking much of the energy away from the anode surface. The

  14. Current constriction of high-current vacuum arc in vacuum interrupters

    SciTech Connect

    Wang Lijun; Jia Shenli; Zhang Ling; Yang Dingge; Shi Zongqian; Gentils, Francois; Jusselin, Benoit

    2008-03-15

    Compared with previous paper [L. Wang et al., J. Appl. Phys. 100, 113304 (2006)], higher-current vacuum arc is simulated and analyzed based on magnetohydrodynamics model, and current constriction phenomenon in arc column is mainly paid attention to and analyzed in this paper. According to simulation results, it can be found that significant current constriction only appears near anode regions for lower-current vacuum arc. However, with the increase of arc current, current constriction also appears near the cathode side, and with the further increase of arc current, current constriction near the cathode side can become more significant than that near the anode side. The current constriction near the cathode side can be mainly caused by very high current level. The increase of axial magnetic field (AMF) strength will inhibit current constriction in the whole arc column. For influence of AMF distribution, saddle-shaped distributed AMF can more efficiently inhibit current constriction of arc column than bell-shaped AMF. The phenomenon of current constriction near the cathode side has also been found by many experiments, which also can verify the correctness of simulation results.

  15. Development and fabrication of a high current, fast recovery power diode

    NASA Astrophysics Data System (ADS)

    Berman, A. H.; Balodis, V.; Devance, D. C.; Gaugh, C. E.; Karlsson, E. A.

    1983-10-01

    A high voltage (VR = 1200 V), high current (IF = 150 A), fast recovery ( 700 ns) and low forward voltage drop ( 1.5 V) silicon rectifier was designed and the process developed for its fabrication. For maximum purity, uniformity and material characteristic stability, neutron transmutation n-type doped float zone silicon is used. The design features a hexagonal chip for maximum area utilization of space available in the DO-8 diode package, PIN diffused junction structure with deep diffused D(+) anode and a shallow high concentration n(+) cathode. With the high temperature glass passivated positive bevel mesa junction termination, the achieved blocking voltage is close to the theoretical limit of the starting material. Gold diffusion is used to control the lifetime and the resulting effect on switching speed and forward voltage tradeoff. For solder reflow assembly, trimetal (Al-Ti-Ni) contacts are used. The required major device electrical characteristics were achieved. Due to the tradeoff nature of forward voltage drop and reverse recovery time, a compromise was reached for these values.

  16. Integrating a Machine Protection System for High-Current Free Electron Lasers and Energy Recovery Linacs

    SciTech Connect

    Trent Allison; James Coleman; Richard Evans; Al Grippo; Kevin Jordan

    2002-09-01

    A fully integrated Machine Protection System (MPS) is critical to efficient commissioning and safe operation of all high-current accelerators. The MPS needs to monitor the status of all devices that could enter the beam path, the beam loss monitors (BLMs), magnet settings, beam dump status, etc. This information is then presented to the electron source controller, which must limit the beam power or shut down the beam completely. The MPS for the energy recovery linac (ERL) at the Jefferson Lab Free Electron Laser [1] generates eight different power limits, or beam modes, which are passed to the drive laser pulse controller (DLPC) (photocathode source controller). These range from no beam to nearly 2 megawatts of electron beam power. Automatic masking is used for the BLMs during low-power modes when one might be using beam viewers. The system also reviews the setup for the two different beamlines, the IR path or the UV path, and will allow or disallow operations based on magnet settings and valve positions. This paper will describe the approach taken for the JLab 10-kW FEL. Additional details can be found on our website http://laser.jlab.org [2].

  17. A strong-focusing 800 MeV cyclotron for high-current applications

    NASA Astrophysics Data System (ADS)

    Pogue, N.; Assadi, S.; Badgley, K.; Comeaux, J.; Kellams, J.; McInturff, A.; McIntyre, P.; Sattarov, A.

    2013-04-01

    A superconducting strong-focusing cyclotron (SFC) is being developed for high-current applications. It incorporates four innovations. Superconducting quarter-wave cavities are used to provide >20 MV/turn acceleration. The orbit separation is thereby opened so that bunch-bunch interactions between successive orbits are eliminated. Quadrapole focusing channels are incorporated within the sectors so that alternating-gradient strong-focusing transport is maintained throughout. Dipole windings on the inner and outer orbits provide enhanced control for injection and extraction of bunches. Finally each sector magnet is configured as a flux-coupled stack of independent apertures, so that any desired number of independent cyclotrons can be integrated within a common footprint. Preliminary simulations indicate that each SFC should be capable of accelerating 10 mA CW to 800 MeV with very low loss and >50% energy efficiency. A primary motivation for SFC is as a proton driver for accelerator-driven subcritical fission in a molten salt core. The cores are fueled solely with the transuranics from spent nuclear fuel from a conventional nuclear power plant. The beams from one SFC stack would destroy all of the transuranics and long-lived fission products that are produced by a GWe reactor [1]. This capability offers the opportunity to close the nuclear fuel cycle and provide a path to green nuclear energy.

  18. Langmuir probe diagnostics of plasma in high current electron cyclotron resonance proton ion source

    NASA Astrophysics Data System (ADS)

    Roychowdhury, P.; Kewlani, H.; Mishra, L.; Patil, D. S.; Mittal, K. C.

    2013-07-01

    A high current Electron Cyclotron Resonance (ECR) proton ion source has been developed for low energy high intensity proton accelerator at Bhabha Atomic Research Centre. Langmuir probe diagnostics of the plasma generated in this proton ion source is performed using Langmuir probe. The diagnostics of plasma in the ion source is important as it determines beam parameters of the ion source, i.e., beam current, emittance, and available species. The plasma parameter measurement in the ion source is performed in continuously working and pulsed mode using hydrogen as plasma generation gas. The measurement is performed in the ECR zone for operating pressure and microwave power range of 10-4-10-3 mbar and 400-1000 W. An automated Langmuir probe diagnostics unit with data acquisition system is developed to measure these parameters. The diagnostics studies indicate that the plasma density and plasma electron temperature measured are in the range 5.6 × 1010 cm-3 to 3.8 × 1011 cm-3 and 4-14 eV, respectively. Using this plasma, ion beam current of tens of mA is extracted. The variations of plasma parameters with microwave power, gas pressure, and radial location of the probe have been studied.

  19. Electromagnetic and beam dynamics studies of a high current drift tube linac for LEHIPA

    NASA Astrophysics Data System (ADS)

    Roy, S.; Rao, S. V. L. S.; Pande, R.; Krishnagopal, S.; Singh, P.

    2014-06-01

    We have performed detailed electromagnetic and beam dynamics studies of a 352.21 MHz drift-tube linac (DTL) that will accelerate a 30 mA CW proton beam from 3 to 20 MeV. At such high currents space charge effects are important, and therefore the effect of linear as well as non-linear space charge has been studied (corresponding to uniform and Gaussian initial beam distributions), in order to avoid space charge instabilities. To validate the electromagnetic simulations, a 1.2 m long prototype of the DTL was fabricated. RF measurements performed on the prototype were in good agreement with the simulations. A detailed simulation study of beam halos was also performed, which showed that beyond a current of 10 mA, significant longitudinal beam halos are excited even for a perfectly matched beam, whereas for a mis-matched beam transverse beam halos are also excited. However, these do not lead to any beam loss within the DTL.

  20. Microstructures and properties of zirconium-702 irradiated by high current pulsed electron beam

    NASA Astrophysics Data System (ADS)

    Yang, Shen; Cai, Jie; Lv, Peng; Zhang, Conglin; Huang, Wei; Guan, Qingfeng

    2015-09-01

    The microstructure, hardness and corrosion resistance of zirconium-702 before and after high-current pulsed electron beam (HCPEB) irradiation have been investigated. The microstructure evolution and surface morphologies of the samples were characterized by using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental results indicate that the sample surface was melted after HCPEB irradiation, and martensitic phase transformation occurred. Besides, two kinds of craters as well as ultrafine structures were obtained in the melted layer. TEM observations suggest that high density dislocations and deformation twins were formed after HCPEB irradiation. With the increasing of pulses, microhardness of the irradiated samples was increased from the initial 178 Hv to 254 Hv. The corrosion resistance was tested by using electrode impedance spectroscopy (EIS) and potentiodynamic polarization curves. Electrochemical results show that, after HCPEB irradiation, all the samples had better corrosion resistance in 1 mol HNO3 solution compared to the initial one, among which the 5-pulsed sample owned the best corrosion resistance. Ultrafine structures, martensitic phase transformation, surface porosities, dislocations and deformation twins are believed to be the dominant reasons for the improvement of the hardness and corrosion resistance.

  1. Sharp burnout failure observed in high current-carrying double-walled carbon nanotube fibers.

    PubMed

    Song, Li; Toth, Geza; Wei, Jinquan; Liu, Zheng; Gao, Wei; Ci, Lijie; Vajtai, Robert; Endo, Morinobu; Ajayan, Pulickel M

    2012-01-13

    We report on the current-carrying capability and the high-current-induced thermal burnout failure modes of 5-20 μm diameter double-walled carbon nanotube (DWNT) fibers made by an improved dry-spinning method. It is found that the electrical conductivity and maximum current-carrying capability for these DWNT fibers can reach up to 5.9 × 10(5) S m(-1) and over 1 × 10(5) A cm(-2) in air. In comparison, we observed that standard carbon fiber tended to be oxidized and burnt out into cheese-like morphology when the maximum current was reached, while DWNT fiber showed a much slower breakdown behavior due to the gradual burnout in individual nanotubes. The electron microscopy observations further confirmed that the failure process of DWNT fibers occurs at localized positions, and while the individual nanotubes burn they also get aligned due to local high temperature and electrostatic field. In addition a finite element model was constructed to gain better understanding of the failure behavior of DWNT fibers. PMID:22156276

  2. High current pulsed electron beam treatment of AZ31 Mg alloy

    SciTech Connect

    Gao Bo; Hao Shengzhi; Zou Jianxin; Grosdidier, Thierry; Jiang Limin; Zhou Jiyang; Dong Chuang

    2005-11-15

    This paper reports, for the first time, an analysis of the effect of High Current Pulsed Electron Beam (HCPEB) on a Mg alloy. The AZ31 alloy was HCPEB treated in order to see the potential of this fairly recent technique in modifying its wear resistance. For the 2.5 J/cm{sup 2} beam energy density used in the present work, the evaporation mode was operative and led to the formation of a ''wavy'' surface and the absence of eruptive microcraters. The selective evaporation of Mg over Al led to an Al-rich melted surface layer and precipitation hardening from the over saturated solid solution. Due to the increase in hardness of the top surface layer, the friction coefficient values were lowered by more than 20% after the HCPEB treatments, and the wear resistance was drastically (by a factor of 6) improved. The microhardness of the HCPEB samples was also increased significantly down to a depth of about 500 {mu}m, far exceeding the heat-affected zone (about 40 {mu}m). This is due to the effect of the propagation of the shockwave associated with this HCPEB treatment.

  3. A cookbook for building a high-current dimpled H– magnetron source for accelerators

    DOE PAGESBeta

    Bollinger, Daniel S.; Karns, Patrick R.; Tan, Cheng -Yang

    2015-10-30

    A high-current (>50 mA) dimpled H– magnetron source has been built at Fermilab for supplying H– beam to the entire accelerator complex. Despite many decades of expertise with slit H– magnetron sources at Fermilab, we were faced with many challenges from the dimpled H– magnetron source, which needed to be overcome in order to make it operational. Dimpled H– sources for high-energy physics are not new: Brookhaven National Laboratory has operated a dimpled H- source for more than two decades. However, the transference of that experience to Fermilab took about two years because a cookbook for building this type ofmore » source did not exist and seemingly innocuous or undocumented choices had a huge impact on the success or failure for this type of source. Moreover, it is the goal of this paper to document the reasons for these choices and to present a cookbook for building and operating dimpled H– magnetron sources.« less

  4. End station design and wafer quality control for a high current oxygen implanter

    NASA Astrophysics Data System (ADS)

    Douglas-Hamilton, D. H.; Ruffell, John P.; Kaim, R. E.; Izumi, K.

    The end station of the Eaton NV-200 high current oxygen implanter is described. In this machine the beam enters at 30° from the horizontal and the wafers are mounted on the inside surface of a slightly conical drum which rotates about a vertical axis. A cone half angle of 16° results in an implant angle of 14°. The drum rotates at a high speed and the beam is broadened into a line which fully illuminates the wafers without scanning, resulting in a uniform implant as the wafers pass through it on the rotating drum. By adjusting the ion source apertures and beam line optics implant uniformity within a few percent has been achieved over the whole wafer. The drum holds twenty-five 4 in. wafers per batch. Sampling holes located in the drum together with a Faraday plate in the end station are used to monitor beam uniformity. Dose measurement is done calorimetrically using the power into the end station to calculate the integrated dose. The end station is equipped with heater lamps which will preheat the wafers to the desired temperature before the implantation process is begun. These lamps are also utilized to maintain the wafers at an elevated temperature if the implant is interrupted.

  5. Langmuir probe diagnostics of plasma in high current electron cyclotron resonance proton ion source

    SciTech Connect

    Roychowdhury, P.; Kewlani, H.; Mishra, L.; Mittal, K. C.; Patil, D. S.

    2013-07-15

    A high current Electron Cyclotron Resonance (ECR) proton ion source has been developed for low energy high intensity proton accelerator at Bhabha Atomic Research Centre. Langmuir probe diagnostics of the plasma generated in this proton ion source is performed using Langmuir probe. The diagnostics of plasma in the ion source is important as it determines beam parameters of the ion source, i.e., beam current, emittance, and available species. The plasma parameter measurement in the ion source is performed in continuously working and pulsed mode using hydrogen as plasma generation gas. The measurement is performed in the ECR zone for operating pressure and microwave power range of 10{sup −4}–10{sup −3} mbar and 400–1000 W. An automated Langmuir probe diagnostics unit with data acquisition system is developed to measure these parameters. The diagnostics studies indicate that the plasma density and plasma electron temperature measured are in the range 5.6 × 10{sup 10} cm{sup −3} to 3.8 × 10{sup 11} cm{sup −3} and 4–14 eV, respectively. Using this plasma, ion beam current of tens of mA is extracted. The variations of plasma parameters with microwave power, gas pressure, and radial location of the probe have been studied.

  6. Current halo structures in high-current plasma experiments: {theta}-pinch

    SciTech Connect

    Matveev, Yu. V.

    2007-03-15

    Experimental data elucidating mechanisms for halo formation in {theta}-pinch discharges are presented and discussed. The experiments were performed with different gases (H{sub 2}, D{sub 2}, He, and Ar) in a theta-pinch device with a porcelain vacuum chamber and an excitation coil 15 cm in diameter and 30 cm in length. The stored energy, the current in the excitation coil, and the current half-period were W = 10 kJ, I = 400 kA, and T/2 = 14 {mu}s, respectively. It is found that the plasma rings (halos) surrounding the pinch core arise as a result of coaxial pinch stratification due to both the excitation of closed currents (inductons) inside the pinch and the radial convergence of the plasma current sheaths produced after the explosion of T-layers formed near the wall in the initial stage of the discharge. It is concluded that halo structures observed in pinches, tokamaks, and other high-current devices used in controlled fusion research have the same nature.

  7. High current density PQQ-dependent alcohol and aldehyde dehydrogenase bioanodes.

    PubMed

    Aquino Neto, Sidney; Hickey, David P; Milton, Ross D; De Andrade, Adalgisa R; Minteer, Shelley D

    2015-10-15

    In this paper, we explore the bioelectrooxidation of ethanol using pyrroloquinoline quinone (PQQ)-dependent alcohol and aldehyde dehydrogenase (ADH and AldDH) enzymes for biofuel cell applications. The bioanode architectures were designed with both direct electron transfer (DET) and mediated electron transfer (MET) mechanisms employing high surface area materials such as multi-walled carbon nanotubes (MWCNTs) and MWCNT-decorated gold nanoparticles, along with different immobilization techniques. Three different polymeric matrices were tested (tetrabutyl ammonium bromide (TBAB)-modified Nafion; octyl-modified linear polyethyleneimine (C8-LPEI); and cellulose) in the DET studies. The modified Nafion membrane provided the best electrical communication between enzymes and the electrode surface, with catalytic currents as high as 16.8 ± 2.1 µA cm(-2). Then, a series of ferrocene redox polymers were evaluated for MET. The redox polymer 1,1'-dimethylferrocene-modified linear polyethyleneimine (FcMe2-C3-LPEI) provided the best electrochemical response. Using this polymer, the electrochemical assays conducted in the presence of MWCNTs and MWCNTs-Au indicated a Jmax of 781 ± 59 µA cm(-2) and 925 ± 68 µA cm(-2), respectively. Overall, from the results obtained here, DET using the PQQ-dependent ADH and AldDH still lacks high current density, while the bioanodes that operate via MET employing ferrocene-modified LPEI redox polymers show efficient energy conversion capability in ethanol/air biofuel cells.

  8. Deformation of contact surfaces in a vacuum interrupter after high-current interruptions

    NASA Astrophysics Data System (ADS)

    Wang, Haoran; Wang, Zhenxing; Zhou, Zhipeng; Jiang, Yanjun; Wang, Jianhua; Geng, Yingsan; Liu, Zhiyuan

    2016-08-01

    In a high-current interruption, the contact surface in a vacuum interrupter might be severely damaged by constricted vacuum arcs causing a molten area on it. As a result, a protrusion will be initiated by a transient recovery voltage after current zero, enhancing the local electric field and making breakdowns occur easier. The objective of this paper is to simulate the deformation process on the molten area under a high electric field by adopting the finite element method. A time-dependent Electrohydrodynamic model was established, and the liquid-gas interface was tracked by the level-set method. From the results, the liquid metal can be deformed to a Taylor cone if the applied electric field is above a critical value. This value is correlated to the initial geometry of the liquid metal, which increases as the size of the liquid metal decreases. Moreover, the buildup time of a Taylor cone obeys the power law t = k × E-3, where E is the initial electric field and k is a coefficient related to the material property, indicating a temporal self-similar characteristic. In addition, the influence of temperature has little impact on the deformation but has great impact on electron emission. Finally, the possible reason to initiate a delayed breakdown is associated with the deformation. The breakdown does not occur immediately when the voltage is just applied upon the gap but is postponed to several milliseconds later when the tip is formed on the liquid metal.

  9. Prediction of SFL Interruption Performance from the Results of Arc Simulation during High-Current Phase

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Chul; Lee, Won-Ho; Kim, Woun-Jea

    2015-09-01

    The design and development procedures of SF6 gas circuit breakers are still largely based on trial and error through testing although the development costs go higher every year. The computation cannot cover the testing satisfactorily because all the real processes arc not taken into account. But the knowledge of the arc behavior and the prediction of the thermal-flow inside the interrupters by numerical simulations are more useful than those by experiments due to the difficulties to obtain physical quantities experimentally and the reduction of computational costs in recent years. In this paper, in order to get further information into the interruption process of a SF6 self-blast interrupter, which is based on a combination of thermal expansion and the arc rotation principle, gas flow simulations with a CFD-arc modeling are performed during the whole switching process such as high-current period, pre-current zero period, and current-zero period. Through the complete work, the pressure-rise and the ramp of the pressure inside the chamber before current zero as well as the post-arc current after current zero should be a good criterion to predict the short-line fault interruption performance of interrupters.

  10. Gamma-resonance Contraband Detection using a high current tandem accelerator

    SciTech Connect

    Milton, B. F.; Beis, J.; Dale, D.; Rogers, J.; Ruegg, R.; Debiak, T.; Kamykowski, E.; Melnychuk, S.; Rathke, J.; Sredniawski, J.

    1999-04-26

    TRIUMF and Northrop Grumman have developed a new system for the detection of concealed explosives and drugs. This Contraband Detection System (CDS) is based on the resonant absorption by {sup 14}N of gammas produced using {sup 13}C(p,{gamma}){sup 14}N. The chosen reaction uses protons at 1.75 MeV and the gammas have an energy of 9.17 MeV. By measuring both the resonant and the non-resonant absorption using detectors with good spatial resolution, and applying standard tomographic techniques, we are able to produce 3D images of both the nitrogen partial density and the total density. The images together may be utilized with considerable confidence to determine if small amounts of nitrogen based explosives, heroin or cocaine are present in the interrogated containers. Practical Gamma Resonant Absorption (GRA) scanning requires an intense source of protons. However this proton source must also be very stable, have low energy spread, and have good spatial definition. These demands suggested a tandem as the accelerator of choice. We have therefore constructed a 2 MeV H{sup -} tandem optimized for high current (10 mA) operation, while minimizing the overall size of the accelerator. This has required several special innovations which will be presented in the paper. We will also present initial commissioning results.

  11. Incorporation of Ca and P on anodized titanium surface: Effect of high current density.

    PubMed

    Laurindo, Carlos A H; Torres, Ricardo D; Mali, Sachin A; Gilbert, Jeremy L; Soares, Paulo

    2014-04-01

    This study systematically evaluated the surface and corrosion characteristics of commercially pure titanium (grade 2) modified by plasma electrolytic oxidation (PEO) with high current density. The anodization process was carried out galvanostatically (constant current density) using a solution containing calcium glycerophosphate (0.02mol/L) and calcium acetate (0.15mol/L). The current densities applied were 400, 700, 1000 and 1200mA/cm(2) for a period of 15s. Composition, crystalline structure, morphology, roughness, wettability and "in-vitro" bioactivity test in SBF of the anodized layer were evaluated by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, profilometry and contact angle measurements. Corrosion properties were evaluated by open circuit potential, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The results show that the TiO2 oxide layers present an increase of thickness, porosity, roughness, wettability, Ca/P ratio, and bioactivity, with the applied current density up to 1000mA/cm(2). Corrosion resistance also increases with applied current density. It is observed that for 1200mA/cm(2), there is a degradation of the oxide layer. In general, the results suggest that the anodized TiO2 layer with better properties is formed with an applied current of 1000mA/cm(2).

  12. Sharp burnout failure observed in high current-carrying double-walled carbon nanotube fibers

    NASA Astrophysics Data System (ADS)

    Song, Li; Toth, Geza; Wei, Jinquan; Liu, Zheng; Gao, Wei; Ci, Lijie; Vajtai, Robert; Endo, Morinobu; Ajayan, Pulickel M.

    2012-01-01

    We report on the current-carrying capability and the high-current-induced thermal burnout failure modes of 5-20 µm diameter double-walled carbon nanotube (DWNT) fibers made by an improved dry-spinning method. It is found that the electrical conductivity and maximum current-carrying capability for these DWNT fibers can reach up to 5.9 × 105 S m - 1 and over 1 × 105 A cm - 2 in air. In comparison, we observed that standard carbon fiber tended to be oxidized and burnt out into cheese-like morphology when the maximum current was reached, while DWNT fiber showed a much slower breakdown behavior due to the gradual burnout in individual nanotubes. The electron microscopy observations further confirmed that the failure process of DWNT fibers occurs at localized positions, and while the individual nanotubes burn they also get aligned due to local high temperature and electrostatic field. In addition a finite element model was constructed to gain better understanding of the failure behavior of DWNT fibers.

  13. Evaluation of conductor stresses in a pulsed high-current toroidal transformer

    SciTech Connect

    Turchi, Peter J; Rousculp, Chritopher L; Reass, William A; Oro, David M; Merrill, Frank E; Greigo, Jeffery R; Reinovsky, Robert E

    2009-01-01

    The Precision, High-Energy Density, Liner Implosion Experiment (PHELIX) pulsed power driver is currently under development at Los Alamos National Laboratory. When operational PHELIX will provide 5-10 MAmps of peak current with pulse rise-time of {approx} 5-10 ms. Crucial to the performance of PHELIX is a multi-turn primary, single-turn secondary, current step-up toroidal transformer, R{sub major} {approx} 30 cm, R{sub minor} {approx} 10 cm. The transformer lifetime should exceed 100 shots. Therefore it is essential that the design be robust enough to survive the magnetic stresses produced by high currents. In order to evaluate their design, two methods have been utilized. First, an analytical evaluation has been performed. By identifying the magnetic forces as J{sub 1}{sup 2}/2 {del}L{sub 1} + J{sub 1}J{sub 2}{del}M{sub 12}, where J{sub 1} and J{sub 2} are currents in two circuits, coupled by mutual inductance M{sub 12} and L{sub 1} is the self-inductance of the circuit carrying current J{sub 1}, analytical estimates of stress can be obtained. These results are then compared to a computational MHD model of the same system and to a full finite-element, electromagnetic simulation.

  14. Hybrid monitor for both beam position and tilt of pulsed high-current beams

    SciTech Connect

    Pang, J. He, X.; Ma, C.; Zhao, L.; Li, Q.; Dai, Z.

    2014-09-15

    A Hybrid beam monitor, integrated with both azimuthal and axial B-dot probes, was designed for simultaneous measurement of both beam position and beam angle for pulsed high-current beams at the same location in beam pipe. The output signals of axial B-dot probes were found to be mixed with signals caused by transverse position deviation. In order to eliminate the unwanted signals, an elimination method was developed and its feasibility tested on a 50-Ω coaxial line test stand. By this method, a waveform, shape-like to that of input current and proportional to the tilt angle, was simulated and processed by following integration step to achieve the tilt angle. The tests showed that the measurement error of displacement and tilt angle less than 0.3 mm and 1.5 mrad, respectively. The latter error could be reduced with improved probes by reducing the inductance of the axial B-dot probe, but the improvement reached a limit due to some unknown systemic mechanism.

  15. Scalability of buried microreflector light-emitting diodes for high-current applications

    NASA Astrophysics Data System (ADS)

    Illek, Stefan; Pietzonka, Ines; Ploessl, Andreas; Stauss, Peter; Wegleiter, Walter; Windisch, Reiner; Wirth, Ralph; Zull, Heribert; Streubel, Klaus P.

    2003-07-01

    The combination of wafer soldering using metal layers and the introduction of buried micro-reflector structures has proven to be a promising approach to fabricate high brightness, substrate-less LEDs in the AlGaInP material system. In addition to the enhanced light output, the scalability of this approach has been predicted as a major advantage. In contrast to other approaches, larger area LEDs can be fabricated without altering the epitaxial structure and thickness of layers simply by offering a larger area for light generation. First samples of amber (λ = 615 nm) buried micro-reflector LEDs with side-length up to 1000 μm have been realized. Devices mounted in packages with improved heat sinks are capable of low voltage CW operation with currents as high as 600 mA (Vfw<= 2,8 V) without significant thermal flattening of the light-current characteristics. The maximum luminous flux achieved at these oeprating conditions is 46 lumen. Already these first experiments demonstrate the potential of the concept of buried micro-reflector LEDs not only for high-brightness but also for high-current operation. The results are among the best values of high-flux LEDs in this wavelength range.

  16. Development and fabrication of a high current, fast recovery power diode

    NASA Technical Reports Server (NTRS)

    Berman, A. H.; Balodis, V.; Devance, D. C.; Gaugh, C. E.; Karlsson, E. A.

    1983-01-01

    A high voltage (VR = 1200 V), high current (IF = 150 A), fast recovery ( 700 ns) and low forward voltage drop ( 1.5 V) silicon rectifier was designed and the process developed for its fabrication. For maximum purity, uniformity and material characteristic stability, neutron transmutation n-type doped float zone silicon is used. The design features a hexagonal chip for maximum area utilization of space available in the DO-8 diode package, PIN diffused junction structure with deep diffused D(+) anode and a shallow high concentration n(+) cathode. With the high temperature glass passivated positive bevel mesa junction termination, the achieved blocking voltage is close to the theoretical limit of the starting material. Gold diffusion is used to control the lifetime and the resulting effect on switching speed and forward voltage tradeoff. For solder reflow assembly, trimetal (Al-Ti-Ni) contacts are used. The required major device electrical characteristics were achieved. Due to the tradeoff nature of forward voltage drop and reverse recovery time, a compromise was reached for these values.

