250 kW High efficiency gyrotron oscillator operating at 60 GHz

Progress in the development of a 200 kW CW gyrotron operating at 60 GHz is presented. The best test results to date are 285 kW output power and 44% efficiency at low duty. An unusual feature of this gyrotron is that the power and efficiency maximizes at the same operating conditions, whereas previous devices reached their highest efficiencies at lower beam current and anode voltage than that for maximum power. This gyrotron operates in the TE
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circular electric mode with an axisymmetric collector and a single disc output window. Test results are compared with theoretical predictions.