Azimuthally segmented MIG-type electron beam for terahertz harmonic gyrotron

We propose an azimuthally segmented configuration of a MIG-type (magnetron injection gun) electron beam with azimuthal periodicity for terahertz harmonic gyrotrons, featuring enhanced mode selection. By azimuthally modulating the emitter ring of MIG into segments to generate several electron beamlets (small-orbit) evenly distributed in the electron guiding phase, we can selectively induce the degeneracy of the oppositely rotating waves of the desired harmonic mode, forming a standing-wave like pattern that nearly doubles the mode's coupling strength to the beam. The proposed approach can help to mitigate the mode competition and increase the output power of the terahertz harmonic gyrotron, paving the way for advancement in the development of gyrotrons with higher frequencies and higher harmonics.