Progress on a gridded electron gun for a sheet beam klystron

Calabazas Creek Research Inc. (CCR) is developing rectangular, gridded, thermionic dispenser-cathode guns for sheet beam devices. The first application is expected to be klystrons for advanced particle accelerators and colliders. The current generation of accelerators typically use klystrons with a cylindrical beam generated by a Pierce-type electron gun. As RF power is pushed to higher levels, space charge forces in the electron beam limit the amount of current that can be transmitted at a given voltage. The options are to increase the beam voltage, leading to problems with X-ray shielding and modulator and power supply design, or to develop new techniques for lowering the space charge forces in the electron beam. The current development program addresses issues related to beam formation at the emitter surface, design and implementation of shadow and control grids in a rectangular geometry, and the high voltage insulator.