Three-dimensional modeling of multistage depressed collectors

Summary form only given. The results of the computer modeling of instantaneous currents within three-dimensional multistage depressed collectors (MDCs) will be presented. The classic method for the analysis and design of collectors, which has been used for more than 20 years at NASA Lewis Research Center, uses two types of two-dimensional codes. First, a large signal analysis code produces the spatial and energetic distributions of the spent electron beam. An electron trajectory code then uses those distributions to perform the actual collector analysis. While this computational procedure is successful in the analysis of circularly symmetric collectors, it can only be applied as an approximation to the analysis of asymmetric collectors which many manufacturers produce. In addition, most electron trajectory codes use a steady state solver that must disregard any phase space information associated with the spent beam model.