Simulation Design of a Ka-Band Helically Corrugated Waveguide Gyro-TWA Based on Axis-Encircling Electron Beam

Gyrotron traveling wave amplifiers (Gyro-TWA) have both the characteristics of high power and broadband, which have wide application prospects in many important military fields, such as millimeter wave detection, high-resolution imaging radar, electronic countermeasures, and so on. The gyro-TWA based on axis encircling electron beam can stably operate at high-order harmonic state, reducing the operating magnetic field linearly proportional with the harmonic number and even achieving superconducting free operation. It can improve the flexibility and maneuverability of gyro-TWA. In this article, a Ka-band second-harmonic gyro-TWA with an interaction circuit of helically corrugated waveguide (HCW) is designed. The simulation results indicate that the gyro-TWT driven by a 75-kV, 7-A axis-encircling electron beam can achieve about 160-kW maximum power with a saturation gain of 29 dB, an efficiency of 30.48%, and a bandwidth of 4 GHz from 27 to 31 GHz. Meanwhile, the design details of the circular polarizer and input coupler are reported.