1. State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China
2. Department of Physics, Harbin Institute of Technology, Harbin 150001, China
3. Center for Fusion Science of Southwestern Institute of Physics, Chengdu 610041, China
4. China Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, China