Plasma and Fusion Research

Volume 3, S1005 (2008)

Regular Articles

Impurity Retention Effect in the Edge Ergodic Layer of the Large Helical Device

Masahiro KOBAYASHI, Yuehe FENG¹⁾, Sigeru MORITA, Kuninori SATO, Malay Bikas CHOWDHURI²⁾, Suguru MASUZAKI, Mamoru SHOJI, Yukio NAKAMURA, Masayuki TOKITANI, Nobuyoshi OHYABU, Motoshi GOTO, Tomohiro MORISAKI, Ichihiro YAMADA, Kazumichi NARIHARA, Naoko ASHIKAWA, Hiroshi YAMADA, Akio KOMORI, Osamu MOTOJIMA and the LHD experimental group

National Institute for Fusion Science, Toki 509-5292, Japan
1): Max-Planck-Institute fuer Plasmaphysik, Wendelsteinstrasse 1, D-17491 Greifswald, Germany
2): Graduate University for Advanced Studies, Toki, Gifu 509-5292, Japan

(Received 30 November 2007 / Accepted 12 March 2008 / Published 5 August 2008)

Abstract

The impurity transport characteristics in the ergodic layer of the Large Helical Device (LHD) are analyzed using the 3D edge transport code (EMC3-EIRENE), in comparison with the experimental data. The 3D modeling predicts the impurity retention (screening) in the ergodic layer at the high-density plasma. It is found that the edge surface layer plays an important role in impurity retention, where the friction force significantly dominates over the thermal force. The line intensity measurements of CIII to CVI show consistent behavior with the modeling, indicating impurity retention in the ergodic layer. The applicability of the model for high-Z impurity is also discussed, and it is found that the experimental data is consistent with the results of edge transport modeling.

Keywords

ergodic layer, impurity transport, LHD

DOI: 10.1585/pfr.3.S1005

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This paper may be cited as follows:

Masahiro KOBAYASHI, Yuehe FENG, Sigeru MORITA, Kuninori SATO, Malay Bikas CHOWDHURI, Suguru MASUZAKI, Mamoru SHOJI, Yukio NAKAMURA, Masayuki TOKITANI, Nobuyoshi OHYABU, Motoshi GOTO, Tomohiro MORISAKI, Ichihiro YAMADA, Kazumichi NARIHARA, Naoko ASHIKAWA, Hiroshi YAMADA, Akio KOMORI, Osamu MOTOJIMA and the LHD experimental group, Plasma Fusion Res. 3, S1005 (2008).