Plasma and Fusion Research

Volume 3, 029 (2008)

Rapid Communications

Quasi-Periodic Growth of a Single Helical Instability in a Low-Aspect Ratio RFP
Ryuya IKEZOE, Takumi ONCHI, Kensuke OKI, Akio SANPEI, Haruhiko HIMURA and Sadao MASAMUNE
Kyoto Institute of Technology, Kyoto 606-8585, Japan
(Received 6 April 2008 / Accepted 2 May 2008 / Published 30 May 2008)

Abstract

Quasi-periodic growth of a single core-resonant instability has been observed in a low-aspect ratio (low-A) reversed field pinch experiment in RELAX. In round-topped current discharges, the innermost core resonant m = 1/n = 4 mode grows with suppression of the neighboring m = 1/n = 5, 6 modes. The resultant toroidal mode spectrum of the m = 1 modes is similar to that of the quasi-single helicity (QSH) state with higher amplitudes. These phenomena are discussed along with the low-A characteristic of RELAX, indicating simpler MHD mode dynamics and easier access to the QSH state.

Keywords

RFP, aspect ratio, magnetic fluctuation, tearing mode, mode dynamics

DOI: 10.1585/pfr.3.029

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References

  • [1] J.S. Sarff et al., Nucl. Fusion 43, 1684 (2003).
  • [2] B. Chapman et al., Bull. Am. Phys. Soc. 51, JP8.00116 (2007).
  • [3] D.F. Escande et al., Phys. Rev Lett. 85, 1662 (2000).
  • [4] S. Shiina et al., Phys. Plasmas 12, 080702 (2005).
  • [5] S. Masamune et al., J. Phys. Soc. Jpn. 76, 123501 (2007).
  • [6] Y. Hirano et al., Phys. Plasmas 13, 122511 (2006).
  • [7] L. Frassinetti et al., Phys. Plasmas 14, 112510 (2007).

This paper may be cited as follows:

Ryuya IKEZOE, Takumi ONCHI, Kensuke OKI, Akio SANPEI, Haruhiko HIMURA and Sadao MASAMUNE, Plasma Fusion Res. 3, 029 (2008).