  17. Management of high current transients in the CWDD Injector 200 kV power system

    SciTech Connect

    Carwardine, J.A.; Pile, G.; Zinneman, T.E.

    1993-06-01

    The injector for the Continuous Wave Deuterium Demonstrator is designed to deliver a high current CW negative deuterium ion beam at an energy of 200 keV to a Radio Frequency Quadrupole. The injector comprises a volume ion source, triode accelerator, high-power electron traps and low-energy beam transport with a single focusing solenoid. Some 75 Joules of energy are stored in stray capacitance around the high voltage system and discharged in a few microseconds following an injector breakdown. In order to limit damage to the accelerator grids, a magnetic snubber is incorporated to absorb most of the energy. Nevertheless, large current transients flow around the system as a result of an injector breakdown; these have frequently damaged power components and caused spurious behavior in many of the supporting systems. The analytical and practical approaches taken to minimize the effects of these transients are described. Injector breakdowns were simulated using an air spark gap and measurements made using standard EMC test techniques. The power circuit was modeled using an electrical simulation code; good agreement was reached between the model and measured results.

  18. Development of fundamental power coupler for high-current superconducting RF cavity

    SciTech Connect

    Jain P.; Belomestnykh, S.; Ben-Zvi, I.; Xu, W.

    2012-05-20

    Brookhaven National Laboratory took a project of developing a 704 MHz five-cell superconducting RF cavity for high-current linacs, including Energy Recovery Linac (ERL) for planned electron-hadron collider eRHIC. The cavity will be fed by a high-power RF amplifier using a coaxial Fundamental Power Coupler (FPC), which delivers 20 kW of CW RF power to the cavity. The design of FPC is one of the important aspects as one has to take into account the heat losses dissipated on the surface of the conductor by RF fields along with that of the static heat load. Using a simple simulation model we show the temperature profile and the heat load dissipated along the coupler length. To minimize the heat load on FPC near the cavity end, a thermal intercept is required at an appropriate location on FPC. A 10 K intercept was chosen and its location optimized with our simulation code. The requirement on the helium gas flow rate for the effective heat removal from the thermal intercept is also discussed.

  19. Design and characterization of the annular cathode high current pulsed electron beam source for circular components

    NASA Astrophysics Data System (ADS)

    Jiang, Wei; Wang, Langping; Wang, Xiaofeng

    2016-08-01

    In order to irradiate circular components with high current pulsed electron beam (HCPEB), an annular cathode based on carbon fiber bunches was designed and fabricated. Using an acceleration voltage of 25 kV, the maximum pulsed irradiation current and energy of this annular cathode can reach 7.9 kA and 300 J, respectively. The irradiation current density distribution of the annular cathode HCPEB source measured along the circumferential direction shows that the annular cathode has good emission uniformity. In addition, four 9310 steel substrates fixed uniformly along the circumferential direction of a metal ring substrate were irradiated by this annular cathode HCPEB source. The surface and cross-section morphologies of the irradiated samples were characterized by scanning electron microscopy (SEM). SEM images of the surface reveal that crater and surface undulation have been formed, which hints that the irradiation energy of the HCPEB process is large enough for surface modification of 9310 steel. Meanwhile, SEM cross-section images exhibit that remelted layers with a thickness of about 5.4 μm have been obtained in all samples, which proves that a good practical irradiation uniformity can be achieved by this annular cathode HCPEB source.

  20. Langmuir probe diagnostics of plasma in high current electron cyclotron resonance proton ion source.

    PubMed

    Roychowdhury, P; Kewlani, H; Mishra, L; Patil, D S; Mittal, K C

    2013-07-01

    A high current Electron Cyclotron Resonance (ECR) proton ion source has been developed for low energy high intensity proton accelerator at Bhabha Atomic Research Centre. Langmuir probe diagnostics of the plasma generated in this proton ion source is performed using Langmuir probe. The diagnostics of plasma in the ion source is important as it determines beam parameters of the ion source, i.e., beam current, emittance, and available species. The plasma parameter measurement in the ion source is performed in continuously working and pulsed mode using hydrogen as plasma generation gas. The measurement is performed in the ECR zone for operating pressure and microwave power range of 10(-4)-10(-3) mbar and 400-1000 W. An automated Langmuir probe diagnostics unit with data acquisition system is developed to measure these parameters. The diagnostics studies indicate that the plasma density and plasma electron temperature measured are in the range 5.6 × 10(10) cm(-3) to 3.8 × 10(11) cm(-3) and 4-14 eV, respectively. Using this plasma, ion beam current of tens of mA is extracted. The variations of plasma parameters with microwave power, gas pressure, and radial location of the probe have been studied.

  1. Field Emission Properties of Carbon Nanotube Fibers and Sheets for a High Current Electron Source

    NASA Astrophysics Data System (ADS)

    Christy, Larry

    Field emission (FE) properties of carbon nanotube (CNT) fibers from Rice University and the University of Cambridge have been studied for use within a high current electron source for a directed energy weapon. Upon reviewing the performance of these two prevalent CNT fibers, cathodes were designed with CNT fibers from the University of Cincinnati Nanoworld Laboratory. Cathodes composed of a single CNT fiber, an array of three CNT fibers, and a nonwoven CNT sheet were investigated for FE properties; the goal was to design a cathode with emission current in excess of 10 mA. Once the design phase was complete, the cathode samples were fabricated, characterized, and then analyzed to determine FE properties. Electrical conductivity of the CNT fibers was characterized with a 4-probe technique. FE characteristics were measured in an ultra-high vacuum chamber at Wright-Patterson Air Force Base. The arrayed CNT fiber and the enhanced nonwoven CNT sheet emitter design demonstrated the most promising FE properties. Future work will include further analysis and cathode design using this nonwoven CNT sheet material to increase peak current performance during electron emission.

  2. Development of a compact high current low emittance RF ion source

    NASA Astrophysics Data System (ADS)

    Menon, Ranjini; Nabhiraj, P. Y.

    2013-12-01

    A 13.56 MHz inductively coupled plasma based RF ion source is developed for production of high brightness focused ion beams of heavy gaseous elements for high speed milling and light ions for high speed imaging. In order to obtain ion beams with low emittance, no magnetic field of any kind is used in the ion source. However, to achieve the high plasma density, the plasma chamber volume is reduced to couple RF power as high as 8-12 W/cm3 to the plasma. Measurements show that the normalized rms emittance of 0.6 mA Ar1+ beam to be as low as 0.0075 mm-mrad while it is 0.004 mm-mrad for 1.2 mA of ion beam from hydrogen plasma. With a simple parallel plate extraction system with an aperture of 2 mm diameter, 80 mA/cm2 of ion beam from hydrogen plasma could be extracted at 3.5 kV extraction potential and 300 W of RF power. The ion source has been operated with other heavy gases and results show that more than 1 mA of xenon and krypton ion beam could easily be extracted at 5 kV extraction potential and 200 W of RF power. In this article, the capability of the ion source to produce high current, low emittance heavy as well as light ion beams is presented.

  3. High yield neutron generator based on a high-current gasdynamic electron cyclotron resonance ion source

    SciTech Connect

    Skalyga, V.; Sidorov, A.; Izotov, I.; Golubev, S.; Razin, S.; Strelkov, A.; Tarvainen, O.; Koivisto, H.; Kalvas, T.

    2015-09-07

    In present paper, an approach for high yield compact D-D neutron generator based on a high current gasdynamic electron cyclotron resonance ion source is suggested. Results on dense pulsed deuteron beam production with current up to 500 mA and current density up to 750 mA/cm{sup 2} are demonstrated. Neutron yield from D{sub 2}O and TiD{sub 2} targets was measured in case of its bombardment by pulsed 300 mA D{sup +} beam with 45 keV energy. Neutron yield density at target surface of 10{sup 9} s{sup −1} cm{sup −2} was detected with a system of two {sup 3}He proportional counters. Estimations based on obtained experimental results show that neutron yield from a high quality TiD{sub 2} target bombarded by D{sup +} beam demonstrated in present work accelerated to 100 keV could reach 6 × 10{sup 10} s{sup −1} cm{sup −2}. It is discussed that compact neutron generator with such characteristics could be perspective for a number of applications like boron neutron capture therapy, security systems based on neutron scanning, and neutronography.

  4. Probe characterization of high-current driven metal plasma in a vacuum-arc rail gun

    NASA Astrophysics Data System (ADS)

    Vijayan, T.; Roychowdhury, P.; Venkatramani, N.

    2004-10-01

    The characteristics of metal plasma launched by high-current electric arc in a vacuum-arc rail gun are determined by employing electrical and magnetic probes. These measurements are validated by results from theoretical simulations. The arc coupled nonlinear circuit equations are solved simultaneously with the Newtonian arc motion and revealed the undercritically damped behavior of the arc current identical to the arc-current signal recorded by the Rogowski magnetic probe. Similarly the arc velocity and displacement derived from the signatures of B-dot probes are shown to concur closely with the results of J ×B propulsion from simulation. The heating of plasma is formulated in a three-electron population regime with direct arc energy coupling through magnetohydrodynamic, ion-acoustic, Coulomb, and neutral interactions. This results in high temperature (Te) of hundreds of eV in the arc as revealed by the simulation. Hence Te of the rapidly cooling and equilibrating plasma that emerged from the muzzle is high around 80-90eV, which is confirmed by Langmuir electric probe measurements. Density ne of this metal plasma is shown to be in the range 4×1021-6×1021m-3 and includes multiple ion charge states. The exit velocity of the plasma measured by a pair of Langmuir probes is close to 2.2×106cm/s and matched well with the arc velocity determined by the B-dot probes and the results from simulation.

  5. Numerical studies of high current beam compression in heavy ion fusion

    SciTech Connect

    Bisognano, J.; Lee, E.P.; Mark, J.W.K.

    1985-05-10

    The process of longitudinal compression of a drifting heavy ion pulse to be used as an ICF driver is examined with the aid of particle simulation. Space charge forces play a vital role in halting compression before the final focus lens system is reached. This must take place with minimal growth of transverse emittance and momentum spread. Of particular concern is the distortion of longitudinal phase space by the rounded transverse profile of the longitudinal self-electric field.

  6. A time-resolved imaging and electrical study on a high current atmospheric pressure spark discharge

    NASA Astrophysics Data System (ADS)

    Palomares, J. M.; Kohut, A.; Galbács, G.; Engeln, R.; Geretovszky, Zs.

    2015-12-01

    We present a time-resolved imaging and electrical study of an atmospheric pressure spark discharge. The conditions of the present study are those used for nanoparticle generation in spark discharge generator setups. The oscillatory bipolar spark discharge was generated between two identical Cu electrodes in different configurations (cylindrical flat-end or tipped-end geometries, electrode gap from 0.5 to 4 mm), in a controlled co-axial N2 flow, and was supplied by a high voltage capacitor. Imaging data with nanosecond time resolution were collected using an intensified CCD camera. This data were used to study the time evolution of plasma morphology, total light emission intensity, and the rate of plasma expansion. High voltage and high current probes were employed to collect electrical data about the discharge. The electrical data recorded allowed, among others, the calculation of the equivalent resistance and inductance of the circuit, estimations for the energy dissipated in the spark gap. By combining imaging and electrical data, observations could be made about the correlation of the evolution of total emitted light and the dissipated power. It was also observed that the distribution of light emission of the plasma in the spark gap is uneven, as it exhibits a "hot spot" with an oscillating position in the axial direction, in correlation with the high voltage waveform. The initial expansion rate of the cylindrical plasma front was found to be supersonic; thus, the discharge releases a strong shockwave. Finally, the results on equivalent resistance and channel expansion are comparable to those of unipolar arcs. This shows the spark discharge has a similar behavior to the arc regime during the conductive phase and until the current oscillations stop.

  7. Effects of Neutral Density on Energetic Ions Produced Near High-Current Hollow Cathodes

    NASA Technical Reports Server (NTRS)

    Kameyama, Ikuya

    1997-01-01

    Energy distributions of ion current from high-current, xenon hollow cathodes, which are essential information to understand erosion phenomena observed in high-power ion thrusters, were obtained using an electrostatic energy analyzer (ESA). The effects of ambient pressure and external flow rate introduced immediately downstream of hollow cathode on ion currents with energies greater than that associated with the cathode-to-anode potential difference were investigated. The results were analyzed to determine the changes in the magnitudes of ion currents to the ESA at various energies. Either increasing the ambient pressure or adding external flow induces an increase in the distribution of ion currents with moderate energies (epsilon less than 25 to 35 eV) and a decrease in the distribution for high energies (epsilon greater than 25 to 35 eV). The magnitude of the current distribution increase in the moderate energy range is greater for a cathode equipped with a toroidal keeper than for one without a keeper, but the distribution in the high energy range does not seem to be affected by a keeper. An MHD model, which has been proposed to describe energetic-ion production mechanism in hollow cathode at high discharge currents, was developed to describe these effects. The results show, however, that this model involves no mechanism by which a significant increase of ion current could occur at any energy. It was found, on the other hand, that the potential-hill model of energetic ion production, which assumes existence of a local maximum of plasma potential, could explain combined increases in the currents of ions with moderate energies and decreases in high energy ions due to increased neutral atom density using a charge-exchange mechanism. The existing, simplified version of the potential-hill model, however, shows poor quantitative agreement with measured ion-current-energy-distribution changes induced by neutral density changes.

  8. Field Testing of High Current Electrokinetic Nanoparticle Treatment for Corrosion Mitigation in Reinforced Concrete

    NASA Technical Reports Server (NTRS)

    Cardenas, Henry; Alexander, Joshua; Kupwade-Patil, Kunal; Calle, Luz marina

    2010-01-01

    Electrokinetic Nanoparticle (EN) treatment was used as a rapid repair measure to mitigate chloride induced corrosion of reinforced concrete in the field. EN treatment uses an electric field to transport positively charged nanoparticles to the reinforcement through the concrete capillary pores. Cylindrical reinforced concrete specimens were batched with 4.5 wt % salt content (based on cement mass). Three distinct electrokinetic treatments were conducted using high current density (up to 5 A/m2) to form a chloride penetration barrier that was established in 5 days, as opposed to the traditional 6-8 weeks, generally required for electrochemical chloride extraction (ECE). These treatments included basic EN treatment, EN with additional calcium treatment, and basic ECE treatment. Field exposures were conducted at the NASA Beachside Corrosion Test Site, Kennedy Space Center, Florida, USA. The specimens were subjected to sea water immersion at the test site as a posttreatment exposure. Following a 30-day post-treatment exposure period, the specimens were subjected to indirect tensile testing to evaluate treatment impact. The EN treated specimens exhibited 60% and 30% increases in tensile strength as compared to the untreated controls and ECE treated specimens respectively. The surfaces of the reinforcement bars of the control specimens were 67% covered by corrosion products. In contrast, the EN treated specimens exhibited corrosion coverage of only 4%. Scanning electron microscopy (SEM) revealed a dense concrete microstructure adjacent to the bars of the treated specimens as compared to the control and ECE specimens. Energy dispersive spectroscopic (EDS) analysis of the polished EN treated specimens showed a reduction in chloride content by a factor of 20 adjacent to the bars. This study demonstrated that EN treatment was successful in forming a chloride penetration barrier rapidly. This work also showed that the chloride barrier was effective when samples were exposed to

  9. Characterization of a high current pulsed arc using optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Sousa Martins, R.; Zaepffel, C.; Chemartin, L.; Lalande, Ph; Soufiani, A.

    2016-10-01

    In this paper, we present the investigation realized on an experimental setup that simulates an arc column subjected to the transient phase of a lightning current waveform in laboratory conditions. Optical emission spectroscopy is employed to assess space- and time-resolved properties of this high current pulsed arc. Different current peak levels are utilised in this work, ranging from 10 kA to 100 kA, with a peak time around 15 µs. Ionic lines of nitrogen and oxygen are used to determine the radial profiles of temperature and electron density of the arc channel over time from 2 µs to 36 µs. A combination of 192 N II and O II lines is considered in the calculation of the bound-bound contribution of the absorption coefficient of the plasma channel. Calculations of the optical thickness showed that self-absorption of these ionic lines in the arc column is important. To obtain temperature and electron density profiles in the arc, we solved the radiative transfer equation across the channel under an axisymmetric assumption and considering the channel formed by uniform concentric layers. For the 100 kA current peak level, the temperature reaches more than 38 000 K and the electron density reaches 5  ×  1018 cm-3. The pressure inside the channel is calculated using the air plasma composition at local thermodynamic equilibrium, and reaches 45 bar. The results are discussed and utilised to estimate the electrical conductivity of the arc channel.

  10. THE POTENTIAL FOR NEUTRINO PHYSICS AT MUON COLLIDERS AND DEDICATED HIGH CURRENT MUON STORAGE RINGS

    SciTech Connect

    BIGI,I.; BOLTON,T.; FORMAGGIO,J.; HARRIS,D.; MORFIN,J.; SPENTZOURIS,P.; YU,J.; KAYSER,B.; KING,B.J.; MCFARLAND,K.; PETROV,A.; SCHELLMAN,H.; VELASCO,M.; SHROCK,R.

    2000-05-11

    Conceptual design studies are underway for both muon colliders and high-current non-colliding muon storage rings that have the potential to become the first true neutrino factories. Muon decays in long straight sections of the storage rings would produce uniquely intense and precisely characterized two-component neutrino beams--muon neutrinos plus electron antineutrinos from negative muon decays and electron neutrinos plus muon antineutrinos from positive muons. This article presents a long-term overview of the prospects for these facilities to greatly extend the capabilities for accelerator-based neutrino physics studies for both high rate and long baseline neutrino experiments. As the first major physics topic, recent experimental results involving neutrino oscillations have motivated a vigorous design effort towards dedicated neutrino factories that would store muon beams of energies 50 GeV or below. These facilities hold the promise of neutrino oscillation experiments with baselines up to intercontinental distances and utilizing well understood beams that contain, for the first time, a substantial component of multi-GeV electron-flavored neutrinos. In deference to the active and fast-moving nature of neutrino oscillation studies, the discussion of long baseline physics at neutrino factories has been limited to a concise general overview of the relevant theory, detector technologies, beam properties, experimental goals and potential physics capabilities. The remainder of the article is devoted to the complementary high rate neutrino experiments that would study neutrino-nucleon and neutrino-electron scattering and would be performed at high performance detectors placed as close as is practical to the neutrino production straight section of muon storage rings in order to exploit beams with transverse dimensions as small as a few tens of centimeters.

  11. Probe characterization of high-current driven metal plasma in a vacuum-arc rail gun

    SciTech Connect

    Vijayan, T.; Roychowdhury, P.; Venkatramani, N.

    2004-10-15

    The characteristics of metal plasma launched by high-current electric arc in a vacuum-arc rail gun are determined by employing electrical and magnetic probes. These measurements are validated by results from theoretical simulations. The arc coupled nonlinear circuit equations are solved simultaneously with the Newtonian arc motion and revealed the undercritically damped behavior of the arc current identical to the arc-current signal recorded by the Rogowski magnetic probe. Similarly the arc velocity and displacement derived from the signatures of B-dot probes are shown to concur closely with the results of JxB propulsion from simulation. The heating of plasma is formulated in a three-electron population regime with direct arc energy coupling through magnetohydrodynamic, ion-acoustic, Coulomb, and neutral interactions. This results in high temperature (T{sub e}) of hundreds of eV in the arc as revealed by the simulation. Hence T{sub e} of the rapidly cooling and equilibrating plasma that emerged from the muzzle is high around 80-90 eV, which is confirmed by Langmuir electric probe measurements. Density n{sub e} of this metal plasma is shown to be in the range 4x10{sup 21}-6x10{sup 21} m{sup -3} and includes multiple ion charge states. The exit velocity of the plasma measured by a pair of Langmuir probes is close to 2.2x10{sup 6} cm/s and matched well with the arc velocity determined by the B-dot probes and the results from simulation.

  12. Numerical studies of high current beam compression in heavy ion fusion

    SciTech Connect

    Bisognano, J.; Lee, F.P.; Mark, J.W.K.

    1985-10-01

    The process of longitudinal compression of a drifting heavy ion pulse to be used as an ICF driver is examined with the aid of particle simulation. Space charge forces play a vital role in halting compression before the final focus lens system is reached. This must take place with minimal growth of transverse emittance and momentum spread. Of particular concern are the distortion of longitudinal phase space by the rounded transverse profile of the longitudinal self-electric field. For application as an ICF reactor driver, a heavy-ion beam pulse must be longitudinally compressed by 1 to 2 orders of magnitude to achieve the peak power required to ignite a target. This process, among others, will be tested in a facility known as the ''High-Temperature Experiment'' in heavy-ion fusion. Beam compression is a critical element of an accelerator for heavy-ion fusion; it occurs primarily after the main phase of acceleration and before final focus onto target. Here we examine the compression of a drifting heavy-ion pulse with the aid of particle simulations. We describe initial theoretical results for an in-principle solution to this problem. Further refinements including integration into a complete driver system are necessary before the least costly solution can be chosen.

  13. Biomimetic Particles as Therapeutics

    PubMed Central

    Green, Jordan J.

    2015-01-01

    In recent years, there have been major advances in the development of novel nanoparticle and microparticle-based therapeutics. An emerging paradigm is the incorporation of biomimetic features into these synthetic therapeutic constructs to enable them to better interface with biological systems. Through the control of size, shape, and material consistency, particle cores have been generated that better mimic natural cells and viruses. In addition, there have been significant advances in biomimetic surface functionalization of particles through the integration of bio-inspired artificial cell membranes and naturally derived cell membranes. Biomimetic technologies enable therapeutic particles to have increased potency to benefit human health. PMID:26277289

  14. RESULTS OF BEAM TESTS ON A HIGH CURRENT EBIS TEST STAND.

    SciTech Connect

    BEEBE,E.; ALESSI,J.; BELLAVIA,S.; HERSHCOVITCH,A.; KPONOU,A.; LOCKEY,R.; PIKIN,A.; PRELEC,K.; KUZNETSOV,G.; TIUNOV,M.

    1999-03-29

    At Brookhaven National Laboratory there is an R&D program to design an Electron Beam Ion Source (EBIS) for use in a compact ion injector to be developed for the relativistic heavy ion collider (RHIC). The BNL effort is directed at developing an EBIS with intensities of 3 x 10{sup 9} particles/pulse of ions such as Au{sup 35+} and U{sup 45+}, and requires an electron beam on the order of 10A. The construction of a test stand (EBTS) with the full electron beam power and 1/3 the length of the EBIS for RHIC is nearing completion. Initial commissioning of the EBTS was made with pulsed electron beams of duration < 1ms and current up to 13 A. Details of the EBTS construction, results of the pulse tests, and preparations for DC electron beam tests are presented.

  15. Simulating Electron Clouds in High-Current Ion Accelerators withSolenoid Focusing

    SciTech Connect

    Sharp, W.M.; Grote, D.P.; Cohen, R.H.; Friedman, A.; Vay, J.-L.; Seidl, P.A.; Roy, P.K.; Coleman, J.E.; Armijo, J.; Haber, I.

    2006-09-20

    Contamination from electrons is a concern for the solenoid-focused ion accelerators being developed for experiments in high-energy-density physics (HEDP). These electrons are produced directly by beam ions hitting lattice elements and intercepting diagnostics, or indirectly by ionization of desorbed neutral gas, and they are believed responsible for time dependence of the beam radius, emittance, and focal distance seen on the Solenoid Transport Experiment (STX) at Lawrence Berkeley National Laboratory. The electrostatic particle-in-cell code WARP has been upgraded to included the physics needed to simulate electron-cloud phenomena. We present preliminary self-consistent simulations of STX experiments suggesting that the observed time dependence of the beam stems from a complicated interaction of beam ions, desorbed neutrals, and electrons.

  16. Simulating Electron Clouds in High-Current Ion Accelerators with Solenoid Focusing

    SciTech Connect

    Sharp, W; Grote, D; Cohen, R; Friedman, A; Vay, J; Seidl, P; Roy, P; Coleman, J; Armijo, J; Haber, I

    2006-08-15

    Contamination from electrons is a concern for the solenoid-focused ion accelerators being developed for experiments in high-energy-density physics (HEDP). These electrons are produced directly by beam ions hitting lattice elements and intercepting diagnostics, or indirectly by ionization of desorbed neutral gas, and they are believed responsible for time dependence of the beam radius, emittance, and focal distance seen on the Solenoid Transport Experiment (STX) at Lawrence Berkeley National Laboratory. The electrostatic particle-in-cell code WARP has been upgraded to included the physics needed to simulate electron-cloud phenomena. We present preliminary self-consistent simulations of STX experiments suggesting that the observed time dependence of the beam stems from a complicated interaction of beam ions, desorbed neutrals, and electrons.

  17. Simulations of Bunch Precompression at High Currents in the SLC Damping Rings

    SciTech Connect

    Bane, K.L.F.; Minty, M.G.; Chao, A.W.; /SLAC

    2011-08-09

    In the Stanford Linear Collider (SLC) each beam, after leaving a damping ring, is compressed in the Ring-to-Linac (RTL) transfer line before entering the linear accelerator. At a bunch population of 4.0 x 10{sup 10} particles, due to the limited energy acceptance of the RTL, approximately 15% of the beam has normally been lost. During the 1996 run, however, to eliminate this loss the bunch was partially precompressed in the damping ring, just before extraction; the beam loss in the RTL was reduced to almost zero. The operation and performance of precompression are presented by Minty et al. (1999). Also given is an analysis which, however, does not include the effects of the longitudinal wakefield on the beam dynamics. In this report we extend that analysis to include these effects.

  18. Modeling Electron Clouds in High-Current Ion Accelerators with Solenoid Focusing

    NASA Astrophysics Data System (ADS)

    Sharp, W. M.; Cohen, R. H.; Grote, D. P.; Vay, J.-L.; Haber, I.

    2006-10-01

    Contamination from electrons is a concern for solenoid-focused ion accelerators being developed for experiments in high-energy-density physics (HEDP). These electrons, produced directly by beam ions hitting lattice elements or indirectly by ionization of desorbed neutral gas, can potentially alter the beam dynamics, leading to beam deflection, increased emittance, halo, and possibly electron-ion instabilities. The electrostatic particle-in-cell code WARP is used to simulate electron-cloud studies on the solenoid-transport experiment (STX) at Lawrence Berkeley National Laboratory. We present self-consistent simulations of several STX configurations to show the evolution of the electron and ion-beam distributions first in idealized 2-D solenoid fields and then in the 3-D field values obtained from probes. Comparisons are made with experimental data, and several techniques to mitigate electron effects are demonstrated numerically.

  19. Simulating electron clouds in high-current ion accelerators with solenoid focusing

    NASA Astrophysics Data System (ADS)

    Sharp, W. M.; Grote, D. P.; Cohen, R. H.; Friedman, A.; Vay, J.-L.; Seidl, P. A.; Roy, P. K.; Coleman, J. E.; Armijo, J.; Haber, I.

