Two-dimensional plasma structure in the edge region of the compact helical system

K. Nakamura, H. Iguchi, J. Schweinzer, A. Shimizu, M. Isobe, C. Takahashi, S. Nishimura, C. Suzuki, Y. Yoshimura, K. Nagaoka, T. Minami, T. Akiyama, K. Ida, K. Matsuoka, S. Okamura

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Two-dimensional edge plasma structures of the l ≤ 2 helical system CHS have been investigated with the use of a neutral lithium beam probe. Two different types of edge magnetic configuration have been compared, namely, an inboard-wall limiter configuration and an ergodic magnetic divertor configuration which is intrinsic to non-axisymmetric helical devices. The scrape-off plasma in the limiter configuration is essentially one-dimensional and the radial scale length is well described by a simple diffusion model with finite connection length of the magnetic field line. While in the ergodic divertor configuration, edge plasma structure shows up-down asymmetry in the steady state near the outer separatrix region regardless of the symmetric magnetic structure. The asymmetry reverses when the magnetic field direction is reversed. Plasma shift is apparently in the direction of ion B × ∇B drift. The result suggests that plasma equilibrium in the ergodic layer is not determined simply by the magnetic field structure. The effect of plasma flow and drift motions would be important. Such asymmetry in plasma structure may induce non-uniform heat deposition on the divertor plates. Modelling of plasma equilibrium in the ergodic layer is necessary for practical helical divertor design.

Original languageEnglish
Article number002
Pages (from-to)251-256
Number of pages6
JournalNuclear Fusion
Volume47
Issue number4
DOIs
Publication statusPublished - Apr 1 2007

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configurations
plasma equilibrium
asymmetry
magnetic fields
plasma drift
magnetohydrodynamic flow
lithium
heat
probes
shift
ions

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

Cite this

Nakamura, K., Iguchi, H., Schweinzer, J., Shimizu, A., Isobe, M., Takahashi, C., ... Okamura, S. (2007). Two-dimensional plasma structure in the edge region of the compact helical system. Nuclear Fusion, 47(4), 251-256. [002]. https://doi.org/10.1088/0029-5515/47/4/002

Two-dimensional plasma structure in the edge region of the compact helical system. / Nakamura, K.; Iguchi, H.; Schweinzer, J.; Shimizu, A.; Isobe, M.; Takahashi, C.; Nishimura, S.; Suzuki, C.; Yoshimura, Y.; Nagaoka, K.; Minami, T.; Akiyama, T.; Ida, K.; Matsuoka, K.; Okamura, S.

In: Nuclear Fusion, Vol. 47, No. 4, 002, 01.04.2007, p. 251-256.

Research output: Contribution to journalArticle

Nakamura, K, Iguchi, H, Schweinzer, J, Shimizu, A, Isobe, M, Takahashi, C, Nishimura, S, Suzuki, C, Yoshimura, Y, Nagaoka, K, Minami, T, Akiyama, T, Ida, K, Matsuoka, K & Okamura, S 2007, 'Two-dimensional plasma structure in the edge region of the compact helical system', Nuclear Fusion, vol. 47, no. 4, 002, pp. 251-256. https://doi.org/10.1088/0029-5515/47/4/002
Nakamura K, Iguchi H, Schweinzer J, Shimizu A, Isobe M, Takahashi C et al. Two-dimensional plasma structure in the edge region of the compact helical system. Nuclear Fusion. 2007 Apr 1;47(4):251-256. 002. https://doi.org/10.1088/0029-5515/47/4/002
Nakamura, K. ; Iguchi, H. ; Schweinzer, J. ; Shimizu, A. ; Isobe, M. ; Takahashi, C. ; Nishimura, S. ; Suzuki, C. ; Yoshimura, Y. ; Nagaoka, K. ; Minami, T. ; Akiyama, T. ; Ida, K. ; Matsuoka, K. ; Okamura, S. / Two-dimensional plasma structure in the edge region of the compact helical system. In: Nuclear Fusion. 2007 ; Vol. 47, No. 4. pp. 251-256.
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