The Streaming Ray Formulation of Electron Transport

An electron transport solver has been developed based on a streaming ray (SR) solution to the Spencer-Lewis equation. Several special numerical techniques were used to make the algorithm fast and accurate. These include,an efficient routine for simulating energy loss straggling,use of extended-transport-corrected and Fokker-Planck equivalent cross sections, which speed convergence and reduce both angular and spatial differencing errors,a discrete transport correction, which further speeds convergence and further reduces spatial differencing errors,the method of numerical shoves and countershoves, which attempts to estimate and correct the remaining spatial differencing errors.The extended transport correction and the Fokker-Planck equivalent cross sections were originally developed for S_N computations. The remaining techniques are new. The use of all these techniques together with the SR method has led to a complicated but highly efficient electron transport algorithm. Its efficiency is especially evident in energy spectrum calculations for which other fast algorithms such as the S_N method often yield poor results. Several sample calculations involving electron transport in aluminum slabs are presented.