Gbar-range Hugoniot equation of state of Boron*

Using convergent drive geometries and large-scale laser facilities, it is now possible to experimentally access high-pressure, high-temperature regimes of phase space where the thermal excitation of bound electrons has a measurable effect on plasma compressibility.~ These states are important for modeling extreme astrophysical phenomena and fusion-energy experiments.~~ Equation of state models have high uncertainty in this regime because of the lack of benchmarking experimental data.~ We will present new data on elemental boron spanning pressures of 10's of Mbar to near 1 Gbar, using planar and spherically-convergent drive platforms on the NIF laser facility, to test a range of equation of state models.~