1. Department of Modern Physics and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
2. Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026, China
3. Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
4. Theory and Simulation Division, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China