Calculation of free-free Gaunt factors for 1 keV electrons in a 1 keV normal density Ce plasma

We compare numerical results for free-free Gaunt factors in a hot dense cesium plasma, obtained in the average atom approximation either with a simple approximate analytic potential or with the finite temperature Thomas-Fermi model. We obtain results (for the spectrum of radiation from a 1 keV electron incident on a cesium ion in a 1 keV plasma) from an exact numerical calculation in partial waves of the relativistic electron Bremsstrahlung cross section treated as a single electron transition within these potentials. Comparison shows that Born approximation results in the same potentials fail by large factors, especially at the soft photon end of the spectrum.