1. Rowan University, Glassboro, New Jersey 08028, USA
2. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
3. Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
4. Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109, USA
5. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA