Fast-Ion Profiles During Ion Cyclotron Heating,

Fast wave heating at the 4th-8th harmonic is combined with neutral beam injection. For 60 MHz heating at the 4th-6th harmonic, an energetic deuterium tail is observed by the fast-ion $D_\alpha$ (FIDA) diagnostic [1,2]. FIDA profiles are compared with the fast-ion profiles inferred from the equilibrium, as well as neutral particle data. Under some conditions, enhanced losses of fast ions at the vessel wall occurs during the rf. The fast-ion tail is largest near the resonance layer. For 116 MHz heating at the 8th harmonic, little evidence of a fast-ion tail is observed, even in higher density plasmas where fast-ion absorption was originally predicted. The FIDA spectra and profiles for cases with and without fast-ion heating are compared with calculations of the expected fast-ion acceleration. \par\vskip6pt\noindent [1] W.W. Heidbrink et al., Plasma Phys. Control. Fusion \textbf{46} (2004) 1855. \par\noindent [2] Y. Luo et al., Rev. Sci. Instrum. \textbf{75} (2004) 3468.