Measurements of non-resonant inelastic X-ray scattering from warm dense Argon plasmas at the LCLS*

Measuring bound-free transitions from X-ray Thomson scattering, or non-resonant inelastic X-ray scattering from core or semi-core electrons, is a powerful technique to probe matter in extreme conditions. Here we present measurements of high signal-to-noise, spectrally resolved inelastic X-ray scattering from shock compressed Argon at the MEC end-station of the LCLS. Combining a coherent X-ray laser coupled with a novel Argon micro-jet that is shock-heated using a 1 Hz temporally stretched Ti:Saphire laser has enabled dynamic measurements of ionization, densities, and temperatures from ps-laser driven samples approaching the warm dense state. Our results show time resolved measurements of heated Argon using spectrally resolved X-ray scattering with unprecedented dynamic range. Measurements were performed using a energy-dispersive spectrometer equipped with a Highly Annealed Pyrolytic Graphite (HAPG) crystal in combination with a Cornell-SLAC Pixel Array Detector (CSPAD) that was configured in the von Hamos geometry.