Dealing with Non-Ideal and Real World Physics in Computational Electron Optics

Electron beam optics codes are presently used in the design of vacuum electron devices. The goal in using codes of this type, such as MICHELLE, is to produce a sufficiently accurate design of a device that the manufacturer can build the tube based exclusively on that design. Devices with high-brightness electron beams involve non-ideal physical mechanisms that can cause non-acceptable divergence between the design and the actual device operation. In the proposed work, we will investigate several candidate mechanisms. We will investigate secondary electron emission, particularly at grazing angles of incidence, thermionic and space-charge-limited emission, particularly in how the interplay between the two regimes affect the electron beam, and electron-impact ionization of background gas. Physics models for these effects will be devised, algorithms abstracted from the models, and corresponding code will be tested. The eventual goal is to transfer the algorithms into production-level beam optics codes such as MICHELLE.