Using pulsed power for hydrodynamic code validation

Abstract

As part of ongoing hydrodynamic code verification and validation efforts, a series of near-term liner experiments (NTLX) was designed for the Shiva Star capacitor bank at the Air Force Research Laboratory . An aluminum liner that is magnetically imploded onto a central target by self-induced Lorentz forces drove the experiments. Target design utilized the adaptive mesh refinement Eulerian hydrodynamics code radiative adaptive grid eulerian (RAGE) in twoand three-dimensions. One-dimensional simulations of the liner driver utilizing the lagrangian magnetohydrodynamics code RAVEN are used to set the initial temperature and density profiles as well as liner velocity at impact time. During liner/target impact, a convergent shock is generated in the target that drives subsequent hydrodynamics experiments. In concentric targets, a cylindrically symmetric shock will converge on axis. The degree of shock symmetry observed characterizes the liner symmetry at impact. By shifting the target center away from the liner driver axis, variations in shock propagation velocity generate off-center shock convergence. Results indicate that RAVEN and RAGE are in excellent agreement for the calculated shock trajectory. However, a small but significant discrepancy does occur during the last few millimeters of run-in when convergence effects are greatest. The codes predict shock arrival times that are approximately 100 ns faster than those observed experimentally.