1. Department of Engineering, Fukuoka Institute of Technology, 3-30-1 Wajirohigashi Fukuoka, Japan, 811-0295
2. Plasma Research Center, University of Tsukuba, 1-1-1 Tennnodai Tsukuba Ibaraki, Japan, 305-8577
3. Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasugakoen Kasuga Fukuoka, Japan, 816-8580
4. National Institute for Fusion Science, 6-1 Oroshicho Toki Gifu, 509-5292, Japan