    2007-07-01

    Contamination from electrons is a concern for the solenoid-focused ion accelerators being developed for experiments in high-energy density physics (HEDP). These electrons are produced directly by beam ions hitting lattice elements and intercepting diagnostics, or indirectly by ionization of desorbed neutral gas, and they are believed responsible for time dependence of the beam radius, emittance, and focal distance seen on the solenoid transport experiment (STX) at Lawrence Berkeley National Laboratory. The electrostatic particle-in-cell code WARP has been upgraded to include the physics needed to simulate electron-cloud phenomena. We present preliminary self-consistent simulations of STX experiments suggesting that the observed time dependence of the beam stems from a complicated interaction of beam ions, desorbed neutrals, and electrons.

  20. Demonstration of high current carbon nanotube enabled vertical organic field effect transistors at industrially relevant voltages

    NASA Astrophysics Data System (ADS)

    McCarthy, Mitchell

    lifetime and the potential for an all transparent display. And because carbon nanotubes (CNTs) and organics are used, CN-VFET and CN-VOLET devices are compatible with flexible displays. This dissertation describes the first ever demonstration of CN-VFETs and CN-VOLETs and relates their performance to the specific properties of the CNTs and the new device architecture. In the work that followed, the CN-VFET was systematically optimized overcoming the problems revealed in the demonstration devices. The large undesired hysteresis was decreased by 96%, the on/off ratio was improved three orders of magnitude and the operating voltages were reduced to state of the art values. Additionally, the current output per device area of the CN-VFET was demonstrated to be greater than any other low resolution patterned organic transistor by a factor of 3.9. Moreover, it was demonstrated that the CNTs induce a reorientation of the high mobility plane in small molecule organics like pentacene to coincide with the vertical direction, giving additional explanation for the large currents observed in the CN-VFET. The ability to drive high currents and potentially inexpensive fabrication may provide the solution for the AMOLED backplane problem.

  1. The effect of asphaltene particle size and distribution on the temporal advancement of the asphaltene deposition profile in the well column

    NASA Astrophysics Data System (ADS)

    Zeinali Hasanvand, Mahdi; Mosayebi Behbahani, Reza; Feyzi, Farzaneh; Ali Mousavi Dehghani, Seyed

    2016-05-01

    Asphaltene deposition in oil wells is an inconvenient production problem. Generating a precise deposition model for the well column is essential for optimal well design and prevention/reduction of deposition-associated difficulties. The goal of this study is to determine the effects of various parameters on the deposition process. These parameters include oil viscosity, temperature, flow velocity, well diameter and asphaltene particle size and particle size distribution. The first five parameters are analyzed using Escobedo and Mansoori (2010), Cleaver and Yates (1975) and Friedlander and Johnstone (1957) asphaltene deposition models. The last parameter (asphaltene particle size distribution) is not directly included in the asphaltene deposition models. Therefore, a dynamic well column model is generated by combining transport phenomena (mass, heat and momentum transfer) equations with thermodynamic models. The model is fine-tuned and verified based on field data from an Iranian producing oil well with frequent asphaltene deposition problem and subsequently used for predicting the time-dependent development of the asphaltene deposition profile in the well column for a series of asphaltene particle size distributions. The results show the effect of the said parameters depends on how the buffer layer and Brownian motion are defined. The Escobedo and Mansoori (2010) model is found to make better predictions of deposited asphaltene in the studied well.

  2. Inclusive Focus Particles in English and Korean

    ERIC Educational Resources Information Center

    Kang, Sang-gu

    2011-01-01

    When discussing focus particles, it has been common practice to rely on the dichotomy of inclusive vs. exclusive particles, "a la" Konig (1991). Inclusive focus particles are often further divided into scalar particles, such as "also", "too", and "either", and non-scalar particles, such as "even". In this thesis, I advance a comparative analysis…

  3. Space-charge effects in ultra-high current electron bunches generated by laser-plasma accelerators

    SciTech Connect

    Grinner, F. J.; Schroeder, C. B.; Maier, A. R.; Becker, S.; Mikhailova, J. M.

    2009-02-11

    Recent advances in laser-plasma accelerators, including the generation of GeV-scale electron bunches, enable applications such as driving a compact free-electron-laser (FEL). Significant reduction in size of the FEL is facilitated by the expected ultra-high peak beam currents (10-100 kA) generated in laser-plasma accelerators. At low electron energies such peak currents are expected to cause space-charge effects such as bunch expansion and induced energy variations along the bunch, potentially hindering the FEL process. In this paper we discuss a self-consistent approach to modeling space-charge effects for the regime of laser-plasma-accelerated ultra-compact electron bunches at low or moderate energies. Analytical treatments are considered as well as point-to-point particle simulations, including the beam transport from the laser-plasma accelerator through focusing devices and the undulator. In contradiction to non-self-consistent analyses (i.e., neglecting bunch evolution), which predict a linearly growing energy chirp, we have found the energy chirp reaches a maximum and decreases thereafter. The impact of the space-charge induced chirp on FEL performance is discussed and possible solutions are presented.

  4. Optimization of solenoid based low energy beam transport line for high current H+ beams

    NASA Astrophysics Data System (ADS)

    Pande, R.; Singh, P.; Rao, S. V. L. S.; Roy, S.; Krishnagopal, S.

    2015-02-01

    A 20 MeV, 30 mA CW proton linac is being developed at BARC, Mumbai. This linac will consist of an ECR ion source followed by a Radio Frequency Quadrupole (RFQ) and Drift tube Linac (DTL). The low energy beam transport (LEBT) line is used to match the beam from the ion source to the RFQ with minimum beam loss and increase in emittance. The LEBT is also used to eliminate the unwanted ions like H2+ and H3+ from entering the RFQ. In addition, space charge compensation is required for transportation of such high beam currents. All this requires careful design and optimization. Detailed beam dynamics simulations have been done to optimize the design of the LEBT using the Particle-in-cell code TRACEWIN. We find that with careful optimization it is possible to transport a 30 mA CW proton beam through the LEBT with 100% transmission and minimal emittance blow up, while at the same time suppressing unwanted species H2+ and H3+ to less than 3.3% of the total beam current.

  5. High brightness, high current injector design for the ATF upgrade at Brookhaven National Laboratory

    NASA Astrophysics Data System (ADS)

    Stratakis, Diktys

    2015-04-01

    Brookhaven National Accelerator Test Facility (BNL ATF) is in the process of moving to a new place and upgrading its major capabilities: The electron beam energy and CO2 laser power. Specifically, the maximum electron beam energy will be first projected to 100-150 MeV and then upgraded to 500 MeV while at the same time the laser power will increase 100 fold, thus making the new ATF a powerful tool in advanced accelerator concept research. The bright electron bunch produced by the new state-of-the-art photocathode rf gun will be accelerated and optionally delivered to multiple beamlines. The injector is a key element of this accelerator upgrade. It must deliver a high average current beam with very small transverse and longitudinal emittances, at a sufficiently high energy that space charge effects are under control. We review here the detailed injector design and present first results from beam dynamics simulations. We give emphasis in the production of compressed flat beams which have important applications in novel light-source concepts and could possibly alleviate the need for damping rings in lepton colliders. We present a theoretical model and with the aid of simulation examine the influence of space charge, bunch compression and suggest a operating regime with minimal phase space dilutions.

  6. Proceedings of the 1987 IEEE particle accelerator conference: Volume 2

    SciTech Connect

    Lindstrom, E.R.; Taylor, L.S.

    1987-01-01

    This report contains papers from the IEEE particle accelerator conference. This second volume of three covers the following main topics: Instrumentation and control, accelerators for medium energies and nuclear physics, high current accelerators, and beam dynamics. (LSP)

  7. Double disordered YBCO coated conductors of industrial scale: high currents in high magnetic field

    NASA Astrophysics Data System (ADS)

    Abraimov, D.; Ballarino, A.; Barth, C.; Bottura, L.; Dietrich, R.; Francis, A.; Jaroszynski, J.; Majkic, G. S.; McCallister, J.; Polyanskii, A.; Rossi, L.; Rutt, A.; Santos, M.; Schlenga, K.; Selvamanickam, V.; Senatore, C.; Usoskin, A.; Viouchkov, Y. L.

    2015-11-01

    A significant increase of critical current in high magnetic field, up to 31 T, was recorded in long tapes manufactured by employing a double-disorder route. In a double-disordered high-temperature superconductor (HTS), a superimposing of intrinsic and extrinsic disorder takes place in a way that (i) the intrinsic disorder is caused by local stoichiometry deviations that lead to defects of crystallinity that serve as pining centers in the YBa2Cu3O x-δ matrix and (ii) the extrinsic disorder is introduced via embedded atoms or particles of foreign material (e.g. barium zirconate), which create a set of lattice defects. We analyzed possible technological reasons for this current gain. The properties of these tapes over a wider field-temperature range as well as field anisotropy were also studied. Record values of critical current as high as 309 A at 31 T, 500 A at 18 Tm and 1200 A at 5 T were found in 4 mm wide tape at 4.2 K and B perpendicular to tape surface. HTS layers were processed in medium-scale equipment that allows a maximum batch length of 250 m while 22 m long batches were provided for investigation. Abnormally high ratios (up to 10) of critical current density measured at 4.2 K, 19 T to critical current density measured at 77 K, self-field were observed in tapes with the highest in-field critical current. Anisotropy of the critical current as well as angular dependences of n and α values were investigated. The temperature dependence of critical current is presented for temperatures between 4.2 and 40 K. Prospects for the suppression of the dog-bone effect by Cu plating and upscale of processing chain to >500 m piece length are discussed.

  8. Progress in the high current experiment (HCX) February-July 2002

    SciTech Connect

    Seidl, P.A.; Baca, D.; Bieniosek, F.M.; Bukh, B.; Celata, C.M.; Coorey, A.; Dugan, C.; Faltens, A.; Friedman, A.; Grote, D.P.; Haber, I.; Jordan, K.; Kwan, J.W.; Lund, S.M.; Lee. E.P.; Logan, B.G.; Molvik, A.W.; Prost, L.; Sabbi, G.; Waldron, W.W.

    2002-09-09

    This paper reports progress in the HCX experimental program since the last HIF-VNL Program Advisory Committee Review (February 14-15 2002). On July 25 2002 the experiment was shut down for about four weeks to move the control room. A principal area of effort has been to obtain and evaluate the first experimental results carried out with a matched and well-aligned K+ ion beam transported through 10 electrostatic transport quadrupoles. These are the main results and highlights to date: (1) There is no emittance growth within the sensitivity of the diagnostics, and little beam loss. The beam centroid is aligned to within 0.5 mm and 2 mrad of the central axis of the channel, and the envelope mismatch amplitude is <2 mm. (2) A long-life, alumino-silicate source has replaced a contact-ionization source, eliminating depletion induced experimental uncertainties. (3) Significant differences between the experimental data and early theoretical calculations of the beam envelope propagating through the electrostatic quadrupoles were encountered. More detailed envelope models and simulations were developed and experimental parameter sensitivities were analyzed. This work has resolved most of the discrepancy and achievable limits on envelope predictability and control are being probed. (4) The experimental current density distribution, J(x,y), and phase-space data are being used to initialize high-resolution simulations to enable realistic modeling and detailed comparisons to experiment. In other areas of HCX R&D: (1) We have made progress in the development of new time-resolved phase-space diagnostics that will speed up data acquisition in this and other upcoming beam experiments in the HIF-VNL. (2) Preliminary results from a Gas, Electron Source Diagnostic (GESD) are presented, which measures gas desorption and secondary electrons. The secondary emission yield varies as cos-1(q), as predicted theoretically. Data from the GESD will be relevant to upcoming experiments on particle

  9. Transport studies in polymer electrolyte fuel cell with porous metallic flow field at ultra high current density

    NASA Astrophysics Data System (ADS)

    Srouji, Abdul-Kader

    Achieving cost reduction for polymer electrolyte fuel cells (PEFC) requires a simultaneous effort in increasing power density while reducing precious metal loading. In PEFCs, the cathode performance is often limiting due to both the slow oxygen reduction reaction (ORR), and mass transport limitation caused by limited oxygen diffusion and liquid water flooding at high current density. This study is motivated by the achievement of ultra-high current density through the elimination of the channel/land (C/L) paradigm in PEFC flow field design. An open metallic element (OME) flow field capable of operating at unprecedented ultra-high current density (3 A/cm2) introduces new advantages and limitations for PEFC operation. The first part of this study compares the OME with a conventional C/L flow field, through performance and electrochemical diagnostic tools such as electrochemical impedance spectroscopy (EIS). The results indicate the uniqueness of the OME's mass transport improvement. No sign of operation limitation due to flooding is noted. The second part specifically examines water management at high current density using the OME flow field. A unique experimental setup is developed to measure steady-state and transient net water drag across the membrane, in order to characterize the fundamental aspects of water transport at high current density with the OME. Instead of flooding, the new limitation is identified to be anode side dry-out of the membrane, caused by electroosmotic drag. The OME improves water removal from the cathode, which immediately improves oxygen transport and performance. However, the low water content in the cathode reduces back diffusion of water to the membrane, and electroosmotic drag dominates at high current density, leading to dry-out. The third part employs the OME flow field as a tool that avoids C/L effects endemic to a typical flow field, in order to study oxygen transport resistance at the catalyst layer of a PEFC. In open literature, a

  10. Advanced biostack experiment

    NASA Technical Reports Server (NTRS)

    Buecker, H.

    1981-01-01

    The Advanced Biostack Experiment is described. The objectives are: (1) to confirm, complement, and enlarge the information obtained from the previous experiments by applying improved and advanced methods of localization and physical and biological evaluation, performing advanced experiments based on these data, and including additional biological specimens and additional radiation detectors; (2) to determine the biological importance of nuclear disintegration stars; (3) to determine the interference of HZE particle induced effects with those of other space flight factors (e.g., weightlessness); and (4) to determine the distribution of HZE particles and of disintegration stars at different locations inside the module and on the pallet.

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

    SciTech Connect

    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.

  12. A Model of an Electrical Discharge in the Flance Contacts With Omega Seals at High Currents in PEP-II

    SciTech Connect

    Novokhatski, A; Seeman, J.; Sullivan, M.; /SLAC

    2008-07-11

    During PEP-II operation with high currents in the High Energy Ring (HER), elevated temperatures were found at many locations in the vacuum chamber where they have an RF seal for the flex flange. Most of these omega RF seals were badly damaged and had evidence of metal vaporization from sparks and electrical discharge. They suggest a physical model, which may explain this effect.

  13. Issues concerning high current lower energy electron beams required for ion cooling between EBIS LINAC and booster

    SciTech Connect

    Hershcovitch,A.

    2009-03-01

    Some issues, regarding a low energy high current electron beam that will be needed for electron beam cooling to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster, are examined. Options for propagating such an electron beam, as well as the effect of neutralizing background plasma on electron and ion beam parameters are calculated. Computations and some experimental data indicate that none of these issues is a show stopper.

  14. Ignition of a combustible gas mixture by a high-current electric discharge in a closed volume

    SciTech Connect

    Berezhetskaya, N. K.; Gritsinin, S. I.; Kop'ev, V. A.; Kossyi, I. A.; Kuleshov, P. S.; Popov, N. A.; Starik, A. M.; Tarasova, N. M.

    2009-06-15

    Results are presented from experimental studies and numerical calculations of the ignition of a stoichiometric CH{sub 4}: O{sub 2} gas mixture by a high-current gliding discharge. It is shown that this type of discharge generates an axially propagating thermal wave (precursor) that penetrates into the gas medium and leads to fast gas heating. This process is followed by an almost simultaneous ignition of the gas mixture over the entire reactor volume.

  15. High Current Responsivity and Wide Modulation Bandwidth Terahertz Detector Using High-Electron-Mobility Transistor for Wireless Communication

    NASA Astrophysics Data System (ADS)

    Suzuki, S.; Nukariya, T.; Ueda, Y.; Otsuka, T.; Asada, M.

    2016-07-01

    A high-current-responsivity terahertz (THz) detector was fabricated using a broadband bow-tie antenna and an InAlAs/InGaAs high-electron-mobility transistor (HEMT) with a short gate length. High-current responsivity can be achieved by using a short gate length; the resulting high transconductance exhibited ballistic transport in the channel. We fabricated the HEMT detector with a 50-nm-long channel; the transconductance was 1.2 S/mm and the subthreshold slope was 120 mV/dec, yielding a high-current responsivity (˜5 A/W) and a cutoff frequency of 460 GHz. We also measured the modulation bandwidth of the THz detector using a heterodyne mixing technique with a uni-traveling carrier photodiode (UTC-PD) for providing the radio frequency (RF) and a frequency multiplier as a local oscillator. The intensity of the intermediate signal (IF) was measured by changing the frequency of the UTC-PD; very high bandwidths of up to 26 GHz were obtained. The experimental results agree well with electromagnetic simulations, which indicate that the bandwidth is determined by the external circuit. The conversion gain from RF to IF was -2 dB in the heterodyne mixing by using the HEMT detector.

  16. Advanced Gradient Heating Facility (AGHF)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This section of the publication includes papers entitled: (1) Coupled growth in hypermonotectics; (2) Directional solidification of refined Al-4 wt.% Cu alloys; (3) Effects of convection on interface curvature during growth of concentrated ternary compounds; (4) Directional solidification of Al-1.5 wt.% Ni alloys; (5) Interactive response of advancing phase boundaries to particles; (6) INTeractive Response of Advancing Phase boundaries to Particles-INTRAPP; and (7) Particle engulfment and pushing by solidifying interfaces.

  17. An advanced coarse-grained nucleosome core particle model for computer simulations of nucleosome-nucleosome interactions under varying ionic conditions.

    PubMed

    Fan, Yanping; Korolev, Nikolay; Lyubartsev, Alexander P; Nordenskiöld, Lars

    2013-01-01

    In the eukaryotic cell nucleus, DNA exists as chromatin, a compact but dynamic complex with histone proteins. The first level of DNA organization is the linear array of nucleosome core particles (NCPs). The NCP is a well-defined complex of 147 bp DNA with an octamer of histones. Interactions between NCPs are of paramount importance for higher levels of chromatin compaction. The polyelectrolyte nature of the NCP implies that nucleosome-nucleosome interactions must exhibit a great influence from both the ionic environment as well as the positively charged and highly flexible N-terminal histone tails, protruding out from the NCP. The large size of the system precludes a modelling analysis of chromatin at an all-atom level and calls for coarse-grained approximations. Here, a model of the NCP that include the globular histone core and the flexible histone tails described by one particle per each amino acid and taking into account their net charge is proposed. DNA wrapped around the histone core was approximated at the level of two base pairs represented by one bead (bases and sugar) plus four beads of charged phosphate groups. Computer simulations, using a Langevin thermostat, in a dielectric continuum with explicit monovalent (K(+)), divalent (Mg(2+)) or trivalent (Co(NH(3))(6) (3+)) cations were performed for systems with one or ten NCPs. Increase of the counterion charge results in a switch from repulsive NCP-NCP interaction in the presence of K(+), to partial aggregation with Mg(2+) and to strong mutual attraction of all 10 NCPs in the presence of CoHex(3+). The new model reproduced experimental results and the structure of the NCP-NCP contacts is in agreement with available data. Cation screening, ion-ion correlations and tail bridging contribute to the NCP-NCP attraction and the new NCP model accounts for these interactions. PMID:23418426

  18. An advanced coarse-grained nucleosome core particle model for computer simulations of nucleosome-nucleosome interactions under varying ionic conditions.

    PubMed

    Fan, Yanping; Korolev, Nikolay; Lyubartsev, Alexander P; Nordenskiöld, Lars

    2013-01-01

    In the eukaryotic cell nucleus, DNA exists as chromatin, a compact but dynamic complex with histone proteins. The first level of DNA organization is the linear array of nucleosome core particles (NCPs). The NCP is a well-defined complex of 147 bp DNA with an octamer of histones. Interactions between NCPs are of paramount importance for higher levels of chromatin compaction. The polyelectrolyte nature of the NCP implies that nucleosome-nucleosome interactions must exhibit a great influence from both the ionic environment as well as the positively charged and highly flexible N-terminal histone tails, protruding out from the NCP. The large size of the system precludes a modelling analysis of chromatin at an all-atom level and calls for coarse-grained approximations. Here, a model of the NCP that include the globular histone core and the flexible histone tails described by one particle per each amino acid and taking into account their net charge is proposed. DNA wrapped around the histone core was approximated at the level of two base pairs represented by one bead (bases and sugar) plus four beads of charged phosphate groups. Computer simulations, using a Langevin thermostat, in a dielectric continuum with explicit monovalent (K(+)), divalent (Mg(2+)) or trivalent (Co(NH(3))(6) (3+)) cations were performed for systems with one or ten NCPs. Increase of the counterion charge results in a switch from repulsive NCP-NCP interaction in the presence of K(+), to partial aggregation with Mg(2+) and to strong mutual attraction of all 10 NCPs in the presence of CoHex(3+). The new model reproduced experimental results and the structure of the NCP-NCP contacts is in agreement with available data. Cation screening, ion-ion correlations and tail bridging contribute to the NCP-NCP attraction and the new NCP model accounts for these interactions.

  19. Magnetic particle characterization-magnetophoretic mobility and particle size.

    PubMed

    Zhou, Chen; Boland, Eugene D; Todd, Paul W; Hanley, Thomas R

    2016-06-01

    Quantitative characterization of magnetic particles is useful for analysis and separation of labeled cells and magnetic particles. A particle velocimeter is used to directly measure the magnetophoretic mobility, size, and other parameters of magnetic particle suspensions. The instrument provides quantitative video analysis of particles and their motion. The trajectories of magnetic particles in an isodynamic magnetic field are recorded using a high-definition camera/microscope system for image collection. Image analysis software then converts the image data to the parameters of interest. The distribution of magnetophoretic mobility is determined by combining fast image analysis with velocimetry measurements. Particle size distributions have been characterized to provide a better understanding of sample quality. The results have been used in the development and operation of analyzer protocols for counting particle concentrations accurately and measuring magnetic susceptibility and size for simultaneous display for routine application to particle suspensions and magnetically labeled biological cells. © 2016 International Society for Advancement of Cytometry.

  20. Three-dimensional hollow-structured binary oxide particles as an advanced anode material for high-rate and long cycle life lithium-ion batteries

    SciTech Connect

    Wang, Deli; Wang, Jie; He, Huan; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wu, Zexing; Liu, Hongfang

    2015-12-30

    Transition metal oxides are among the most promising anode candidates for next-generation lithium-ion batteries for their high theoretical capacity. However, the large volume expansion and low lithium ion diffusivity leading to a poor charging/discharging performance. In this study, we developed a surfactant and template-free strategy for the synthesis of a composite of CoxFe3–xO4 hollow spheres supported by carbon nanotubes via an impregnation–reduction–oxidation process. The synergy of the composite, as well as the hollow structures in the electrode materials, not only facilitate Li ion and electron transport, but also accommodate large volume expansion. Using state-of-the-art electron tomography, we directly visualize the particles in 3-D, where the voids in the hollow structures serve to buffer the volume expansion of the material. These improvements result in a high reversible capacity as well as an outstanding rate performance for lithium-ion battery applications. As a result, this study sheds light on large-scale production of hollow structured metal oxides for commercial applications in energy storage and conversion.

  1. Three-dimensional hollow-structured binary oxide particles as an advanced anode material for high-rate and long cycle life lithium-ion batteries

    DOE PAGESBeta

    Wang, Deli; Wang, Jie; He, Huan; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wu, Zexing; Liu, Hongfang

    2015-12-30

    Transition metal oxides are among the most promising anode candidates for next-generation lithium-ion batteries for their high theoretical capacity. However, the large volume expansion and low lithium ion diffusivity leading to a poor charging/discharging performance. In this study, we developed a surfactant and template-free strategy for the synthesis of a composite of CoxFe3–xO4 hollow spheres supported by carbon nanotubes via an impregnation–reduction–oxidation process. The synergy of the composite, as well as the hollow structures in the electrode materials, not only facilitate Li ion and electron transport, but also accommodate large volume expansion. Using state-of-the-art electron tomography, we directly visualize themore » particles in 3-D, where the voids in the hollow structures serve to buffer the volume expansion of the material. These improvements result in a high reversible capacity as well as an outstanding rate performance for lithium-ion battery applications. As a result, this study sheds light on large-scale production of hollow structured metal oxides for commercial applications in energy storage and conversion.« less

  2. A facile hydrothermal recovery of nano sealed MnO2 particle from waste batteries: An advanced material for electrochemical and environmental applications

    NASA Astrophysics Data System (ADS)

    Mylarappa, M.; Venkata Lakshmi, V.; Vishnu Mahesh, K. R.; Nagaswarupa, H. P.; Raghavendra, N.

    2016-09-01

    This work deliberates a method for manganese (Mn) recovery as manganese oxide obtained by leaching of waste batteries with 3M sulphuric acid. The Experimental test for the recovery of Mn present within the waste dry cell batteries were carried out by a reductive leachant. Elemental composition of leached sample was confirmed by Energy Dispersive X-ray analysis (EDAX), and Surface morphology of the recovered MnO2 was examined by using Scanning Electron microscopy (SEM). Phase composition was confirmed from X-ray Diffractro meter (XRD). The obtained leached solution was treated with 4M NaOH, yielded to Manganese Dioxide with high extraction degree, while it do not touches the Zn content within the solutions. The recovered samples were characterized using XRD, EDAX, SEM and Fourier transform infrared spectrometry (FTIR). The electrochemical properties of the as-recovered sample from leached solution was examined used cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Remarkably, the 80 wt.% MnO2 displays reversibility, diffusion constant, smaller equivalent series resistance and charge transfer resistance in 0.5M NaOH showed superior results as compared to alternative electrolytes. The ideal capacitive behaviour of MnO2 electrode and nano particle was applied to photocatalytic degradation of dyes.

  3. High current induction linacs

    NASA Astrophysics Data System (ADS)

    Barletta, W.; Faltens, A.; Henestroza, E.; Lee, E.

    1994-07-01

    Induction linacs are among the most powerful accelerators in existence. They have accelerated electron bunches of several kiloamperes, and are being investigated as drivers for heavy ion driven inertial confinement fusion (HIF), which requires peak beam currents of kiloamperes and average beam powers of some tens of megawatts. The requirement for waste transmutation with an 800 MeV proton or deuteron beam with an average current of 50 mA and an average power of 40 MW lies midway between the electron machines and the heavy ion machines in overall difficulty. Much of the technology and understanding of beam physics carries over from the previous machines to the new requirements. The induction linac allows use of a very large beam aperture, which may turn out to be crucial to reducing beam loss and machine activation from the beam halo. The major issues addressed here are transport of high intensity beams, availability of sources, efficiency of acceleration, and the state of the needed technology for the waste treatment application. Because of the transformer-like action of an induction core and the accompanying magnetizing current, induction linacs make the most economic sense and have the highest efficiencies with large beam currents. Based on present understanding of beam transport limits, induction core magnetizing current requirements, and pulse modulators, the efficiencies could be very high. The study of beam transport at high intensities has been the major activity of the HIF community. Beam transport and sources are limiting at low energies but are not significant constraints at the higher energies. As will be shown, the proton beams will be space-charge-dominated, for which the emittance has only a minor effect on the overall beam diameter but does determine the density falloff at the beam edge.

