Dynamical structure factor in high energy density plasmas and application to X-ray Thomson scattering

Abstract

The Dynamical Structure Factor (DSF) is a key observable in high energy density science that is directly measured e.g. using inelastic x-ray scattering techniques. The DSF delivers a wealth of information about macroscopic equation of state data (temperature of electrons and of ion species, average ionization states, electron density), collective and single-particle dynamics, static correlations, electron-ion collisions, and electronic structure. In a strongly coupled, partly degenerate many-body system, such as warm dense matter generated by intense laser-matter interaction and shock wave compression, calculations of the DSF are a formidable task. In this talk, I present the state of the art theoretical framework for DSF calculations in the context of x-ray scattering plasma diagnostics The theoretical foundation is given by the many-body quantum field theory and linear response theory. The DSF or two-particle correlation function is expressed via many-body Green functions and calculated by aid of Feynman diagrams and partial summations to achieve a self-consistent treatment of field propagators and self-energies. The resulting expressions are identified with the components of the Chihara separation of the DSF into free-free, bound-bound, and bound-free processes and suitable approximations for each process can be given. The predictive and analytical strength of this approach will be demonstrated using recently obtained experimental data which led to novel insights in high energy density science.