[Table of Contents]

Plasma and Fusion Research

Volume 3, S1064 (2008)

Regular Articles

Observation of the Internal Structure of Energetic Particle-Driven MHD Modes in a Large Helical Device
Tokihiko TOKUZAWA, Akira EJIRI1), Kazuo KAWAHATA and LHD Experimental Group
National Institute for Fusion Science, Toki 509-5292, Japan
Graduate School of Frontier Sciences, Tokyo University, Kashiwa 277-8561, Japan
(Received 15 November 2007 / Accepted 7 March 2008 / Published 6 August 2008)


For the preparation study of a future burning plasma, experimental information about the internal structure of energetic particle-driven MHD instabilities, such as toroidal Alfvén eigenmodes, is important. In the Large Helical Device, three microwave reflectometer systems have been recently installed for measuring the density fluctuation in the wide radial region with a high spatial resolution. One of the three systems has three channels with fixed frequencies. The others are operated in a frequency-hopping mode. These systems are used for measuring the internal structures of an MHD mode and its temporal behaviors. Using these systems, strongly localized MHD instabilities driven by the energetic particles are measured in the plasma core region, and the measured values are consistent with the theoretical expectation.


Alfvén eigenmode, internal structure, MHD, density fluctuation, microwave reflectometer

DOI: 10.1585/pfr.3.S1064


  • [1] S.E. Sharapov et al., Phys. Rev. Lett. 93, 165001 (2004).
  • [2] R. Nazikian et al., Phys. Rev. Lett. 91, 125003 (2003).
  • [3] H. Kimura et al., Nucl. Fusion 38, 1303 (1998).
  • [4] S. Yamamoto et al., Nucl. Fusion 45, 326 (2005).
  • [5] C. Nührenberg, Phys. Plasmas 6, 137 (1999).
  • [6] O. Motojima et al., Nucl. Fusion 43, 1674 (2003).
  • [7] H. Nakanishi et al., Fusion Eng. Des. 66-68, 827(2003).
  • [8] L. Cupio et al., Rev. Sci. Instrum. 75, 3865 (2004).
  • [9] S. da Graca et al., Plasma Phys. Control. Fusion 49, 1849 (2007).
  • [10] T. Tokuzawa et al., 31st EPS Conf. P5-114 (2004).

This paper may be cited as follows:

Tokihiko TOKUZAWA, Akira EJIRI, Kazuo KAWAHATA and LHD Experimental Group, Plasma Fusion Res. 3, S1064 (2008).