1. Fusion Simulation Center, Peking University, Beijing 100871, China
2. Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
3. Beijing National Laboratory for Condensed Matter Physics and CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100871, China
4. General Atomics, San Diego, California 92186, USA
5. Department of Physics, Nankai University, Tianjin 300071, China