Circuit design and simulation of a 220-GHz 100-W extended interaction Klystron

This paper introduces the design results of RF circuit system for use in a G-band Extended Interaction Klystron (EIK). And the EIK can produce an output power of over 100 W, whose operating voltage is 16 kV with a beam current of 0.35 A. The RF system design adopts 2π operating mode and trapezoidal slow wave structure, meanwhile the tuning structure for cavity is considered by choke piston. Considering the power loss caused by the roughness and itself of copper material in the practical engineering, the conductivity of copper material is respectively set to 1.5e+7S/m. Structure parameters of the RF system are simulated and optimized by PIC (Particle in Cell) code. Then, simulation results of final RF system show that: When the material loss is considered, in the case of bandwidth great than 1.4 GHz, the output power is greater than 100 W, the gain is over 33.4 dB, the efficiency is over 3.4%, the spectral characteristics is good, to meet the requirements.