1. School of Nuclear Science and Engineering, North China Electric Power University, Beijing 102206, China.
2. Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China.
3. Institute of Plasma Physics, CAS, Hefei 230031, China.
4. NW Institute of Nuclear Technology, Xian 710024, China.