1. Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto, Japan
2. Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto, Japan
3. Laboratorio Nacional de Fusión, EURATOM-CIEMAT, Madrid, Spain
4. National Institute for Fusion Science, Oroshi-cho, Toki, Gifu, Japan