A self-consistent system of equations (known as single-mode gyrotron equations) is extended to describe the beam-wave interaction in a cylindrical gyrotron cavity with mode-converting longitudinal corrugations, which produce coupling of azimuthal basis modes. The system of equations is applied to investigate the effect of corrugations on starting currents of the cavity modes. For these modes, eigenvalues, ohmic losses, field structure, and beam-wave coupling coefficients are investigated with respect to the corrugation parameters. It is shown that properly sized mode-converting corrugations are capable of improving the selectivity properties of cylindrical cavities for second-harmonic gyrotrons.

扩展了一个自洽方程组（称为单模回旋管方程），以描述具有模式转换纵向波纹的圆柱形回旋管腔中的束波相互作用，从而产生方位角基模耦合。应用方程组研究波纹对腔模启动电流的影响。对于这些模式，针对波纹参数研究了特征值，欧姆损耗，场结构和束波耦合系数。结果表明，适当尺寸的模转换波纹能够改善二次谐波回旋管圆柱腔的选择性。