M. Isobe, K. Ogawa, K. Toi, M. Osakabe, K. Nagaoka, T. Tokuzawa, S. Kobayashi, D.A. Spong, D.S. Darrow and LHD experiment group Characteristics of Anomalous Transport and Losses of Energetic Ions Caused by Alfvenic Modes in LHD Plasmas


22 IAEA Fusion Energy Conference, EXW/P7-09

Date of publication:

Nov. 2010

Key words:

22 IAEA Fusion Energy Conference, EXW/4-3Rb


Anomalous transport and losses of energetic ions caused by Alfvenic modes in neutral beam-heated Large Helical Device (LHD) plasmas are studied with a scintillator-based lost fast-ion probe (SLIP) and a charge-exchanged neutral particle analyzer. Correlated with recurrent bursting toroidicity-induced Alfven eigenmodes (TAEs), significant increases of energetic-ion losses are observed. Co-going transit energetic ions are responsible for destabilization of TAEs in LHD and are anomalously expelled through a diffusive-type loss mechanism. A particle simulation with a modeled perturbed magnetic field suggests that energetic-ion losses increase as the amplitude of the perturbed field increases. Experimentally measured pitch-angle distributions of escaping beam ions are reproduced by particle simulation.

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