1. Institute of Plasma Physics, Nagoya University, Nagoya 464, Japan
2. Institute of Atomic Energy, Kyoto University, Uji, Kyoto 611, Japan
3. Institute for Fusion Studies University of Texas at Austin, Austin, Texas 78712
4. Niigata University Department of Physics, Niigata 950-21, Japan
5. Himeji Institute of Technology Department of Electricity, Himeji 671-22, Japan
6. Plasma Physics Laboratory Osaka University, Suita, Osaka 565, Japan
7. Fusion Studies Laboratory University of Illinois, Department of Nuclear Engineering, Urbana, Illinois 61801