Advancements in codes for computer aided design of depressed collectors and tracing of backscattered electrons II. Improvements in modeling of the physics of secondary electron emission and backscattering

The BSCAT computer code being developed by us for the design of depressed collectors for gyrotrons employs a special algorithm for tracing the trajectories of backscattered electrons. Monte Carlo techniques are used on a large ensemble of rays to ensure accurate representation of the stochastic process. Recent work has focused on improvement of the modeling of the electron backscatter phenomenon itself. We have introduced more accurate models for the backscatter coefficients for true secondaries, as well as elastically and inelastically backscattered primaries. These models are adapted to the energy ranges and the angles of incidence of the primaries. They are linked with experimental data as available in current literature or with Monte Carlo simulations. Analytical representations have been used where they closely approximate the experimental or simulation data, in an effort to make the computation as versatile and computationally inexpensive as feasible. The same has been done for angular and energy distributions of the emitted electrons.