Stable 2 MW, 35 GHz, third-harmonic TE/sub 41/ gyro-TWT amplifier

A third-harmonic gyro-TWT amplifier operating in the TE/sub 41/ mode is described that is predicted to generate 2 MW at 35 GHz. The device is based on the proven concept that the electron beam current can be significantly higher in a stable harmonic gyro-TWT amplifier than at the fundamental due to the comparatively weaker harmonic interaction. For stability, the circuit is sliced to suppress electromagnetic modes without the desired symmetry and the 100 kV, 100 A electron beam from a magnetron injection gun is placed at the null of the strongest remaining gyro-BWO mode. The single-stage gyro-TWT is predicted to produce 2 MW with 20% efficiency, 30 dB saturated gain and 3.5% constant-drive bandwidth.