1. Kyoto Institute of Technology, Matsugaki, Sakyo-ku, Kyoto 606-8585, Japan
2. National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
3. The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8561, Japan
4. Japan Atomic Energy Agency, 801-1, Mukoyama, Naka 311-0193, Japan
5. Kyoto University, Gokasho, Uji 611-0011, Japan
6. Kurchatov Institute, Kurchatov-Sq., Moscow 123182, Russia