Intrinsic Resonance in Gyrotron Using Non-resonant RF Structure

Tien-Fu Yang^1*, Hsin-Yu Yao², Shih-Hung Chen³, Tsun-Hsu Chang¹

¹Physics, National Tsing Hua University, Hsinchu, Taiwan
²Physics, National Chung Cheng University, Chiayi, Taiwan
³Physics, National Central University, Taoyuan, Taiwan

* Presenter:Tien-Fu Yang, email:yang168@gapp.nthu.edu.tw

In this work, comparative studies on the linear and nonlinear behaviors of uniform-tube gyrotrons are investigated. The forward and backward waves are observed to co-generate and exhibit similar characteristics of ultra-slow group velocity under near-cutoff operation. This situation allows the as-generated forward wave to modulate the fresh beam, establishing a new backward-wave-like internal feedback loop. Additionally, the quasi-degenerate nature of the bi-directional propagating waves ensures their intrinsic in-phase relationship. The consequent constructive interference enables the uniform tube to function as a high-Q resonator. These findings are found to be independent of the choices of TE or TM modes, providing valuable insights into the underlying interaction mechanism of gyrotron devices.

Keywords: Electron Cyclotron Maser, Gyrotron Oscillator, Intrinsic Resonance, Absolute Instability