1. Institute of Plasma Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
2. Science Island Branch, Graduate School of University of Science and Technology of China, Hefei 230026, China
3. School of Electric Engineering, University of South China, Hengyang 421001, China
4. Institute of Modern Physics, Fudan University, Shanghai 200433, China
5. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China