The Atlas High-Energy Density Physics Project Davis, Harold A.; Keinigs, Rhon K.; Anderson, Wallace E. ...
Japanese Journal of Applied Physics,
02/2001, Letnik:
40, Številka:
2S
Journal Article
Recenzirano
Atlas is a pulsed-power facility under development at Los Alamos National Laboratory to drive high-energy density experiments. Atlas will be operational in the summer of 2000 and is optimized for the ...study of dynamic material properties, hydrodynamics, and dense plasmas under extreme conditions. Atlas is designed to implode heavy-liner loads in a z-pinch configuration. The peak current of 30 MA is delivered in 4 µs. A typical Atlas liner is a 47-gram-aluminum cylinder with ∼4-cm radius and 4-cm length. Three to five MJ of kinetic energy will be delivered to the load. Using composite layers and a variety of interior target designs, a wide variety of experiments in ∼cm
3
volumes will be performed. Atlas applications, machine design, and the status of the project are reviewed.
Summary form only given. The first experiment to implode a solid liner under driving currents comparable to full ATLAS currents was recently completed using an explosive magnetic generator (EMG) ...designed and built at VNIIEF. Diagnostics, including faraday rotation coils, VISAR, optical pins, and inductive magnetic probes, were jointly fielded in a collaboration between LANL and VNIIEF. We present one- and two-dimensional MHD calculations that were done in support of this experiment. The calculations are consistent with data, but demonstrate a sensitivity to conductivity models. Both data and calculations concur that the final liner velocity exceeded 12 km/s and that the inner surface of the liner was still intact at the time of impact with a Central Measuring Unit. The calculations showed a high level of fluid Rayleigh-Taylor disruption on the outer surface of the liner. The occurrence of this level of instability had little effect on the quality of the inner surface. The calculations indicated that most of the liner had melted before impact, but that the region near the inner surface should still be unmelted. Detailed comparisons between data and calculations will be presented.
Summary form only given. One experimental campaign planned for the pulse power facility, Atlas, will be devoted to the investigation of strongly-coupled plasma (SCP) effects on transport phenomena ...and equations-of-state in high-Z materials. Methods for forming strongly coupled plasmas using the pulsed-power facility, Atlas, are currently under investigation. For SCP experiments being planned, a metal plasma (/spl rho///spl rho//sup 0//spl sim/0.1, and T/spl sim/1-2 eV) imbedded in gas or foam (/spl rho//spl sim/.05 /spl rho//sub metal/, T/spl sim/0.5 eV) can produce initial values of /spl Gamma/ (coupling parameter) between 2-20. One approach to forming a plasma with the desired properties involves using an auxiliary capacitor bank to ohmically heat a thin metal shell to vaporization. The expansion of the plasma is impeded by the imbedding gas. Both one and two-dimensional magnetohydrodynamic models are being employed to characterize the plasma and determine the tamping conditions required for its confinement. Results for a titanium plasma, the confinement dynamics for this system, and values obtained for /spl Gamma/ will be presented. Means for experimentally diagnosing such plasmas will also be discussed.
Theory and simulation of liner implosions at thirty megaamperes Keinigs, R.K.; Trainer, R.J.; Atchison, W.L. ...
