Selection of Symmetric and Asymmetric Modes in the Oversize Slow-Wave Structure of a Multiwave Cherenkov Generator

Abstract

The resonances of the slow-wave structure of a multiwave Cherenkov generator have been determined theoretically for a frequency range close to the π-type frequency of the lower symmetric mode. The ratio of the diameter of the slow-wave structure to the wavelength of the microwave radiation was equal to four. The resonance frequencies and Q factors of symmetric and asymmetric modes have been found in relation to the length of the drift tube. It has been shown that these relations strongly affect the spectral composition of the resonances. At some ratios of the slow-wave structure diameter to the radiation wavelength, high-Q resonances of higher oscillation types (locked modes) occur. Examples of the slow-wave structure geometries are given for which resonances of some modes have an advantage of higher Q factor.