Analysis of laser shock experiments on precompressed samples using a quartz reference and application to warm dense hydrogen and helium

Megabar (1 Mbar = 100GPa) laser shocks on precompressed samples allow reaching unprecedented high densities and moderately high similar to 10(3)-10(4) K temperatures. We describe here a complete analysis framework for the velocimetry (VISAR) and pyrometry (SOP) data produced in these experiments. Since the precompression increases the initial density of both the sample of interest and the quartz reference for pressure-density, reflectivity, and temperature measurements, we describe analytical corrections based on available experimental data on warm dense silica and density-functional-theory based molecular dynamics computer simulations. Using our improved analysis framework, we report a re-analysis of previously published data on warm dense hydrogen and helium, compare the newly inferred pressure, density, and temperature data with most advanced equation of state models and provide updated reflectivity values. (C) 2015 AIP Publishing LLC.