[Table of Contents]

Plasma and Fusion Research

Volume 10, 3402061 (2015)

Regular Articles

Observation of Intermittent Transition by Electrode Biasing in Heliotron J
Kosuke SHIMIZU, Sumio KITAJIMA, Atsushi OKAMOTO, Yu SATO, Jo TACHIBANA, Toshihiro OKU, Masakazu TAKAYAMA1), Fumimichi SANO2), Tohru MIZUUCHI2), Kazunobu NAGASAKI2), Hiroyuki OKADA2), Shinichiro KADO2), Shinji KOBAYASHI2), Satoshi YAMAMOTO2), Shinsuke OHSHIMA2), Yasuhiro SUZUKI3), Masayuki YOKOYAMA3) and Hiromi TAKAHASHI3)
Department of Quantum Science and Energy Engineering, Tohoku University, Sendai 980-8579, Japan
1)
Akita Prefectural University, Honjyo, Akita 015-0055, Japan
2)
Institute of Advanced Energy, Kyoto University, Gokasho, Uji 611-0011, Japan
3)
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
(Received 21 November 2014 / Accepted 3 March 2015 / Published 26 May 2015)

Abstract

We observed intermittent increases in the electrode current in electrode biasing experiments in Heliotron J. In addition, electron density and floating potential showed pulsating behavior associated with the electrode current. The relation between line density and electrode current and that between floating potential and electrode current showed a hysteresis feature in transitions. Then it is evident that the pulsating behavior was the intermittent transition between two distinctive states. We also observed the mode (∼10 kHz) that accompanied the pulsating behavior in the power spectrum density of the floating potential and ion saturation current obtained via fast Fourier transform. The electron density gradient increased, and subsequently the power spectrum density of the fluctuation increased.

Keywords

stellarator, heliotron, electrode biasing, H-mode transition, turbulent transport, pulsation

DOI: 10.1585/pfr.10.3402061

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References

  • [1] S. Kitajima et al., Nucl. Fusion 46, 200 (2006).
  • [2] S. Kitajima et al., Nucl. Fusion 53, 073014 (2013).
  • [3] K. Itoh et al., Plasma Fusion Res. 8, 1102168 (2013).
  • [4] G.D. Conway et al., Phys. Rev. Lett. 106, 65001 (2011).
  • [5] L. Schmitz et al., Phys. Rev. Lett. 108, 155002 (2012).
  • [6] J. Cheng et al., Phys. Rev. Lett. 110, 265002 (2013).
  • [7] T. Kobayashi et al., Phys. Rev. Lett. 111, 035002 (2013).
  • [8] S. Ohshima et al., Rev. Sci. Instrum. 81, 10E137 (2010).
  • [9] A. Fujisawa et al., Phys. Rev. Lett. 81, 2256 (1998).
  • [10] G. Van Oost et al., Plasma Phys. Control. Fusion 45, 621 (2003).
  • [11] H. Takahashi et al., Plasma Phys. Control. Fusion 48, 39 (2006).

This paper may be cited as follows:

Kosuke SHIMIZU, Sumio KITAJIMA, Atsushi OKAMOTO, Yu SATO, Jo TACHIBANA, Toshihiro OKU, Masakazu TAKAYAMA, Fumimichi SANO, Tohru MIZUUCHI, Kazunobu NAGASAKI, Hiroyuki OKADA, Shinichiro KADO, Shinji KOBAYASHI, Satoshi YAMAMOTO, Shinsuke OHSHIMA, Yasuhiro SUZUKI, Masayuki YOKOYAMA and Hiromi TAKAHASHI, Plasma Fusion Res. 10, 3402061 (2015).