1. Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
2. Center for Energy Research & Department of Mechanical and Aerospace Engineering, 460 EBU-II University of California San Diego, 9500 Gilman Drive La Jolla, California 92093-0417, USA
3. Department of Physics and Engineering Physics, University of Tulsa, Oklahoma 74104, USA
4. Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA