[Table of Contents]

Plasma and Fusion Research

Volume 5, S2004 (2010)

Regular Articles


Progress in Impurity-Related Physics Experiments in LHD
Shigeru MORITA, Chunfeng DONG1), Motoshi GOTO, Masahiro KOBAYASHI, Sadatsugu MUTO, Kozo YAMAZAKI2), Masayuki YOKOYAMA, Hangyu ZHOU1), Tsuyoshi AKIYAMA, Naoko ASHIKAWA, Zhengying CUI3), Keisuke FUJII4), Xiang GAO5), Masahiro HASUO4), Katsumi IDA, Katsunori IKEDA, Atsushi IWAMAE6), Osamu KANEKO, Suguru MASUZAKI, Junichi MIYAZAWA, Tomohiro MORISAKI, Kenichi NAGAOKA, Kazumichi NARIHARA, Satoshi OHDACHI, Masaki OSAKABE, Satoru SAKAKIBARA, Ryuichi SAKAMOTO, Mamoru SHOJI, Yasuhiko TAKEIRI, Kenji TANAKA, Kazuo TOI, Masayuki TOKITANI, Tokihiko TOKUZAWA, Katsuyoshi TSUMORI, Kiyomasa WATANABE, Hiroshi YAMADA, Ichihiro YAMADA, Jun YANAGIBAYASHI4), Mikiro YOSHINUMA, Akio KOMORI and LHD experiment group
National Institute for Fusion Science, Toki 509-5292, Gifu, Japan
1)
Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu, Japan
2)
Department of Energy Engineering and Science, Nagoya University, Nagoya 464-8603, Japan
3)
Southwestern Institute of Physics, Chengdu 610041, China
4)
Department of Engineering Physics, Kyoto University, Kyoto 606-8502, Japan
5)
Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031, China
6)
Naka Fusion Institute, Japan Atomic Energy Agency, Naka 311-0193, Ibaraki, Japan
(Received 18 February 2010 / Accepted 6 May 2010 / Published 10 December 2010)

Abstract

A variety of density profiles observed in the Large Helical Device (LHD) have suggested an interesting core impurity transport. The edge impurity transport in the ergodic layer formed by stochastic magnetic field lines with long connection length (10-2000 m) can also exhibit interesting phenomena in the competition of perpendicular and parallel transport. The LHD discharge is highly robust against impurity buildup, and operation is possible essentially up to the global power balance limit because current-driven instability does not principally exist. The LHD plasma has therefore provided information on many interesting physics issues closely related to impurities. Recent results of impurity-related physics experiments in the LHD are briefly reviewed. The specific contents presented here are (1) core impurity behavior with perpendicular transport, (2) edge impurity behavior with parallel transport, (3) high-Z discharges with high ion temperature, (4) impurity pellet injection with improved plasma performance, (5) impurity pellet ablation in the presence of energetic ions with high heat flux and (6) observation of magnetic dipole forbidden transitions for high-Z elements. A result from the Compact Helical System (CHS) is used only in the impurity pellet ablation study, because detailed data have not yet been obtained from the LHD. Finally, the results are summarized and future directions in these topics are noted.


Keywords

impurity transport, high ion temperature, high-Z discharge, impurity pellet injection

DOI: 10.1585/pfr.5.S2004


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This paper may be cited as follows:

Shigeru MORITA, Chunfeng DONG, Motoshi GOTO, Masahiro KOBAYASHI, Sadatsugu MUTO, Kozo YAMAZAKI, Masayuki YOKOYAMA, Hangyu ZHOU, Tsuyoshi AKIYAMA, Naoko ASHIKAWA, Zhengying CUI, Keisuke FUJII, Xiang GAO, Masahiro HASUO, Katsumi IDA, Katsunori IKEDA, Atsushi IWAMAE, Osamu KANEKO, Suguru MASUZAKI, Junichi MIYAZAWA, Tomohiro MORISAKI, Kenichi NAGAOKA, Kazumichi NARIHARA, Satoshi OHDACHI, Masaki OSAKABE, Satoru SAKAKIBARA, Ryuichi SAKAMOTO, Mamoru SHOJI, Yasuhiko TAKEIRI, Kenji TANAKA, Kazuo TOI, Masayuki TOKITANI, Tokihiko TOKUZAWA, Katsuyoshi TSUMORI, Kiyomasa WATANABE, Hiroshi YAMADA, Ichihiro YAMADA, Jun YANAGIBAYASHI, Mikiro YOSHINUMA, Akio KOMORI and LHD experiment group, Plasma Fusion Res. 5, S2004 (2010).