1. Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
2. National Research Nuclear University MEPhI, 115409 Moscow, Russia
3. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
4. Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
5. Department of Physics and Space Science Center, University of New Hampshire, Durham, New Hampshire 03824, USA