Angular Fokker-Planck Decomposition and Representation Techniques

Two new methods for decomposing scattering cross sections into the forward-peaked and smooth components required for Boltzmann-Fokker-Planck calculations are presented. The first is slightly simpler than existing methods and offers the same level of effectiveness. The second is more expensive than existing methods, but is much more effective. Legendre moments that give a positive representation for the angular Fokker-Planck operator and can be used in standard S_n codes are presented. Computational results are given that demonstrate the effectiveness of these new decomposition and representation techniques.