Abstract
This study proposes a mode-selective circuit to suppress the competing modes in a TE01 gyrotron backward-wave oscillator (gyro-BWO). The circuit, also functioning as an interaction structure, comprises of several transverse slices. It eliminates the restrictions of the mode competitions and allows a longer interaction structure to optimize interacting efficiency. Mode-selective effect will be analyzed. Experimental results indicate that the Ka -band TE01 fundamental harmonic gyro-BWO is capable of continuous tuning from 31.4 to 36.4 GHz with a peak efficiency of 23.7%, corresponding to 100 kW at I b =4.5 A and Vb =93.6 kV. © 2009 American Institute of Physics.