Electron beam-cavity system of 170 GHz gyrotron for ITER

The opportunity of using TE/sub 28.7/, TE/sub 31.8/ and TE/sub 25.10/ operating modes for a CW 170 GHz/1 MW gyrotron for ITER is assessed. Parameters are optimized to achieve maximum efficiency of the gyrotron with an acceptable ohmic load on the cavity. Results of an experimental investigation of short pulse prototypes of the TE/sub 28.7/ and TE/sub 25.10/ gyrotrons are presented. Mauimum output power 1.4 MW, efficiency 36%, and 65% with single-stage depressed collector were achieved.