Experimental Investigation on Trapped Electrons Oscillation Suppression for W-Band Gyro-TWT

The fluctuation of current can destroy the performance of the gyrotron traveling-wave tube (Gyro-TWT). We found that the fluctuation of the current is related to the generation of trapped electrons in the interaction circuit. Through experimental and simulation verification, it has been found that the oscillation characteristics of the current are consistent with the motion characteristics of the trapped electrons in the interaction circuit. This indicates that trapped electrons have a significant impact on the current. To suppress the trapped electrons, a novel magnetron injection gun (MIG) with the rear electrode (MSRE) has been designed. The absorbed power of the interaction circuit has decreased by 50%. When a W-band Gyro-TWT with MSRE is operated at 60.5 kV/10.15 A, zero drive with a pulse duration of
$200~\mu $
s, and a duty cycle of 15%, there is no current fluctuation. The tube achieves a peak power of 136 kW, a gain of 71 dB, and an average power of 20.54 kW at 94 GHz. The hot test shows that MSRE can suppress the generation of trapped electrons. This greatly enhances the stability of the tube.