Isentropic compression of lead and lead alloy using the 'Z' machine

We have performed experiments on the quasi-isentropic compression of lead (both bulk and single-crystal) and lead-antimony alloy to ∼500kbar using magnetic-pressure drive from Sandia National Laboratory's Z machine. Multiple point VISARs were used to record free-surface velocities of multiple thicknesses of the three materials - analysis is by calculating sound-speed as a function of particle velocity from the different times at which the samples reach the same velocity. This apparently simple process is complicated by: formation of shocks, the time-dependent pressure profile, including surface reflections of ramp waves, and calculation of in-situ particle velocity from free-surface velocity. This article will describe the experiments and present a preliminary analysis of the data