1. International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics, State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China
2. Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543, USA
3. Advanced Energy Research Center, Shenzhen University, Shenzhen 518060, People’s Republic of China