1. Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, China
2. National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan
3. The Graduate University for Advanced Studies, SOKENDAI, Toki 509-5292, Japan
4. College of Physics, Sichuan University, Chengdu 610065, China