Solid state modulator for klystron/gyrotron conditioning, testing, and operation

The conditioning, test, and operation of high power microwave tubes, such as klystrons and gyrotrons, is a complex and costly process. Tubes must be conditioned over a range of increasing voltages, pulsewidths, pulse frequency, and input power levels to achieve reliable performance without damage. The process requires significant freedom of control of voltage, pulsewidth, and PRF, often at average power greater than 1 MW, peak powers greater than 20 MW, and voltages greater than 100 kV. Conventional modulator and power supply technologies capable of handling these high power levels are limited in their flexibility, and require significant operator knowledge, and take a long time to allow a tube to reach full performance. To address these issues, Diversified Technologies, Inc. (DTI) collaborated with Communication and Power Industries (CPI) in Palo Alto, CA under a Department of Energy grant to apply solid state technology to the conditioning and testing processes. DTI combined two high power switches in a unique modulator/buck regulator configuration to provide the required efficiency and control. The configuration was installed in CPI's MSR test set, where many of CPI's high power klystrons and gyrotrons are tested.