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Data are presented describing refined simulations of perturbation growth in a three-layer cylindrical liner system tested with disk explosive magnetic flux compression generators (DEMGs) to study the strength properties of copper and polyethylene at shocklessly applied pressures of up to ~15 GPa. The calculated performance for the same liner system in the experiments to study the strength properties of copper at shockless loading of up to ~40-GPa pressures is presented. The feasibility of similar strength experiments with quasi-isentropic material compression to ~2000 GPa using DEMGs is demonstrated. Index Terms--Growth of initial perturbations, magnetic implosion, muitilayer liner systems, Rayleigh-Taylor instability, shear strength of materials, strain rate, 2-D computations.

Pulsed-power hydrodynamics (PPH) is an evolving application of low-impedance pulsed-power technology. PPH is particularly useful for the study of problems in advanced hydrodynamics, instabilities, turbulence, and material properties. PPH techniques provide a precisely characterized controllable environment at the currently achievable extremes of pressure and material velocity. The Atlas facility, which is designed and built by Los Alamos National Laboratory, is the world's first, and only, laboratory pulsed-power system designed specifically for this relatively new family of pulsed-power applications. Atlas joins a family of low-impedance high-current drivers around the world, which is advancing the field of PPH. The high-precision cylindrical magnetically imploded liner is the tool most frequently used to convert electromagnetic energy into the hydrodynamic (particle kinetic) energy needed to drive strong shocks, quasi-isentropic compression, or large-volume adiabatic compression for the experiments. At typical parameters, a 30-g 1-mm-thick liner with an initial radius of 5 cm and a moderate current of 20 MA can be accelerated to 7.5 km/s, producing megabar shocks in medium density targets. Velocities of up to 20 km/s and pressures of > 20 Mbar in high-density targets are possible. The first Arias liner implosion experiments were conducted in Los Alamos in September 2001. Sixteen experiments were conducted in the first year of operation before Arias was disassembled, moved to the Nevada Test Site (NTS), and recommissioned in 2005. The experimental program resumed at the NTS in July 2005. The first Atlas experiments at the NTS included two implosion dynamics experiments, two experiments exploring damage and material failure, a new advanced hydrodynamics series aimed at studying the behavior of particles of damaged material ejected from a free surface into a gas, and a series exploring friction at sliding interfaces under conditions of high normal pressure and high relative velocities. Longer term applications of PPH and the Atlas system include the study of material interfaces subjected to multimegagauss magnetic fields, material strength at high strain rate, the properties of strongly coupled plasmas, and the equation of state of materials at pressures approaching 10 Mbar. Index Terms--Capacitor banks, circuit model, damage, friction, high current, hydrodynamics, hydrodynamic simulation, liner implosion, material properties, pulsed-power, radiography, spall.

A very high-current liner implosion experiment was conducted, using an explosive magnetic-compression generator (EMG) to deliver a peak current of 102 [+ or -] 3 MA, to implode a 4.0-mm-thick aluminum liner. Analysis of experimental data showed that the inner surface of the liner had attained a velocity of between 6.8-8.4 km/s, consistent with detailed numerical calculations. Both calculations and data were consistent with a final liner state that was still substantially solid at target impact time and had a total kinetic energy of over 20 MJ. Index Terms--Electromagnetic flux generator, liners, MHD calculations.

Results of experiments conducted to characterize the performance of a surface tracking switch employing surface discharge phenomena as a high-performance, self-dosing, isolation switch for high-energy applications are described. These experiments, conducted under both dc and pulsed conditions, lead to a model of switch operation that enables the design of such switches for multi-megampere operation. This paper describes the successful implementation of a surface tracking switch as an operational component in several high-current pulsed power systems, and offers some insight into the operation of surface-tracking switches that may assist in future work to apply the technique as a triggered switch in very-high-energy and high-voltage systems. Index Terms--Pulsed power system switches, surface discharge, switch.

We discuss the design, fabrication, and operation of a liner implosion system at peak currents of 16 MA. Liners of 1100 aluminum, with initial length, radius, and thickness of 4 cm, 5 cm, and 1 mm, respectively, implode under the action of an axial current, rising in 8 [micro]s. Fields on conductor surfaces exceed 0.6 MG. Design and fabrication issues that were successfully addressed include: Pulsed Power--especially current joints at high magnetic fields and the possibility of electrical breakdown at connection of liner cassette insulator to bank insulation; Liner Physics--including the angle needed to maintain current contact between liner and glide-plane/electrode without jetting or buckling; Diagnostics--X-radiography through cassette insulator and outer conductor without shrapnel damage to film. Index Terms--Diagnostics, implosions, liners, megampere.

