Self-modulation spectrum variation in gyrotrons with Bragg type output reflector

A new approach to the line spectrum control in the gyrotrons is discussed. This method is based on introduction of the additional reflector in the output waveguide to form quasi-equidistant mode spectrum in the hybrid cavity which includes interaction region and a section of the output waveguide limited by a such reflector. Under sufficiently large exceeding operating current over threshold in the self-modulation regime a spectrum of generation could be close to the set of eigenfrequencies of the hybrid cavity. In this situation the distance between spectrum lines could be controlled by varying the reflector position. The operability of suggested method was demonstrated in the experimental studies of relativistic Ka-band gyrotron where for the first time the selective Bragg-type reflector was used.