50 TPa Hugoniot measurements using laser-driven Mach waves

Plasma equation of state models in the tens of TPa pressure regime are based almost entirely on quantum mechanical theories since prior experiments could not reach these conditions. Achieving experimental data in this regime is important because the models tested at lower pressures cannot be simply extrapolated. At high pressures the contribution to the free energy from thermally-excited electrons starts to become comparable to the cold and ionic contributions, and is predicted to drive significant changes in properties like compressibility, opacity and transport. These models are important because these conditions are reached in the interiors of stars and large planets, and in ICF and HED plasma experiments. In this talk we will describe the design, implementation, and development progress at the Omega and NIF laser facilities of a laser-driven Mach wave platform for generating ultra-high pressure planar shock waves to drive stepped physics packages that can be probed using interferometric velocimetry. We will report results from impedance-matching measurements of the Au Hugoniot near 50 TPa.