Self-Driving Energy-Recirculating Micromachined ${G}$ -Band Folded-Waveguide Traveling-Wave Tube Oscillator

We propose a self-driving folded-waveguide traveling-wave tube (TWT) oscillator internally driven by a backward-wave oscillator (BWO). As a driving source, the initial beam energy obtained from the electrostatic field is converted to electromagnetic energy in the BWO. The TWT is designed to amplify the radio frequency signal from the spent electron beam condition as an energy-recirculating method. This paper presents a detailed design study and analysis of the individual circuits, as well as those of the combined circuit, which are conducted using the CST particle-in-cell commercial software and MAGIC code. A maximum average output power of 82.63 W at a frequency of 272 GHz is predicted under the lossless condition. Although the proposed self-driving circuit exhibits a relatively low output power, the key concept behind the novel circuit, which uses a spent electron beam as an amplification source, is validated via simulation. Furthermore, the tunable frequency of the proposed device is tested by changing the initial electron energy using CST Particle Studio, and the expected tunable frequency is 268-272GHz.