22-70 GHz gyrotron development

This paper describes our gyrotron development which has been carried out since 1980. We have made a 22 GHz, 40 kW experimental tube and obtained useful test results on the efficiency characteristics. A 70 GHz, 25 kW tube is now under evaluation. and experimental data is shown. Finally, the design concept of a 28 GHz, 200 kW gyrotron which is now under design is discussed briefly.