Circuit Design of a W-Band High-Power Extended Interaction Multibeam Klystron

This article designed a W-band multibeam extended interaction klystron (EIK) RF circuit, aiming to achieve high-power output. By introducing a compression ring structure into the cavity, the circuit performance was enhanced. Regarding the cavity design, key issues including frequency tuning, optimization of field distribution uniformity between the gaps and the electron beams, and mode suppression were analyzed. The finally designed cavity exhibits good field distribution uniformity. The frequency spacing between the high band and low band is 1.355 and 1.18 GHz, respectively, with significant suppression of nonoperating mode competition. Furthermore, this article conducted an in-depth analysis of the performance enhancement effect of the compression ring structure on the extended interaction cavity (EIC). Particle-in-cell (PIC) simulation results indicate that under the driving conditions of a 40-kV operating voltage and a 2.4-A operating current (input power: 281.25 mW), the circuit achieves a output power of 17.33 kW at a frequency of 94.588 GHz. The instantaneous 3-dB bandwidth is 260 MHz, with a gain and an efficiency of 47.9 dB and 18.1%, respectively.