Development of Dual-Frequency Gyrotron with Triode Magnetron Injection Gun

A high power dual-frequency gyrotron is designed and tested. The design is based on a 170 GHz single-frequency gyrotron with a triode magnetron injection gun (MIG). The triode MIG enables to choose variety of oscillation modes for different frequencies with suitable pitch factor, which is the great advantage for a multi-frequency gyrotron. Another frequency of 137 GHz is selected in order to use a 1.853-mm-thick single-disk output window. Cavity modes are TE31.11 and TE25.9 for 170 and 137 GHz, respectively, which have high mode conversion efficiency to the RF beam mode with similar radiation angles. In short-pulse experiments, the maximum power of more than 1.3 MW is achieved with high-efficiency for both frequencies. (C) 2011 The Japan Society of Applied Physics