Research On Coaxial-Loaded Cylindrical Waveguide Slow-Wave Structure

The demand of the modern military science and technology provides a favorable environment for the high power microwave technology to develop. As one of the important field of the high power microwave, the high power microwave source technology also make great progress these years. The key component of a high-power microwave device is the RF structure in which the beam and wave interact. To Traveling Wave Tube (TWT), it is the slow-wave structure(SWS) which basically determine the performance of the TWT. Owing to having the advantages of large size, good thermal conductivity, high precision of manufacturing and assembling, the all-metal slow-wave structures are widely used in the wide-band, high power TWT and relativistic TWT. Furthermore, the disc-loaded cylindrical waveguide is one of the most important slow-wave structures in the all-metal SWS. In this dissertation, we have made detailed theoretical study, numerical simulation and experiment study on some new types of the coaxial disc-loaded SWS. The major achievements are listed as the followings:1. For the first time, a coaxial step-disc-loaded system is presented. By using the field-matching method, the dispersion equations and the coupling impedance of this structure are obtained. The dispersion equation can be used to analyze the coaxial or non-coaxial ridged and disc-loaded structures as the unified expression. The differences in the characteristics of the variant type of the coaxial step-disc-loaded structures are compared, moreover, the influence of various circuit dimensions on the dispersion relation and the coupling impedance are discussed. Compared with the coaxial disc-loaded and ridged-disc-loaded structures, the pass-band of coaxial step-disc-loaded structure is the broadest.2. The dispersion of the coaxial step-disc-loaded slow-wave structure with an annular electron beam is obtained according to the self-consistent filed theory. The computation results of the hot dispersion equation indicate the influence of the circuit dimensions and the electron beam parameters on the small signal gain. The 3dB bandwidth of this tube can reach 30%.