Plasma and Fusion Research

Volume 3, S1077 (2008)

Regular Articles

First Demonstration of Rotational Transform Control by Electron Cyclotron Current Drive in Large Helical Device

Takashi NOTAKE, Takashi SHIMOZUMA, Shin KUBO, Hiroshi IDEI¹⁾, Katsumi IDA, Kiyomasa WATANABE, Satoru SAKAKIBARA, Taiki YAMAGUCHI²⁾, Mikirou YOSHINUMA, Takashi KOBUCHI³⁾, Shigeru INAGAKI¹⁾, Tokihiko TOKUZAWA, Yasuo YOSHIMURA, Hiroe IGAMI, Tetsuo SEKI, Hitoshi TANAKA⁴⁾, Kazunobu NAGASAKI⁴⁾ and LHD Experimental Group

National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
1): Research Institute for Applied Mechanics, Kyushu University, Fukuoka 816-8580, Japan
2): Fusion Research Development Division, Japan Atomic Energy Agency, Naka 311-0193, Japan
3): Faculty of engineering, Tohoku University, Sendai 980-8579, Japan
4): Graduate school of Energy Science, Kyoto University, Kyoto 606-8501, Japan

(Received 16 November 2007 / Accepted 5 February 2008 / Published 25 June 2008)

Abstract

An active current drive is a promising technique for improving plasma performances by controlling rotational transform and/or magnetic shear profiles in helical devices. A current drive based on electron cyclotron resonance heating is the most appropriate scheme for this purpose in terms of locality of driven current. Optimum conditions for an efficient electron cyclotron current drive (ECCD) in Large Helical Device (LHD) are being investigated using three-dimensional ray-tracing code, which can simulate propagation and power dissipation of electron cyclotron waves with large parallel refractive index. In the present experiment, inversion of directions of driven plasma current corresponding to injected ECCD modes was demonstrated successfully, and the results could be elucidated by the Fisch-Boozer theory. In addition, clear shifts of rotational transform were observed by motional Stark effect polarimetry. Our findings verified that the ECCD can be used as an effective actuator for controlling the rotational transform and magnetic shear profile in LHD.

Keywords

electron cyclotron current drive, magnetic shear control, rotational transform control, motional stark effect, large helical device

DOI: 10.1585/pfr.3.S1077

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References

[1] O. Sauter, M.A. Henderson, F. Hofmann, T. Goodman et al., Phys. Rev. Lett. 84, 3322 (2000).
[2] T.C. Luce, Y.R. Lin-Liu, R.W. Harvey, G. Giruzzi et al., Phys. Rev. Lett. 83, 4550 (1999).
[3] T. Suzuki, S. Ide, K. Hamamatsu, A. Isayama, T. Fujita et al., Nucl. Fusion 44, 699 (2004).
[4] V. Erckmann and U. Gasparino, Plasma Phys. Control. Fusion 36, 1869 (1994).
[5] R. Prater, Phys. Plasmas 11, 2349 (2004).
[6] H. Maabberg, M. Rome, V. Erckmann et al., Plasma Phys Control. Fusion 47,1137 (2005).
[7] A. Fernandez et al., to be published in Fusion Science and Technology.
[8] M. Rome, V. Erckmann, H.P. Laqua et al., Plasma Phys. Control. Fusion 45, 783 (2003).
[9] V. Tribaldos, J.A. Jimenez, J. Guasp and B.P. Milligen, Plasma Phys. Control. Fusion 40, 2113 (1998).
[10] O. Motojima, H. Yamada, A. Komori, N. Ohyabu et al., Nucl. Fusion 47, 668 (2007).
[11] A. Komori, N. Ohyabu, H. Yamada, O. Kaneko et al., Plasma Phys. Control. Fusion 45, 671 (2003).
[12] T. Notake, S. Ito, S. Kubo et al., Trans. Fusion Scie. Technol. 51, 409 (2007).
[13] T. Notake, H. Idei, T. Shimozuma, M. Sato et al., Fusion Eng. Des. 73, 9 (2005).
[14] J.L. Doane, Infrared and Millimeter Waves 13, chapter 5 (1985).
[15] T. Notake, H. Idei, S. Kubo, T.Shimozuma et al., Rev. Sci. Instrum. 76, 023504 (2005).
[16] P.U. Lamalle et al., Trans. Fusion Sci. Technol. 45, 153 (2004).
[17] E. Westerhof et al., Trans. Fusion Sci. Technol. 45, 159 (2004).
[18] S. Kubo, T. Shimozuma, H. Idei et al., J. Plasma Fusion Res. Series 5, 584 (2002).
[19] M.Bornatciti, Nucl. Fusion 23, 1153 (1983).
[20] Nathaniel J. Fisch, Rev. Mod. Phys. 59, 175 (1987).
[21] T. Notake, S. Kubo, T.Shimozuma et al., Plasma Phys. Control. Fusion 47, 531 (2005).
[22] T. Shimozuma, S. Kubo, H. Idei, S. Inagaki et al., Nucl. Fusion 45, 1396 (2005).
[23] F.M. Levinton, R.J. Fonck et al., Phys. Rev. lett. 63, 2060 (1989).
[24] T. Suzuki, S. Ide, T. Oikawa et al., Plasma Phys. and Control. Fusion 44, 1 (2002).
[25] K. Ida, M. Yoshinuma, K.Y. Watanabe et al., Rev. Sci. Instrum. 76, 053505 (2005).

This paper may be cited as follows:

Takashi NOTAKE, Takashi SHIMOZUMA, Shin KUBO, Hiroshi IDEI, Katsumi IDA, Kiyomasa WATANABE, Satoru SAKAKIBARA, Taiki YAMAGUCHI, Mikirou YOSHINUMA, Takashi KOBUCHI, Shigeru INAGAKI, Tokihiko TOKUZAWA, Yasuo YOSHIMURA, Hiroe IGAMI, Tetsuo SEKI, Hitoshi TANAKA, Kazunobu NAGASAKI and LHD Experimental Group, Plasma Fusion Res. 3, S1077 (2008).