1. Mechanical and Aerospace Engineering Department and Center for Energy Research, 460 EBU-II, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0438, USA
2. University of Wisconsin, Fusion Technology Institute, Madison, WI 53706, USA
3. Fusion Nuclear Technology Consulting, Fliederweg 3, 76351 Linkenheim, Germany
4. Center for Energy Research, 460 EBU-II, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0438, USA