Plasma and Fusion Research

Volume 3, S1038 (2008)

Regular Articles

Study of a Closed Divertor Configuration for the Three-Dimensionally Complicated Magnetic Structure in the LHD Plasma Periphery
Mamoru SHOJI, Masahiro KOBAYASHI, Suguru MASUZAKI, Atsushi IWAMAE1), Tsuguhiro WATANABE, Hiroshi YAMADA, Akio KOMORI and LHD experimental groups
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
1)
Department of Engineering Physics and Mechanics, Graduate School of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan
(Received 15 November 2007 / Accepted 19 March 2008 / Published 1 August 2008)

Abstract

The distribution of strike points in a closed divertor configuration with additional baffle plates installed in the toroidal ends of closed divertor components near lower/upper ports is calculated by tracing magnetic field lines from the last closed flux surface in various magnetic configurations (radial position of the magnetic axis, Rax = 3.50 ∼ 3.90 m). The calculation shows that the ratio of the number of strike points on additional plates is maximum for Rax = 3.60 m, showing that the plates are effective in this magnetic configuration. Neutral particle transport is investigated using a fully three-dimensional code EIRENE with one-dimensional plasma fluid analysis of divertor legs, where the plasma parameter profiles on the legs are obtained by an iterative calculation including interaction processes between the plasma and neutral particles. The plates raise the pressure of molecular hydrogen locally near the baffle plates to more than 0.2 Pa, which is enough for efficient particle control using vacuum pumping systems installed near the plates. The simulation proposes one possible candidate of optimized closed divertor configuration for the three-dimensionally complicated magnetic structure in the LHD plasma periphery.

Keywords

plasma edge transport, neutral particle transport, EIRENE, closed divertor, plasma fluid analysis, strike point, baffle plate

DOI: 10.1585/pfr.3.S1038

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This paper may be cited as follows:

Mamoru SHOJI, Masahiro KOBAYASHI, Suguru MASUZAKI, Atsushi IWAMAE, Tsuguhiro WATANABE, Hiroshi YAMADA, Akio KOMORI and LHD experimental groups, Plasma Fusion Res. 3, S1038 (2008).