TECHNIQUES FOR HIGH-POWER MICROWAVE SOURCES AT HIGH AVERAGE POWER

Generation of microwaves at high power has progressed largely on singl e shot devices. Applications, however, require high average power, imp lying operation at substantial repetition rates. This is in a new doma in for microwave devices. The technical challenge is to achieve very h igh electric fields in the source on a repetitive basis without breakd own. We describe experiments on CLIA, a Compact Linear Induction Accel erator, capable of generating 750 kV and 10 kA into a matched load usi ng magnetic switching to produce 60 ns long pulses. As a first applica tion we used CLIA to drive a water-cooled L-band magnetron at repetiti on rates as high as 250 Hz with no breakdown or pulse shortening. This gave 6.3 kW average power. A short burst at 1 kHz demonstrated operat ion that would translate to an average power of almost-equal-to 25 kW. In this regime operation is not limited by gas build-up, electrode er osion or microwhisker depletion. We are now operating on CLIA with a h igh current relativistic klystron. Beams with modulated current powers of almost-equal-to 1 GW have been generated at 100 Hz for bursts as l ong as 5000 pulses. There are no apparent obstacles to much higher ave rage powers at higher peak powers.