Single and multistage depressed collector design in high power linear beam tubes

Summary form only given. One means to improve overall efficiency in linear beam devices such as traveling wave tubes and klystrons is to use a single or multistage depressed collector to recapture a portion of the power in the spent beam which would be otherwise dissipated as heat. Numerical tools which are useful in their design are discussed. One useful code, TRUE103, accepts spectral energy data from large signal codes and then processes it to dermine optimum depression voltages, current splits, and overall tube efficiency. This code also sets up a finite emittance spent beam model for use by DEMEOS, a deformable triangular mesh gun code. DEMEOS can thereupon be used to determine the electrostatic design of the collector. The variable mesh feature of DEMEOS allows DC klystron beams to be modelled all the way from gun to collector. DEMEOS allows full or partial ion neutralization of beam space charge to enable study of relativistic beam collapse within very high power klystron collectors. Collector simulations have led to novel means which may reduce or eliminate plasma-induced beam collapse.