An Ultra-high Gain Gyrotron Traveling-Wave Amplifier with High Stability
具有高稳定性的超高增益回旋行波管放大器

The linear theory together with the self-consistent nonlinear theory are applied to systematically study the stability of a Ka-band TE11 mode ultra-high gain gyrotron Traveling-Wave Amplifier (gyro-TWA). The analysis reveals the differences between the forward-wave absolute instability and the backward-wave oscillation, as well as the suppressing effect to these self-excited oscillations by using distributed loss technique. Using properly down-tapering the magnetic in the nonlinear stage to improve the stability of the system is proposed for the first time. Based on the analysis, a Ka-band TE11 mode gyro-TWA with ultra-high gain ability is designed, which adopts an electron beam with voltage of 100 kV, current of 7 A, velocity spread of 5%, and is capable of obtaining the -1 dB saturated bandwidth about 5 GHz and the highest gain about 80dB.