25th Anniversary, IEEE Conference Record - Abstracts. 1998 IEEE International Conference on Plasma Science (Cat. No.98CH36221),
1998
Conference Proceeding
Summary form only given. The next generation of high current, pulsed-power machine to be built is Atlas. Atlas is a 24 MJ, pulsed power facility being constructed at Los Alamos National Laboratory in ...support of the Department of Energy's stockpile stewardship program. It is projected to be operational in the year 2000, and capable of providing 100 shots per year. In support of stockpile stewardship Atlas will be used to investigate states of matter under extreme conditions. Included in these investigations will be equation-of-state (EOS) experiments performed at pressures exceeding 10 megabars. Hugoniot measurements at these pressures, and in convergent geometry represent an exciting challenge for the experimentalist. Results from one-dimensional simulations indicate that pressures exceeding ten megabars can be generated when an aluminum/tungsten liner collides with a hollow tungsten target placed at a radius of approximately 1 cm. However, in order to accurately infer a hugoniot from the measurements will require that the impactor be relatively flat and solid over a sufficiently large surface area. Thus, success will rely upon our ability to stably implode thin, composite-material liners to velocities greater than 10 km/ms, with a portion of the liner remaining in the solid phase. At peak currents of 27.5 MA much of the liner is melted at early times within the implosion, making it susceptible to growth of Rayleigh-Taylor instabilities. In addition to these instabilities feeding through to the inner or outer tungsten surfaces, bowing of this surface may arise due to interaction with the angled glide plane. In this poster we present results of two-dimensional MHD simulations that incorporate these effects on liner integrity. Theoretical predictions for growth rates in the presence of strength in the materials will also be presented.
The microstructural distribution and nature of damage from three different cylindrically convergent spallation experiments performed on the pulsed power machine named Atlas are presented. ...Longitudinal momentum trapping was used to minimize the influence of release waves and thereby decrease the dimensionality of the experiments. Two of the experiments involved soft capture of the spalled piece. The material used is a proprietary directionally cast Al alloy with a mostly equiaxed grain morphology and essentially random texture in the region of spallation. The damage was most distributed in the lowest impact velocity shot and became progressively more narrow with increasing impact velocity. The effectiveness of the momentum trap design increased with increasing impact velocity. The influence of the material texture on the loading geometry and damage is discussed.
Material science experiments on the Atlas facility Keinigs, R.K.; Atchison, W.L.; Anderson, W.E. ...
PPPS-2001 Pulsed Power Plasma Science 2001. 28th IEEE International Conference on Plasma Science and 13th IEEE International Pulsed Power Conference. Digest of Papers (Cat. No.01CH37251),
2001, Letnik:
1
Conference Proceeding
Odprti dostop
Three material properties experiments that are to be performed on the Atlas pulsed power facility are described; friction at sliding metal interfaces, spallation and damage in convergent geometry, ...and plastic flow at high strain and high strain rate. Construction of this facility has been completed and experiments in high energy density hydrodynamics and material dynamics will begin in 2001.
High gradient issues in a two-beam accelerator Faehl, R. J.; Keinigs, R. K.; Sheppard, M. G.
1990 8th International Conference on High-Power Particle Beams,
1990-July
Conference Proceeding
Injection of modulated intense relativistic electron beams into resonant structures can result in highly efficient transfer of beam energy into electromagnetic fields. We have performed ...electromagnetic PIC simulations of a simple, but representative two-beam accelerator configuration to understand the self-consistent dynamics which affect accelerator performance. Among the issues examined are the effects of the impedances of the primary and secondary beams.
An overview of the Atlas pulsed-power systems Parsons, W.M.; Baldwin, C.C.; Ballard, E.O. ...
Digest of Technical Papers. 11th IEEE International Pulsed Power Conference (Cat. No.97CH36127),
1997, Letnik:
1
Conference Proceeding
Odprti dostop
Atlas is a facility being designed at Los Alamos National Laboratory (LANL) to perform high energy-density experiments in support of weapon-physics and basic-research programs. It is designed to be ...an international user facility, providing experimental opportunities to researchers from national laboratories and academic institutions. For hydrodynamic experiments, it will be capable of achieving pressures exceeding 20-Mbar in a several cm/sup 3/ volume. With the development of a suitable opening switch, it will also be capable of producing soft X-rays. The 36 MJ capacitor bank will consist of 240 kV Marx modules arranged around a central target chamber. The Marx modules will be discharged through vertical triplate transmission lines to a parallel plate collector inside the target chamber. The capacitor bank is designed to deliver a peak current of 45 to 50 MA with a 4- to 5-/spl mu/s risetime. The Marx modules are designed to be reconfigured to a 480 kV configuration for opening switch development. Predicted performance with a typical load is presented. Descriptions of the major subsystems are also presented.
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