Efficiency Enhancement of a 170 GHz Confocal Gyrotron Traveling Wave Tube

Confocal gyrotron traveling wave tube (gyro-TWT) is a novel gyrotron amplifier capable of operating in higher order modes while generating high power at the same time. Confocal gyro-TWT suppresses lower-order modes at the cost of reduction of efficiency. According to the characteristics of confocal system, in this paper, we theoretically design a special magnetron injection gun (MIG) for a 170 GHz confocal gyro-TWT, and then compare it with the traditional MIG. The efficiency is found to be as high as 33 %, deservedly higher than the traditional less than 10 %. The output power increases trebly accordingly.