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Standardized aluminum liner for Pegasus. As the Marx capacitor bank discharges, electrical current flows in the liner's outer skin creating a strong magnetic field (B). The interaction of the current and magnetic field produces forces that implode the liner. The experimental target is often located inside the liner.
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The Pegasus Pulsed-Power Facility, which fired its last shot in 1999, provided a unique capability for delivering strong, converging, shock-driven or adiabatically driven compressions with excellent diagnostics. Pegasus allowed physicists to gather important data on material behavior at high-energy-densities, which are necessary for weapons physics and basic science. Hydrodynamic InstabilitiesOur studies of the hydrodynamic flow of materials under extreme conditions are crucial to developing and testing weapons models. Our experiments focussed on instabilities at the interface between two materials of different densities. Material PropertiesOur studies of the properties of materials under extreme conditions included topics such as material failure through spall and ejecta, plastic deformations, strain and strain-rate effects, and interfacial friction. One significant series, carried out in collaboration with Livermore, focussed on spallation of shocked aluminum targets and the growth of instabilities (see images at right). Basic Science and TechnologyWe explored the electronic properties of materials in the presence of strong magnetic fields, and we collaborated with Russian scientists to study liner stability. In preparation for the future Atlas facility, we also conducted experiments on mechanical joints that can carry high current-densities. Atlas: The Next Generation of Pulsed PowerThe Atlas Pulsed-Power Facility is now under construction. This facility will deliver 2 to 5 MJ of kinetic energy to nominal 8-cm-diameter, 50-g liners, making possible many new experiments in dynamic materials properties and hydrodynamics. For more information, see the full Pegasus research highlight (PDF 118 KB), or contact David Oro. |
Flash radiographs of the LLNL-5 experiment before and 3.38 microseconds after the liner has impacted the target. The 2.2 km/s impact resulted in a 140-kbar shock. In the later image, the shock has left the aluminum target and is traveling toward the xenon center. Visible are the boundary between shocked and unshocked xenon, layers of spalled aluminum, regions of "failed" aluminum, and jets seeded by perturbations in the target's inner surface.
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