R. Ding, R. A. Pitts, D. Borodin, F. Ding, M. Kocan, S. Carpentier, W.R. Wampler, P.C. Stangeby, A. Kirschner, H.M. Mao, W.Z. Wang, H.Q. Wang, K.F. Gan, X.Z. Gong, G.-N. Luo, H.Y. Guo, J.L. Chen, and J.G. Li Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, P.R.China. ITER Organization, Route de Vinon sur Verdon, 13115 St Paul Lez Durance, France. Institute of Energy and Climate Research—Plasma Physics, Forschungszentrum Julich GmbH, Association EURATOM–FZJ, Trilateral Euregio Cluster, Julich, Germany. Sandia National Laboratories, Albuquerque, New Mexico USA 87185. University of Toronto Institute for Aerospace Studies, Toronto, M3H 5T6, Canada.