1. Energy Technology Research Institute (ETRI), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan
2. College of Science and Technology, Nihon University, Tokyo 101-8308, Japan
3. Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, corso Stati Uniti 4, 35127 Padova, Italy