1. Center for Momentum Transport and Flow Organization, University of California San Diego, La Jolla, California 92093, USA
2. Center for Energy Research, University of California San Diego, La Jolla, California 92093, USA
3. Center for Astrophysics and Space Sciences (CASS) and Department of Physics, University of California San Diego, La Jolla, California 92093, USA
4. Laboratoire de Physique des Plasmas, Ecole Polytechnique, Palaiseau, France