A novel electromagnetic analysis of a TM02 mode dielectric assist accelerating structure

In this paper, an analytical method based on the transmission line model is proposed for the electromagnetic analysis of a C-band standing-wave dielectric assist accelerating (DAA) structure operating in TM02 mode at 5.712 GHz. This DAA structure consists of dielectric cylinders and disks periodically arranged in a metallic enclosure. To use the transmission line model analysis, the accelerator is divided into 13 uniform sections along the structure categorized into three types: two-layer, three-layer, and five-layer dielectric-loaded waveguides (DLWs). Then, every dielectric-loaded section is modeled by a dielectric-filled one, provided that the dielectric-loaded and corresponding dielectric-filled sections have the same phase and attenuation constants, power dissipation in the dielectric and metal parts, and inner radius of the metal body. Thus, the DAA structure is considered a series of transmission lines, and the whole circuit model is short-ended at both ends according to the metal plates at the entry and exit of the beam. Important electromagnetic features of the accelerator such as operating frequency, amplitude of the axial electric field component on the central axis, and shunt impedance per unit length are calculated. Moreover, the analytical results are compared with simulation results obtained by full-wave electromagnetic software and it is demonstrated that there is a good agreement between the proposed method and simulation results.