Fast scheme for photon-Maxwellian electron cross sections

A fast and accurate method for computing temperature-corrected photon-Maxwellian electron cross sections with distribution averaged electron energies and scatterig angles in presented. Use is made of the covariant (frame independent) picture of scattering for relativistic electrons. The scheme is motivated and detailed, predictions are obtained an compared with exact values and appropriate limiting forms which retain the Thomson and Klein-Nishina cross section structure are also recovered. The method is amenable to further pointwise (Monte Carlo) or multigroup (S/sub n/) cross section processing. A two parameter fit to the relativistic cross sections is also described that resembles the Klein-Nishina formula in structure and can be used to generate temperature corrections within existing static electron algorithms