Calculation of free-free Gaunt factors in hot dense plasmas

We have obtained predictions for free-free Gaunt factors, using a full relativistic numerical partial-wave and multipole calculation of the bremsstrahlung process as a single electron transition in a potential. We study hot dense cesium plasmas, at various densities and temperatures, using the finite-temperature and -density Thomas-Fermi potential. We consider incident electron energies in the range 1-50 keV. Our results show that use of isolated neutral or ion Gaunt factors has only limited applicability in this environment, while use of the Elwert-Born approximation can lead to a factor-of-3 discrepancy for low incident electron energies.