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Optimization of the particle pusher in a diode simulation code

Description: The particle pusher in Sandia's particle-in-cell diode simulation code has been rewritten to reduce the required run time of a typical simulation. The resulting new version of the code has been found to run up to three times as fast as the original with comparable accuracy. The cost of this optimization was an increase in storage requirements of about 15%. The new version has also been written to run efficiently on a CRAY-1 computing system. Steps taken to affect this reduced run time are described. Various test cases are detailed.
Date: September 1, 1979
Creator: Theimer, M.M. & Quintenz, J.P.
Partner: UNT Libraries Government Documents Department

GEPOIS: a two dimensional nonuniform mesh Poisson solver

Description: A computer code is described which solves Poisson's equation for the electric potential over a two dimensional cylindrical (r,z) nonuniform mesh which can contain internal electrodes. Poisson's equation is solved over a given region subject to a specified charge distribution with either Neumann or Dirichlet perimeter boundary conditions and with Dirichlet boundary conditions on internal surfaces. The static electric field is also computed over the region with special care given to normal electric field components at boundary surfaces.
Date: June 1, 1979
Creator: Quintenz, J.P. & Freeman, J.R.
Partner: UNT Libraries Government Documents Department

Progress in the pulsed power Inertial Confinement Fusion program

Description: Pulsed power accelerators are being used in Inertial Confinement Fusion (ICF) research. In order to achieve our goal of a fusion yield in the range of 200 - 1000 MJ from radiation-driven fusion capsules, it is generally believed that {approx}10 MJ of driver energy must be deposited within the ICF target in order to deposit {approx}1 MJ of radiation energy in the fusion capsule. Pulsed power represents an efficient technology for producing both these energies and these radiation environments in the required short pulses (few tens of ns). Two possible approaches are being developed to utilize pulsed power accelerators in this effort: intense beams of light ions and z- pinches. This paper describes recent progress in both approaches. Over the past several years, experiments have successfully answered many questions critical to ion target design. Increasing the ion beam power and intensity are our next objectives. Last year, the Particle Beam Fusion Accelerator H (PBFA II) was modified to generate ion beams in a geometry that will be required for high yield applications. This 2048 modification has resulted in the production of the highest power ion beam to be accelerated from an extraction ion diode. We are also evaluating fast magnetically-driven implosions (z-pinches) as platforms for ICF ablator physics and EOS experiments. Z-pinch implosions driven by the 20 TW Saturn accelerator have efficiently produced high x- ray power (> 75 TW) and energy (> 400 kJ). Containing these x-ray sources within a hohlraum produces a unique large volume (> 6000 mm{sup 3}), long lived (>20 ns) radiation environment. In addition to studying fundamental ICF capsule physics, there are several concepts for driving ICF capsules with these x-ray sources. Progress in increasing the x-ray power on the Saturn accelerator and promise of further increases on the higher power PBFA II accelerator will ...
Date: December 1, 1996
Creator: Quintenz, J.P.; Matzen, M.K. & Mehlhorn, T.A.
Partner: UNT Libraries Government Documents Department

Pulsed Power Fusion Program update

Description: The US Department of Energy has supported a substantial research program in Inertial Confinement Fusion (ICF) since the early 1970s. Over the course of the ensuing 25 years, pulsed power energy, efficiency, and relatively low cost of the technology when compared to the mainline ICF approach involving large glass lasers. These compelling advantages of pulsed power, however, have been tempered with the difficulty that has been encountered in concentrating the energy in space and time to create the high energy and power density required to achieve temperatures useful in indirect drive ICF. Since the Beams `96 meeting two years ago, the situation has changed dramatically and extremely high x-ray power ({approximately}290 TW) and energy ({approximately}1.8 MJ) have been produced in fast x-pinch implosions on the Z accelerator. These sources have been utilized to heat hohlraums to >150 eV and have opened the door to important ICF capsule experiments.
Date: June 1, 1998
Creator: Quintenz, J.P.; Adams, R.G. & Allshouse, G.O.
Partner: UNT Libraries Government Documents Department

Progress in pulsed power fusion

Description: Pulsed power offers and efficient, high energy, economical source of x-rays for inertial confinement fusion (ICF) research. We are pursuing two main approaches to ICF driven with pulsed power accelerators: intense light ion beams and z-pinches. This paper describes recent progress in each approach and plans for future development.
Date: July 1, 1996
Creator: Quintenz, J.P.; Adams, R.G. & Bailey, J.E.
Partner: UNT Libraries Government Documents Department

