1. Department of Mechanical and Aerospace Engineering, University of California at San Diego, La Jolla, California 92093, USA
2. Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
3. Institute for Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf e.V., 01328 Dresden, Germany
4. Institute of Laser Engineering, Osaka University, Osaka 565-0871, Japan