[Table of Contents]

Plasma and Fusion Research

Volume 3, S1074 (2008)

Regular Articles

Simulation Study of Energetic Ion Transport due to Alfvén Eigenmodes in LHD Plasma
Yasushi TODO, Noriyoshi NAKAJIMA, Masaki OSAKABE, Satoshi YAMAMOTO1) and Donald A. SPONG2)
National Institute for Fusion Science,322-6 Oroshi-cho, Toki 509-5292, Japan
Kyoto University Pioneering Research Unit for Next Generation, Gokasho, Uji 611-0011, Japan
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
(Received 16 November 2007 / Accepted 15 January 2008 / Published 25 June 2008)


The creation of holes and clumps in an energetic ion energy spectrum associated with Alfvén eigenmodes was examined using the neutral particle analyzer (NPA) on the LHD shot #47645. The difference in slowingdown times between the holes and clumps suggested that the energetic ions were transported over 10% of the plasma minor radius. The spatial profile and frequency of the Alfvén eigenmodes were analyzed with the AE3D code. The phase space structures of the energetic ions on the NPA line-of-sight were investigated with Poincaré plots, where an oscillating Alfvén eigenmode was employed for each plot. The phase space regions trapped by the Alfvén eigenmodes appeared as islands in the Poincaré plots. The radial width of the islands corresponded to the transport distance of the energetic ions. Since island width depends on Alfvén eigenmode amplitude, it was found that Alfvén eigenmodes with amplitude δBr/B ∼ 10-3 transported energetic ions over 10% of the minor radius.


energetic ion transport, Alfvén eigenmode, Poincaré plot, LHD, neutral particle analyzer

DOI: 10.1585/pfr.3.S1074


  • [1] M. Osakabe et al., Nucl. Fusion 46, S911 (2006).
  • [2] D.A. Spong and Y. Todo, “Shear Alfvén spectrum and mode structures for 3D configurations,” 49th Annual Meeting of the Division of Plasma Physics (12-16 November 2007, Orlando), PP8.00098.
  • [3] K. Harafuji, T. Hayashi and T. Sato, J. Comput. Phys. 81, 169 (1989).
  • [4] Y. Todo, H.L. Berk and B.N. Breizman, Phys. Plasmas 10, 2888 (2003).

This paper may be cited as follows:

Yasushi TODO, Noriyoshi NAKAJIMA, Masaki OSAKABE, Satoshi YAMAMOTO and Donald A. SPONG, Plasma Fusion Res. 3, S1074 (2008).