1. Graduate school of Engineering, Hiroshima University, Hiroshima 739-8527, Japan
2. Institute of Advanced Energy Kyoto University, Kyoto 611-0011, Japan
3. Southwestern Institute of Physics, Chengdu, China
4. Graduate School of Energy Science, Kyoto University, Kyoto 611-0011, Japan
5. Plasma Research Center, University of Tsukuba, Ibaraki 305-8577, Japan
6. National Institute of Fusion Science, Gifu 509-5292, Japan
7. Graduate School of Engineering Sciences, Kyushu Univ., Kasuga 816-8580, Japan
8. Research Institute for Applied Mechanics, Kyushu Univ., Kasuga 816-8580, Japan