Recent test results on a 95 GHz, 2 MW Gyrotron

A 95 GHz, multi-megawatt continuous-wave (CW) gyrotron oscillator is currently under development at CPI. During the initial experimental campaign peak output power levels up to 1 MW at 40A beam current were demonstrated at pulse lengths up to 5 ms. In addition, pulses up to 15 s in duration at 25 A beam current, the long-pulse limit of the CPI test stand, and 630 kW peak output power were achieved. Since the initial tests, modifications to the CPI test stand were made to allow for short-pulse operation up to 75 A. A second test campaign, aimed at demonstrating peak output power in excess of 1 MW, is now underway. Power levels up to 1.45 MW have been obtained thus far but efficiencies at higher beam currents appear to be limited by oscillations in the beam tunnel portion of the tube. Efforts to understand the cause of the oscillations are in progress.