Experimental study of gyrotron efficiency enhancement by improvement of electron beam quality

The methods for suppressing parasitic low- frequency oscillations (LFOs) have been applied to improve electron beam quality in a 4-mm 100-kW gyrotron. In the conditions of suppressed LFOs and of high cathode emission uniformity, the stable operation of this gyrotron at pitch factor values high than 1.5 has been achieved. As a result, the efficiency of the gyrotron at the main TE
_12,3
mode has been increased from 32 % (corresponds to the designed regime with pitch factor of 1.28) up to 42 %.