1. Japan Atomic Energy Research Institute Naka Fusion Research Establishment, Naka-shi, Inaraki 319-0193, Japan
2. University of Wisconsin, Madison, Wisconsin 53706
3. Hokkaido University Sapporo, Hokkaido 060-8628, Japan
4. Tokyo Institute of Technology, Meguro-ku Tokyo 152-8550, Japan
5. The Institute of Physical and Chemical Research, Wako, Saitama 351-0198, Japan
6. National Institute for Fusion Science, Toki-shi 509-5292, Japan