Experimental measurements of competition between fundamental and second harmonic emission in a quasi-optical gyrotron

Abstract

A quasi-optical gyrotron (QOG) designed for operation at the fundamental ( fce≂100 GHz) exhibits simultaneous emission at fce and 2fce (second harmonic). For a beam current of 4 A, 20% of the total rf power is emitted at the second harmonic. The experimental measurements show that the excitation of the second harmonic is only possible when the fundamental is present. The frequency of the second harmonic is locked by the frequency of the fundamental. Experimental evidence shows that when the second harmonic is not excited, total efficiency is enhanced.