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Using perpendicular electron-cyclotron emission to diagnose the thermal barrier electrons in TMX-Upgrade. Progress report

Description: Possibilities are explored for diagnosing the hot-electron distribution function for the thermal barriers of tandem mirrors using perpendicular electron-cyclotron emission. Emission from a relativistic bimaxwellian with a loss cone is calculated in the single-particle limit. Formulae are derived for finding T/sub perpendicular/ for a bimaxwellian by measuring frequencies of the harmonic intensity maxima at optically thin frequencies, or the intensity at optically thick frequencies. A positive par. delta f/par. delta p/sub perpendicular/ in the distribution function is shown to lead to decreased absorption, and instability for low T/sub perpendicular/. Methods are discussed for diagnosing the loss-cone distribution by comparing numerical calculation with measured intensity ratios and frequencies at the harmonic peaks. Finally, the perpendicular source function in the single-particle limit for this distribution function is calculated.
Date: January 1, 1983
Creator: Celata, C.M.
Partner: UNT Libraries Government Documents Department

Simulation of transverse combining of space-charge dominated beams

Description: Rms emittance growth in the transverse plane due to the transverse combining of four identical elliptical beams of uniform density has been investigated. The emittance growth can be related by conservation of energy to the change in the electrostatic field energy. Its dependence on initial beam positions and radii has been calculated analytically for round beams and by computer simulation for elliptical beams.
Date: June 1, 1986
Creator: Celata, C.M.
Partner: UNT Libraries Government Documents Department

Synthesizing a four-dimensional beam particle distribution frommultiple two-dimensional views

Description: The transverse dynamics of a nearly-monoenergetic particle beam are described by the evolution of the 4D distribution f(x,y,x',y'), where x and y are the transverse spatial coordinates and x' {triple_bond} p{sub x}/p{sub z} and y' {triple_bond} p{sub y}/p{sub z} are the corresponding momentum components divided by the longitudinal momentum component. In present-day experimental practice, such beams are often diagnosed by passing them through an axially-separated pair of slits parallel to the y axis. This selects for x and x' and integrates over y and y'. A sequence of pulses (with the slits at various x positions) yields a 2D projection of the beam phase space, f(x,x'). Another scanner might yield f(y,y') or, using crossed slits, f(x,y). The challenge is that a small set of such 2D scans does not uniquely specify f(x,y,x',y'); correlations in planes other than those measured are unknown. We have developed Monte-Carlo methods and formulated physically-motivated constraints to synthesize a ''reasonable'' set of particles having 2D projectional densities consistent with the experimental data. Such a set may be used to initialize simulations of the downstream beam. The methods and their performance on model problems are described.
Date: February 20, 2002
Creator: Friedman, A.; Grote, D. P.; Celata, C. M. & Staples, J. W.
Partner: UNT Libraries Government Documents Department

Effect of focusing field nonlinearities in MBE-4 on transverse beam dynamics

Description: A particle simulation code was used to study the effect on transverse beam dynamics of nonlinearities of the focusing field in a linear accelerator transporting a multiple beam array. Nonlinear field strengths for various multiple-beam design geometries were calculated by relaxation codes for use in the simulation calculation. Nonlinearities due to asymmetry of the electrode array with respect to a single beam were found to be negligible. Electrode end effect nonlinearities led to emittance growth for off-axis beams, though for the geometry of MBE-4, this was negligible. For misaligned beams, a dodecapole field caused significant emittance growth. This was not seen in single particle tracking calculations. Fields due to induced charge on the electrodes can reduce this effect, or the dodecapole field can be eliminated by proper choice of the electrode radius.
Date: May 1, 1985
Creator: Celata, C.M.; Brady, V.O.; Laslett, L.J.; Smith, L. & Haber, I.
Partner: UNT Libraries Government Documents Department

