Simulation design and power distribution calculations of linac collinear load based on Kanthal alloy

In order to miniaturize irradiation accelerators, the collinear load is proposed to substitute for the waveguide load. The key technique is to dissipate the remnant power in load cavities which are coated with efficient microwave-absorbing materials on their inner walls. Taking advantage of a 2π/3 mode resonance structure, the S-band collinear load based on Kanthal(Fe-Cr-Al) which is a kind of surface-attenuating metal is studied in CST. The influences of the coating position and area on the operation frequency and cavity quality factor are analyzed. The compensation of cavity dimensions for tuning at 2 856 MHz is determined. A two-period collinear load composed of six cavities is designed, with one-way attenuation of -18.63 dB. The power density calculations of the coatings and copper wa