Equation of state measurements of proton-heated warm dense matter using streaked X-ray radiography

We report on ongoing short-pulse proton heating experiments to measure the equation of state of low-Z warm dense matter conducted at the AWE Orion laser facility. Picosecond resolution streaked X-ray radiographs were analysed using the method proposed by M. Foord et al. [Rev. Sci. Instrum. 75, 2586 (2004)] to generate isentropes, extending from 0.01 to 4 Mbar at temperatures up to 20 eV. To date, isentropes have been extracted for parylene-N plastic, boron carbide and diamond; all show a systematic disagreement with Thomas-Fermi-based predictions at low densities. The latest results are presented including attempts to use streaked optical pyrometry to measure the initial plasma temperature.