Measurements of Prompt and MHD-Induced Fast Ion Loss from National Spherical Torus Experiment Plasmas
Authors: D.S. Darrow, S.S. Medley, A.L. Roquemore, W.W. Heidbrink, A. Alekseyev, F.E. Cecil, J. Egedal, V.Ya. Goloborod'ko, N.N. Gorelenkov, M. Isobe, S. Kaye, M. Miah, F. Paoletti, M.H. Redi, S.N. Reznik, A. Rosenberg, R. White, D. Wyatt, and V.A. Yavorskij
Date of PPPL Report: October 2002
To be presented at: the Nineteenth IAEA Fusion Energy Conference, October 14-19, 2002, in Lyon, France.
A range of effects may make fast ion confinement in spherical tokamaks worse than in conventional aspect ratio tokamaks. Data from neutron detectors, a neutral particle analyzer, and a fast ion loss diagnostic on the National Spherical Torus Experiment (NSTX) indicate that neutral beam ion confinement is consistent with classical expectations in quiescent plasmas, within the approximately 25% errors of measurement. However, fast ion confinement in NSTX is frequently affected by magnetohydrodynamic (MHD) activity, and the effect of MHD can be quite strong.