Improved modeling of backscattered electron effects in a code for depressed collector design

A suite of codes for the computer aided design of depressed collectors has been under development at the Institute for Research in Electronics and Applied Physics in the past few years. A critical feature of these codes is the modeling of secondary electron emission, both the correct emission coefficients, and the correct distributions of emission angle and energy. The BSCAT code which handles the generation of secondary and backscattered electrons uses a method of ray coalescing to give a representative sample of the backscattered electrons while limiting the number of trajectories that must be traced. Recent work has focused on improving the physical model used for the MonteCarlo process of generating secondary electrons. This has involved both incorporating known, accurate models for emission characteristics, and the development of models to describe certain aspects of backscattering. Here we are showing additional examples of usage of the general approach. We have also added capabilities to the code for showing the trajectories of the electrons and for calculating the heat deposited on the collector surface.