1. Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451, USA
2. FOM Institute DIFFER—Dutch Institute for Fundamental Energy Research, P.O. Box 6336, 5600 HH Eindhoven, The Netherlands
3. ITER Organization, Route de Vinon sur Verdon, 13067 St. Paul Lez Durance Cedex, France
4. University of Wisconsin-Madison, Madison, Wisconsin 53706-1609, USA
5. Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany