Measurement of a release adiabat from ∼8 Mbar in lead using magnetically driven flyer impact

Abstract

Using magnetically driven aluminium flyers to generate ∼8 Mbar shocks in lead, which were then transmitted into lower-impedance material samples, points on a lead release adiabat have been measured. The pressure–particle-velocity points were calculated from known sample principal Hugoniots and from shock velocities measured using arrays of fiber-optic active and passive shock breakout diagnostics, and point and line velocity interferometer for a surface of any reflectivity (VISARs). The measured points agree closely with adiabats calculated using models which do not include ionization, or do include it both with, and without, atomic shell effects. Though the data are not sufficient to discriminate between widely different models we may qualitatively identify errors within these models. This is the first attempt to measure a release adiabat from such high pressures.