  4. The structure and properties of boron carbide ceramics modified by high-current pulsed electron-beam

    NASA Astrophysics Data System (ADS)

    Ivanov, Yuri; Tolkachev, Oleg; Petyukevich, Maria; Teresov, Anton; Ivanova, Olga; Ikonnikova, Irina; Polisadova, Valentina

    2016-01-01

    The present work is devoted to numerical simulation of temperature fields and the analysis of structural and strength properties of the samples surface layer of boron carbide ceramics treated by the high-current pulsed electron-beam of the submillisecond duration. The samples made of sintered boron carbide ceramics are used in these investigations. The problem of calculating the temperature field is reduced to solving the thermal conductivity equation. The electron beam density ranges between 8…30 J/cm2, while the pulse durations are 100…200 μs in numerical modelling. The results of modelling the temperature field allowed ascertaining the threshold parameters of the electron beam, such as energy density and pulse duration. The electron beam irradiation is accompanied by the structural modification of the surface layer of boron carbide ceramics either in the single-phase (liquid or solid) or two-phase (solid-liquid) states. The sample surface of boron carbide ceramics is treated under the two-phase state (solid-liquid) conditions of the structural modification. The surface layer is modified by the high-current pulsed electron-beam produced by SOLO installation at the Institute of High Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia. The elemental composition and the defect structure of the modified surface layer are analyzed by the optical instrument, scanning electron and transmission electron microscopes. Mechanical properties of the modified layer are determined measuring its hardness and crack resistance. Research results show that the melting and subsequent rapid solidification of the surface layer lead to such phenomena as fragmentation due to a crack network, grain size reduction, formation of the sub-grained structure due to mechanical twinning, and increase of hardness and crack resistance.

  5. A comparison of high current and low voltage electrical stunning systems on broiler breast rigor development and meat quality.

    PubMed

    Craig, E W; Fletcher, D L

    1997-08-01

    Experiments were conducted to compare the effects of a high current (HC) stunning system to a low voltage (LV) stunning system on broiler carcass and meat quality. A total of 360 broiler chickens were individually stunned using either 125 mA, 50 Hz, constant AC for 5 s (HC) or using 10.5 V, 500 Hz pulsed DC for 10 s (LV). Birds were individually weighted, killed by conventional neck cut, bled for 150 s, and reweighed to determine blood loss. Breast fillets (Pectoralis major) were removed from the carcass immediately after picking (0 h) or after aging for 24 h in a static ice-water slush. Breast muscle pH was determined at both 0 and 24 h. Raw breast meat color (CIELAB) and cooked breast meat Allo-Kramer shear values were determined on samples held at 2 C for 48 h. The LV stunning treatment significantly increased (P < 0.05) blood loss (4.0 vs 3.7%) and significantly reduced initial muscle pH (6.47 vs 6.67) when compared to the HC stunning treatment. There were no significant differences between the stunning systems for 24 h pH, raw breast color, and Allo-Kramer shear. High current stunning reduced initial blood loss and delayed early rigor development compared to the LV treatment, but appeared to have little effect on final meat quality. PMID:9251149

  6. A high-current electron gun for the electron beam ion trap at the National Superconducting Cyclotron Laboratory

    SciTech Connect

    Schwarz, S. Baumann, T. M.; Kittimanapun, K.; Lapierre, A.; Snyder, A.

    2014-02-15

    The Electron Beam Ion Trap (EBIT) in NSCL’s reaccelerator ReA uses continuous ion injection and accumulation. In order to maximize capture efficiency and minimize breeding time into high charge states, the EBIT requires a high-current/high current-density electron beam. A new electron gun insert based on a concave Ba-dispenser cathode has been designed and built to increase the current transmitted through the EBIT’s superconducting magnet. With the new insert, stable EBIT operating conditions with 0.8 A of electron beam have been established. The design of the electron gun is presented together with calculated and measured perveance data. In order to assess the experimental compression of the electron beam, a pinhole CCD camera has been set up to measure the electron beam radius. The camera observes X-rays emitted from highly charged ions, excited by the electron beam. Initial tests with this camera setup will be presented. They indicate that a current density of 640 A/cm{sup 2} has been reached when the EBIT magnet was operated at 4 T.

  7. Rare particles

    SciTech Connect

    Kutschera, W.

    1984-01-01

    The use of Accelerator Mass Spectrometry (AMS) to search for hypothetical particles and known particles of rare processes is discussed. The hypothetical particles considered include fractionally charged particles, anomalously heavy isotopes, and superheavy elements. The known particles produced in rare processes discussed include doubly-charged negative ions, counting neutrino-produced atoms in detectors for solar neutrino detection, and the spontaneous emission of /sup 14/C from /sup 223/Ra. 35 references. (WHK)

  8. Particle separation

    NASA Technical Reports Server (NTRS)

    Moosmuller, Hans (Inventor); Chakrabarty, Rajan K. (Inventor); Arnott, W. Patrick (Inventor)

    2011-01-01

    Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

  9. Particle separation

    DOEpatents

    Moosmuller, Hans; Chakrabarty, Rajan K.; Arnott, W. Patrick

    2011-04-26

    Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

  10. Automated optical microscopy of coated particle fuel

    SciTech Connect

    Kercher, Andrew K; Hunn, John D; Price, Jeffery R; Pappano, Peter J

    2008-01-01

    Fundamental technological advances have occurred during the 20 year hiatus in US research on coated particle nuclear fuel. As part of the recent US Department of Energy s Advanced Gas Reactor Fuel Development and Qualification program, Oak Ridge National Laboratory has utilized advancements in computer automation, digital imaging, and image analysis to modernize US optical microscopy techniques for coated particle nuclear fuel. Automated optical microscopy has enabled detailed and objective analysis of individual particles (hundreds of measurements per particle) and of large sample sizes that far exceed the capabilities of conventional manual microscopy methods (analysis of 1500-5000 particles is common). Demonstrative examples of the capabilities of this automated optical microscopy are given for: (a) shadow imaging of kernels, coated fuel particles, and graphite matrix overcoated particles and (b) cross-sectional analysis of coated fuel particles to determine layer thicknesses.

  11. Development of high current Bi and Au beams for the synchrotron operation at the GSI accelerator facility

    SciTech Connect

    Adonin, A.; Hollinger, R.

    2012-02-15

    In this work, the latest results of developing high current ion beams of Au and Bi at GSI facility are described. The difficulties in the production of required charge state in vacuum arc discharge ion sources using the pure materials in the cathodes are discussed. As a possible solution, admix of a small amount of more refractory metal to the cathode material is considered. As a significant result, a dramatic improvement in the production of high charge state Bi ions using the mixed Bi-Cu cathodes (with 8%-15% of Cu admixed) compared to pure Bi cathodes is presented. The preliminary results of investigation of the material structure of Bi-Cu cathodes are discussed. As a next step, it is planned to test the composition of Au with Pd, Zr, and Fe as cathode materials.

  12. Efficiency roll-off suppression in organic light-emitting diodes at high current densities using gold bowtie nanoantennas

    NASA Astrophysics Data System (ADS)

    Zhao, Yukun; Yun, Feng; Wu, Zhaoxin; Li, Yufeng; Jiao, Bo; Huang, Yaping; Li, Sanfeng; Feng, Lungang; Guo, Maofeng; Ding, Wen; Zhang, Ye; Dou, Juan

    2016-02-01

    In this study, large-scale gold (Au) bowtie nanoantennas have been utilized to suppress the efficiency roll-off in organic light-emitting diodes (OLEDs) numerically and experimentally. Compared with the OLED without nanoantennas, the experimental roll-off ratio of the OLED with Au bowtie nanoantennas significantly decreases from 59.4 to 51.3% at a high current density of 1000 mA/cm2. We attribute the roll-off suppression to the localized surface plasmon (LSP) effect, which leads to a shorter radiative lifetime. The insufficient coupling between radiated light and LSP resonance could also be improved by a strong resonance coupling between the tips of bowtie nanoantennas.

  13. Cathode performance during two beam operation of the high current high polarization electron gun for eRHIC

    SciTech Connect

    Rahman, O.; Ben-Zvi, I.; Degen, C.; Gassner, D. M.; Lambiase, R.; Meng, W.; Pikin, A.; Rao, T.; Sheehy, B.; Skaritka, J.; Wang, E.; Pietz, J.; Ackeret, M.; Yeckel, C.; Miller, R.; Dobrin, E.; Thompson, K.

    2015-05-03

    Two electron beams from two activated bulk GaAs photocathodes were successfully combined during the recent beam test of the High Current High Polarization Electron gun for eRHIC. The beam test took place in Stangenes Industries in Palo Alto, CA, where the cathodes were placed in diagonally opposite locations inside the high voltage shroud. No significant cross talking between the cathodes was found for the pertinent vacuum and low average current operation, which is very promising towards combining multiple beams for higher average current. This paper describes the cathode preparation, transport and cathode performance in the gun for the combining test, including the QE and lifetimes of the photocathodes at various steps of the experiment.

  14. Propagation of a surface microwave along the afterglow plasma column of a high-current pulsed discharge

    SciTech Connect

    Sergeichev, K. F.; Karfidov, D. M.

    2011-09-15

    It is demonstrated experimentally that the lifetime of the afterglow plasma of a high-current pulsed discharge in a dielectric tube filled with a mixture of argon with saturated mercury vapor is longer than 1 ms. Such a long lifetime, during which the electron density decreases from 10{sup 14} to 10{sup 12} cm{sup -3}, is explained by the chemi-ionization of mercury vapor by long-lived metastable argon atoms. During this time, the afterglow plasma can serve as a microwave waveguide for a weakly damped low-noise E{sub 0}-type axisymmetric surface mode, which allows one to use it for transmission of signals in the centimeter wavelength range.

  15. High-current density, high-brightness electron beams from large-area lanthanum hexaboride cathodes. Memorandum report

    SciTech Connect

    Loschialpo, P.; Kapetanakos, C.A.

    1987-12-13

    Large (approx. 5 cm) diameter lanthanum hexaboride (LaB/sub 6/) cathodes operated at 10 kV produced 1-5 micro electron pulses with current density between 10 and 20 A/sq. cm. Normalized beam brightness was consistently measured. To obtain this high current density, the LaB/sub 6/ cathodes have been heated to temperatures between approx 1600 to 1800 C. Very uniform temperature profiles are obtained by applying a carefully tailored electron-bombardment heating power distribution. These measurements have been made between pressure .000001 to .00001 Torr, i.e., under much less-demanding vacuum conditions than that required by conventional dispenser-type cathodes.

  16. Characterization of High Current RRP(R) Wires as a Function of Magnetic Field, Temperature and Strain

    SciTech Connect

    Godeke, A.; Mentink, M.G.T.; Dietderich, D. R.; den Ouden, A.

    2009-08-16

    A new instrument for the characterization of superconducting materials as a function of Magnetic Field, Temperature and Strain, was designed, constructed and tested at Lawrence Berkeley National Laboratory (LBNL). A U-shaped bending spring was selected, since that design has proven to enable accurate characterizations of a multitude of superconducting materials for more than a decade. The new device is validated though measurements on very high current Rod Restack Processed (RRP) Internal-Tin (IT) wires, for which we will present initial results, including parameterizations of the superconducting phase boundaries and comparisons with other wire types. Accurate parametrization of modern high magnetic field conductors is important for the analysis of the performance of magnet systems.

  17. A HIGH CURRENT, HIGH VOLTAGE SOLID-STATE PULSE GENERATOR FOR THE NIF PLASMA ELECTRODE POCKELS CELL

    SciTech Connect

    Arnold, P A; Barbosa, F; Cook, E G; Hickman, B C; Akana, G L; Brooksby, C A

    2007-07-27

    A high current, high voltage, all solid-state pulse modulator has been developed for use in the Plasma Electrode Pockels Cell (PEPC) subsystem in the National Ignition Facility. The MOSFET-switched pulse generator, designed to be a more capable plug-in replacement for the thyratron-switched units currently deployed in NIF, offers unprecedented capabilities including burst-mode operation, pulse width agility and a steady-state pulse repetition frequency exceeding 1 Hz. Capable of delivering requisite fast risetime, 17 kV flattop pulses into a 6 {Omega} load, the pulser employs a modular architecture characteristic of the inductive adder technology, pioneered at LLNL for use in acceleration applications, which keeps primary voltages low (and well within the capabilities of existing FET technology), reduces fabrication costs and is amenable to rapid assembly and quick field repairs.

  18. The high current transient generator, theory and operation for simulating lightning induced voltages into aerospace electrical circuits

    NASA Technical Reports Server (NTRS)

    Schulte, E. H.

    1975-01-01

    Because of the difficulty, hazard, and cost of simulating full-scale lightning currents on flight vehicles, a nondestructive test technique using reduced-scale lightning currents was used to determine if threat level voltages will be induced into aircraft electrical circuits in the event the aircraft is actually struck by lightning. The reasoning and theory of selecting a particular simulated lightning waveshape and magnitude is given, showing that extrapolation of induced waveforms over several orders of magnitude should be avoided. The operation of high-current transient generators and hardware are described along with typical applications. The means by which voltages were generated, induced, and measured, as well as possible sources of error, are discussed.

  19. Analysis of the wake field effects in the PEP-II storage rings with extremely high currents

    NASA Astrophysics Data System (ADS)

    Novokhatski, A.; Seeman, J.; Sullivan, M.

    2014-01-01

    We present the history and analysis of different wake field effects throughout the operational life of the PEP-II SLAC B-factory. Although the impedance of the high and low energy rings is small, the intense high-current beams generated a lot of power. The effects from these wake fields are: heating and damage of vacuum beam chamber elements like RF seals, vacuum valves, shielded bellows, BPM buttons and ceramic tiles; vacuum spikes, vacuum instabilities and high detector background; and beam longitudinal and transverse instabilities. We also discuss the methods used to eliminate these effects. Results of this analysis and the PEP-II experience may be very useful in the design of new storage rings and light sources.

  20. Spatially resolved high-resolution x-ray spectroscopy of high-current plasma-focus discharges

    SciTech Connect

    ZajaPc, S.; Rzadkiewicz, J.; Scholz, M.; Paduch, M.; Zielinska, E.; Rosmej, O.; Yongtao, Zhao; Gojska, A.

    2010-10-15

    Soft x-ray emission from a Mather-type plasma-focus device (PF-1000) operated at {approx}400 kJ was measured. The high density and temperature plasma were generated by the discharge in the deuterium-argon gas mixture in the modified (high-current) plasma-focus configuration. A spherically bent mica crystal spectrograph viewing the axial output of the pinch region was used to measure the x-ray spectra. Spatially resolved spectra including the characteristic x-ray lines of highly ionized Ar and continua were recorded by means of an x-ray film. The x-ray emission of PF-1000 device was studied at different areas of the pinch.

  1. Development of a High-Brightness and High-Current Electron Gun for High-Flux γ-Ray Generation

    NASA Astrophysics Data System (ADS)

    Nishimori, N.; Nagai, R.; Matsuba, S.; Hajima, R.; Yamamoto, M.; Honda, Y.; Miyajima, T.; Uchiyama, T.; Kuriki, M.

    2015-10-01

    A high-flux mono-energetic γ-ray beam can be generated via Compton scattering of high-power laser by high-brightness electron beam. We have developed a high-brightness and high-current electron gun for generation of the high-flux γ-ray beam. Recently we demonstrated 500 keV electron beam generation, which meets the high-brightness requirement, from our DC photocathode gun at Japan Atomic Energy Agency. The gun was transported to High Energy Accelerator Research Organization (KEK) and connected to the following accelerator system. The gun operational status at KEK and our plan to develop a multialkali photocathode with a long lifetime are presented.

  2. Magnetic Particle Imaging

    SciTech Connect

    Minard, Kevin R.

    2010-02-01

    Rapid advances in the synthesis of superparamagnetic nanoparticles has stimulated widespread interest in their use as contrast agents for visualizing biological processes with Magnetic Resonance Imaging (MRI). With this approach, strong particle magnetism alters the MRI signal from nearby water protons and this, in turn, affects observed image contrast. Magnetic particle detection with MRI is therefore indirect and suffers from several associated problems, including poor quantification and tissuedependent performance. Magnetic Particle Imaging (MPI) overcomes these by directly measuring the amount of superparamagnetic material at each location. Mass sensitivity, spatial resolution, and imaging time is also comparable to or better than that achieved with MRI. Moreover, MPI is relatively inexpensive, meets all current safety guidelines, is quantitative, provides unambiguous contrast with tissue-independent performance, and can detect lower particle concentrations. Here, the basic principles behind MPI are described, factors affecting sensitivity and resolution are discussed, and potential utility for biomedical use is examined.

  3. Submillimeter SIS Mixers Using High Current Density Nb/AIN/Nb Tunnel Junctions and NbTiN Films

    NASA Astrophysics Data System (ADS)

    Kawamura, J.; Miller, D.; Chen, J.; Kooi, J.; Zmuidzinas, J.; Bumble, B.; Leduc, H.; Stern, J.

    1999-03-01

    We are currently exploring ways to improve the performance of SIS mixers above 700 GHz. One approach is to use NbTiN in place of Nb for all or some of the mixer circuitry. With its high gap frequency and low losses demonstrated up to 800 GHz, it should be possible to fabricate an all-NbTiN SIS mixer with near quantum-limited noise performance up to 1.2 THz. Using a quasioptical twin-slot two-junction mixer with NbTiN ground plane and wiring and hybrid Nb/A1N/NbTiN junctions, we measured an uncorrected receiver noise temperature of TRx ~ 500 K across 790-850 GHz at 4.2 K bath temperature. Our second approach is to reduce the RC product of the mixer by employing very high current density Nb/A1N/Nb junctions. By using these we will greatly relax the requirement on tuning circuits, which is where substantial losses occur in mixers operating above the Nb gap frequency. These junctions have resistance-area products of R_N*A ~ 5.6 Ohm um2, good subgap to normal resistance ratios, R_sg/R_N ~ 10, and good run-to-run reproducibility. From FTS measurements we infer that omega*R_N*C = 1 at 270 GHz in these junctions. This is a substantial improvement over that available using Nb/Al0x/Nb technology. The sensitivity of a receiver incorporating these high current density mixers is T_Rx = 110 K at 533 GHz using a design for lower J_c mixers, which is close to the best we have measured with lower J_c Nb/Al0x/Nb mixers.

  4. Beam envelope, injection, and acceleration in a compact, high-current, strong-focused recirculating accelerator scheme. Technical report

    SciTech Connect

    Prakash, A.

    1988-12-01

    In order to meet the criterion of compactness in developing high-current, high-energy electron accelerators, it is advantageous to recirculate the electron beam through an accelerating module. Various such recirculating-accelerator concepts that use strong-focusing magnetic fields may be conveniently referred to as SFRA (Strong Focused Recirculating Accelerators). The strong-focusing field can be produced by external current-carrying stellarator or torsatron windings. SLIA, Stellatron, RIA and rebatron are examples of SFRA. High current electron beam transport in externally applied stellarator and longitudinal magnetic fields is analyzed. It is shown that a constant of motion exists for a matched beam of rotating elliptical cross section, with self-fields included. A differential equation for the beam envelope is derived and is shown to reduce to the familiar beam envelope equation for a beam of circular cross section when the stellarator field is turned off. A summary description of beam dynamics of acceleration in one SFRA, the rebatron, is given. Although a rebatron with major radius 100 cm and minor radius 10 cm can accelerate electrons to gamma about 65 with a fixed vertical (bending) magnetic field, the insensitivity to energy mismatch poses a problem for beam-trapping and injection. It is shown that a beam trapping scheme, in which a rapidly varying vertical magnetic field is applied before activating the rebatron acceleration gap, would work for a 10-kA beam of 1-cm radius injected near the wall of a rebatron of minor radius 16 cm.

  5. Particle generator

    DOEpatents

    Hess, Wayne P.; Joly, Alan G.; Gerrity, Daniel P.; Beck, Kenneth M.; Sushko, Peter V.; Shlyuger, Alexander L.

    2005-06-28

    Energy tunable solid state sources of neutral particles are described. In a disclosed embodiment, a halogen particle source includes a solid halide sample, a photon source positioned to deliver photons to a surface of the halide, and a collimating means positioned to accept a spatially defined plume of hyperthermal halogen particles emitted from the sample surface.

  6. The ADvanced SEParation (ADSEP)

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The ADvanced SEParation (ADSEP) commercial payload is making use of major advances in separation technology: The Phase Partitioning Experiment (PPE); the Micorencapsulation experiment; and the Hemoglobin Separation Experiment (HSE). Using ADSEP, commercial researchers will attempt to determine the partition coefficients for model particles in a two-phase system. With this information, researchers can develop a higher resolution, more effective cell isolation procedure that can be used for many different types of research and for improved health care. The advanced separation technology is already being made available for use in ground-based laboratories.

  7. General defocusing particle tracking.

    PubMed

    Barnkob, Rune; Kähler, Christian J; Rossi, Massimiliano

    2015-09-01

    A General Defocusing Particle Tracking (GDPT) method is proposed for tracking the three-dimensional motion of particles in Lab-on-a-chip systems based on a set of calibration images and the normalized cross-correlation function. In comparison with other single-camera defocusing particle-tracking techniques, GDPT possesses a series of key advantages: it is applicable to particle images of arbitrary shapes, it is intuitive and easy to use, it can be used without advanced knowledge of optics and velocimetry theory, it is robust against outliers and overlapping particle images, and it requires only equipment which is standard in microfluidic laboratories. We demonstrate the method by tracking the three-dimensional motion of 2 μm spherical particles in a microfluidic channel using three different optical arrangements. The position of the particles was measured with an estimated uncertainty of 0.1 μm in the in-plane direction and 2 μm in the depth direction for a measurement volume of 1510 × 1270 × 160 μm(3). A ready-to-use GUI implementation of the method can be acquired on . PMID:26201498

  8. Recent trends in particle size analysis techniques

    NASA Technical Reports Server (NTRS)

    Kang, S. H.

    1984-01-01

    Recent advances and developments in the particle-sizing technologies are briefly reviewed in accordance with three operating principles including particle size and shape descriptions. Significant trends of the particle size analysing equipment recently developed show that compact electronic circuitry and rapid data processing systems were mainly adopted in the instrument design. Some newly developed techniques characterizing the particulate system were also introduced.

  9. Spatial dynamics of high current turn-on in low-voltage AlGaAs/GaAs phototransistors

    NASA Astrophysics Data System (ADS)

    Slipchenko, S. O.; Podoskin, A. A.; Soboleva, O. S.; Pikhtin, N. A.; Bagaev, T. A.; Ladugin, M. A.; Marmalyuk, A. A.; Simakov, V. A.; Tarasov, I. S.

    2016-03-01

    Dynamic characteristics of low-voltage AlGaAs/GaAs heterostructure N-p-N phototransistors operating in the high-current mode have been studied. It was found that, above critical voltages, the turn-on process of a phototransistor consists of two phases separated in space and time. It is shown that the power of an optical-activation source affects the turn-on delay of the phototransistor and has no effect on the maximum current. An analysis of the spatial current dynamics in the plane of the collector p-n junction demonstrated that the first phase of the turn-on process is localized in the optical activation (optical window) region. In this case, the region of current localization during the first phase may be smaller than the optical-activation region. It was found that the whole current during the second phase is localized at the boundary between the optical window and the ohmic contact. The turn-on delay of the second phase is associated with the carrier transport in the base layer from the optical-activation region to the boundary with the ohmic collector contact.

  10. A cookbook for building a high-current dimpled H magnetron source for accelerators

    SciTech Connect

    Bollinger, Daniel S.; Karns, Patrick R.; Tan, Cheng -Yang

    2015-10-30

    A high-current (>50 mA) dimpled H magnetron source has been built at Fermilab for supplying H beam to the entire accelerator complex. Despite many decades of expertise with slit H magnetron sources at Fermilab, we were faced with many challenges from the dimpled H magnetron source, which needed to be overcome in order to make it operational. Dimpled H sources for high-energy physics are not new: Brookhaven National Laboratory has operated a dimpled H- source for more than two decades. However, the transference of that experience to Fermilab took about two years because a cookbook for building this type of source did not exist and seemingly innocuous or undocumented choices had a huge impact on the success or failure for this type of source. Moreover, it is the goal of this paper to document the reasons for these choices and to present a cookbook for building and operating dimpled H magnetron sources.

  11. Homoleptic and heteroleptic N-alkylimidazole zinc(ii)-containing ionic liquids for high current density electrodeposition.

    PubMed

    Steichen, Marc; Brooks, Neil R; Van Meervelt, Luc; Fransaer, Jan; Binnemans, Koen

    2014-08-28

    New homoleptic and heteroleptic zinc(ii)-containing liquid metal salts with N-alkylimidazole (AlkIm) ligands and bis(trifluoromethylsulfonyl)imide (Tf2N(-)) anions are described. The general formulae of the complexes are [Zn(AlkIm)6][Tf2N]2 and [Zn(AlkIm)6-x(AlkIm')x][Tf2N]2. Single-crystal X-ray diffraction revealed that, in the solid state, the cations consist of octahedral zinc(ii) centres. The heteroleptic complexes contain two different N-alkylimidazole ligands. The melting points of the liquid metal salts are below or slightly above room temperature. The dependence of the melting points, viscosity and crystal structure on the alkyl chain length of the N-alkylimidazole ligand for the homoleptic complexes and on the ratio of the two N-alkylimidazole ligands AlkIm and AlkIm' for the heteroleptic compounds is discussed. The possibility of incongruent melting and the presence of a mixture of the four-coordinate zinc(ii) centre and neutral ligands is discussed. The new zinc(ii)-containing liquid metal salts have been used as non-aqueous electrolytes for electrodeposition of zinc. A highly reversible deposition-stripping behaviour was found. Zinc electroplating was possible at very high current densities of more than -200 mA cm(-2) in unstirred solutions. Compact and highly crystalline zinc deposits were obtained.

  12. A HIgh Current Density Low Cost Niobium 3 Tin Titanium Doped Conductor Utilizing A Novel Internal Tin Process

    SciTech Connect

    Bruce A Zeitlin

    2005-02-23

    An internal tin conductor has been developed using a Mono Element Internal Tin (MEIT) with an integral Nb barrier surrounding the Nb filaments. High current densities of 3000 A/mm2+ at 12 T and 1800 A/mm2 at 15 T have been achieved in conductors as small as 0.152 mm with the use of Nb7.5Ta filaments and Ti in the Sn core. In contrast, conductors with pure Nb and Ti in the Sn achieved 2700 A/mm2 at 12 T. Two internal fins, developed and patented on the project, were introduced into the filament array and reduced the effective filament diameter (Deff) by 38%. Additional fins will further reduce Deff The conductor was produced from 152.4 mm diameter billets to produce wire as small as 0.152 mm. The process promises be scaleable to 304 mm diameter billets yielding wire of 0.304 mm diameter. The MEIT process wire was easy to draw with relatively few breaks. The cost of this conductor in large production quantities based on the cost model presented could meet the 1.5 $/kilo amp meter(KAM) target of the HEP community

  13. Characterization of Downstream Ion Energy Distributions From a High Current Hollow Cathode in a Ring Cusp Discharge Chamber

    NASA Technical Reports Server (NTRS)

    Foster, John E.; Patterson, Michael J.

    2003-01-01

    The presence of energetic ions produced by a hollow cathodes operating at high emission currents (greater than 10 Angstroms) has been documented in the literature. As part of an ongoing effort to uncover the underlying physics of the formation of these ions, ion efflux from a high current hollow cathode operating in an ion thruster discharge chamber was investigated. Using a spherical sector electrostatic energy analyzer located downstream of the discharge cathode, the ion energy distribution over a 0 to 60 eV energy range was measured. The sensitivity of the ion energy distribution function to zenith angle was also assessed at 3 different positions: 0, 15, and 25 degrees. The measurements suggest that the majority of the ion current at the measuring point falls into the analyzer with an energy approximately equal to the discharge voltage. The ion distribution, however, was found to be quite broad. The high energy tail of the distribution function tended to grow with increasing discharge current. Sensitivity of the profiles to flow rate at fixed discharge current was also investigated. A simple model is presented that provides a potential mechanism for the production of ions with energies above the discharge voltage.

