1. Graduate School of Engineering, Nagoya University, Furo-chou, Chikusa-ku, Nagoya-shi, Aichi-ken 464-8603, Japan
2. Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan
3. ITER International Team, Garching, Max-Planck-Institut für Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching, bei München, Germany