Heavy-ion fusion driver research at Berkeley and Livermore

Description: The Department of Energy is restructuring the U.S. fusion program to place a greater emphasis on science. As a result, we will not build the ILSE or Elise heavy ion fusion (HIF) facilities described in 1992 and 1994 conferences. Instead we are performing smaller experiments to address important scientific questions. Accelerator technology for HIF is similar to that for other applications such as high energy physics and nuclear physics. The beam physics, however, differs from the physics encountered in most accelerators, where the pressure arising from the beam temperature (emittance) is the dominant factor determining beam size and focusing system design. In HIF, space charge is the dominant feature, leading us into a parameter regime where.the beam plasma frequency becomes comparable to the betatron frequency. Our experiments address the physics of non-neutral plasmas in this novel regime. Because the beam plasma frequency is low, Particle-in-cell (PIC) simulations provide a good description of most of our experiments. Accelerators for HIF consist of several subsystems: ion sources, injectors, matching sections, combiners, acceleration sections with electric and magnetic focusing, beam compression and bending sections, and a system to focus the beams onto the target. We are currently assembling or performing experiments to address the physics of all these subsystems. This paper will discuss experiments in injection, combining, and bending.
Date: August 1, 1996
Creator: Seidl, P.; Bangerter, R. & Celata, C.M.
Partner: UNT Libraries Government Documents Department

A new intense neutron generator and high-resolution detector for well logging applications

Description: Advances in both ion source and gamma-ray detector technology at LBNL are being used to develop a new high-sensitivity neutron logging instrument. Up to 37 mA of current per 10-20 {mu}s pulse, 80-95% D{sup +}, has been produced by a 2 inch diameter pulsed multicusp ion source. A D-T neutron flux of 10{sup 9}-10{sup 10} n/s is projected from this data. CdZnTe is being developed as a possible gamma-ray detector because of its potential for good energy resolution and efficiency, and ability to operate at room temperature. 3-D time-dependent Monte Carlo calculations show the utility of this system for locating contaminants, especially chlorine-containing solvents, at remediation sites.
Date: October 1, 1996
Creator: Celata, C.M.; Amman, M. & Donahue, R.
Partner: UNT Libraries Government Documents Department

Effect of induced charge at boundaries on transverse dynamics of a space-charge-dominated beam

Description: A particle simulation code has been used to study the effect of transverse beam dynamics of charge induced on focusing electrodes. A linear transport system was assumed. The initial particle distribution was taken to be that of a uniform elliptical beam with a Gaussian velocity distribution. For misaligned, highly space-charge-dominated beams (betatron phase advance per lattice period less than or equal to 10/sup 0/), a large oscillation of the rms emittance occurred in a beat pattern. Linearized Vlasov analysis shows the oscillation to be a sextupole oscillation, driven by the beam coherent betatron motion. Emittance growth accompanied the oscillation. Preliminary experimental results from the Single Beam Transport Experiment (SBTE) are consistent with the code results. Addition of a dodecapole nonlinearity to the computational focusing field greatly reduces the oscillation amplitude.
Date: May 1, 1985
Creator: Celata, C.M.; Haber, I.; Laslett, L.J.; Smith, L. & Tiefenback, M.G.
Partner: UNT Libraries Government Documents Department

Particle-in-Cell Calculationsof the Electron Cloud in the ILCPositron Damping Ring Wigglers

Description: The self-consistent code suite WARP-POSINST is being used to study electron cloud effects in the ILC positron damping ring wiggler. WARP is a parallelized, 3D particle-in-cell code which is fully self-consistent for all species. The POSINST models for the production of photoelectrons and secondary electrons are used to calculate electron creation. Mesh refinement and a moving reference frame for the calculation will be used to reduce the computer time needed by several orders of magnitude. We present preliminary results for cloud buildup showing 3D electron effects at the nulls of the vertical wiggler field. First results from a benchmark of WARP-POSINST vs. POSINST are also discussed.
Date: July 1, 2007
Creator: Celata, C.M.; Furman, M.A.; Vay, J.-L. & Grote, D.P.
Partner: UNT Libraries Government Documents Department

Electron Cloud Cyclotron Resonances in the Presence of a Short-bunch-length Relativistic Beam

Description: Computer simulations using the 2D code"POSINST" were used to study the formation of the electron cloud in the wiggler section of the positron damping ring of the International Linear Collider. In order to simulate an x-y slice of the wiggler (i.e., a slice perpendicular to the beam velocity), each simulation assumed a constant vertical magnetic field. At values of the magnetic field where the cyclotron frequency was an integral multiple of the bunch frequency, and where the field strength was less than approximately 0.6 T, equilibrium average electron densities were up to three times the density found at other neighboring field values. Effects of this resonance between the bunch and cyclotron frequency are expected to be non-negligible when the beam bunch length is much less than the product of the electron cyclotron period and the beam velocity, for a beam moving at v~;;c. Details of the dynamics of the resonance are described.
Date: September 2, 2008
Creator: Celata, C. M.; Furman, Miguel A.; Vay, J.-L. & Yu, Jennifer W.
Partner: UNT Libraries Government Documents Department

