Simulation of axi-symmetric multistage depressed collectors with secondary electron emission effects

A CAD program, MSDC, for simulation of axi-symmetric multistage depressed collectors (MDCs) for microwave tubes has been developed in Beijing Vacuum Electronics Research Institute. This program is based on an exiting reliable electron gun program. The main features of the program are a user-friendly interface and graphic output, and the solution of secondary electron trajectories. The influences of space charges of the secondary electrons are considered in the program. In every calculating iteration, the space-charge effects of both the primaries and secondaries are involved. The simulation results of axi-symmetric collectors were compared with the experimental values and the good results were found. By using the MSDC program, we can verify and refine a preliminary design of an MDC, or obtain a new MDC.