[Table of Contents]

Plasma and Fusion Research

Volume 3, 030 (2008)

Rapid Communications

Measurement of Radial Structure of Energetic-Ion-Driven MHD Modes with a Fast Response Hα-Detector Array in the Large Helical Device
Kunihiro OGAWA, Kazuo TOI1), Mitsutaka ISOBE1), Fumitake WATANABE, Chihiro SUZUKI1), Daiji KATO1), Kuninori SATO1) and LHD Experimental Group1)
Department of Energy Science and Engineering, Nagoya University, Nagoya 464-8603, Japan
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
(Received 15 February 2008 / Accepted 3 May 2008 / Published 29 May 2008)


In the Large Helical Device, coherent fluctuations related to energetic-ion-driven magneto-hydrodynamic (MHD) instabilities such as Alfvén eigenmodes (AEs) were detected for the first time using an Hα detector array having high-frequency response up to 200 kHz. Correlation analysis between detector and magnetic probe signals has enabled us to successfully extract coherent fluctuations in the AE frequency range. The radial profile of the excess of the coherence from the background value (Δγ) has a clear peak around the predicted toroidal Alfvén eigenmode (TAE) gap.


Alfvén eigenmode (AE), fast-response Hα detector, correlation analysis, radial structure, TAE

DOI: 10.1585/pfr.3.030


  • [1] A. Fasoli et al., Nucl. Fusion 47, S264 (2007).
  • [2] C.Z. Cheng et al., Phys. Fluids 29, 3695 (1986).
  • [3] L. Chen, Phys. Plasmas 1, 5 (1994).
  • [4] M.A. Van Zeeland et al., Phys. Rev. Lett. 97, 135001 (2006).
  • [5] S.da Graca et al., Plasma Phys. Control. Fusion 49, 1849 (2007).
  • [6] M.A. Van Zeeland et al., Nucl. Fusion 46, S880 (2006).
  • [7] K. Toi et al., Plasma Phys. Control. Fusion 46, S1 (2004).
  • [8] S. Yamamoto et al., Nucl. Fusion 45, 326 (2005).
  • [9] F. Watanabe et al., J. Plasma Fusion Res. 81, 967 (2005).
  • [10] Y.I. Kolesnichenko et al., Phys. Plasmas 11, 1 (2004).

This paper may be cited as follows:

Kunihiro OGAWA, Kazuo TOI, Mitsutaka ISOBE, Fumitake WATANABE, Chihiro SUZUKI, Daiji KATO, Kuninori SATO and LHD Experimental Group, Plasma Fusion Res. 3, 030 (2008).