Beam optics calculations in very high power microwave tubes

The author outlines advances in computer simulation, computer-aided design procedures, and technology related to the formation, focusing, and collection of very high power beams used in superpower klystrons for advanced linear colliders, free-electron lasers, and other such high-power microwave (HPM) devices. Grading electrodes can be included in the beam formation region of Pierce guns and between the ceramic insulators to increase the high-voltage standoff limit (as in Van de Graaff accelerators). A theoretical basis for their use is established here. Recent improvements in the fully relativistic version of the deformable triangular mesh beam optics code written by the author are described. Selected test cases and examples of its use are presented. A high-perveance 1 MV Pierce gun having three grading electrodes is described which can provide a 1.83 GW 9.13 kJ./pulse beam.<>