Long-pulse and CW tests of a 110-GHz gyrotron with an internal, quasi-optical converter

A high-power gyrotron, employing an internal converter that produces a Gaussian-like output mode, has been designed and tested. The tube employed a TE(22,6,1)-mode interaction cavity that was designed for operation at a frequency of 110 GHz, An internal converter, consisting of an advanced launcher design and four mirrors, produced a Gaussian mode that had a relatively uniform profile at the tube output window to minimize the peak power density. Tests on the tube resulted in output power levels of 680, 530, and 350 kW for pulse durations of 0.5, 2.0, and 10.0 s, respectively, Measurements of the temperature of the output window were made during the long-pulse tests, Output power levels of 1 MW were achieved under short-pulse (1 ms) operation and the tube was operated at CW power levels in excess of 100 kW.