Monte Carlo simulations of neutron well-logging in granite and sand to detect water and trichloroethane (TCA)

Description: The Monte Carlo code MCNP is used in simulations of neutron well logging in granite to detect water and TCA (C{sub 2}H{sub 3}Cl{sub 3}), a common ground contaminant, in fractures of 1 cm and 1 mm thickness at various distances and orientations. Also simulated is neutron well logging in wet sand to detect TCA and lead (Pb) at various uniform concentrations. The {sup 3}H(d,n) (DT) and{sup 2}H(d,n) (DD) neutron producing reactions are used in the simulations to assess the relative performance of each. Simulations are also performed to determine the efficiency of several detector materials such as CdZnTe, Ge and NaI as a function of photon energy. Results indicate that, by examining the signal from the 6.11 MeV gamma from the thermal neutron capture of Cl in TCA, trace amounts (few ppm) are detectable in saline free media. Water and TCA filled fractures are also detectable. These results are summarized in Tables 7--21. Motivation for this work is based on the need for detection of trace environmental pollutants as well as possible fracture characterization of geologic media.
Date: January 1, 1998
Creator: Hua, D.D.; Donahue, R.J.; Celata, C.M. & Greenspan, E.
Partner: UNT Libraries Government Documents Department

Use of projectional phase space data to infer a 4D particle distribution

Description: We consider beams which are described by a 4D transverse distribution f(x,y,x{prime},y{prime}), where x{prime} {triple_bond} p{sub x}/p{sub z} and z is the axial coordinate. A two-slit scanner is commonly employed to measure, over a sequence of shots, a 2D projection of such a beam's phase space, e.g., f(x,x{prime}). Another scanner might yield f(y,y{prime}) or, using crossed slits, f(x,y). A small set of such 2D scans does not uniquely specify f(x,y,x{prime},y{prime}). We have developed ''tomographic'' techniques to synthesize a ''reasonable'' set of particles in a 4D phase space having 2D densities consistent with the experimental data. These techniques are described in a separate document [A. Friedman, et. al., submitted to Phys. Rev. ST-AB, 2002]. Here we briefly summarize one method and describe progress in validating it, using simulations of the High Current Experiment at Lawrence Berkeley National Laboratory.
Date: May 20, 2002
Creator: Friedman, A.; Grote, D.P.; Celata, C.M. & Staples, J.W.
Partner: UNT Libraries Government Documents Department

The Dynamic Aperture of an Electrostatic Quadrupole Lattice

Description: In heavy-ion-driven inertial fusion accelerator concepts, dynamic aperture is important to the cost of the accelerator, most especially for designs which envision multibeam linacs, where extra clearance for each beam greatly enlarges the transverse scale of the machine. In many designs the low-energy end of such an accelerator uses electrostatic quadrupole focusing. The dynamic aperture of such a lattice has been investigated here for intense, space-charge-dominated ion beams using the 2-D transverse slice version of the 3-D particle-in-cell simulation code WARP. The representation of the focusing field used is a 3-D solution of the Laplace equation for the biased focusing elements, as opposed to previous calculations, which used a less-accurate multipole approximation. 80-85% radial filling of the aperture is found to be possible. Results from the simulations, as well as corroborating data from the High Current Experiment at LBNL, are presented.
Date: May 1, 2005
Creator: Celata, C.M.; Bieniosek, F.M.; Prost, L.; Seidl, P.A.; Friedman,A. & Grote, D.P.
Partner: UNT Libraries Government Documents Department

