Southwestern Institute of Physics, PO Box 432, Chengdu 610041;
Southwestern Institute of Physics, PO Box 432, Chengdu 610041;
Southwestern Institute of Physics, PO Box 432, Chengdu 610041;
Institute of Physics, Chinese Academy of Sciences, Beijing 100080;
Associazione EURATOM-ENEA, Sulla Fusione, C.P. 65-00044 Frascati, Rome, Italy;