1. School of Electronic Science and Engineering, University of Electronic Science and Technology of China,National Key Laboratory of Science and Technology on Vacuum Electronics in Chengdu,Chengdu,China,611731
2. Guoli Vacuum (GLVAC) Industrial Technology Research Institute of High Power Devices Co. Ltd.,Suzhou,China,215300
3. Spallauion Neutron Source Science Center, Institute of High Energy Physics, Chinese Academy of Sciences,Dongguan,China,523803