Electron Cyclotron Resonances in Electron Cloud Dynamics

Description: We report a previously unknown resonance for electron cloud dynamics. The 2D simulation code"POSINST" was used to study the electron cloud buildup at different z positions in the International Linear Collider positron damping ring wiggler. An electron equilibrium density enhancement of up to a factor of 3 was found at magnetic field values for which the bunch frequency is an integral multiple of the electron cyclotron frequency. At low magnetic fields the effects of the resonance are prominent, but when B exceeds ~;;(2 pi mec/(elb)), with lb = bunch length, effects of the resonance disappear. Thus short bunches and low B fields are required for observing the effect. The reason for the B field dependence, an explanation of the dynamics, and the results of the 2D simulations and of a single-particle tracking code used to elucidate details of the dynamics are discussed.
Date: June 25, 2008
Creator: Celata, Christine; Celata, C.M.; Furman, Miguel A.; Vay, J.-L. & Yu, Jennifer W.
Partner: UNT Libraries Government Documents Department

Particle-in-cell simulations of the dynamic Aperture of the HCX

Description: The HIF-VNL High Current Experiment (HCX) [1] is exploring transport issues such as dynamic aperture, effects of quadrupole rotation, and the effects on the beam of non-ideal distribution function, mismatch, and electrons, using one driver-scale 0.2 microcoulomb/m, 2-10 microsecond coasting K{sup +} beam. 2D and 3D simulations are being done, using the particle-in-cell (PIC) code WARP to study these phenomena. We present results which predict that the dynamic aperture in the electrostatic focusing transport section will be set by particle loss.
Date: May 1, 2002
Creator: Celata, C.M.; Friedman, A.F.; Grote, D.P.; Haber, I. & Henestroza, E.
Partner: UNT Libraries Government Documents Department

Design choices for the integrated beam experiment (IBX)

Description: Over the next three years the research program of the Heavy Ion Fusion Virtual National Laboratory (HIF-VNL), a collaboration among LBNL, LLNL, and PPPL, is focused on separate scientific experiments in the injection, transport and focusing of intense heavy ion beams at currents from 100 mA to 1 A. As a next major step in the HIF-VNL program, they aim for a complete ''source-to-target'' experiment, the Integrated Beam Experiment (IBX). By combining the experience gained in the current separate beam experiments IBX would allow the integrated scientific study of the evolution of a high current ({approx}1 A) single heavy ion beam through all sections of a possible heavy ion fusion accelerator: the injection, acceleration, compression, and beam focusing. This paper describes the main parameters and technology choices of the proposed IBX experiment. IBX will accelerate singly charged potassium or argon ion beams up to 10 MeV final energy and a longitudinal beam compression ratio of 10, resulting in a beam current at the target of more than 10 Amperes. The different accelerator cell design options are described in detail, in particular the induction core modules incorporating either room temperature pulsed focusing-magnets or superconducting magnets.
Date: May 2003
Creator: Leitner, M. A.; Celata, C. M.; Lee, E. P.; Logan, B. G.; Sabbi, G.; Waldron, W. L. et al.
Partner: UNT Libraries Government Documents Department

A Moment Equation Approach to a Muon Collider Cooling Lattice

Description: Equations are derived which describe the evolution of the second order moments of the beam distribution function in the ionization cooling section of a muon collider. Ionization energy loss, multiple scattering, and magnetic fields have been included, but forces are linearized. A computer code using the equations agrees well with tracking calculations. The code is extremely fast, and can be used for preliminary design, where such issues as beam halo, which must be explored using a tracking code, are not the focus.
Date: June 1, 1998
Creator: Celata, C.M.; Sessler, A.M.; Lee, P.B.; Shadwick, B.A. & Wurtele, J.S.
Partner: UNT Libraries Government Documents Department

Transverse combining of 4 beams in MBE-4

Description: Transverse beam combining is a cost-saving optio employed in many designs for induction linac heavy ion fusion drivers. But resultant transverse emittance increase, due predominantly to anharmonic space charoe forces, must be kept minimal so as not to sacrifice focusability at the target. A prototype combining experiment has been built, using the MBE-4 experiment. Four sources produce four 4 mA Cs{sup +} beams at 200 keV. The ion sources are angled toward each other, so that beams converge. Focusing upstream of the merge consists of 4 quadrupoles and a final combined-function element (quadrupole & dipole). All lattice elements are electrostatic. Due to the small distance between beams at the last element ({approximately} 2 mm), the electrodes here are a cage of small wires, each at different voltage. The beams emerge into the 30 period transport lattice of MBE-4 where emittance growth due to merging, as well as the subsequent evolution of the distribution function, can be diagnosed. The combiner design, simulation predictions, and preliminary results from the experiment are presented.
Date: May 1, 1995
Creator: Celata, C.M.; Chupp, W.; Faltens, A.; Fawley, W.M.; Ghiorso, W.; Hahn, K.D. et al.
Partner: UNT Libraries Government Documents Department

