Repetitively pulsed electron beam generator

Repetitively pulsed electron beam generators must be developed for future high average power applications such as laser pumping and plasma heating for fusion reactors. We have begun the development of high average power technology at the parameter level required for electron beam sustained CO
₂
lasers, thus most of the results discussed were obtained from a system with the following nominal characteristics: average power 30 kW, beam voltage 250 kV, 50 pps, pulselength 3 microseconds, beam area 15 cm × 50 cm, current density 1 A/cm
²
. The parameter range investigated included repetition rates up to 1000 pps and pulse durations to 20 microseconds. Topics to be presented include: cathode erosion and lifetime, beam focussing electrodes in the diode, gas generation and vacuum system requirements, and diode impedance. The extension of this technology to the more difficult parameter regimes required for future applications is also discussed.