Approximate averaged Gaunt factors for free-free Bremsstrahlung emission from a weakly degenerate plasma

Abstract

The aim of the paper is the analysis of some aspects of the theoretical models used for the description of the Bremsstrahlung emission from non-Maxwellian plasmas, more precisely when quantum weak degeneracy effects come into play. Referring to the standard Sommerfeld Parameter ρ as a measure of the degree of degeneracy, we considered some reference physical environments, as Inertial Confinement Fusion experiments or the first stage of LIBS, characterized by high densities (even higher than solid state values) and relatively low temperatures (tens of eV). We investigated the relevance of the first order in ρ analytical corrections into the Born and Kramers approximations for the Gaunt factors calculations due to the evaluated non-Maxwellian electron distribution function for the weakly degenerate plasma. The shown results suggest that the degeneracy effects produce up to a 20% correction to the classical values for the Gaunt factors that should be taken into account to properly validate Bremsstrahlung spectra resulting from experiments.