Analysis of gyrotron coaxial cavities with corrugated inner conductor based on the method of moments

To reduce the influence of possible competing modes, coaxial cavities with longitudinal corrugations on the inner conductor have been proposed as electrodynamic structures for the design of high-power high-frequency CW gyrotron oscillators. The technique proposed here to investigate such cavities, based on the Method of Moments, allows a rigorous analysis of the effect of the geometrical parameters of the corrugations on the eigenfrequency spectrum. The study of the variation of the transverse eigenvalues with the coaxial parameter C, defined as the ratio of the outer radius to the inner radius of the cavity, is more particularly emphasized. The results obtained with this method are compared with the surface-impedance model and checked against simulations carried out with the finite integration technique code MAFIA.