[Table of Contents]

Plasma and Fusion Research

Volume 2, S1077 (2007)

Regular Articles

Effects of Radially Sheared Electric Field on Turbulence Reduction Analyzed with End-Loss Analysing Systems
Mafumi HIRATA, Teruji CHO, Junko KOHAGURA, Tomoharu NUMAKURA, Serina KIMINAMI, Marie ITO, Naoyuki MORIMOTO, Katsuaki HIRAI, Tooru YAMAGISHI, Toshinori IKUNO, Shohei NAMIKI, Yoshiaki MIYATA, Ryutaro MINAMI, Kazuo OGURA1), Takashi KONDOH2), Tsuyoshi KARIYA, Tsuyoshi IMAI and Syoichi MIYOSHI
Plasma Research Center, University of Tsukuba, Ibaraki 305-8577, Japan
1)
Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan
2)
Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan
(Received 9 December 2006 / Accepted 17 April 2007 / Published 20 November 2007)

Abstract

Mirror devices, having open-ended regions, provide intrinsic important advantages in terms of the control of radial-potential or Er shear profiles on the basis of axial particle loss control for ambipolar potential formation. From the viewpoint of the mechanism investigation of radially localized transport-barrier formation, an idea of off-axis-resonant electron-cyclotron heating (ECH) is proposed and applied in the tandem mirror GAMMA 10, by the use of the aforementioned intrinsic advantage of mirror devices. The off-axis ECH produces a cylindrical layer with energetic electrons and facilitates the formation for a localized bumped ambipolar potential with a strong shear of radial electric fields Er. Remarkable effects of dEr/dr on the suppression of turbulent fluctuations with plasma confinement improvement are found by the use of signals of end-loss currents flowing from the central cell as well as the central-cell soft x ray. In association with the reduction of the fluctuations due to strong Er shear formation, increases in ion and electron temperatures are found.

Keywords

tandem mirror, radially sheared electric field, electron-cyclotron heating, transport-barrier, end-loss analyzer

DOI: 10.1585/pfr.2.S1077

Full Text

PDF format (412Kbytes) PDF Download

References

  • [1] P.H. Diamond et al., Plasma Phys. Control. Fusion 47, R35 (2005).
  • [2] Y. Kishimoto et al., Nucl. Fusion 40, 667 (2000).
  • [3] V.P. Pastukhov Plasma Phys. Reports 31, 577 (2005).
  • [4] T. Cho et al., Phys. Rev. Lett. 97, 055001 (2006).
  • [5] T. Cho et al., Nuclear Fusion 45, 1650 (2005).
  • [6] T. Cho et al., Phys. Rev. Lett. 94, 085002 (2005).
  • [7] M. Hirata et al., Trans. Fusion Sci. Tech. 47, 215 (2005).
  • [8] T. Cho et al., Trans. Fusion Sci. Tech. 47, 9 (2005).
  • [9] T. Cho et al., J. Plasma Fusion Research 80, 81 (2004).
  • [10] T. Cho et al., Nuclear Fusion 43, 293 (2003).
  • [11] T. Cho et al., Phys. Rev. Lett. 86, 4310 (2001).
  • [12] T. Numakura et al., Trans. Fusion Sci. Tech. 43, 222 (2003)
  • [13] M. Hirata et al., Nucl. Fusion 31, 752 (1991).
  • [14] G.I. Dimov, J. Fusion Energy 19, 87 (2001).
  • [15] T. Cho et al., Nuclear Fusion 41, 1161 (2001).
  • [16] T. Cho et al., Phys. Rev. A45, 2532 (1992).
  • [17] T. Cho et al., Phys. Rev. Lett. 64, 1373 (1990).
  • [18] M. Hirata et al., Jpn. J. Appl. Phys. 28, 96 (1989).
  • [19] T. Cho et al., Nucl. Fusion 28, 2187 (1988).
  • [20] T. Cho et al., Nucl. Fusion 27, 1421 (1987).
  • [21] M. Hirata et al., Nucl. Instrum. Methods B66, 479 (1992).
  • [22] T. Cho et al., Nucl. Instrum. Methods A348, 475 (1994).
  • [23] T. Cho et al., Phys. Rev. A 46, 3024 (1992).
  • [24] J. Kohagura et al., Phys. Rev. E56, 5884 (1997).
  • [25] M. Hirata et al., Rev. Sci. Instrum. 66, 2311 (1995).
  • [26] M. Hirata et al., Nucl. Instrum. Methods A477, 210 (2002).
  • [27] T. Numakura et al., Plasma Phys. Control. Fusion 45, 807 (2003).
  • [28] J. Kohagura et al., Rev. Sci. Instrum. 66, 2317 (1995).
  • [29] Y. Sakamoto et al., Rev. Sci. Instrum. 66, 4928 (1995).
  • [30] M. Hirata et al., Rev. Sci. Instrum. 74, 1913 (2003).
  • [31] M. Hirata et al., Trans. Fusion Tech. 39, 281 (2001).
  • [32] M. Hirata et al., Rev. Sci. Instrum. 75, 3631 (2004).

This paper may be cited as follows:

Mafumi HIRATA, Teruji CHO, Junko KOHAGURA, Tomoharu NUMAKURA, Serina KIMINAMI, Marie ITO, Naoyuki MORIMOTO, Katsuaki HIRAI, Tooru YAMAGISHI, Toshinori IKUNO, Shohei NAMIKI, Yoshiaki MIYATA, Ryutaro MINAMI, Kazuo OGURA, Takashi KONDOH, Tsuyoshi KARIYA, Tsuyoshi IMAI and Syoichi MIYOSHI, Plasma Fusion Res. 2, S1077 (2007).