1. Faculty of Engineering and Resource Science, Akita University, Tegata-gakuen-cho1-1, AKITA 010-8502 Japan
2. Interdisciplinary Graduate School of Engineering Science, Kyushu University, Hakozaki 6-10-1, Higashi-ku, FUKUOKA 812-8581 Japan
3. National Insittute of Fusion Scinece, Oroshi-cho 322-6, Toki-city, GIFU 509-5292 Japan