Modeling of T-shaped vane loaded helical slow-wave structures

In this paper, the finite-size vane (FSV) sheath-helix model is proposed to calculate the cold-test characteristics of T-shaped vane loaded helical slow-wave structures (SWSs), in which the effects of the finite number and dimensions of the T-shaped vanes are taken into account, and also the angular harmonics generated due to the angular periodicity of the vanes are considered. Based on this model, the dispersion relation and the interaction impedance are derived and then are applied to an actual structure. The theoretical predictions are also compared with the MAFIA simulation results, and the error are analyzed and interpreted. In the end, the influences of the inner radius and inner width of the T-shaped vanes on the cold-test characteristics are illustrated