Technology choices for the Integrated Beam Experiment (IBX)

Description: Over the next three years the research program of the Heavy Ion Fusion Virtual National Laboratory (HIF-VNL), a collaboration among LBNL, LLNL, and PPPL, is focused on separate scientific experiments in the injection, transport and focusing of intense heavy ion beams at currents from 100 mA to 1 A. As a next major step in the HIF-VNL program, we aim for a complete ''source-to-target'' experiment, the Integrated Beam Experiment (IBX). By combining the experience gained in the current separate beam experiments IBX would allow the integrated scientific study of the evolution of a single heavy ion beam at high current ({approx}1 A) through all sections of a possible heavy ion fusion accelerator: the injection, acceleration, compression, and beam focusing. This paper describes the main parameters and technology choices of the planned IBX experiment. IBX will accelerate singly charged potassium or argon ion beams up to 10 MeV final energy and a longitudinal beam compression ratio of 10, resulting in a beam current at target of more than 10 Amperes. Different accelerator cell design options are described in detail: Induction cores incorporating either room temperature pulsed focusing-magnets or superconducting magnets.
Date: October 31, 2002
Creator: Leitner, M.A.; Celata, C.M.; Lee, E.P.; Sabbi, G.; Waldron, W.L. & Barnard, J.J.
Partner: UNT Libraries Government Documents Department

Particle-in-cell simulations of the high current experiment

Description: The particle-in-cell code WARP has been used to simulate beam dynamics for the intense ion beam of the High Current Experiment. First a study was done of the dynamic aperture of the alternating-gradient electrostatic quadrupole lattice of the experiment, including nonlinearity due to image forces and imperfections of the focusing lattice field. It was found that particle loss, rather than emittance growth, determined the usable aperture. Simulations of transport in the High Current Experiment were then performed, and the results compared to measured data. We present the results of both of these studies.
Date: May 1, 2003
Creator: Celata, C.M.; Bieniosek, F.M.; Prost, L.; Seidl, P.A.; Friedman, A. & Grote, D.P.
Partner: UNT Libraries Government Documents Department

Preliminary design of a 10 MV ion accelerator

Description: At the low energy end of an induction linac HIF driver the beam current is limited by our ability to control space charge by a focusing system. As a consequence, HIF induction accelerator designs feature simultaneous acceleration of many beams in parallel within a single accelerator structure. As the speed of the beams increase, the focusing system changes from electrostatic to magnetic quadrupoles with a corresponding increase in the maximum allowable current. At that point the beams are merged thereby decreasing the cost of the subsequent accelerator structure. The LBL group is developing an experiment to study the physics of merging and of focusing ion beams. In the design, parallel beams of ions (C/sup +/, Al/sup +/, or Al/sup + +/) are accelerated to several MV and merged transversely. The merged beams are then further accelerated and the growth in transverse and longitudinal emittance is determined for comparison with theory. The apparatus will then be used to study the problems associated with focusing ion beams to a small spot. Details of the accelerator design and considerations of the physics of combining beams are presented.
Date: June 1, 1986
Creator: Fessenden, T.J.; Celata, C.M.; Faltens, A.; Henderson, T.; Judd, D.L.; Keefe, D. et al.
Partner: UNT Libraries Government Documents Department

Toward fully self-consistent simulation of the interaction of E-Clouds and beams with WARP-POSINST

