Design and verification of a backward wave oscillation suppression circuit for the Ka-band gyrotron travelling-wave tube

Yuan Ma; Guo Liu; Changbiao Lei; Yingjian Cao; Weijie Wang; Yu Wang; Yelei Yao; Wei Jiang; Jianxun Wang; Yong Luo

doi:10.1063/5.0164265

Design and verification of a backward wave oscillation suppression circuit for the Ka-band gyrotron travelling-wave tube

Rev Sci Instrum. 2023 Oct 1;94(10):104709. doi: 10.1063/5.0164265.

Authors

Yuan Ma¹, Guo Liu¹, Changbiao Lei^{1

2}, Yingjian Cao¹, Weijie Wang¹, Yu Wang¹, Yelei Yao¹, Wei Jiang¹, Jianxun Wang¹, Yong Luo^{1

3}

Affiliations

¹ School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China.
² System Engineering Research Institute, Beijing 100191, China.
³ Laboratory of Electromagnetic Space Cognition and Intelligent Control, Beijing 100089, China.

PMID: 37823769
DOI: 10.1063/5.0164265

Abstract

Backward wave oscillation seriously degrades the stability of gyrotron travelling-wave tubes (gyro-TWTs), especially during high average/continuous wave operation. To solve this problem, a selective mode suppression structure (SMSS) based on the mode coupling principle is proposed and applied in the nonlinear beam-wave interaction region to suppress the parasitic TE11 mode. It is capable of obtaining a high power and improving the tube stability. Simulation results demonstrate that the SMSS can raise the starting current from 10 to 18 A and the starting pitch factor from 1.2 to 1.6. Based on this proposed circuit, a Ka-band TE01 mode gyro-TWT was designed, and the particle-in-cell simulation shows that it can achieve a saturated output power of over 150 kW from 29.7 to 31.7 GHz with a velocity spread of 2.2%. For verification, a SMSS is manufactured and cold tested. The measurement of S-parameters reveals that it can effectively suppress the parasitic TE11 mode.