Using X-ray Thomson Scattering to Characterize Highly Compressed, Near-Degenerate Plasmas at the NIF*

We are developing x-ray Thomson scattering for implosion experiments at the National Ignition Facility to characterize plasma conditions in plastic and beryllium capsules near stagnation, reaching more than 20x compression and electron densities of 10$^{25}$ cm$^{-3}$, corresponding to a Fermi energy of 170 eV. Using a zinc He-$\alpha$ x-ray source at 9 keV, experiments at a large scattering angle of 120$^{\circ}$ measure non-collective scattering spectra with high sensitivity to K-shell ionization, and find higher charge states than predicted by widely used ionization models. Reducing the scattering angle to 30$^{\circ}$ probes the collective scattering regime with sensitivity to collisions and conductivity. We will discuss recent results and future plans.