  14. Proceedings of the DOE workshop on the role of a high-current accelerator in the future of nuclear medicine

    SciTech Connect

    Moody, D.C.; Peterson, E.J.

    1989-05-01

    The meeting was prompted by recent problems with isotope availability from DOE accelerator facilities; these difficulties have resulted from conflicting priorities between physics experiments and isotope production activities. The workshop was a forum in which the nuclear medicine community, isotope producers, industry, and other interested groups could discuss issues associated with isotope availability (including continuous supply options), the role of DOE and industry in isotope production, and the importance of research isotopes to the future of nuclear medicine. The workshop participants endorsed DOE's presence in supplying radioisotopes for research purposes and recommended that DOE should immediately provide additional support for radionuclide production in the form of personnel and supplies, DOE should establish a policy that would allow income from sales of future ''routine'' radionuclide production to be used to support technicians, DOE should obtain a 70-MeV, 500-/mu/A variable-energy proton accelerator as soon as possible, and DOE should also immediately solicit proposals to evaluate the usefulness of a new or upgraded high-energy, high-current machine for production of research radionuclides. This proceedings volume is a summary of workshop sessions that explored the future radionuclide needs of the nuclear medicine community and discussed the DOE production capabilities that would be required to meet these needs.

  15. Streak-Camera Measurements with High Currents in PEP-II and Variable Optics in SPEAR3

    SciTech Connect

    Cheng, Weixeng; Fisher, Alan, a Corbett, Jeff; /SLAC

    2008-06-05

    A dual-axis, synchroscan streak camera was used to measure longitudinal bunch profiles in three storage rings at SLAC: the PEP-II low- and high-energy rings, and SPEAR3. At high currents, both PEP rings exhibit a transient synchronous-phase shift along the bunch train due to RF-cavity beam loading. Bunch length and profile asymmetry were measured along the train for a range of beam currents. To avoid the noise inherent in a dual-axis sweep, we accumulated single-axis synchroscan images while applying a 50-ns gate to the microchannel plate. To improve the extinction ratio, an upstream mirror pivoting at 1 kHz was synchronized with the 2kHz MCP gate to deflect light from other bunches off the photocathode. Bunch length was also measured on the HER as a function of beam energy. For SPEAR3 we measured bunch length as a function of single-bunch current for several lattices: achromatic, low-emittance and low momentum compaction. In the first two cases, resistive and reactive impedance components can be extracted from the longitudinal bunch profiles. In the low-alpha configurations, we observed natural bunch lengths approaching the camera resolution, requiring special care to remove instrumental effects, and saw evidence of periodic bursting.

  16. New IES Scheme for Power Conditioning at Ultra-High Currents: from Concept to MHD Modeling and First Experiments

    NASA Astrophysics Data System (ADS)

    Chuvatin, Alexandre S.; Rudakov, Leonid I.; Kokshenev, Vladimir A.; Aranchuk, Leonid E.; Huet, Dominique; Gasilov, Vladimir A.; Krukovskii, Alexandre Yu.; Kurmaev, Nikolai E.; Fursov, Fiodor I.

    2002-12-01

    This work introduces an inductive energy storage (IES) scheme which aims pulsed-power conditioning at multi- MJ energies. The key element of the scheme represents an additional plasma volume, where a magnetically accelerated wire array is used for inductive current switching. This plasma acceleration volume is connected in parallel to a microsecond capacitor bank and to a 100-ns current ruse-time useful load. Simple estimates suggest that optimized scheme parameters could be reachable even when operating at ultra-high currents. We describe first proof-of-principle experiments carried out on GIT12 generator [1] at the wire-array current level of 2 MA. The obtained confirmation of the concept consists in generation of a 200 kV voltage directly at an inductive load. This load voltage value can be already sufficient to transfer the available magnetic energy into kinetic energy of a liner at this current level. Two-dimensional modeling with the radiational MHD numerical tool Marple [2] confirms the development of inductive voltage in the system. However, the average voltage increase is accompanied by short-duration voltage drops due to interception of the current by the low-density upstream plasma. Upon our viewpoint, this instability of the current distribution represents the main physical limitation to the scheme performance.

  17. Surface modification of 40CrNiMo7 steel with high current pulsed electron beam treatment

    NASA Astrophysics Data System (ADS)

    Hao, Shengzhi; Wang, Huihui; Zhao, Limin

    2016-02-01

    High current pulsed electron beam (HCPEB) treatment was conducted on 40CrNiMo7 steel with accelerating voltage 27 kV, energy density 3 J/cm2, pulse duration 2.5 μs and 1-50 pulses. The evolutions of surface microstructure were investigated by using optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) techniques. It was found that the carbides in the surface remelted layer of depth ∼4 μm were dissolved gradually along with the increasing number of HCPEB pulses. Eventually, the surface microstructure of 40CrNiMo7 steel was transformed to a complex structure composed of very refined ∼150 nm austenite as the main part and a little quantity of martensite phases. After 15 pulses of HCPEB treatment, the surface microhardness was doubled to 553 HV, and the wear rate decreased to one third of the initial state correspondingly.

  18. Very High Current Density Nb/AlN/Nb Tunnel Junctions for Low-Noise Submillimeter Mixers

    NASA Technical Reports Server (NTRS)

    Kawamura, Jonathan; Miller, David; Chen, Jian; Zmuidzinas, Jonas; Bumble, Bruce; LeDuc, Henry G.; Stern, Jeff A.

    2000-01-01

    We have fabricated and tested submillimeter-wave superconductor-insulator-superconductor (SIS) mixers using very high current density Nb/AlN/Nb tunnel junctions (J(sub c) approximately equal 30 kA/sq cm) . The junctions have low resistance-area products (R(sub N)A approximately 5.6 Omega.sq micron), good subgap to normal resistance ratios R(sub sg)/R(sub N) approximately equal 10, and good run-to-run reproducibility. From Fourier transform spectrometer measurements, we infer that omega.R(sub N)C = 1 at 270 GHz. This is a factor of 2.5 improvement over what is generally available with Nb/AlO(x)/Nb junctions suitable for low-noise mixers. The AlN-barrier junctions are indeed capable of low-noise operation: we measure an uncorrected receiver noise temperature of T(sub RX) = 110 K (DSB) at 533 GHz for an unoptimized device. In addition to providing wider bandwidth operation at lower frequencies, the AlN-barrier junctions will considerably improve the performance of THz SIS mixers by reducing RF loss in the tuning circuits.

  19. Very high-current-density Nb/AlN/Nb tunnel junctions for low-noise submillimeter mixers

    NASA Astrophysics Data System (ADS)

    Kawamura, Jonathan; Miller, David; Chen, Jian; Zmuidzinas, Jonas; Bumble, Bruce; LeDuc, Henry G.; Stern, Jeff A.

    2000-04-01

    We have fabricated and tested submillimeter-wave superconductor-insulator-superconductor (SIS) mixers using very high-current-density Nb/AlN/Nb tunnel junctions (Jc≈30 kA cm-2). The junctions have low-resistance-area products (RNA≈5.6 Ω μm2), good subgap-to-normal resistance ratios Rsg/RN≈10, and good run-to-run reproducibility. From Fourier transform spectrometer measurements, we infer that ωRNC=1 at 270 GHz. This is a factor of 2.5 improvement over what is generally available with Nb/AlOx/Nb junctions suitable for low-noise mixers. The AlN-barrier junctions are indeed capable of low-noise operation: we measure an uncorrected double-sideband receiver noise temperature of TRX=110 K at 533 GHz for an unoptimized device. In addition to providing wider bandwidth operation at lower frequencies, the AlN-barrier junctions will considerably improve the performance of THz SIS mixers by reducing rf loss in the tuning circuits.

  20. Research on soft x-rays in high-current plasma-focus discharges and estimation of plasma electron temperature

    NASA Astrophysics Data System (ADS)

    Skladnik-Sadowska, E.; Zaloga, D.; Sadowski, M. J.; Kwiatkowski, R.; Malinowski, K.; Miklaszewski, R.; Paduch, M.; Surala, W.; Zielinska, E.; Tomaszewski, K.

    2016-09-01

    The paper presents results of experimental studies of dense and high-temperature plasmas, which were produced by pulsed high-current discharges within a modernised PF-1000U facility operated at different initial gas conditions, and supplied from a condenser bank which delivered energy of about 350 kJ. The investigated discharges were performed at the initial deuterium filling under pressure of 1.6-2.0 hPa, with or without an additional puffing of pure deuterium (1 cm3, under pressure 0.15 MPa, at instants 1.5-2 ms before the main discharge initiation). For a comparison discharges were also performed at the initial neon filling under pressure of 1.1-1.3 hPa, with or without the addition of deuterium puffing. The recorded discharge current waveforms, laser interferometric images, signals of hard x-rays and fusion neutrons, as well as time-integrated x-ray pinhole images and time-resolved x-ray signals were compared. From a ratio of the x-ray signals recorded behind beryllium filters of different thickness there were estimated values of a plasma electron temperature (T e) in a region at the electrode outlets. For pure deuterium discharges an averaged T e value amounted to 150-170 eV, while for neon discharges with the deuterium puffing it reached 330-880 eV (with accuracy of  ±20%).

  1. Modification of polymer velvet cathode via metallic Mo coating for enhancement of high-current electron emission performances

    SciTech Connect

    Xiong, Ying; Wang, Bing; Yi, Yong; Xia, Liansheng; Zhang, Huang

    2013-09-15

    The effect of surface Mo coating on the high-current electron emission performances for polymer velvet cathode has been investigated in a diode with A-K gap of 11.5 cm by the combination of time-resolved electrical diagnostic and temporal pressure variation. Compared with uncoated polymer velvet cathode under the single-pulsed emission mode, the Mo-coated one shows lower outgassing levels (∼0.40 Pa L), slower cathode plasma expansion velocity (∼2.30 cm/μs), and higher emission stability as evidences by the change in cathode current, temporal pressure variation, and diode perveance. Moreover, after Mo coating, the emission consistency of the polymer velvet cathode between two adjacent pulses is significantly improved in double-pulsed emission mode with ∼500 ns interval between two pulses, which further confirms the effectiveness of Mo coating for enhancement of electron emission performance of polymer velvet cathodes. These results should be of interest to the high-repetitive high-power microwave systems with cold cathodes.

  2. Particle therapy

    SciTech Connect

    Raju, M.R.

    1993-09-01

    Particle therapy has a long history. The experimentation with particles for their therapeutic application got started soon after they were produced in the laboratory. Physicists played a major role in proposing the potential applications in radiotherapy as well as in the development of particle therapy. A brief review of the current status of particle radiotherapy with some historical perspective is presented and specific contributions made by physicists will be pointed out wherever appropriate. The rationale of using particles in cancer treatment is to reduce the treatment volume to the target volume by using precise dose distributions in three dimensions by using particles such as protons and to improve the differential effects on tumors compared to normal tissues by using high-LET radiations such as neutrons. Pions and heavy ions combine the above two characteristics.

  3. Particle astrophysics

    NASA Technical Reports Server (NTRS)

    Sadoulet, Bernard; Cronin, James; Aprile, Elena; Barish, Barry C.; Beier, Eugene W.; Brandenberger, Robert; Cabrera, Blas; Caldwell, David; Cassiday, George; Cline, David B.

    1991-01-01

    The following scientific areas are reviewed: (1) cosmology and particle physics (particle physics and the early universe, dark matter, and other relics); (2) stellar physics and particles (solar neutrinos, supernovae, and unconventional particle physics); (3) high energy gamma ray and neutrino astronomy; (4) cosmic rays (space and ground observations). Highest scientific priorities for the next decade include implementation of the current program, new initiatives, and longer-term programs. Essential technological developments, such as cryogenic detectors of particles, new solar neutrino techniques, and new extensive air shower detectors, are discussed. Also a certain number of institutional issues (the funding of particle astrophysics, recommended funding mechanisms, recommended facilities, international collaborations, and education and technology) which will become critical in the coming decade are presented.

  4. Magnetic particles

    NASA Technical Reports Server (NTRS)

    Chang, Manchium (Inventor); Colvin, Michael S. (Inventor)

    1989-01-01

    Magnetic polymer particles are formed by swelling porous, polymer particles and impregnating the particles with an aqueous solution of precursor magnetic metal salt such as an equimolar mixture of ferrous chloride and ferric chloride. On addition of a basic reagent such as dilute sodium hydroxide, the metal salts are converted to crystals of magnetite which are uniformly contained througout the pores of the polymer particle. The magnetite content can be increased and neutral buoyancy achieved by repetition of the impregnaton and neutralization steps to adjust the magnetite content to a desired level.

  5. Advanced stellarators

    NASA Astrophysics Data System (ADS)

    Schlüter, Arnulf

    1983-03-01

    Toroidal confinement of a plasma by an external magnetic field is not compatible with axisymmetry, in contrast to confinement by the pinch effect of induced electric currents as in a tokomak or by the reversed field pinch configuration. The existence of magnetic surfaces throughout the region in which grad p ≠ 0 is therefore not guaranteed in such configurations, though it is necessary for MHD-equilibrium when the lines of force possess a finite twist (or "rotational transform"). These twisted equilibria are called stellarators. The other type of external confinement requires all lines of force to be closed upon themselves and p to be function of the well defined quantity Q = φ d l/ B only. The resulting "bumpy" tori are sometimes also referred to as being M + S like. By discussing specific examples it is shown that stellarator configurations exist which retain as much as possible the properties of M + S like configurations, combine these with the magnetic well, and with an approximation to the isodynamic requirement of D. Palumbo. These so-called Advanced Stellarators shown an improvement in predicted particle confinement and beta-limit compared to the classical stellarators. They can also be viewed as forming a system of linked stabilized mirrors of small mirror ratio. These fields can be produced by modular coils. A prototype of such a configuration is being designed by the stellarator division of IPP under the name of Wendelstein VII-AS. Expected physical data and technical details of W VII-AS are given.

  6. Advanced capacitors

    NASA Astrophysics Data System (ADS)

    Parker, R. D.; Buritz, R. S.; Taylor, A. R.; Bullwinkel, E. P.

    1982-11-01

    An experimental development program was conducted to develop and test advanced dielectric materials for capacitors for airborne power systems. High rep rate and low rate capacitors for use in pulse-forming networks, high voltage filter capacitors, and high frequency ac capacitors for series resonant inverters were considered. The initial goal was to develop an improved polysulfone film. Initially, low breakdown strength was thought to be related to inclusions of conductive particles. The effect of filtration of the casting solution was investigated. These experiments showed that more filtration was not the entire solution to low breakdown. The film samples were found to contain dissolved ionic impurities that move through the dielectric when voltage is applied and cause enhancement of the electric field. These contaminants enter the film via the resin and solvent, and can be partially removed. However, these treatments did not significantly improve the breakdown characteristics. A new material, Ultem, was proposed for use in high energy density capacitors. This new polyetherimide resin has properties similar to polysulfone and polyimide, with improvement in breakdown characteristics and temperature capability. The technique of casting films on a roughened drum was demonstrated, and found useful in preparing textured films. this is the first step toward a replacement for kraft paper.

  7. Advanced Accelerating Structures and Their Interaction with Electron Beams

    SciTech Connect

    Gai Wei

    2009-01-22

    In this paper, we give a brief description of several advanced accelerating structures, such as dielectric loaded waveguides, photonic band gap, metamaterials and improved iris-loaded cavities. We describe wakefields generated by passing high current electron beams through these structures, and applications of wakefields to advanced accelerator schemes. One of the keys to success for high gradient wakefield acceleration is to develop high current drive beam sources. As an example, the high current RF photo injector at the Argonne Wakefield Accelerator, passed a {approx}80 nC electron beam through a high gradient dielectric loaded structure to achieve a 100 MV/m gradient. We will summarize recent related experiments on beam-structure interactions and also discuss high current electron beam generation and propagation and their applications to wakefield acceleration.

  8. Advanced accelerating structures and their interaction with electron beams.

    SciTech Connect

    Gai, W.; High Energy Physics

    2008-01-01

    In this paper, we give a brief description of several advanced accelerating structures, such as dielectric loaded waveguides, photonic band gap, metamaterials and improved iris-loaded cavities. We describe wakefields generated by passing high current electron beams through these structures, and applications of wakefields to advanced accelerator schemes. One of the keys to success for high gradient wakefield acceleration is to develop high current drive beam sources. As an example, the high current RF photo injector at the Argonne Wakefield Accelerator, passed a {approx}80 nC electron beam through a high gradient dielectric loaded structure to achieve a 100 MV/m gradient. We will summarize recent related experiments on beam-structure interactions and also discuss high current electron beam generation and propagation and their applications to wakefield acceleration.

  9. Research on soft x-rays in high-current plasma-focus discharges and estimation of plasma electron temperature

    NASA Astrophysics Data System (ADS)

    Skladnik-Sadowska, E.; Zaloga, D.; Sadowski, M. J.; Kwiatkowski, R.; Malinowski, K.; Miklaszewski, R.; Paduch, M.; Surala, W.; Zielinska, E.; Tomaszewski, K.

    2016-09-01

    The paper presents results of experimental studies of dense and high-temperature plasmas, which were produced by pulsed high-current discharges within a modernised PF-1000U facility operated at different initial gas conditions, and supplied from a condenser bank which delivered energy of about 350 kJ. The investigated discharges were performed at the initial deuterium filling under pressure of 1.6–2.0 hPa, with or without an additional puffing of pure deuterium (1 cm3, under pressure 0.15 MPa, at instants 1.5–2 ms before the main discharge initiation). For a comparison discharges were also performed at the initial neon filling under pressure of 1.1–1.3 hPa, with or without the addition of deuterium puffing. The recorded discharge current waveforms, laser interferometric images, signals of hard x-rays and fusion neutrons, as well as time-integrated x-ray pinhole images and time-resolved x-ray signals were compared. From a ratio of the x-ray signals recorded behind beryllium filters of different thickness there were estimated values of a plasma electron temperature (T e) in a region at the electrode outlets. For pure deuterium discharges an averaged T e value amounted to 150–170 eV, while for neon discharges with the deuterium puffing it reached 330–880 eV (with accuracy of  ±20%).

  10. Diagnostics and electron-optics of a high current electron beam in the TANDEM free electron laser - status report

    SciTech Connect

    Arensburg, A.; Avramovich, A.; Chairman, D.

    1995-12-31

    In the construction of the Israeli TANDEM FEL the major task is to develop a high quality electron optic system. The goal is to focus the e-beam to a minimal radius (1 mm) in the interaction region (the wiggler). Furthermore, good focusing throughout the accelerator is essential in order to achieve high transport efficiency avoiding discharge and voltage drop of the high voltage terminal. We have completed the electron optical design and component procurement, including 8 quadrupole lenses 4 steering coils and an electrostatic control system. All are being assembled into the high voltage terminal and controlled by a fiber optic link. Diagnostic means based on fluorescent screens and compact CCD camera cards placed at the HV terminal and at the end of the e-gun injector have been developed. We report first measurements of the beam emittance at the entrance to the Tandem accelerator tube using the {open_quote}pepper pot{close_quote} technique. The experiment consists of passing the 0.5 Amp beam through a thin plate which is perforated with an army of 0.5 mm holes. The spots produced on a fluorescent screen placed 90 cm from the pepper pot were recorded with a CCD camera and a frame grabber. The measured normalized emittance is lower than 10{pi} mm mR which is quite close to the technical limit of dispenser cathode e-guns of the kind we have. Recent results of the measured transport efficiency and the diagnostics of the high current (1A, 1.5MV) electron-optical system will be reported.

  11. Final Results from the High-Current, High-Action Closing Switch Test Program at Sandia National Laboratories

    SciTech Connect

    Savage, M.E.

    1999-06-23

    We tested a variety of high-current closing switches for lifetime and reliability on a dedicated 2 MJ, 500 kA capacitor bank facility at Sandia National Laboratories. Our interest was a switch capable of one shot every few minutes, switching a critically damped, DC-charged 6.2 mF bank at 24 kV, with a peak current of 500 kA. The desired lifetime is 24 thousand shots. Typical of high-energy systems, particularly multi-module systems, the primary parameters of interest related to the switch are: (1) reliability, meaning absence of both pre-fires and no-fires, (2) total switch lifetime or number of shots between maintenance, and (3) cost. Cost was given lower priority at this evaluation stage because there are great uncertainties in estimating higher-quantity prices of these devices, most of which have been supplied before in only small quantities. The categories of switches tested are vacuum discharge, high-pressure discharge, and solid-state. Each group varies in terms of triggering ease, ease of maintenance, and tolerance to faults such as excess current and current reversal. We tested at least two variations of each technology group. The total number of shots on the switch test facility is about 50 thousand. We will present the results from the switch testing. The observed lifetime of different switches varied greatly: the shortest life was one shot; one device was still operating after six thousand shots. On several switches we measured the voltage drop during conduction and calculated energy dissipated in the switch; we will show these data also.

  12. Particle preconcentrator

    SciTech Connect

    Linker, K.L.; Conrad, F.J.; Custer, C.A.; Rhykerd, C.L. Jr

    2000-07-11

    An apparatus and method are disclosed for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a previous screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  13. Particle preconcentrator

    DOEpatents

    Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

    1998-01-01

    An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  14. Particle preconcentrator

    DOEpatents

    Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

    2000-01-01

    An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  15. Particle preconcentrator

    DOEpatents

    Linker, Kevin L.; Conrad, Frank J.; Custer, Chad A.; Rhykerd, Jr., Charles L.

    2005-09-20

    An apparatus and method for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents.

  16. Particle preconcentrator

    DOEpatents

    Linker, K.L.; Conrad, F.J.; Custer, C.A.; Rhykerd, C.L. Jr.

    1998-12-29

    An apparatus and method are disclosed for preconcentrating particles and vapors. The preconcentrator apparatus permits detection of highly diluted amounts of particles in a main gas stream, such as a stream of ambient air. A main gas stream having airborne particles entrained therein is passed through a pervious screen. The particles accumulate upon the screen, as the screen acts as a sort of selective particle filter. The flow of the main gas stream is then interrupted by diaphragm shutter valves, whereupon a cross-flow of carrier gas stream is blown parallel past the faces of the screen to dislodge the accumulated particles and carry them to a particle or vapor detector, such as an ion mobility spectrometer. The screen may be heated, such as by passing an electrical current there through, to promote desorption of particles therefrom during the flow of the carrier gas. Various types of screens are disclosed. The apparatus and method of the invention may find particular utility in the fields of narcotics, explosives detection and chemical agents. 3 figs.

  17. A high current pulsed power generator CQ-3-MMAF with co-axial cable transmitting energy for material dynamics experiments.

    PubMed

    Wang, Guiji; Chen, Xuemiao; Cai, Jintao; Zhang, Xuping; Chong, Tao; Luo, Binqiang; Zhao, Jianheng; Sun, Chengwei; Tan, Fuli; Liu, Cangli; Wu, Gang

    2016-06-01

    A high current pulsed power generator CQ-3-MMAF (Multi-Modules Assembly Facility, MMAF) was developed for material dynamics experiments under ramp wave and shock loadings at the Institute of Fluid Physics (IFP), which can deliver 3 MA peak current to a strip-line load. The rise time of the current is 470 ns (10%-90%). Different from the previous CQ-4 at IFP, the CQ-3-MMAF energy is transmitted by hundreds of co-axial high voltage cables with a low impedance of 18.6 mΩ and low loss, and then hundreds of cables are reduced and converted to tens of cables into a vacuum chamber by a cable connector, and connected with a pair of parallel metallic plates insulated by Kapton films. It is composed of 32 capacitor and switch modules in parallel. The electrical parameters in short circuit are with a capacitance of 19.2 μF, an inductance of 11.7 nH, a resistance of 4.3 mΩ, and working charging voltage of 60 kV-90 kV. It can be run safely and stable when charged from 60 kV to 90 kV. The vacuum of loading chamber can be up to 10(-2) Pa, and the current waveforms can be shaped by discharging in time sequences of four groups of capacitor and switch modules. CQ-3-MMAF is an adaptive machine with lower maintenance because of its modularization design. The COMSOL Multi-physics® code is used to optimize the structure of some key components and calculate their structural inductance for designs, such as gas switches and cable connectors. Some ramp wave loading experiments were conducted to check and examine the performances of CQ-3-MMAF. Two copper flyer plates were accelerated to about 3.5 km/s in one shot when the working voltage was charged to 70 kV. The velocity histories agree very well. The dynamic experiments of some polymer bonded explosives and phase transition of tin under ramp wave loadings were also conducted. The experimental data show that CQ-3-MMAF can be used to do material dynamics experiments in high rate and low cost shots. Based on this design concept, the peak

  18. A high current pulsed power generator CQ-3-MMAF with co-axial cable transmitting energy for material dynamics experiments.

    PubMed

    Wang, Guiji; Chen, Xuemiao; Cai, Jintao; Zhang, Xuping; Chong, Tao; Luo, Binqiang; Zhao, Jianheng; Sun, Chengwei; Tan, Fuli; Liu, Cangli; Wu, Gang

    2016-06-01

    A high current pulsed power generator CQ-3-MMAF (Multi-Modules Assembly Facility, MMAF) was developed for material dynamics experiments under ramp wave and shock loadings at the Institute of Fluid Physics (IFP), which can deliver 3 MA peak current to a strip-line load. The rise time of the current is 470 ns (10%-90%). Different from the previous CQ-4 at IFP, the CQ-3-MMAF energy is transmitted by hundreds of co-axial high voltage cables with a low impedance of 18.6 mΩ and low loss, and then hundreds of cables are reduced and converted to tens of cables into a vacuum chamber by a cable connector, and connected with a pair of parallel metallic plates insulated by Kapton films. It is composed of 32 capacitor and switch modules in parallel. The electrical parameters in short circuit are with a capacitance of 19.2 μF, an inductance of 11.7 nH, a resistance of 4.3 mΩ, and working charging voltage of 60 kV-90 kV. It can be run safely and stable when charged from 60 kV to 90 kV. The vacuum of loading chamber can be up to 10(-2) Pa, and the current waveforms can be shaped by discharging in time sequences of four groups of capacitor and switch modules. CQ-3-MMAF is an adaptive machine with lower maintenance because of its modularization design. The COMSOL Multi-physics® code is used to optimize the structure of some key components and calculate their structural inductance for designs, such as gas switches and cable connectors. Some ramp wave loading experiments were conducted to check and examine the performances of CQ-3-MMAF. Two copper flyer plates were accelerated to about 3.5 km/s in one shot when the working voltage was charged to 70 kV. The velocity histories agree very well. The dynamic experiments of some polymer bonded explosives and phase transition of tin under ramp wave loadings were also conducted. The experimental data show that CQ-3-MMAF can be used to do material dynamics experiments in high rate and low cost shots. Based on this design concept, the peak

  19. Ti/Pd/Ag Contacts to n-Type GaAs for High Current Density Devices

    NASA Astrophysics Data System (ADS)

    Huo, Pengyun; Rey-Stolle, Ignacio

    2016-06-01

    The metallization stack Ti/Pd/Ag on n-type Si has been readily used in solar cells due to its low metal/semiconductor specific contact resistance, very high sheet conductance, bondability, long-term durability, and cost-effectiveness. In this study, the use of Ti/Pd/Ag metallization on n-type GaAs is examined, targeting electronic devices that need to handle high current densities and with grid-like contacts with limited surface coverage (i.e., solar cells, lasers, or light emitting diodes). Ti/Pd/Ag (50 nm/50 nm/1000 nm) metal layers were deposited on n-type GaAs by electron beam evaporation and the contact quality was assessed for different doping levels (from 1.3 × 1018 cm-3 to 1.6 × 1019 cm-3) and annealing temperatures (from 300°C to 750°C). The metal/semiconductor specific contact resistance, metal resistivity, and the morphology of the contacts were studied. The results show that samples doped in the range of 1018 cm-3 had Schottky-like I- V characteristics and only samples doped 1.6 × 1019 cm-3 exhibited ohmic behavior even before annealing. For the ohmic contacts, increasing annealing temperature causes a decrease in the specific contact resistance ( ρ c,Ti/Pd/Ag ~ 5 × 10-4 Ω cm2). In regard to the metal resistivity, Ti/Pd/Ag metallization presents a very good metal conductivity for samples treated below 500°C ( ρ M,Ti/Pd/Ag ~ 2.3 × 10-6 Ω cm); however, for samples treated at 750°C, metal resistivity is strongly degraded due to morphological degradation and contamination in the silver overlayer. As compared to the classic AuGe/Ni/Au metal system, the Ti/Pd/Ag system shows higher metal/semiconductor specific contact resistance and one order of magnitude lower metal resistivity.