Relativistic electron beam energy deposition in thin gold and aluminum targets

Description: Relativistic electron beam (REB) energy deposition in thin gold and aluminum targets has been investigated experimentally using radiation temperature measurements in the soft x-ray, vacuum ultraviolet (XUV) and optical spectral regions on two different particle accelerators. Energy deposition measurements were compared with numerical calculations utilizing particle-in-cell (PIC) diode codes, condensed history Monte-Carlo codes, and coupled radiation-hydrodynamic codes. The specific power deposited (i.e., power deposited/unit mass) was observed to be greater than that due to an average electron making a single pass through a thin target (6.4 ..mu..m thick gold foil on the Hydra accelerator and 38 and 6 ..mu..m thick aluminum foils on the Proto I accelerator). Self-magnetic field effects were primarily responsible for deposition enhancement in 6.4 ..mu..m gold foils on the Hydra accelerator (..nu../..gamma.. approx. = 2.5). Reduction of electron scattering with aluminum foils on Proto I where ..nu../..gamma.. approx. = 1 led to deposition enhancement due to both self electric and magnetic fields.
Date: January 1, 1979
Creator: Burns, E.J.T.; Goldstein, S.A.; Halbleib, J.A.; Mix, L.P.; Olsen, J.N.; Poukey, J.W. et al.
Partner: UNT Libraries Government Documents Department

Ion beam generation and focusing on PBFA (Particle Beam Fusion Accelerator) II

Description: During the past year we have succeeded in obtaining a 5 TW/cm{sup 2} proton focus on Sandia National Laboratories' Particle Beam Fusion Accelerator (PBFA) II. This has allowed us to shift our experimental emphasis to the implementation of an improved ion diode geometry for higher voltage operation, full azimuthal beam characterization, and especially lithium ion source experiments. We have made significant progress in each of these areas during the past year, demonstrating 10 MV diode operation, {plus minus}10% azimuthal beam symmetry, and promising initial results from lithium ion source experiments. 8 refs., 6 figs.
Date: January 1, 1990
Creator: Stinnett, R.W.; Bailey, J.E.; Bieg, K.W.; Coats, R.S.; Chandler, G.; Derzon, M.S. et al.
Partner: UNT Libraries Government Documents Department

Light ion sources and target results on PBFA II (Particle Beam Fusion Accelerator II)

Description: Advances in ion beam theory, diagnostics, and experiments in the past two years have enabled efficient generation of intense proton beams on PBFA II, and focusing of the beam power to 5.4 TW/cm{sup 2} on a 6-mm-diameter target. Target experiments have been started with the intense proton beams, since the range of protons at 4--5 MeV is equivalent to that of lithium at 30 MeV. Three series of experiments have been conducted using planar, conical, and cylindrical targets. These tests have provided information on ion beam power density, uniformity, and energy deposition. In order to increase the power density substantially for target implosion experiments, we are now concentrating on development of high voltage lithium ion beams. 10 refs., 13 figs.
Date: January 1, 1990
Creator: Cook, D.L.; Bailey, J.E.; Bieg, K.W.; Bloomquist, D.D.; Coats, R.S.; Chandler, G.C. et al.
Partner: UNT Libraries Government Documents Department

Z-Pinch Driven Inertial Confinement Fusion Target Physics Research at Sandia National Laboratories

Description: Three hohlraum concepts are being pursued at Sandia National Laboratories (SNL) to investigate the possibility of using pulsed power driven magnetic implosions (z-pinches) to drive high gain targets capable of yields in the range of 200-1000 MJ. This research is being conducted on SNL'S.Z facility that is capable of driving peak currents of 20 MA in z-pinch loads producing implosion velocities as high as 7.5X 107 cm/s, x-ray energies approaching 2 MJ, and x-ray powers exceeding 200 TW. This paper will discuss each of these hohlraum concepts and will overview the experiments that have been conducted on these systems to date.
Date: October 27, 1998
Creator: Alberts, T.E.; Asay, J.R.; Baca, P.M.; Baker, K.L.; Breeze, S.P.; Chandler, G.A. et al.
Partner: UNT Libraries Government Documents Department