The influence of a coaxial dielectric rod on eigenvalues, ohmic losses, transverse field structure, and beam-wave coupling coefficients is investigated for TE modes of a gyrotron cavity. It is shown that such dielectric insert, when made from a moderate-loss material, results in strong attenuation of all cavity modes, with the exception of those having caustic radii much larger than the insert radius. It is proposed to employ such dielectric loading for selective suppression of competing modes in cavities of second-harmonic gyrotrons. The high performance and flexibility of the proposed method of mode discrimination are demonstrated for the example of the cavity of the high-power 0.39-GHz second-harmonic gyrotron developed at the University of Fukui. In addition, some fascinating capabilities enabled by coaxial inserts made of ultralow-loss dielectrics are discussed.

对于回旋管腔的TE模式，研究了同轴电介质棒对特征值，欧姆损耗，横向场结构和束波耦合系数的影响。已经表明，这种介电插入件由中等损耗的材料制成时，会导致所有腔模的强烈衰减，除了那些具有比插入件半径大得多的苛性半径的腔模。提出采用这种介电负载来选择性抑制二次谐波回旋管腔中的竞争模式。以福井大学开发的大功率0.39 GHz二次谐波回旋管腔为例，证明了所提出的模式识别方法的高性能和灵活性。此外，