  20. A high current pulsed power generator CQ-3-MMAF with co-axial cable transmitting energy for material dynamics experiments

    NASA Astrophysics Data System (ADS)

    Wang, Guiji; Chen, Xuemiao; Cai, Jintao; Zhang, Xuping; Chong, Tao; Luo, Binqiang; Zhao, Jianheng; Sun, Chengwei; Tan, Fuli; Liu, Cangli; Wu, Gang

    2016-06-01

    A high current pulsed power generator CQ-3-MMAF (Multi-Modules Assembly Facility, MMAF) was developed for material dynamics experiments under ramp wave and shock loadings at the Institute of Fluid Physics (IFP), which can deliver 3 MA peak current to a strip-line load. The rise time of the current is 470 ns (10%-90%). Different from the previous CQ-4 at IFP, the CQ-3-MMAF energy is transmitted by hundreds of co-axial high voltage cables with a low impedance of 18.6 mΩ and low loss, and then hundreds of cables are reduced and converted to tens of cables into a vacuum chamber by a cable connector, and connected with a pair of parallel metallic plates insulated by Kapton films. It is composed of 32 capacitor and switch modules in parallel. The electrical parameters in short circuit are with a capacitance of 19.2 μF, an inductance of 11.7 nH, a resistance of 4.3 mΩ, and working charging voltage of 60 kV-90 kV. It can be run safely and stable when charged from 60 kV to 90 kV. The vacuum of loading chamber can be up to 10-2 Pa, and the current waveforms can be shaped by discharging in time sequences of four groups of capacitor and switch modules. CQ-3-MMAF is an adaptive machine with lower maintenance because of its modularization design. The COMSOL Multi-physics® code is used to optimize the structure of some key components and calculate their structural inductance for designs, such as gas switches and cable connectors. Some ramp wave loading experiments were conducted to check and examine the performances of CQ-3-MMAF. Two copper flyer plates were accelerated to about 3.5 km/s in one shot when the working voltage was charged to 70 kV. The velocity histories agree very well. The dynamic experiments of some polymer bonded explosives and phase transition of tin under ramp wave loadings were also conducted. The experimental data show that CQ-3-MMAF can be used to do material dynamics experiments in high rate and low cost shots. Based on this design concept, the peak

  1. Anisotropy of energy losses in high-current Z-pinches produced by the implosion of cylindrical tungsten wire arrays

    NASA Astrophysics Data System (ADS)

    Aleksandrov, V. V.; Volkov, G. S.; Grabovski, E. V.; Gritsuk, A. N.; Lakhtyushko, N. I.; Medovshchikov, S. F.; Oleinik, G. M.; Svetlov, E. V.

    2014-02-01

    Results are presented from measurements of the anisotropy of energy losses in high-current Z-pinches produced by the implosion of wire arrays at the ANGARA-5-1 facility at load currents of up to 4MA. The energy losses were measured in the radial direction and along the pinch axis from the anode side. The main diagnostics were time-integrated thermocouple calorimeters, nanosecond X-ray diodes (XRDs) with different filters, and a foil radiation calorimeter with a time resolution of 2 μs. The azimuthal anisotropy of energy losses was measured for different wire array configurations and different shapes of the high-voltage electrode. The presence of strong initial azimuthal inhomogeneity of the wire mass distribution (sectioned arrays), as well as the use of conical electrodes instead of plane ones, does not increase the azimuthal inhomogeneity of the total energy losses. For cylindrical wire arrays, energy losses in the radial direction are compared with those along the pinch axis. According to XRD and calorimetric measurements, the radiation yield per unit solid angle along the pinch axis is two to three times lower than that in the radial direction. In the axial direction, the energy flux density of the expanding plasma is two to three times lower than the radiation intensity. The measured radiation yield across the pinch is 2.5-5 kJ/sr, while that along the pinch axis is 1-2 kJ/sr. The results obtained by means of XRDs agree to within measurement errors with those obtained using the radiation calorimeter. It is found that the energy per unit solid angle carried by the expanding plasma in the radial direction does not exceed 10% of the soft X-ray yield. Analysis of the structure of time-integrated pinhole images and signals from the radial and axial XRDs shows that radiation emitted in the radial direction from the hot central region of the pinch is partially screened by the less dense surrounding plasma halo, whereas radiation emitted in the axial direction is a

  2. Phase and Structural States Formed in Titanium Nickelide Subsurface Layers Exposed to High-Current Pulsed Electron Beams

    NASA Astrophysics Data System (ADS)

    Neyman, A. A.; Meisner, L. L.; Lotkov, A. I.; Semin, V. O.

    2015-06-01

    The behavior of the non-equilibrium states formed in the subsurface layers of a titanium nickelide-based alloy exposed to electron beams operated in the pulsed surface layer melting mode is investigated experimentally. Using methods of an x-ray diffraction analysis, and optical, scanning, and transmission electron microscopies, an 8-10 μm thick surface layer is shown to exhibit В2 phase-based structure undergoing inhomogeneous lattice microstrain. The core layer located at a depth of 10-20 μm below the irradiated surface contains a small amount (up to 5 vol.%) of a phase with В19' martensite structure along with a slightly distorted lattice and unmelted Ti2Ni phase particles. Electron beam treatment brings about changes in the chemical composition of the surface-modified layer which becomes enriched in titanium owing to the dissolution of the Ti2Ni phase particles therein. Transmission electron microscopy has not revealed martensite phases in the modified layer. The electron beam exposure of the titanium nickelide surface is assumed to give rise to nonequilibrium highly distorted bcc structure.

  3. The Advanced Helical Generator

    SciTech Connect

    Reisman, D B; Javedani, J B; Ellsworth, G F; Kuklo, R M; Goerz, D A; White, A D; Tallerico, L J; Gidding, D A; Murphy, M J; Chase, J B

    2009-10-26

    A high explosive pulsed power (HEPP) generator called the Advanced Helical Generator (AHG) has been designed, built, and successfully tested. The AHG incorporates design principles of voltage and current management to obtain a high current and energy gain. Its design was facilitated by the use of modern modeling tools as well as high precision manufacture. The result was a first-shot success. The AHG delivered 16 Mega-Amperes of current and 11 Mega-Joules of energy to a quasi-static 80 nH inductive load. A current gain of 154 times was obtained with a peak exponential rise time of 20 {micro}s. We will describe in detail the design and testing of the AHG.

  4. Magnetic particles

    NASA Technical Reports Server (NTRS)

    Chang, Manchium (Inventor); Colvin, Michael S. (Inventor); Rembaum, Alan (Inventor); Richards, Gil F. (Inventor)

    1987-01-01

    Metal oxide containing polymers and particularly styrene, acrylic or protein polymers containing fine, magnetic iron oxide particles are formed by combining a NO.sub.2 -substituted polymer with an acid such as hydrochloric acid in the presence of metal, particularly iron particles. The iron is oxidized to fine, black Fe.sub.3 O.sub.4 particles which deposit selectively on the polymer particles. Nitrated polymers are formed by reacting functionally substituted, nitrated organic compounds such as trinitrobenzene sulfonate or dinitrofluoro benzene with a functionally coreactive polymer such as an amine modified acrylic polymer or a protein. Other transition metals such as cobalt can also be incorporated into polymers using this method.

  5. Transition from Beam-Target to Thermonuclear Fusion in High-Current Deuterium Z-Pinch Simulations.

    PubMed

    Offermann, Dustin T; Welch, Dale R; Rose, Dave V; Thoma, Carsten; Clark, Robert E; Mostrom, Chris B; Schmidt, Andrea E W; Link, Anthony J

    2016-05-13

    Fusion yields from dense, Z-pinch plasmas are known to scale with the drive current, which is favorable for many potential applications. Decades of experimental studies, however, show an unexplained drop in yield for currents above a few mega-ampere (MA). In this work, simulations of DD Z-Pinch plasmas have been performed in 1D and 2D for a constant pinch time and initial radius using the code Lsp, and observations of a shift in scaling are presented. The results show that yields below 3 MA are enhanced relative to pure thermonuclear scaling by beamlike particles accelerated in the Rayleigh-Taylor induced electric fields, while yields above 3 MA are reduced because of energy lost by the instability and the inability of the beamlike ions to enter the pinch region.

  6. Auroral particles

    NASA Technical Reports Server (NTRS)

    Evans, David S.

    1987-01-01

    The problems concerning the aurora posed prior to the war are now either solved in principle or were restated in a more fundamental form. The pre-war hypothesis concerning the nature of the auroral particles and their energies was fully confirmed, with the exception that helium and oxygen ions were identified as participating in the auroral particle precipitation in addition to the protons. The nature of the near-Earth energization processes affecting auroral particles was clarified. Charged particle trajectories in various electric field geometries were modeled. The physical problems have now moved from determining the nature and geometry of the electric fields, which accelerate charged particles near the Earth, to accounting for the existence of these electric fields as a natural consequence of the solar wind's interaction with Earth. Ultimately the reward in continuing the work in auroral and magnetospheric particle dynamics will be a deeper understanding of the subtleties of classical electricity and magnetism as applied to situations not blessed with well-defined and invariant geometries.

  7. Parametric study of a high current-density EBIS Charge Breeder regarding Two Stream plasma Instability (TSI)

    NASA Astrophysics Data System (ADS)

    Shornikov, Andrey; Mertzig, Robert; Breitenfeldt, Martin; Lombardi, Alessandra; Wenander, Fredrik; Pikin, Alexander

    2016-06-01

    In this paper we report on our results from the design study of an advanced Electron Beam Ion Source (EBIS) based Charge Breeder (ECB). The ECB should fulfill the requirements of the HIE-ISOLDE upgrade, and if possible be adapted for ion injection into TSR@ISOLDE, as well as serve as an early prototype of a future EURISOL ECB. Fulfilling the HIE-ISOLDE/TSR@ISOLDE specifications requires simultaneous increase in electron beam energy, current and current density in order to provide the requested beams with proper charge state, high intensity and with a specified pulse repetition rate. We have carried out a study on the technical requirements of the ECB. The obtained parameters were optimized to comply with technical limitations arising from the electron beam technology and plasma physics in an ECB.

  8. High current density electrodeposition of silver from silver-containing liquid metal salts with pyridine-N-oxide ligands.

    PubMed

    Sniekers, Jeroen; Brooks, Neil R; Schaltin, Stijn; Van Meervelt, Luc; Fransaer, Jan; Binnemans, Koen

    2014-01-28

    New cationic silver-containing ionic liquids were synthesized and used as non-aqueous electrolytes for the electrodeposition of silver layers. In the liquid state of these ionic liquids, a silver (i) cation is coordinated by pyridine-N-oxide (py-O) ligands in a 1 : 3 metal-to-ligand ratio, although in some cases a different stoichiometry of the silver center crystallized out. As anions, bis(trifluoromethanesulfonyl)imide (Tf2N), trifluoromethanesulfonate (OTf), methanesulfonate (OMs) and nitrate were used, yielding compounds with the formulae [Ag(py-O)3][Tf2N], [Ag(py-O)3][OTf], [Ag(py-O)3][OMs] and [Ag(py-O)3][NO3], respectively. The compounds were characterized by CHN analysis, FTIR, NMR, DSC, TGA and the electrodeposition of silver was investigated by cyclic voltammetry, linear potential scans, scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX). With the exception of [Ag(py-O)3][Tf2N], which melts at 108 °C, all the silver(i) compounds have a melting point below 80 °C and were tested as electrolytes for silver electrodeposition. Interestingly, very high current densities were observed at a potential of -0.5 V vs. Ag/Ag(+) for the compounds with fluorine-free anions, i.e. [Ag(py-O)3][NO3] (current density of -10 A dm(-2)) and [Ag(py-O)3][OMs] (-6.5 A dm(-2)). The maximum current density of the compound with the fluorinated anion trifluoromethanesulfonate, [Ag(py-O)3][OTf], was much lower: -2.5 A dm(-2) at -0.5 V vs. Ag/Ag(+). Addition of an excess of ligand to [Ag(py-O)3][OTf] resulted in the formation of the room-temperature ionic liquid [Ag(py-O)6][OTf]. A current density of -5 A dm(-2) was observed at -0.5 V vs. Ag/Ag(+) for this low viscous silver salt. The crystal structures of several silver complexes could be determined by X-ray diffraction, and it was found that several of them had a stoichiometry different from the 1 : 3 metal-to-ligand ratio used in their synthesis. This indicates that the compounds form crystals

  9. Summary of the particle physics and technology working group

    SciTech Connect

    Stephan Lammel et al.

    2002-12-10

    Progress in particle physics has been tightly related to technological advances during the past half century. Progress in technologies has been driven in many cases by the needs of particle physics. Often, these advances have benefited fields beyond particle physics: other scientific fields, medicine, industrial development, and even found commercial applications. The particle physics and technology working group of Snowmass 2001 reviewed leading-edge technologies recently developed or in the need of development for particle physics. The group has identified key areas where technological advances are vital for progress in the field, areas of opportunities where particle physics may play a principle role in fostering progress, and areas where advances in other fields may directly benefit particle physics. The group has also surveyed the technologies specifically developed or enhanced by research in particle physics that benefit other fields and/or society at large.

  10. Particle Sizer

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Microspheres are tiny plastic beads that represent the first commercial products manufactured in orbit. An example of how they are used is a new aerodynamic particle sizer designated APS 33B produced by TSI Incorporated. TSI purchased the microspheres from the National Bureau of Standards which certified their exact size and the company uses them in calibration of the APS 33B* instrument, latest in a line of TSI systems for generating counting and weighing minute particles of submicron size. Instruments are used for evaluating air pollution control devices, quantifying environments, meteorological research, testing filters, inhalation, toxicology and other areas where generation or analysis of small airborne particles is required. * The APS 33B is no longer being manufactured. An improved version, APS 3320, is now being manufactured. 2/28/97

  11. Carbon particles

    DOEpatents

    Hunt, Arlon J.

    1984-01-01

    A method and apparatus whereby small carbon particles are made by pyrolysis of a mixture of acetylene carried in argon. The mixture is injected through a nozzle into a heated tube. A small amount of air is added to the mixture. In order to prevent carbon build-up at the nozzle, the nozzle tip is externally cooled. The tube is also elongated sufficiently to assure efficient pyrolysis at the desired flow rates. A key feature of the method is that the acetylene and argon, for example, are premixed in a dilute ratio, and such mixture is injected while cool to minimize the agglomeration of the particles, which produces carbon particles with desired optical properties for use as a solar radiant heat absorber.

  12. Integration of an Axcelis Optima HD Single Wafer High Current Implanter for p- and n-S/D Implants in an Existing Batch Implanter Production Line

    SciTech Connect

    Schmeide, Matthias; Kontratenko, Serguei; Krimbacher, Bernhard; Mueller, Ralf Peter

    2008-11-03

    This paper is focused on the integration and qualification of an Axcelis Optima HD single wafer high current spot beam implanter in an existing 200 mm production line with different types of Axcelis batch implanters for high current applications. Both the design of the beamline and the beam shape are comparable between single wafer and batch high current spot beam implanters. In contrast to the single wafer high current ribbon beam implanter, energy contamination is not a concern for the considered spot beam tool because the drift mode can be used down to energies in the 2 keV region. The most important difference between single wafer and batch high current implanters is the significantly higher dose rate and, therefore, the higher damage rate for the single wafer tool due to the different scanning architecture. The results of the integration of high dose implantations, mainly for p- and n-S/D formation, for DRAM 110 nm without pre-amorphization implantation (PAI), CMOS Logic from around 250 nm down to 90 nm without and with PAI, are presented and discussed. Dopant concentration profile analysis using SIMS was performed for different technologies and implantation conditions. The impurity activation was measured using sheet resistance and in some cases spreading resistance technique was applied. The amorphous layer thickness was measured using TEM. Finally, device data are presented in combination with dose, energy and beam current variations. The results have shown that the integration of implantation processes into crystalline structure without PAI is more complex and time consuming than implantations into amorphous layer where the damage difference due to the different dose rates is negligible.

  13. Particle blender

    DOEpatents

    Willey, Melvin G.

    1981-01-01

    An infinite blender that achieves a homogeneous mixture of fuel microspheres is provided. Blending is accomplished by directing respective groups of desired particles onto the apex of a stationary coaxial cone. The particles progress downward over the cone surface and deposit in a space at the base of the cone that is described by a flexible band provided with a wide portion traversing and in continuous contact with the circumference of the cone base and extending upwardly therefrom. The band, being attached to the cone at a narrow inner end thereof, causes the cone to rotate on its arbor when the band is subsequently pulled onto a take-up spool. As a point at the end of the wide portion of the band passes the point where it is tangent to the cone, the blended particles are released into a delivery tube leading directly into a mold, and a plate mounted on the lower portion of the cone and positioned between the end of the wide portion of the band and the cone assures release of the particles only at the tangent point.

  14. The charged particle radiation environment for AXAF

    NASA Technical Reports Server (NTRS)

    Joy, Marshall

    1990-01-01

    The Advanced X Ray Astrophysics Facility (AXAF) will be subjected to several sources of charged particle radiation during its 15-year orbital lifetime: geomagnetically-trapped electrons and protons, galactic cosmic ray particles, and solar flare events. These radiation levels are presented for the AXAF orbit for use in the design of the observatory's science instruments.

  15. Advance care directives

    MedlinePlus

    ... advance directive; Do-not-resuscitate - advance directive; Durable power of attorney - advance care directive; POA - advance care directive; Health care agent - advance care directive; Health care proxy - ...

  16. Janus particles for biological imaging and sensing.

    PubMed

    Yi, Yi; Sanchez, Lucero; Gao, Yuan; Yu, Yan

    2016-06-21

    Janus particles, named after the two-faced Roman god Janus, have different surface makeups, structures or compartments on two sides. This review highlights recent advances in employing Janus particles as novel analytical tools for live cell imaging and biosensing. Unlike conventional particles used in analytical science, two-faced Janus particles provide asymmetry and directionality, and can combine different or even incompatible properties within a single particle. The broken symmetry enables imaging and quantification of rotational dynamics, revealing information beyond what traditional measurements offer. The spatial segregation of molecules on the surface of a single particle also allows analytical functions that would otherwise interfere with each other to be decoupled, opening up opportunities for novel multimodal analytical methods. We summarize here the development of Janus particles, a few general methods for their fabrication and, more importantly, the emerging and novel applications of Janus particles as multi-functional imaging probes and sensors. PMID:27052001

  17. Influence of intense equilibrium self-fields on the cyclotron maser instability in high-current gyrotrons

    NASA Astrophysics Data System (ADS)

    Uhm, Han S.; Davidson, Ronald C.

    1986-08-01

    The linearized Vlasov-Maxwell equations are used to investigate the influence of intense equilibrium self-fields on the cyclotron maser instability. A uniform density (n̂b) electron beam propagates parallel to an applied axial magnetic field B0êz with average axial velocity βbc. The particle trajectories are calculated including the influence of the radial self-electric field and the azimuthal self-magnetic field. Moreover, the linearized Vlasov-Maxwell equations are analyzed for body-wave perturbations localized to the beam interior, assuming electromagnetic perturbations about the equilibrium distribution function f0b=(n̂b/2pπ⊥) ×δ(p⊥-γbmV⊥) ×δ(pz-γbmβbc). Near the beam axis (ω2pbr2/c2≪1), it is found that the transverse electron motion is biharmonic, with oscillatory components at the frequencies ω+b and ω-b defined by ω±b =(ωcb/2) ×{1±[1-(2ω2pb/ω2cb) ×(1-β2b)]1/2}. Similarly, the electromagnetic dispersion relation for waves propagating parallel to B0êz exhibits two types of resonance conditions: a high-frequency resonance (HFR) corresponding to ω-kβbc=ω+b, and a low-frequency resonance (LFR) corresponding to ω-kβbc=ω-b. Both the HFR branch and the LFR branch exhibit instability, with detailed stability properties depending on the value of the self-field parameter s=ω2pb/ω2cb. Moreover, the LFR branch is entirely caused by self-field effects, whereas the HFR branch represents a generalization of the conventional cyclotron maser mode to include self-field effects. The full dispersion relation is analyzed numerically, and the real oscillation frequency ωr=Re ω and growth rate ωi=Im ω are calculated for both types of modes over a wide range of system parameters s, β⊥, βb, and kc/ωcb. Analytic estimates are made of the cyclotron maser growth properties in circumstances where β2⊥γ2z/2 is treated as a small parameter. [Here, γz=(1-β2b)-1/2. ] It is found that the maximum growth rate is given by ωi=(2γ2z)-1

  18. Particle acceleration at collisionless shocks: An overview

    SciTech Connect

    Zank, G.P.; Li Gang; Webb, G.M.; Le Roux, J.A.; Florinski, V.; Ao, X.; Rice, W.K.M.

    2005-08-01

    An overview of shock acceleration is presented, focusing primarily on interplanetary shocks and the termination shock as examples. An extended discussion of recent advances in modeling real solar energetic particle (SEP) and energetic storm particle (ESP) events is presented. When the energy of accelerated particles becomes very large, their back reaction on the flow can result in a shock that is significantly mediated, and as an example, we consider some results for the termination shock.

  19. Transport of Dust Particles in Tokamak Devices

    SciTech Connect

    Pigarov, A Y; Smirnov, R D; Krasheninnikov, S I; Rognlien, T D; Rozenberg, M

    2006-06-06

    Recent advances in the dust transport modeling in tokamak devices are discussed. Topics include: (1) physical model for dust transport; (2) modeling results on dynamics of dust particles in plasma; (3) conditions necessary for particle growth in plasma; (4) dust spreading over the tokamak; (5) density profiles for dust particles and impurity atoms associated with dust ablation in tokamak plasma; and (6) roles of dust in material/tritium migration.

  20. Particle processing technology

    NASA Astrophysics Data System (ADS)

    Sakka, Yoshio

    2014-02-01

    In recent years, there has been strong demand for the development of novel devices and equipment that support advanced industries including IT/semiconductors, the environment, energy and aerospace along with the achievement of higher efficiency and reduced environmental impact. Many studies have been conducted on the fabrication of innovative inorganic materials with novel individual properties and/or multifunctional properties including electrical, dielectric, thermal, optical, chemical and mechanical properties through the development of particle processing. The fundamental technologies that are key to realizing such materials are (i) the synthesis of nanoparticles with uniform composition and controlled crystallite size, (ii) the arrangement/assembly and controlled dispersion of nanoparticles with controlled particle size, (iii) the precise structural control at all levels from micrometer to nanometer order and (iv) the nanostructural design based on theoretical/experimental studies of the correlation between the local structure and the functions of interest. In particular, it is now understood that the application of an external stimulus, such as magnetic energy, electrical energy and/or stress, to a reaction field is effective in realizing advanced particle processing [1-3]. This special issue comprises 12 papers including three review papers. Among them, seven papers are concerned with phosphor particles, such as silicon, metals, Si3N4-related nitrides, rare-earth oxides, garnet oxides, rare-earth sulfur oxides and rare-earth hydroxides. In these papers, the effects of particle size, morphology, dispersion, surface states, dopant concentration and other factors on the optical properties of phosphor particles and their applications are discussed. These nanoparticles are classified as zero-dimensional materials. Carbon nanotubes (CNT) and graphene are well-known one-dimensional (1D) and two-dimensional (2D) materials, respectively. This special issue also

  1. Sampling of respirable isocyanate particles.

    PubMed

    Gylestam, Daniel; Gustavsson, Marcus; Karlsson, Daniel; Dalene, Marianne; Skarping, Gunnar

    2014-04-01

    An advanced design of a denuder impactor (DI) sampler has been developed for characterization of possible airborne isocyanate exposure in different particle size fractions. The sampler is equipped with 12 different parallel denuder tubes, 4 impaction stages with the cut-off values (d50) of: 9.5, 4, 2.5 and 1 µm, and an end filter that collects particles < 1 µm. All collecting parts were impregnated with di-n-butylamine DBA as the reagent in a mixture with acetic acid. The performance of the DI sampler was studied on a standard atmosphere containing gas and particulate isocyanates. The isocyanate atmosphere was generated by liquid permeation of 2,4-, 2,6-Toluene Diisocyanate (TDI), 1,6-Hexamethylene Diisocyanate (HDI) and Isophorone Diisocyanate (IPDI). 4,4'-Methylene Diphenyl Diisocyanate (MDI) particles were generated by heating of technical MDI and condensing the mixture of gas and particle-borne MDI in an atmosphere containing mixed salt particles. The study was performed in a 0.85 m3 environmental chamber with stainless steel walls. With the advancement of the DI sampler it is now possible to collect isocyanate particle samples for up to 320 min. The performance of the DI sampler is essentially unaffected by the humidity. The DI sampler and the ASSET EZ4-NCO sampler (Sigma-Aldrich/Supelco, Bellefonte, PA, USA) gave similar results. Sample losses within the DI sampler are low. In the environmental chamber it was observed that the particle distribution may be affected by the humidity and ageing. A scanning mobility particle sizer (SMPS) was used to separate a flow of selected fractions containing MDI particles from mixed MDI and salt particles. The particle-size distribution had a maximum at about 300 nm, but later in the environmental chamber 1 µm dominated. The distribution was very different as compared to with only NaCl or MDI present. The biological relevance for studying isocyanate nano particles is significant as these have the possibility to reach the

  2. Particle acceleration

    NASA Technical Reports Server (NTRS)

    Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.; Alissandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.; Ellison, D.

    1986-01-01

    Data is compiled from Solar Maximum Mission and Hinothori satellites, particle detectors in several satellites, ground based instruments, and balloon flights in order to answer fundamental questions relating to: (1) the requirements for the coronal magnetic field structure in the vicinity of the energization source; (2) the height (above the photosphere) of the energization source; (3) the time of energization; (4) transistion between coronal heating and flares; (5) evidence for purely thermal, purely nonthermal and hybrid type flares; (6) the time characteristics of the energization source; (7) whether every flare accelerates protons; (8) the location of the interaction site of the ions and relativistic electrons; (9) the energy spectra for ions and relativistic electrons; (10) the relationship between particles at the Sun and interplanetary space; (11) evidence for more than one acceleration mechanism; (12) whether there is single mechanism that will accelerate particles to all energies and also heat the plasma; and (13) how fast the existing mechanisms accelerate electrons up to several MeV and ions to 1 GeV.

