1. Institute of Plasma Physics, Chinese Academy of Sciences, PO Box 1126, Hefei 230031, People's Republic of China
2. University of Science and Technology of China, Hefei 230026, People's Republic of China
3. General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
4. Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543-0451, USA
5. University of California - San Diego, La Jolla, California 92186, USA
6. Lawrence Livermore National Laboratory, Livermore, California 94550, USA