1. Southwestern Institute of Physics 1 , Chengdu 610041, People's Republic of China
2. School of Physics, Huazhong University of Science and Technology 2 , Wuhan 430074, People's Republic of China
3. International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology 3 , Wuhan 430074, People's Republic of China