  3. Transportation of high-current ion and electron beams in the accelerator drift gap in the presence of an additional electron background

    NASA Astrophysics Data System (ADS)

    Karas', V. I.; Kornilov, E. A.; Manuilenko, O. V.; Tarakanov, V. P.; Fedorovskaya, O. V.

    2015-12-01

    The dynamics of a high-current ion beam propagating in the drift gap of a linear induction accelerator with collective focusing is studied using 3D numerical simulations in the framework of the full system of the Vlasov-Maxwell equations (code KARAT). The ion beam is neutralized by a comoving electron beam in the current density and, partially, in space charge, since the velocities of electrons and ions differ substantially. The dynamics of the high-current ion beam is investigated for different versions of additional neutralization of its space charge. It is established that, for a given configuration of the magnetic field and in the presence of a specially programmed injection of additional electrons from the boundary opposite to the ion injection boundary, the angular divergence of the ion beam almost vanishes, whereas the current of the ion beam at the exit from the accelerator drift gap changes insignificantly and the beam remains almost monoenergetic.

  4. Transportation of high-current ion and electron beams in the accelerator drift gap in the presence of an additional electron background

    SciTech Connect

    Karas’, V. I. Kornilov, E. A.; Manuilenko, O. V.; Tarakanov, V. P.; Fedorovskaya, O. V.

    2015-12-15

    The dynamics of a high-current ion beam propagating in the drift gap of a linear induction accelerator with collective focusing is studied using 3D numerical simulations in the framework of the full system of the Vlasov–Maxwell equations (code KARAT). The ion beam is neutralized by a comoving electron beam in the current density and, partially, in space charge, since the velocities of electrons and ions differ substantially. The dynamics of the high-current ion beam is investigated for different versions of additional neutralization of its space charge. It is established that, for a given configuration of the magnetic field and in the presence of a specially programmed injection of additional electrons from the boundary opposite to the ion injection boundary, the angular divergence of the ion beam almost vanishes, whereas the current of the ion beam at the exit from the accelerator drift gap changes insignificantly and the beam remains almost monoenergetic.

  5. Electron density profile measurements at a self-focusing ion beam with high current density and low energy extracted through concave electrodes

    SciTech Connect

    Fujiwara, Y. Nakamiya, A.; Sakakita, H.; Hirano, Y.; Kiyama, S.; Koguchi, H.

    2014-02-15

    The self-focusing phenomenon has been observed in a high current density and low energy ion beam. In order to study the mechanism of this phenomenon, a special designed double probe to measure the electron density and temperature is installed into the chamber where the high current density ion beam is injected. Electron density profile is successfully measured without the influence of the ion beam components. Estimated electron temperature and density are ∼0.9 eV and ∼8 × 10{sup 8} cm{sup −3} at the center of ion beam cross section, respectively. It was found that a large amount of electrons are spontaneously accumulated in the ion beam line in the case of self-forcing state.

  6. Method of making a long life high current density cathode from tungsten and iridium powders using a quaternary compound as the impregnant

    SciTech Connect

    Branovich, L.E.; Smith, B.; Freemen, G.L.; Eckart, D.W.

    1990-09-18

    This patent describes a method of making a long life high current density cathode. It is suitable for operation in microwave devices. It is made from tungsten and iridium powders using a quaternary compound including barium, oxygen, a metal selected from the group consisting of osmium, iridium, rhodium, and rhenium, and a metal selected from the group consisting of strontium, calcium, scandium, and titanium as the impregnant.

  7. Development of an all-permanent-magnet microwave ion source equipped with multicusp magnetic fields for high current proton beam production.

    PubMed

    Tanaka, M; Hara, S; Seki, T; Iga, T

    2008-02-01

    An all-permanent-magnet (APM) microwave hydrogen ion source was developed to reduce the size and to simplify structure of a conventional solenoid coil microwave ion source developed for reliability improvement of high current proton linac application systems. The difficulty in developing the APM source was sensitive dependence of the source performance on axial magnetic field in the microwave discharge chamber. It was difficult to produce high current proton beam stably without precise tuning of the magnetic field using solenoid coils. We lowered the sensitivity using multicusp magnetic fields for plasma confinement at the discharge chamber sidewall of the source. This enabled stable high current proton beam production with the APM microwave ion source with no tuning coil. The water cooling and the power supply for the coils are not necessary for the APM source, which leads to better reliability and system simplification. The outer diameter of the APM source was around 300 mm, which was 20% lower than the coil source. The APM source produced a maximum hydrogen ion beam current of 65 mA (high current density of 330 mA/cm(2), proton ratio of 87%, and beam energy of 30 keV) with a 5 mm diameter extraction aperture, pulse width of 400 micros, and 20 Hz repetition rate at 1.3 kW microwave power. This performance is almost the same as the best performances of the conventional coil sources. The extracted ion beams were focused with electrostatic five-grid lens to match beam to acceptance of radio-frequency quadrupole linacs. The maximum focused beam current through the orifice (5 mm radius) and the lens was 36 mA and the 90% focused beam half-width was 1-2 mm.

  8. Interplay of particle shape and suspension properties: a study of cube-like particles.

    PubMed

    Audus, Debra J; Hassan, Ahmed M; Garboczi, Edward J; Douglas, Jack F

    2015-05-01

    With advances in anisotropic particle synthesis, particle shape is now a feasible parameter for tuning suspension properties. However, there is a need to determine how these newly synthesized particles affect suspension properties and a need to solve the inverse problem of inferring the particle shape from property measurements. Either way, accurate suspension property predictions are required. Towards this end, we calculated a set of dilute suspension properties for a family of cube-like particles that smoothly interpolate between spheres and cubes. Using three conceptually different methods, we numerically computed the electrical properties of particle suspensions, including the intrinsic conductivity of perfect conductors and insulators. We also considered hydrodynamic properties relevant to particle solutions including the hydrodynamic radius, the intrinsic viscosity and the intrinsic solvent diffusivity. Additionally, we determined the second osmotic virial coefficient using analytic expressions along with numerical integration. As the particles became more cube-like, we found that all of the properties investigated become more sensitive to particle shape.

  9. Aging characteristics of blue InGaN micro-light emitting diodes at an extremely high current density of 3.5 kA cm-2

    NASA Astrophysics Data System (ADS)

    Tian, Pengfei; Althumali, Ahmad; Gu, Erdan; Watson, Ian M.; Dawson, Martin D.; Liu, Ran

    2016-04-01

    The aging characteristics of blue InGaN micro-light emitting diodes (micro-LEDs) with different sizes have been studied at an extremely high current density 3.5 kA cm-2 for emerging micro-LED applications including visible light communication (VLC), micro-LED pumped organic lasers and optogenetics. The light output power of micro-LEDs first increases and then decreases due to the competition of Mg activation in p-GaN layer and defect generation in the active region. The smaller micro-LEDs show less light output power degradation compared with larger micro-LEDs, which is attributed to the lower junction temperature of smaller micro-LEDs. It is found that the high current density without additional junction temperature cannot induce significant micro-LED degradation at room temperature but the combination of the high current density and high junction temperature leads to strong degradation. Furthermore, the cluster LEDs, composed of a micro-LED array, have been developed with both high light output power and less light output degradation for micro-LED applications in solid state lighting and VLC.

  10. Statistical Physics of Particles

    NASA Astrophysics Data System (ADS)

    Kardar, Mehran

    2006-06-01

    Statistical physics has its origins in attempts to describe the thermal properties of matter in terms of its constituent particles, and has played a fundamental role in the development of quantum mechanics. Based on lectures for a course in statistical mechanics taught by Professor Kardar at Massachusetts Institute of Technology, this textbook introduces the central concepts and tools of statistical physics. It contains a chapter on probability and related issues such as the central limit theorem and information theory, and covers interacting particles, with an extensive description of the van der Waals equation and its derivation by mean field approximation. It also contains an integrated set of problems, with solutions to selected problems at the end of the book. It will be invaluable for graduate and advanced undergraduate courses in statistical physics. A complete set of solutions is available to lecturers on a password protected website at www.cambridge.org/9780521873420. Based on lecture notes from a course on Statistical Mechanics taught by the author at MIT Contains 89 exercises, with solutions to selected problems Contains chapters on probability and interacting particles Ideal for graduate courses in Statistical Mechanics

  11. Particle deposition in ventilation ducts

    SciTech Connect

    Sippola, Mark R.

    2002-09-01

    Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 {micro}m were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on

  12. Solitary waves in particle beams

    SciTech Connect

    Bisognano, J.J.

    1996-07-01

    Since space charge waves on a particle beam exhibit both dispersive and nonlinear character, solitary waves or solitons are possible. Dispersive, nonlinear wave propagation in high current beams is found to be similar to ion-acoustic waves in plasmas with an analogy between Debye screening and beam pipe shielding. Exact longitudinal solitary wave propagation is found for potentials associated with certain transverse distributions which fill the beam pipe. For weak dispersion, the waves satisfy the Korteweg-deVries (KdV) equation, but for strong dispersion they exhibit breaking. More physically realizable distributions which do not fill the beam pipe are investigated and shown to also satisfy a KdV equation for weak dispersion if averaging over rapid transverse motion is physically justified. Scaling laws are presented to explore likely parameter regimes where these phenomena may be observed experimentally.

  13. Advanced Microsensors

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This video looks at a spinoff application of the technology from advanced microsensors -- those that monitor and determine conditions of spacecraft like the Space Shuttle. The application featured is concerned with the monitoring of the health of premature babies.

  14. Advanced Composition

    ERIC Educational Resources Information Center

    Sarantos, R. L.

    1974-01-01

    This is an excerpt from a course for advanced students, designed to teach proficiency in English composition by providing activities specifically geared to the elimination of native language interference. (LG)

  15. Observations and Modeling of Geospace Energetic Particles

    NASA Astrophysics Data System (ADS)

    Li, Xinlin

    2016-07-01

    Comprehensive measurements of energetic particles and electric and magnetic fields from state-of-art instruments onboard Van Allen Probes, in a geo-transfer-like orbit, revealed new features of the energetic particles and the fields in the inner magnetosphere and impose new challenges to any quantitative modeling of the physical processes responsible for these observations. Concurrent measurements of energetic particles by satellites in highly inclined low Earth orbits and plasma and fields by satellites in farther distances in the magnetospheres and in the up stream solar wind are the critically needed information for quantitative modeling and for leading to eventual accurate forecast of the variations of the energetic particles in the magnetosphere. In this presentation, emphasis will be on the most recent advance in our understanding of the energetic particles in the magnetosphere and the missing links for significantly advance in our modeling and forecasting capabilities.

  16. Compositions of energetic particle populations in interplanetary space

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.

    1979-01-01

    Observations of helium and heavier particles with energies below about 10 to 20 MeV/nucleon are discussed with emphasis on the composition of solar flare particles, corotating energetic particle streams, and the anomalous cosmic ray component. Future advances expected from results obtained from ISEE -3, Voyager, and the international solar polar spacecraft are reviewed.

  17. Crystallography of decahedral and icosahedral particles. II - High symmetry orientations

    NASA Technical Reports Server (NTRS)

    Yang, C. Y.; Yacaman, M. J.; Heinemann, K.

    1979-01-01

    Based on the exact crystal structure of decahedral and icosahedral particles, high energy electron diffraction patterns and image profiles have been derived for various high symmetry orientations of the particles with respect to the incident beam. These results form a basis for the identification of small metal particle structures with advanced methods of transmission electron microscopy.

  18. Video Fact Sheets: Everyday Advanced Materials

    SciTech Connect

    2015-10-06

    What are Advanced Materials? Ames Laboratory is behind some of the best advanced materials out there. Some of those include: Lead-Free Solder, Photonic Band-Gap Crystals, Terfenol-D, Aluminum-Calcium Power Cable and Nano Particles. Some of these are in products we use every day.

  19. Video Fact Sheets: Everyday Advanced Materials

    ScienceCinema

    None

    2016-07-12

    What are Advanced Materials? Ames Laboratory is behind some of the best advanced materials out there. Some of those include: Lead-Free Solder, Photonic Band-Gap Crystals, Terfenol-D, Aluminum-Calcium Power Cable and Nano Particles. Some of these are in products we use every day.

  20. High current gain transistor laser.

    PubMed

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-06-10

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge.

  1. High current gain transistor laser

    NASA Astrophysics Data System (ADS)

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-06-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge.

  2. High current gain transistor laser

    PubMed Central

    Liang, Song; Qiao, Lijun; Zhu, Hongliang; Wang, Wei

    2016-01-01

    A transistor laser (TL), having the structure of a transistor with multi-quantum wells near its base region, bridges the functionality gap between lasers and transistors. However, light emission is produced at the expense of current gain for all the TLs reported up to now, leading to a very low current gain. We propose a novel design of TLs, which have an n-doped InP layer inserted in the emitter ridge. Numerical studies show that a current flow aperture for only holes can be formed in the center of the emitter ridge. As a result, the common emitter current gain can be as large as 143.3, which is over 15 times larger than that of a TL without the aperture. Besides, the effects of nonradiative recombination defects can be reduced greatly because the flow of holes is confined in the center region of the emitter ridge. PMID:27282466

  3. Long-pulse production of high current negative ion beam by using actively temperature controlled plasma grid for JT-60SA negative ion source

    SciTech Connect

    Kojima, A.; Hanada, M.; Yoshida, M.; Umeda, N.; Hiratsuka, J.; Kashiwagi, M.; Tobari, H.; Watanabe, K.; Grisham, L. R.

    2015-04-08

    The temperature control system of the large-size plasma grid has been developed to realize the long pulse production of high-current negative ions for JT-60SA. By using this prototype system for the JT-60SA ion source, 15 A negative ions has been sustained for 100 s for the first time, which is three times longer than that obtained in JT-60U. In this system, a high-temperature fluorinated fluid with a high boiling point of 270 degree Celsius is circulated in the cooling channels of the plasma grids (PG) where a cesium (Cs) coverage is formed to enhance the negative ion production. Because the PG temperature control had been applied to only 10% of the extraction area previously, the prototype PG with the full extraction area (110 cm × 45 cm) was developed to increase the negative ion current in this time. In the preliminary results of long pulse productions of high-current negative ions at a Cs conditioning phase, the negative ion production was gradually degraded in the last half of 100 s pulse where the temperature of an arc chamber wall was not saturated. From the spectroscopic measurements, it was found that the Cs flux released from the wall might affect to the negative ion production, which implied the wall temperature should be kept low to control the Cs flux to the PG for the long-pulse high-current production. The obtained results of long-pulse production and the PG temperature control method contributes the design of the ITER ion source.

  4. Processes of chemoionization in the course of inflammation of a methane-oxygen mixture by a high-current gliding surface discharge in a closed chamber

    SciTech Connect

    Artem’ev, K. V.; Berezhetskaya, N. K.; Kossyi, I. A. Misakyan, M. A.; Popov, N. A.; Tarasova, N. M.

    2015-05-15

    Results are presented from experiments on the inflammation of a stoichiometric methane-oxygen mixture by a high-current multielectrode spark-gap in a closed cylindrical chamber. It is shown that, in both the preflame and well-developed flame stages, the gas medium is characterized by a high degree of ionization (n{sub e} ≈ 10{sup 12} cm{sup −3}) due to chemoionization processes and a high electron-neutral collision frequency (ν{sub e0} ≈ 10{sup 12} s{sup −1})

  5. Increasing the electric strength of vacuum insulation by treating the electrodes with a low-energy, high-current electron beam

    SciTech Connect

    Batrakov, A.V.; Nazarov, D.S.; Ozur, G.E.

    1996-12-31

    The paper is devoted to the study of how the irradiation of the electrode surface with a low-energy, high-current electron beam affects the prebreakdown current and the electric strength of the vacuum insulation. This study is an extension of the work whose results were presented at the XVI ISDEIV. Experiments have been performed for 0.1-mm vacuum gaps formed by refractory-metal electrodes and for millimeter vacuum gaps with a pulsed voltage of amplitude 250 kV and duration 30-100 ns.

  6. Theoretical Particle Astrophysics

    SciTech Connect

    Kamionkowski, Marc

    2013-08-07

    Abstract: Theoretical Particle Astrophysics The research carried out under this grant encompassed work on the early Universe, dark matter, and dark energy. We developed CMB probes for primordial baryon inhomogeneities, primordial non-Gaussianity, cosmic birefringence, gravitational lensing by density perturbations and gravitational waves, and departures from statistical isotropy. We studied the detectability of wiggles in the inflation potential in string-inspired inflation models. We studied novel dark-matter candidates and their phenomenology. This work helped advance the DoE's Cosmic Frontier (and also Energy and Intensity Frontiers) by finding synergies between a variety of different experimental efforts, by developing new searches, science targets, and analyses for existing/forthcoming experiments, and by generating ideas for new next-generation experiments.

  7. Microfabricated particle focusing device

    DOEpatents

    Ravula, Surendra K.; Arrington, Christian L.; Sigman, Jennifer K.; Branch, Darren W.; Brener, Igal; Clem, Paul G.; James, Conrad D.; Hill, Martyn; Boltryk, Rosemary June

    2013-04-23

    A microfabricated particle focusing device comprises an acoustic portion to preconcentrate particles over large spatial dimensions into particle streams and a dielectrophoretic portion for finer particle focusing into single-file columns. The device can be used for high throughput assays for which it is necessary to isolate and investigate small bundles of particles and single particles.

  8. Effect of high current electron beam in a 30 MeV radio frequency linac for neutron-time-of-flight applications

    NASA Astrophysics Data System (ADS)

    Nayak, B.; Acharya, S.; Rajawat, R. K.; DasGupta, K.

    2016-01-01

    A high power pulsed radio frequency electron linac is designed by BARC, India to accelerate 30 MeV, 10 A, 10 ns beam for neutron-time-of-flight applications. It will be used as a neutron generator and will produce ˜1012-1013 n/s. It is essential to reduce the beam instability caused by space charge effect and the beam cavity interaction. In this paper, the wakefield losses in the accelerating section due to bunch of RMS (Root mean square) length 2 mm (at the gun exit) is analysed. Loss and kick factors are numerically calculated using CST wakefield solver. Both the longitudinal and transverse wake potentials are incorporated in beam dynamics code ELEGANT to find the transverse emittance growth of the beam propagating through the linac. Beam loading effect is examined by means of numerical computation carried out in ASTRA code. Beam break up start current has been estimated at the end of the linac which arises due to deflecting modes excited by the high current beam. At the end, transverse beam dynamics of such high current beam has been analysed.

  9. High current density and high PVCR Si/Si 1-xGe x DQW RTD formed with quadruple-layer buffer

    NASA Astrophysics Data System (ADS)

    Maekawa, Hirotaka; Sano, Yoshihiro; Ueno, Chihiro; Suda, Yoshiyuki

    2007-04-01

    As a strain-relief relaxed Si 1-xGe x buffer that is used for type II band offset formation, we have proposed a quadruple-Si 1-xGe x-layer (QL) buffer where misfit dislocations are evenly distributed in the lower two interfaces and a buffer surface with good crystallinity was obtained. The crystallinity of the buffer surface does not degrade by high P doping with a P concentration of ˜10 19 cm -3 during the buffer growth. A vertical-type electron-tunneling Si/Si 1-xGe x resonant tunneling diode (RTD) formed with the highly P-doped QL buffer exhibits a high current density and a high peak-to-valley current ratio (PVCR) value. A planer-type electron-tunneling Si/ Si 1-xGe x RTD formed with the same buffer using tetramethyl ammonium hydroxide (TMAH) etching and polyimide insulator, which is better suited for device integration, also exhibits a high current density and a high PVCR value and good initial static performance reproducibility.

  10. Progress in the Analysis of Complex Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Gilles, Mary K.; Knopf, Daniel A.; Wang, Bingbing; China, Swarup

    2016-06-01

    This article presents an overview of recent advances in field and laboratory studies of atmospheric particles formed in processes of environmental air-surface interactions. The overarching goal of these studies is to advance predictive understanding of atmospheric particle composition, particle chemistry during aging, and their environmental impacts. The diversity between chemical constituents and lateral heterogeneity within individual particles adds to the chemical complexity of particles and their surfaces. Once emitted, particles undergo transformation via atmospheric aging processes that further modify their complex composition. We highlight a range of modern analytical approaches that enable multimodal chemical characterization of particles with both molecular and lateral specificity. When combined, these approaches provide a comprehensive arsenal of tools for understanding the nature of particles at air-surface interactions and their reactivity and transformations with atmospheric aging. We discuss applications of these novel approaches in recent studies and highlight additional research areas to explore the environmental effects of air-surface interactions.

  11. Progress in the Analysis of Complex Atmospheric Particles.

    PubMed

    Laskin, Alexander; Gilles, Mary K; Knopf, Daniel A; Wang, Bingbing; China, Swarup

    2016-06-12

    This article presents an overview of recent advances in field and laboratory studies of atmospheric particles formed in processes of environmental air-surface interactions. The overarching goal of these studies is to advance predictive understanding of atmospheric particle composition, particle chemistry during aging, and their environmental impacts. The diversity between chemical constituents and lateral heterogeneity within individual particles adds to the chemical complexity of particles and their surfaces. Once emitted, particles undergo transformation via atmospheric aging processes that further modify their complex composition. We highlight a range of modern analytical approaches that enable multimodal chemical characterization of particles with both molecular and lateral specificity. When combined, these approaches provide a comprehensive arsenal of tools for understanding the nature of particles at air-surface interactions and their reactivity and transformations with atmospheric aging. We discuss applications of these novel approaches in recent studies and highlight additional research areas to explore the environmental effects of air-surface interactions. PMID:27306308

  12. Technological Advancements

    ERIC Educational Resources Information Center

    Kennedy, Mike

    2010-01-01

    The influx of technology has brought significant improvements to school facilities. Many of those advancements can be found in classrooms, but when students head down the hall to use the washrooms, they are likely to find a host of technological innovations that have improved conditions in that part of the building. This article describes modern…

  13. Research Advances

    ERIC Educational Resources Information Center

    King, Angela G.

    2004-01-01

    Research advances, a new feature in Journal of Chemical Engineering that brings information about innovations in current areas of research to high school and college science faculty with an intent to provide educators with timely descriptions of latest progress in research that can be integrated into existing courses to update course content and…

  14. Recent Advancements of RF Guns

    NASA Astrophysics Data System (ADS)

    Faillace, Luigi

    High-brightness, high-current electron beams are the main requirement for fourth generation light sources such as free-electron lasers (FELs), energy recovery Linacs (ERLs) and high-energy linear colliders. The most successful device for producing such beams is the Radio-Frequency (RF) photoinjector that has been undergoing a constant evolution over the past nearly 30 years towards the production of ever-lower beam emittances and higher currents. The on-going progress in the technology of higher quality materials as well as the enhanced quality of laser pulse shaping have allowed huge improvements in the generation of higher-quality electron beams. Here, it is presented an overview of recent advancements and future perspectives of RF photoinjectors for a fifth generation light source.

  15. Tracking single particle rotation: Probing dynamics in four dimensions

    DOE PAGESBeta

    Anthony, Stephen Michael; Yu, Yan

    2015-04-29

    Direct visualization and tracking of small particles at high spatial and temporal resolution provides a powerful approach to probing complex dynamics and interactions in chemical and biological processes. Analysis of the rotational dynamics of particles adds a new dimension of information that is otherwise impossible to obtain with conventional 3-D particle tracking. In this review, we survey recent advances in single-particle rotational tracking, with highlights on the rotational tracking of optically anisotropic Janus particles. Furthermore, strengths and weaknesses of the various particle tracking methods, and their applications are discussed.

  16. Measurement of ion species in high current ECR H⁺/D⁺ ion source for IFMIF (International Fusion Materials Irradiation Facility).

    PubMed

    Shinto, K; Senée, F; Ayala, J-M; Bolzon, B; Chauvin, N; Gobin, R; Ichimiya, R; Ihara, A; Ikeda, Y; Kasugai, A; Kitano, T; Kondo, K; Marqueta, A; Okumura, Y; Takahashi, H; Valette, M

    2016-02-01

    Ion species ratio of high current positive hydrogen/deuterium ion beams extracted from an electron-cyclotron-resonance ion source for International Fusion Materials Irradiation Facility accelerator was measured by the Doppler shift Balmer-α line spectroscopy. The proton (H(+)) ratio at the middle of the low energy beam transport reached 80% at the hydrogen ion beam extraction of 100 keV/160 mA and the deuteron (D(+)) ratio reached 75% at the deuterium ion beam extraction of 100 keV/113 mA. It is found that the H(+) ratio measured by the spectroscopy gives lower than that derived from the phase-space diagram measured by an Allison scanner type emittance monitor. The H(+)/D(+) ratio estimated by the emittance monitor was more than 90% at those extraction currents.

  17. Self-focusing of a high current density ion beam extracted with concave electrodes in a low energy region around 150 eV

    SciTech Connect

    Hirano, Y.; Kiyama, S.; Koguchi, H.; Sakakita, H.

    2014-02-15

    Spontaneous self-focusing of ion beam with high current density (J{sub c} ∼ 2 mA/cm{sup 2}, I{sub b} ∼ 65 mA) in low energy region (∼150 eV) is observed in a hydrogen ion beam extracted from an ordinary bucket type ion source with three electrodes having concave shape (acceleration, deceleration, and grounded electrodes). The focusing appears abruptly in the beam energy region over ∼135–150 eV, and the J{sub c} jumps up from 0.7 to 2 mA/cm{sup 2}. Simultaneously a strong electron flow also appears in the beam region. The electron flow has almost the same current density. Probably these electrons compensate the ion space charge and suppress the beam divergence.

  18. Measurements of the Total Charge-Changing Cross Sections for Collisions of Fast Ions with Target Gas Using High Current Experiment

    SciTech Connect

    Covo, Michel Kireeff; Molvik, Arthur W.; Kaganovich, Igor D.; Shnidman, Ariel; Vujic, Jasmina L.

    2009-04-13

    The sum of ionization and charge-exchange cross sections of several gas targets (H2, N2, He, Ne, Kr, Xe, Ar, and water vapor) impacted by 1MeV K+ beam are measured. In a high current ion beam, the self-electric field of the beam is high enough that ions produced from the gas ionization or charge exchange by the ion beam are quickly swept to the sides of accelerator. The flux of the expelled ions is measured by a retarding field analyzer. This allows accurate measuring of the total charge-changing cross sections (ionization plus charge exchange) of the beam interaction with gas. Cross sections for H2, He, and N2 are simulated using classical trajectory Monte Carlo (CTMC) method and compared with the experimental results, showing good agreement.

  19. Continuum model of tensile fracture of metal melts and its application to a problem of high-current electron irradiation of metals

    SciTech Connect

    Mayer, Alexander E. E-mail: mayer.al.evg@gmail.com; Mayer, Polina N.

    2015-07-21

    A continuum model of the metal melt fracture is formulated on the basis of the continuum mechanics and theory of metastable liquid. A character of temperature and strain rate dependences of the tensile strength that is predicted by the continuum model is verified, and parameters of the model are fitted with the use of the results of the molecular dynamics simulations for ultra-high strain rates (≥1–10/ns). A comparison with experimental data from literature is also presented for Al and Ni melts. Using the continuum model, the dynamic tensile strength of initially uniform melts of Al, Cu, Ni, Fe, Ti, and Pb within a wide range of strain rates (from 1–10/ms to 100/ns) and temperatures (from melting temperature up to 70–80% of critical temperature) is calculated. The model is applied to numerical investigation of a problem of the high-current electron irradiation of Al, Cu, and Fe targets.

