1. National Institute for Fusion Science, 322-6 Oroshi-cho, Toki-shi, Gifu 509-5292, Japan
2. General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
3. Palomar College, San Diego, California 92069, USA
4. Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
5. California State University, San Marcos, San Marcos, California 92096, USA