Description: To predict the evolution of electron clouds and their effect on the beam, the high energy physics community has relied so far on the complementary use of 'buildup' and 'single/multi-bunch instability' reduced descriptions. The former describes the evolution of electron clouds at a given location in the ring, or 'station', under the influence of prescribed beams and external fields [1], while the latter (sometimes also referred as the 'quasi-static' approximation [2]) follows the interaction between the beams and the electron clouds around the accelerator with prescribed initial distributions of electrons, assumed to be concentrated at a number of discrete 'stations' around the ring. Examples of single bunch instability codes include HEADTAIL [3], QuickPIC [4, 5], and PEHTS [6]. By contrast, a fully self-consistent approach, in which both the electron cloud and beam distributions evolve simultaneously under their mutual influence without any restriction on their relative motion, is required for modeling the interaction of high-intensity beams with electron clouds for heavy-ion beam-driven fusion and warm-dense matter science. This community has relied on the use of Particle-In-Cell (PIC) methods through the development and use of the WARP-POSINST code suite [1, 7, 8]. The development of novel numerical techniques (including adaptive mesh refinement, and a new 'drift-Lorentz' particle mover for tracking charged particles in magnetic fields using large time steps) has enabled the first application of WARP-POSINST to the fully self-consistent modeling of beams and electron clouds in high energy accelerators [9], albeit for only a few betatron oscillations. It was recently observed [10] that there exists a preferred frame of reference which minimizes the number of computer operations needed to simulate the interaction of relativistic objects. This opens the possibility of reducing the cost of fully self-consistent simulations for the interaction of ultrarelativistic beams with electron cloud by orders of magnitude. The ...
Date: April 9, 2012
Creator: LLNL; Furman, M.A.; Furman, M.A.; Celata, C.M.; Sonnad, K.; Venturini, M. et al.
Partner: UNT Libraries Government Documents Department

Self-Consistent 3D Modeling of Electron Cloud Dynamics and Beam Response

Description: We present recent advances in the modeling of beam electron-cloud dynamics, including surface effects such as secondary electron emission, gas desorption, etc, and volumetric effects such as ionization of residual gas and charge-exchange reactions. Simulations for the HCX facility with the code WARP/POSINST will be described and their validity demonstrated by benchmarks against measurements. The code models a wide range of physical processes and uses a number of novel techniques, including a large-timestep electron mover that smoothly interpolates between direct orbit calculation and guiding-center drift equations, and a new computational technique, based on a Lorentz transformation to a moving frame, that allows the cost of a fully 3D simulation to be reduced to that of a quasi-static approximation.
Date: April 2, 2007
Creator: Furman, Miguel; Furman, M.A.; Celata, C.M.; Kireeff-Covo, M.; Sonnad, K.G.; Vay, J.-L. et al.
Partner: UNT Libraries Government Documents Department

Cyclotron Resonances in Electron Cloud Dynamics

Description: A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where lb<< 2pi c/omega c (with lb = bunch length, omega c = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the electron cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the density is up to a factor ~;;3, and the spatial distribution of the electrons is broader near resonances, lacking the well-defined vertical density"stripes" found for non-resonant cases. Simulations with the 2D computer code POSINST, as well as a single-particle tracking code, were used to elucidate the physics of the dynamics. The existence of the resonances has been confirmed in experiments at PEP-II. The resonances are expected to affect the electron cloud dynamics in the fringe fields of conventional lattice magnets and in wigglers, where the magnetic fields are low. Results of the simulations and experimental observations, the reason for the bunch-length dependence, and details of the dynamics are discussed here.
Date: April 29, 2009
Creator: Celata, C. M.; Furman, Miguel A.; Vay, J.-L.; Ng, J. S.T.; Grote, D. P.; Pivi, M. T. F. et al.
Partner: UNT Libraries Government Documents Department

Beam Energy Scaling of Ion-Induced Electron Yield from K+ Impact on Stainless Steel

Description: Electron clouds limit the performance of many major accelerators and storage rings. Significant quantities of electrons result when halo ions are lost to beam tubes, generating gas which can be ionized and ion-induced electrons that can multiply and accumulate, causing degradation or loss of the ion beam. In order to understand the physical mechanisms of ion-induced electron production, experiments studied the impact of 50 to 400 keV K{sup +} ions on stainless steel surfaces near grazing incidence, using the 500 kV Ion Source Test Stand (STS-500) at LLNL. The experimental electron yield scales with the electronic component (dE{sub e}/dx) of the stopping power and its angular dependence does not follow l/cos({theta}). A theoretical model is developed, using TRIM code to evaluate dE{sub e}/dx at several depths in the target, to estimate the electron yield, which is compared with the experimental results. The experiment extends the range of energy from previous works and the model reproduces the angular dependence and magnitude of the electron yield.
Date: March 6, 2006
Creator: Covo, M K; Molvik, A; Friedman, A; Westenskow, G; Barnard, J J; Cohen, R et al.
Partner: UNT Libraries Government Documents Department