Status of testing activities on gyrotrons for magnetic fusion applications

Gyrotron tests were recently carried out on CPI gyrotrons at frequencies of 117.5 GHz and 140 GHz. At 117.5 GHz, output power levels of 1.67 MW were obtained under short-pulse conditions and long-pulse tests with pulse durations of 1-10 s have been performed with power levels up to 700 kW. Further long-pulse testing to higher power levels will be carried out after shipment of the gyrotron to General Atomics. At 140 GHz, a CPI gyrotron was recently tested up to 800 kW output power for 30-minute pulses at W7-X in Greifswald, Germany. Design details and the latest test results for the two gyrotrons are presented.