[Table of Contents]

Plasma and Fusion Research

Volume 2, 037 (2007)

Regular Articles


A Simultaneous Spectroscopic Measurement of the Global and Edge Local Structures in the Ion Temperature and Plasma Rotation Profiles in the Compact Helical System
Shin NISHIMURA, Ken-ichi NAGAOKA, Yasuo YOSHIMURA, Kiichiro NAKAMURA, Harukazu IGUCHI, Tsuyoshi AKIYAMA, Takashi MINAMI, Tetsutaro OISHI, Katsumi IDA, Kazuo TOI, Akihiro SHIMIZU, Mitsutaka ISOBE, Chihiro SUZUKI, Chihiro TAKAHASHI, Shoichi OKAMURA, Keisuke MATSUOKA and CHS Group
National Institute for Fusion Science
(Received 8 February 2007 / Accepted 27 April 2007 / Published 31 July 2007)

Abstract

In charge exchange spectroscopy (CXS), a simultaneous observation in different plasma toroidal cross sections and/or viewing ports is required to investigate radial distributions of ion temperatures Ti(r), and poloidal rotation velocities Vp(r) in magnetically confined toroidal plasmas. In recent studies of the edge transport barrier (ETB) in the Compact Helical System (CHS), a simultaneous viewing of the vertically elongated and the horizontally elongated plasma cross sections is used to improve the spatial resolution at the edge region. The 90 fibers used for this purpose are connected to one spectrometer, and a 256 × 243 pixel sampling CCD is used to detect the diffraction image. It is found that there is a localized edge ion temperature pedestal region with ΔTi ≈ 100 eV and Δr/a ≈ 0.1, where r and a are flux surface averaged minor radii of measured surfaces and the outermost flux surface, respectively. The negative radial electric field at the edge is increased in the high confinement phase because of the increased ion pressure.


Keywords

visible spectroscopy, non-symmetric toroidal configuration, plasma transport, improved confinement, transport barrier

DOI: 10.1585/pfr.2.037


References

  • [1] R.J. Fonck et al., Phys. Rev. A 29, 3288 (1984).
  • [2] K. Ida and S. Hidekuma, Rev. Sci. Instrum. 60, 867 (1989).
  • [3] ITER Physics Expert Group, Nucl. Fusion 39, 2175 (1999).
  • [4] A. Fujisawa et al., Phys. Rev. Lett. 82, 2669 (1999).
  • [5] T. Minami et al., Nucl. Fusion 44, 342 (2004).
  • [6] S. Okamura et al., Nucl. Fusion 45, 863 (2005).
  • [7] T. Akiyama, S. Okamura, T. Minami et al., Plasma Phys. Control. Fusion 48, 1683 (2006).
  • [8] S. Nishimura et al., Ann. Rep of NIFS 2005 p.271, p.272.
  • [9] K.C. Shaing et al., Phys. Fluids 29, 521 (1986); H. Sugama and W. Horton, Phys. Plasmas 3, 304 (1996).
  • [10] K. Ida et al., Rev. Sci. Instrum. 71, 2360 (2000).
  • [11] S. Nishimura et al., Phys. Plasmas 7, 437 (2000).
  • [12] K. Nakamura et al., Rev. Sci. Instrum. 76, 013504 (2005).
  • [13] A.R. Field, G. Fussmann et al., Nucl. Fusion 32, 1191 (1992).
  • [14] H. Yamada, K. Ida et al., Nucl. Fusion 32, 25 (1992).
  • [15] S. Nishimura et al., Fusion Sci. Technol. 46, 77 (2004).
  • [16] K.C. Shaing, Phys. Fluids B5, 3841 (1993).

This paper may be cited as follows:

Shin NISHIMURA, Ken-ichi NAGAOKA, Yasuo YOSHIMURA, Kiichiro NAKAMURA, Harukazu IGUCHI, Tsuyoshi AKIYAMA, Takashi MINAMI, Tetsutaro OISHI, Katsumi IDA, Kazuo TOI, Akihiro SHIMIZU, Mitsutaka ISOBE, Chihiro SUZUKI, Chihiro TAKAHASHI, Shoichi OKAMURA, Keisuke MATSUOKA and CHS Group, Plasma Fusion Res. 2, 037 (2007).