Magnetically imploded cylindrical metal shells (z-pinch liners) are attractive drivers for experiments exploring hydrodynamics and properties of materials at extreme conditions. As in all z-pinches, the outer surface of a liner is unstable to magneto Rayleigh-Taylor (RT) modes during acceleration, and large-scale distortion arising from RT modes could make such liners unuseable. On the other hand, material strength in the liner should, from first principles, reduce the growth rate of RT modes, and material strength can render some combinations of wavelength and amplitude analytically stable. A series of experiments has been conducted in which high-conductivity, soft, cylindrical aluminum liners were accelerated with 6-MA, 7-[micro]s rise-time driving currents. Small perturbations were machined into the outer surface of the liner and perturbation growth monitored. Two-dimensional magneto-hydrodynamic (2-D-MHD) calculations of the growth of the initial perturbations were in good agreement with experimentally observed perturbation growth through the entire course of the implosions. In general, for high-conductivity and soft materials, theory and simulation adequately predicted the behavior of magneto-RT modes in liners where elastic-plastic behavior applies. This is the first direct verification of the growth of magneto-RT in solids with strength known to the authors. Index Terms--Instabilities, liner, Rayleigh-Taylor.

Pulse power systems delivering in excess of 100 MJ represent one of the next major challenges to the community. While laboratory pulse power systems in this energy range are feasible, they represent very substantial investments of both time and resources. Prudence requires that fundamental proof of principle for the contemplated application be established before such massive resources are committed. Explosive pulse power systems using magnetic flux compression provide a direct path to such demonstrations. Furthermore, as energy requirements grow, they may represent the only affordable source of ultra-high energy environments. In this paper we report the results of an experimental test of a first generation disk generator system. Individual disk segments have been tested with framing camera diagnostics to evaluate overall performance dynamics and material, and fabrication failure points. In general no bulk failures were observed in several shots and the critical weld joints were seen to maintain integrity for at least 4 [[micro]seconds] after arrival of the detonation front. Single module pulse power experiments have been conducted at reduced initial current (1.5-2.0 MA) with a fixed inductance load of 0.22 nH. Index Terms - Disk explosive flux compressor, flux compression generators, high explosive pulsed power, imploding liners, solid liners.

Vladimir Konstantinovich Chernyshev, leader in magnetic flux compression technology, died of cancer in Moscow on 30 April 2005. His crowning achievements were magnetic flux compression generators that have reached performance levels unmatched by any other pulsed-power system in the world.

The design and first successful demonstration of an imploding solid liner with height to diameter ratio, radial convergence, and uniformity suitable for compressing a field reversed configuration is discussed. Radiographs indicated a very symmetric implosion with no instability growth, with ~13x radial compression of the inner liner surface prior to impacting a central measurement unit. The implosion kinetic energy was 1.5 megajoules, 34% of the capacitor stored energy of 4.4 megajoules. Index Terms--Capacitor bank, field reversed configuration, FRC, implosion, magnetized target fusion, megamp, MTF, radiography, solid liner.

In the last five years, a new application of high-performance pulsed power techniques within the Stockpile Stewardship Program has joined the traditional family of radiation source applications. This new application uses low-impedance, high-current drivers to produce high-energy density environments in materials for the study of material properties, instabilities, and hydrodynamics in complex geometries. The principle tool for producing high-energy density environments is the high-precision, magnetically imploded, near-solid density liner. The most attractive pulsed power system for driving such experiments is an ultrahigh current, low-impedance, microsecond rise-time source that is economical both to build and to operate. In this paper, we will review basic scaling arguments that set the scope of high-energy density environments made available by pulsed power-driven liners. We provide a summary of some investigations into the physics limiting the performance of near-solid metal liners under magnetic drive. We will present a few examples of hydrodynamic experiments enabled by liners drive and note some demonstration experiments already performed with interim systems. Finally, we will overview the pulsed power techniques under development at Los Alamos for high-energy density experiments. Index Terms--Capacitor banks, high current, hydrodynamics, pulsed power applications.

A series of experiments to study the behavior of thick wires (0.5–2 mm in diameter) driven by currents of about 1 MA has recently been conducted on the Zebra facility at the University of Nevada, Reno. The objective of these experiments was to study plasma formation on the surface of conductors under the influence of megagauss magnetic fields. Laser shadowgraphy, filtered optical and extreme ultraviolet photodiodes, and extreme ultraviolet spectroscopy used in the experiments provided data on radial expansion of wires and on plasma radiation. This paper focuses on numerical simulations of these experiments. Simulations with wires having diameters up to 1.6 mm demonstrated plasma formation with temperatures above 3 eV, which is in preliminary agreement with the experiment. For 2-mm-diameter wires, although plasma can be observed in the simulations, it has substantially smaller optical thickness than in the simulations of the smaller diameter wires, and the radiation fluxes prove to be much lower. This can shed light on the experimental results where the radiation of the 2-mm wires was very weak. The simulated time dependences of the wire radii agree rather well with the experimental results obtained using laser diagnostics and visible-light imaging. The experimental data of the photodiodes also agree well with the simulated time dependence of the detected radiation. [ABSTRACT FROM PUBLISHER]

The article presents obituaries for physicists who died in 2006, including Darwin Chang, Vladimir Konstantinovich Chernyshev and Edward Forbes Greene.

Surveys the joint experimental work that has been performed in the first scientific collaboration between nuclear design laboratories of the United States and Russia. Details on flux compression principles; Information on ultrahigh-current experiments; High magnetic field applications and progress toward controlled thermonuclear fusion.

Introduces a series of articles regarding pulsed power science and technology.