Ma Yuan, Liu Guo, Lei Changbiao, Cao Yingjian, Wang Weijie, Wang Yu, Yao Yelei, Jiang Wei, Wang Jianxun, Luo Yong
School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China.
System Engineering Research Institute, Beijing 100191, China.
Rev Sci Instrum. 2023 Oct 1;94(10). doi: 10.1063/5.0164265.
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.
