1. National Key Laboratory of Science and Technology on Vacuum Electronics, School of Electronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu, China
2. Guoli Vacuum (GLVAC) Industrial Technology Research Institute of High Power Devices Company Ltd., Suzhou, China
3. China Spallation Neutron Source, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan, China