  20. Measurement of DNA Double-Strand Break Yield in Human Cancer Cells by High-Current, Short-Duration Bunches of Laser-Accelerated Protons

    NASA Astrophysics Data System (ADS)

    Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Maeda, Takuya; Sakaki, Hironao; Hori, Toshihiko; Ogura, Koichi; Nishiuchi, Mamiko; Teshima, Teruki; Nishimura, Hiroaki; Kondo, Kiminori; Bolton, Paul R.; Kawanishi, Shunichi

    2011-10-01

    To investigate the radiobiological effects of high dose rates that are attributed to high current, short bunch beam generation with laser-dreven ion acceleration, we have developed an experimental setup that uses laser-accelerated protons. In-vitro human lung cancer cells: A549 pulmonary adenocarcinoma are irradiated with a laser-accelerated proton bunches with a duration of 2×10-8 s and flux of ˜1015 cm-2 s-1, amounting to single bunch absorbed dose at the 1 Gy level. The double-strand break (DSB) yield in cell DNA is analyzed for the laser-accelerated proton beam at an average LET of 41 keV/µm.

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

    SciTech Connect

    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.

  2. High-resolution X-ray projection radiography of a pin cathode in a high-current vacuum diode using X-pinch radiation

    NASA Astrophysics Data System (ADS)

    Parkevich, E. V.; Tilikin, I. N.; Agafonov, A. V.; Shelkovenko, T. A.; Romanova, V. M.; Mingaleev, A. R.; Savinov, S. Yu.; Mesyats, G. A.; Pikuz, S. A.

    2016-03-01

    To study processes in a high-current vacuum diode with a cathode in the form of a single pin made of a metallic wire 20-30 μm in diameter, the method of high-resolution projection X-ray radiography with an X-pinch as a source has been used. A strong inhomogeneity of the energy contribution to the wire has been revealed. The smallest energy release has been observed near the end of the pin, where the electric field strength is maximal. Hard X rays, as well as the ejection of matter from the anode, have been observed, indicating the generation of an electron beam with the parameters characteristic of explosive electron emission in the diode with this configuration. The data obtained indicate complex processes occurring in the diode. Possible scenarios of their development have been considered.

  3. Advanced Combustion

    SciTech Connect

    Holcomb, Gordon R.

    2013-03-11

    The activity reported in this presentation is to provide the mechanical and physical property information needed to allow rational design, development and/or choice of alloys, manufacturing approaches, and environmental exposure and component life models to enable oxy-fuel combustion boilers to operate at Ultra-Supercritical (up to 650{degrees}C & between 22-30 MPa) and/or Advanced Ultra-Supercritical conditions (760{degrees}C & 35 MPa).

  4. Advanced computing

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Advanced concepts in hardware, software and algorithms are being pursued for application in next generation space computers and for ground based analysis of space data. The research program focuses on massively parallel computation and neural networks, as well as optical processing and optical networking which are discussed under photonics. Also included are theoretical programs in neural and nonlinear science, and device development for magnetic and ferroelectric memories.

  5. Advanced Nanoemulsions

    NASA Astrophysics Data System (ADS)

    Fryd, Michael M.; Mason, Thomas G.

    2012-05-01

    Recent advances in the growing field of nanoemulsions are opening up new applications in many areas such as pharmaceuticals, foods, and cosmetics. Moreover, highly controlled nanoemulsions can also serve as excellent model systems for investigating basic scientific questions about soft matter. Here, we highlight some of the most recent developments in nanoemulsions, focusing on methods of formation, surface modification, material properties, and characterization. These developments provide insight into the substantial advantages that nanoemulsions can offer over their microscale emulsion counterparts.

  6. Generation of High Current Densities by Pure Cultures of Anode-Respiring Geoalkalibacter spp. under Alkaline and Saline Conditions in Microbial Electrochemical Cells

    PubMed Central

    Badalamenti, Jonathan P.; Krajmalnik-Brown, Rosa; Torres, César I.

    2013-01-01

    ABSTRACT Anode-respiring bacteria (ARB) generate electric current in microbial electrochemical cells (MXCs) by channeling electrons from the oxidation of organic substrates to an electrode. Production of high current densities by monocultures in MXCs has resulted almost exclusively from the activity of Geobacter sulfurreducens, a neutrophilic freshwater Fe(III)-reducing bacterium and the highest-current-producing member documented for the Geobacteraceae family of the Deltaproteobacteria. Here we report high current densities generated by haloalkaliphilic Geoalkalibacter spp., thus broadening the capability for high anode respiration rates by including other genera within the Geobacteraceae. In this study, acetate-fed pure cultures of two related Geoalkalibacter spp. produced current densities of 5.0 to 8.3 and 2.4 to 3.3 A m−2 under alkaline (pH 9.3) and saline (1.7% NaCl) conditions, respectively. Chronoamperometric studies of halophilic Glk. subterraneus DSM 23483 and alkaliphilic Glk. ferrihydriticus DSM 17813 suggested that cells performed long-range electron transfer through electrode-attached biofilms and not through soluble electron shuttles. Glk. ferrihydriticus also oxidized ethanol directly to produce current, with maximum current densities of 5.7 to 7.1 A m−2 and coulombic efficiencies of 84 to 95%. Cyclic voltammetry (CV) elicited a sigmoidal response with characteristic onset, midpoint, and saturation potentials, while CV performed in the absence of an electron donor suggested the involvement of redox molecules in the biofilm that were limited by diffusion. These results matched those previously reported for actively respiring Gb. sulfurreducens biofilms producing similar current densities (~5 to 9 A m−2). PMID:23631915

  7. Particle contamination formation in magnetron sputtering processes

    SciTech Connect

    Selwyn, G.S.; Sequeda, F.; Huang, C.

    1997-07-01

    Defects caused by particulate contamination are an important concern in the fabrication of thin film products. Often, magnetron sputtering processes are used for this purpose. Particle contamination generated during thin film processing can be detected using laser light scattering, a powerful diagnostic technique which provides real-time, {ital in situ} imaging of particles {gt}0.3 {mu}m on the target, substrate, or in the plasma. Using this technique, we demonstrate that the mechanisms for particle generation, transport, and trapping during magnetron sputter deposition are different from the mechanisms reported in previously studied plasma etch processes, due to the inherent spatial nonuniformity of magnetically enhanced plasmas. During magnetron sputter deposition, one source of particle contamination is linked to portions of the sputtering target surface exposed to weaker plasma density. There, film redeposition induces filament or nodule growth. Sputter removal of these features is inhibited by the dependence of sputter yield on angle of incidence. These features enhance trapping of plasma particles, which then increases filament growth. Eventually the growths effectively {open_quotes}short-circuit{close_quotes} the sheath, causing high currents to flow through these features. This, in turn, causes mechanical failure of the growth resulting in fracture and ejection of the target contaminants into the plasma and onto the substrate. Evidence of this effect has been observed in semiconductor fabrication and storage disk manufacturing. Discovery of this mechanism in both technologies suggests it may be universal to many sputter processes. {copyright} {ital 1997 American Vacuum Society.}

  8. Relativistic Shocks: Particle Acceleration and Magnetization

    NASA Astrophysics Data System (ADS)

    Sironi, L.; Keshet, U.; Lemoine, M.

    2015-10-01

    We review the physics of relativistic shocks, which are often invoked as the sources of non-thermal particles in pulsar wind nebulae (PWNe), gamma-ray bursts (GRBs), and active galactic nuclei (AGN) jets, and as possible sources of ultra-high energy cosmic-rays. We focus on particle acceleration and magnetic field generation, and describe the recent progress in the field driven by theory advances and by the rapid development of particle-in-cell (PIC) simulations. In weakly magnetized or quasi parallel-shocks (i.e. where the magnetic field is nearly aligned with the flow), particle acceleration is efficient. The accelerated particles stream ahead of the shock, where they generate strong magnetic waves which in turn scatter the particles back and forth across the shock, mediating their acceleration. In contrast, in strongly magnetized quasi-perpendicular shocks, the efficiencies of both particle acceleration and magnetic field generation are suppressed. Particle acceleration, when efficient, modifies the turbulence around the shock on a long time scale, and the accelerated particles have a characteristic energy spectral index of s_{γ}˜eq2.2 in the ultra-relativistic limit. We discuss how this novel understanding of particle acceleration and magnetic field generation in relativistic shocks can be applied to high-energy astrophysical phenomena, with an emphasis on PWNe and GRB afterglows.

  9. Advanced Thermally Stable Jet Fuels

    SciTech Connect

    A. Boehman; C. Song; H. H. Schobert; M. M. Coleman; P. G. Hatcher; S. Eser

    1998-01-01

    The Penn State program in advanced thermally stable jet fuels has five components: 1) development of mechanisms of degradation and solids formation; 2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles during thermal stressing; 3) characterization of carbonaceous deposits by various instrumental and microscopic methods; 4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and 5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics from coal.

  10. Advanced LIGO

    NASA Astrophysics Data System (ADS)

    LIGO Scientific Collaboration; Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V.; Affeldt, C.; Aggarwal, N.; Aguiar, O. D.; Ain, A.; Ajith, P.; Alemic, A.; Allen, B.; Amariutei, D.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J. S.; Ashton, G.; Ast, S.; Aston, S. M.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballmer, S. W.; Barayoga, J. C.; Barbet, M.; Barclay, S.; Barish, B. C.; Barker, D.; Barr, B.; Barsotti, L.; Bartlett, J.; Barton, M. A.; Bartos, I.; Bassiri, R.; Batch, J. C.; Baune, C.; Behnke, B.; Bell, A. S.; Bell, C.; Benacquista, M.; Bergman, J.; Bergmann, G.; Berry, C. P. L.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biscans, S.; Biwer, C.; Blackburn, J. K.; Blackburn, L.; Blair, C. D.; Blair, D.; Bock, O.; Bodiya, T. P.; Bojtos, P.; Bond, C.; Bork, R.; Born, M.; Bose, Sukanta; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Bridges, D. O.; Brinkmann, M.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Buchman, S.; Buikema, A.; Buonanno, A.; Cadonati, L.; Calderón Bustillo, J.; Camp, J. B.; Cannon, K. C.; Cao, J.; Capano, C. D.; Caride, S.; Caudill, S.; Cavaglià, M.; Cepeda, C.; Chakraborty, R.; Chalermsongsak, T.; Chamberlin, S. J.; Chao, S.; Charlton, P.; Chen, Y.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Collette, C.; Cominsky, L.; Constancio, M., Jr.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cutler, C.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; Danzmann, K.; Dartez, L.; Dave, I.; Daveloza, H.; Davies, G. S.; Daw, E. J.; DeBra, D.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; DeRosa, R. T.; DeSalvo, R.; Dhurandhar, S.; D´ıaz, M.; Di Palma, I.; Dojcinoski, G.; Dominguez, E.; Donovan, F.; Dooley, K. L.; Doravari, S.; Douglas, R.; Downes, T. P.; Driggers, J. C.; Du, Z.; Dwyer, S.; Eberle, T.; Edo, T.; Edwards, M.; Edwards, M.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Essick, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fairhurst, S.; Fan, X.; Fang, Q.; Farr, B.; Farr, W. M.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Feldbaum, D.; Ferreira, E. C.; Fisher, R. P.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fuentes-Tapia, S.; Fulda, P.; Fyffe, M.; Gair, J. R.; Gaonkar, S.; Gehrels, N.; Gergely, L. Á.; Giaime, J. A.; Giardina, K. D.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gräf, C.; Graff, P. B.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Grote, H.; Grunewald, S.; Guido, C. J.; Guo, X.; Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hacker, J.; Hall, E. D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harry, G. M.; Harry, I. W.; Hart, M.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Hee, S.; Heintze, M.; Heinzel, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Hollitt, S. E.; Holt, K.; Hopkins, P.; Hosken, D. J.; Hough, J.; Houston, E.; Howell, E. J.; Hu, Y. M.; Huerta, E.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Idrisy, A.; Indik, N.; Ingram, D. R.; Inta, R.; Islas, G.; Isler, J. C.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacobson, M.; Jang, H.; Jawahar, S.; Ji, Y.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Ju, L.; Haris, K.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kawazoe, F.; Keiser, G. M.; Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Key, J. S.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, C.; Kim, K.; Kim, N. G.; Kim, N.; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Koehlenbeck, S.; Kokeyama, K.; Kondrashov, V.; Korobko, M.; Korth, W. Z.; Kozak, D. B.; Kringel, V.; Krishnan, B.; Krueger, C.; Kuehn, G.; Kumar, A.; Kumar, P.; Kuo, L.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lazzarini, A.; Lazzaro, C.; Le, J.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Leong, J. R.; Levin, Y.; Levine, B.; Lewis, J.; Li, T. G. F.; Libbrecht, K.; Libson, A.; Lin, A. C.; Littenberg, T. B.; Lockerbie, N. A.; Lockett, V.; Logue, J.; Lombardi, A. L.; Lormand, M.; Lough, J.; Lubinski, M. J.; Lück, H.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macarthur, J.; MacDonald, T.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Magee, R.; Mageswaran, M.; Maglione, C.; Mailand, K.; Mandel, I.; Mandic, V.; Mangano, V.; Mansell, G. L.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Martin, I. W.; Martin, R. M.; Martynov, D.; Marx, J. N.; Mason, K.; Massinger, T. J.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McGuire, S. C.; McIntyre, G.; McIver, J.; McLin, K.; McWilliams, S.; Meadors, G. D.; Meinders, M.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyers, P. M.; Miao, H.; Middleton, H.; Mikhailov, E. E.; Miller, A.; Miller, J.; Millhouse, M.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohanty, S. D.; Mohapatra, S. R. P.; Moore, B.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mossavi, K.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nash, T.; Nayak, R. K.; Necula, V.; Nedkova, K.; Newton, G.; Nguyen, T.; Nielsen, A. B.; Nissanke, S.; Nitz, A. H.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; Oram, R.; O'Reilly, B.; Ortega, W.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Pai, S.; Palashov, O.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Papa, M. A.; Paris, H.; Patrick, Z.; Pedraza, M.; Pekowsky, L.; Pele, A.; Penn, S.; Perreca, A.; Phelps, M.; Pierro, V.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Post, A.; Poteomkin, A.; Powell, J.; Prasad, J.; Predoi, V.; Premachandra, S.; Prestegard, T.; Price, L. R.; Principe, M.; Privitera, S.; Prix, R.; Prokhorov, L.; Puncken, O.; Pürrer, M.; Qin, J.; Quetschke, V.; Quintero, E.; Quiroga, G.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov, M.; Ramirez, K.; Raymond, V.; Reed, C. M.; Reid, S.; Reitze, D. H.; Reula, O.; Riles, K.; Robertson, N. A.; Robie, R.; Rollins, J. G.; Roma, V.; Romano, J. D.; Romanov, G.; Romie, J. H.; Rowan, S.; Rüdiger, A.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Saleem, M.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J. R.; Sannibale, V.; Santiago-Prieto, I.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.; Sawadsky, A.; Scheuer, J.; Schilling, R.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sergeev, A.; Serna, G.; Sevigny, A.; Shaddock, D. A.; Shahriar, M. S.; Shaltev, M.; Shao, Z.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siemens, X.; Sigg, D.; Silva, A. D.; Simakov, D.; Singer, A.; Singer, L.; Singh, R.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Son, E. J.; Sorazu, B.; Souradeep, T.; Staley, A.; Stebbins, J.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Steplewski, S.; Stevenson, S.; Stone, R.; Strain, K. A.; Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sutton, P. J.; Szczepanczyk, M.; Szeifert, G.; Talukder, D.; Tanner, D. B.; Tápai, M.; Tarabrin, S. P.; Taracchini, A.; Taylor, R.; Tellez, G.; Theeg, T.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tomlinson, C.; Torres, C. V.; Torrie, C. I.; Traylor, G.; Tse, M.; Tshilumba, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; Vallisneri, M.; van Veggel, A. A.; Vass, S.; Vaulin, R.; Vecchio, A.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Vincent-Finley, R.; Vitale, S.; Vo, T.; Vorvick, C.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; Wade, L.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, H.; Wang, M.; Wang, X.; Ward, R. L.; Warner, J.; Was, M.; Weaver, B.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wilkinson, C.; Williams, L.; Williams, R.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Xie, S.; Yablon, J.; Yakushin, I.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yang, Q.; Zanolin, M.; Zhang, Fan; Zhang, L.; Zhang, M.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhu, X. J.; Zucker, M. E.; Zuraw, S.; Zweizig, J.

    2015-04-01

    The Advanced LIGO gravitational wave detectors are second-generation instruments designed and built for the two LIGO observatories in Hanford, WA and Livingston, LA, USA. The two instruments are identical in design, and are specialized versions of a Michelson interferometer with 4 km long arms. As in Initial LIGO, Fabry-Perot cavities are used in the arms to increase the interaction time with a gravitational wave, and power recycling is used to increase the effective laser power. Signal recycling has been added in Advanced LIGO to improve the frequency response. In the most sensitive frequency region around 100 Hz, the design strain sensitivity is a factor of 10 better than Initial LIGO. In addition, the low frequency end of the sensitivity band is moved from 40 Hz down to 10 Hz. All interferometer components have been replaced with improved technologies to achieve this sensitivity gain. Much better seismic isolation and test mass suspensions are responsible for the gains at lower frequencies. Higher laser power, larger test masses and improved mirror coatings lead to the improved sensitivity at mid and high frequencies. Data collecting runs with these new instruments are planned to begin in mid-2015.

  11. Potential Climate Impacts of Engine Particle Emissions

    NASA Technical Reports Server (NTRS)

    Kawa, S. Randy

    1999-01-01

    Solid (soot) and liquid (presumed sulfate) particle emissions from aircraft engines may have serious impacts on the atmosphere. While the direct radiative impact of these particles is expected to be small relative to those from natural sources (Atmospheric Effects of Subsonic Aircraft: Interim Assessment of the Advanced Subsonic Technology Program, NASA Ref. Pub. 1400, 1997), their indirect effects on atmospheric chemistry and cloud formation may have a significant impact. The potential impacts of primary concern are the increase of sulfate surface area and accelerated heterogeneous chemical reactions, and the potential for either modified soot or sulfate particles to serve as cloud nuclei which would change the frequency or radiative characteristics of clouds. Volatile (sulfate) particle concentrations measured behind the Concorde aircraft in flight in the stratosphere were much higher than expected from near-field model calculations of particle formation and growth. Global model calculations constrained by these data calculate a greater level of stratospheric ozone depletion from the proposed High speed Civil Transport (HSCT) fleet than those without particle emission. Soot particles have also been proposed as important in heterogeneous chemistry but this remains to be substantiated. Aircraft volatile particle production in the troposphere has been shown by measurements to depend strongly on fuel sulfur content. Sulfate particles of sufficient size are known to provide a good nucleating surface for cloud growth. Although pure carbon soot is hydrophobic, the solid particle surface may incorporate more suitable nucleating sites. The non-volatile (soot) particles also tend to occupy the large end of aircraft particle size spectra. Quantitative connection between aircraft particle emissions and cloud modification has not been established yet, however, even small changes in cloud amount or properties could have a significant effect on the radiative balance of the

  12. Long-term cycle stability at a high current for nanocrystalline LiFePO4 coated with a conductive polymer

    NASA Astrophysics Data System (ADS)

    Dinh, Hung-Cuong; Lim, Hanjo; Park, Ki Dong; Yeo, In-Hyeong; Kang, Yongku; Mho, Sun-il

    2013-03-01

    Highly uniform hierarchical-microstructured LiFePO4 particles with dumbbell- and donut-shape and individual LiFePO4 nanocrystals were prepared by a hydrothermal method utilizing citric acid or a triblock copolymer (Pluronic P123) as a surfactant. The cathode composed of the individual nanocrystalline LiFePO4 particles exhibited higher specific capacity than the cathodes composed of the hierarchically assembled microparticles. Coating a conductive polymer, poly-3,4-ethylenedioxythiophene (PEDOT), on the surface of LiFePO4 particles improved the battery performances such as large specific capacities, high rate capability and an improved cycle stability. The nanocrystalline LiFePO4 particles coated with PEDOT (20 wt%) exhibited the highest discharge capacities of 175 and 136 mAh g-1 for the first battery cycle and 163 and 128 mAh g-1 after 500 battery cycles, with a degradation rate of 6-7%, at the rates of 1 and 10 C, respectively.

  13. ADVANCED HYBRID PARTICULATE COLLECTOR

    SciTech Connect

    Stanley Miller; Rich Gebert; William Swanson

    1999-11-01

    A new concept in particulate control, called an advanced hybrid particulate collector (AHPC), is being developed under funding from the US Department of Energy. The AHPC combines the best features of electrostatic precipitators (ESPs) and baghouses in a manner that has not been done before. The AHPC concept consists of a combination of fabric filtration and electrostatic precipitation in the same housing, providing major synergism between the two collection methods, both in the particulate collection step and in the transfer of dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emission with conventional ESPs, and it solves the problem of reentrainment and collection of dust in conventional baghouses. The AHPC is currently being tested at the 2.7-MW scale at the Big Stone power station.

  14. ADVANCED HYBRID PARTICULATE COLLECTOR

    SciTech Connect

    Stanley J. Miller; Grant L. Schelkoph

    1999-04-01

    A new concept in particulate control, called an advanced hybrid particulate collector (AHPC), is being developed under funding from the U.S. Department of Energy. The AHPC combines the best features of electrostatic precipitators (ESPs) and baghouses in a manner that has not been done before. The AHPC concept consists of a combination of fabric filtration and electrostatic precipitation in the same housing, providing major synergism between the two collection methods, both in the particulate collection step and in transfer of the dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emission with conventional ESPs, and it solves the problem of reentrainment and collection of dust in conventional baghouses.

  15. ADVANCED HYBRID PARTICULATE COLLECTOR

    SciTech Connect

    Grant L. Schelkoph; Stanley J. Miller

    1999-07-01

    A new concept in particulate control, called an advanced hybrid particulate collector (AHPC), is being developed under funding from the U.S. Department of Energy. The AHPC combines the best features of electrostatic precipitators (ESPs) and baghouses in a manner that has not been done before. The AHPC concept consists of a combination of fabric filtration and electrostatic precipitation in the same housing, providing major synergism between the two collection methods, both in the particulate collection step and in transfer of the dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emission with conventional ESPs, and it solves the problem of reentrainment and collection of dust in conventional baghouses.

  16. Manifestations of advanced civilizations

    NASA Astrophysics Data System (ADS)

    Bracewell, R. N.

    A list of possible modes of detecting advanced civilizations elsewhere in the universe is provided, including EM Alfven, and gravity waves, matter transfer, and exotica such as tachyons, black hole tunneling, and telepathy. Further study is indicated for low frequency radio wave propagation, which may travel along magnetic fields to reach the earth while laser beams are not favored because of the power needed for transmitting quanta instead of waves. IR, X ray, and UV astronomy are noted to be suitable for detecting signals in those ranges, while Alfven wave communication will be best observed by probes outside the orbit of Jupiter, where local anomalies have less effect. Particle propagation communication is viewed as unlikely, except as a trace of an extinct civilization, but panspermia, which involves interstellar spreading of seeds and/or spores, receives serious attention, as does laser probe or pellet propulsion.

  17. Theory of energetic/alpha particle effects on magnetohydrodynamic modes in tokamaks

    SciTech Connect

    Chen, L.; White, R.B.; Rewoldt, G.; Colestock, P.; Rutherford, P.H.; Chen, Y.P.; Ke, F.J.; Tsai, S.T.; Bussac, M.N.

    1989-01-01

    The presence of energetic particles is shown to qualitatively modify the stability properties of ideal as well as resistive magnetohydrodynamic (MHD) modes in tokamaks. Specifically, we demonstrate that, consistent with highpower ICRF heating experiments in JET, high energy trapped particles can effectively stabilize the sawtooth mode, providing a possible route to stable high current tokamak operation. An alternative stabilization scheme employing barely circulating energetic particles is also proposed. Finally, we present analytical and numerical studies on the excitations of high-n MHD modes via transit resonances with circulating alpha particles. 14 refs., 3 figs.

  18. DNA-Grafted Janus Particles

    NASA Astrophysics Data System (ADS)

    Hsueh, Ching; Lin, Keng-Hui; Juan, Wen-Tau

    2008-03-01

    Recently there have been advances in generating Janus microspheres whose two hemispheres have different chemical compositions [1-4]. The new types of particles open up possibilities for assembly of complex structures. Here we attach DNA molecules onto one side of Janus microspheres. The new type of colloidal particles resembles surfactant molecules and may give us interesting new structures.Reference: [1] Y. Lu, H. Xiong, X. Jiang, Y.Xia, M. Prentiss and G. M.Whitesides, J. Am. Chem. Soc. 125, 12724 (2003) [2] O.Cayre, V. N.Paunov and O. D. Velev, J. Mater. Chem. 13, 2445 (2003) [3] R. F. Shepherd, J. C. Conrad, S. K. Rhodes, D. R. Link, M. Marquez, D. A. Weitz and J. A. Lewis, Langmuir 22, 8618 (2006) [4] L. Hong, S. Jiang and S. Granick, Langmuir 22, 9495 (2006)

  19. High current density GaAs/Si rectifying heterojunction by defect free Epitaxial Lateral overgrowth on Tunnel Oxide from nano-seed

    NASA Astrophysics Data System (ADS)

    Renard, Charles; Molière, Timothée; Cherkashin, Nikolay; Alvarez, José; Vincent, Laetitia; Jaffré, Alexandre; Hallais, Géraldine; Connolly, James Patrick; Mencaraglia, Denis; Bouchier, Daniel

    2016-05-01

    Interest in the heteroepitaxy of GaAs on Si has never failed in the last years due to the potential for monolithic integration of GaAs-based devices with Si integrated circuits. But in spite of this effort, devices fabricated from them still use homo-epitaxy only. Here we present an epitaxial technique based on the epitaxial lateral overgrowth of micrometer scale GaAs crystals on a thin SiO2 layer from nanoscale Si seeds. This method permits the integration of high quality and defect-free crystalline GaAs on Si substrate and provides active GaAs/Si heterojunctions with efficient carrier transport through the thin SiO2 layer. The nucleation from small width openings avoids the emission of misfit dislocations and the formation of antiphase domains. With this method, we have experimentally demonstrated for the first time a monolithically integrated GaAs/Si diode with high current densities of 10 kA.cm‑2 for a forward bias of 3.7 V. This epitaxial technique paves the way to hybrid III–V/Si devices that are free from lattice-matching restrictions, and where silicon not only behaves as a substrate but also as an active medium.

  20. Development of a low-energy and high-current pulsed neutral beam injector with a washer-gun plasma source for high-beta plasma experiments.

    PubMed

    Ii, Toru; Gi, Keii; Umezawa, Toshiyuki; Asai, Tomohiko; Inomoto, Michiaki; Ono, Yasushi

    2012-08-01

    We have developed a novel and economical neutral-beam injection system by employing a washer-gun plasma source. It provides a low-cost and maintenance-free ion beam, thus eliminating the need for the filaments and water-cooling systems employed conventionally. In our primary experiments, the washer gun produced a source plasma with an electron temperature of approximately 5 eV and an electron density of 5 × 10(17) m(-3), i.e., conditions suitable for ion-beam extraction. The dependence of the extracted beam current on the acceleration voltage is consistent with space-charge current limitation, because the observed current density is almost proportional to the 3/2 power of the acceleration voltage below approximately 8 kV. By optimizing plasma formation, we successfully achieved beam extraction of up to 40 A at 15 kV and a pulse length in excess of 0.25 ms. Its low-voltage and high-current pulsed-beam properties enable us to apply this high-power neutral beam injection into a high-beta compact torus plasma characterized by a low magnetic field.