Preheat Issues in Hydrodynamic Hedla Experiments

Abstract

Hydrodynamic experiments have become a very active area within High Energy Density Laboratory Astrophysics. In such experiments, preheat of an interior surface due to heating prior to shock arrival can alter the initial conditions for further evolution and can change the nature of the experiment (Olson et al., 2003). Unfortunately, preheat cannot typically be detected without undertaking dedicated experiments for this purpose. We have designed such experiments, relevant to hydrodynamic instability experiments using Omega Laser at intensities of ~10¹⁵ W/cm². Simulations using the HYADES code suggest that radiative preheat alone causes the interface to move approximately 2 μm before the blast wave reaches it. Hot-electron preheat could cause much larger motions. These experiments will use VISAR to examine the motion of an aluminum sample layer at the rear interface of a standard hydrodynamic target during the period before the shock reaches it (Allen and Burton, 1993).