1. Institute of Energy and Climate Research-Plasma Physics, Forschungszentrum Jülich GmbH Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, Jülich, Germany
2. University of California, San Diego, La Jolla, California 92093-0417, USA
3. General Atomics, San Diego, California 92186-5608, USA
4. Lawrence Livermore National Laboratory, Livermore, California, USA
5. University of Toronto, Institute for Aerospace Studies, Toronto, Ontario M3H 5T6, Canada
6. Central Division of Analytical Chemistry, Forschungszentrum Jülich, D 52425 Jülich, Germany