Experimental Study on Continuous Frequency Tuning of a Second-Harmonic 800-GHz Gyrotron

The continuous frequency tuning of a second-harmonic (SH) 800-GHz gyrotron is experimentally studied. The influence of the electron pitch factor on harmonic mode competition and frequency tunability has been thoroughly examined. By controlling the pitch factor, the competition from the fundamental parasitic mode can be effectively suppressed. The stable oscillations of the SH mode were achieved with an output power of up to 150 W and a continuous frequency tuning range of 0.8 GHz around 800 GHz. Similarly, the gyrotron operating in the fundamental mode can achieve wideband continuous frequency tuning range of 8.71 GHz around 385 GHz.