X-ray Thomson scattering in dense plasmas

Summary form only given. The scattering of photons in plasmas is an important diagnostic tool. Dense plasmas as relevant for inertial confinement fusion experiments or planetary interiors can be probed by X-ray Thomson scattering. The scattering cross section is related to the dynamic structure factor which contains contributions from free electrons, electrons tight to the ion motion including screening, and of inelastic scattering off core electrons. Especially, we treat the scattering on free electrons in the plasma beyond the standard RPA by including collisions. The respective dielectric function is determined in the Born-Mermin approximation. We find that collisions modify the dynamic structure factor significantly in the warm dense matter region, i.e. for solid-density plasmas at temperatures of some eV. This is important for plasma diagnostics, i.e. when using the Thomson scattering signal for the determination of plasma densities and temperatures. For instance, we could show that the extracted plasma temperatures differ by a factor of about two when using the standard RPA and the present Born-Mermin approach. Improvements of the Born approximation for the treatment of collisions can be discussed within the Gould-DeWitt scheme.