1. Institute of Laser Engineering, Osaka University, Osaka 565-0871, Japan
2. Graduate School of Science and Engineering, Doshisha University, Kyoto 610-0321, Japan
3. National Institute for Fusion Science, Gifu 509-5292, Japan
4. Department of Applied Physics, Osaka University, Osaka 565-0871, Japan
5. Institute for R&D Promotion, Doshisha University, Kyoto 602-8580, Japan
6. RIKEN SPring-8 Center, Hyogo 679-5148, Japan