Measurement of the lead principal Hugoniot at ∼800 kbar by indirect laser drive

Abstract

We have measured points on the principal Hugoniot of lead, using the impedance-match method, at pressures of ∼800 kbar using indirect laser drive. The experiments used laser-heated hohlraums to drive shocks into stepped targets. An active shock breakout diagnostic consisting of a ruby probe laser and optical streak camera detection system monitored target reflectivity—expected to vanish at shock breakout—and shock velocities were calculated from the target step heights and the measured shock transit times. Hugoniot point parameters were calculated from these shock velocities using the known equation-of-state (EOS) of the aluminium base and one step.Our results agree well with previous measurements made using gas-guns or explosively driven shocks, indicating that there are no intrinsic errors in laser-driven EOS experiments, such as those from using non-bulk material or spatial and temporal shock non-uniformity, and so supporting laser-driven EOS measurements at higher pressures.