[Table of Contents]

Plasma and Fusion Research

Volume 3, S1032 (2008)

Regular Articles

Effect of Ellipticity on Thermal Transport in ECH Plasmas in LHD
Hiroshi YAMADA, Masayuki YOKOYAMA, Sadayoshi MURAKAMI1), Kiyomasa WATANABE, Hisamichi FUNABA, Yoshiro NARUSHIMA, Satoru SAKAKIBARA, Tomohiro MORISAKI, Yoshio NAGAYAMA, Shin KUBO, Takashi SHIMOZUMA, Kenji TANAKA, Tokihiko TOKUZAWA, Ichihiro YAMADA and LHD Experimental Group
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292, Japan
1)
Department of Nuclear Engineering, Kyoto University, Yoshida-honmachi, Sakyo, Kyoto 606-8501, Japan
(Received 9 December 2007 / Accepted 12 February 2008 / Published 5 August 2008)

Abstract

Effect of ellipticity on thermal transport was investigated in ECH plasmas in LHD. Ellipticity κ is scanned from 0.8 to 1.4 by controlling the quadrupole magnetic field. Experimental data of energy confinement time align with the scaling for all configurations; however, there exist systematic offsets. Performance τEexp /τEISS04 is summarized as 0.94 ± 0.02 for κ = 0.8, 1.41 ± 0.07 for κ = 1.0, and 0.91± 0.03 for κ = 1.4. Local transport analysis based on power balance indicates that the anomalous transport predominates the plasma transport. However, the observed anomaly shows correlation with the change in the effective helical ripple εeff. Physical background of this correlation and the dependence on the poloidal viscous damping rate Cp is discussed. The present experimental comparison suggests a negative evidence for the relevance of Cp.

Keywords

thermal transport, configuration effect, neoclassical transport, anomalous transport, net-current free plasmas, ellipticity

DOI: 10.1585/pfr.3.S1032

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References

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This paper may be cited as follows:

Hiroshi YAMADA, Masayuki YOKOYAMA, Sadayoshi MURAKAMI, Kiyomasa WATANABE, Hisamichi FUNABA, Yoshiro NARUSHIMA, Satoru SAKAKIBARA, Tomohiro MORISAKI, Yoshio NAGAYAMA, Shin KUBO, Takashi SHIMOZUMA, Kenji TANAKA, Tokihiko TOKUZAWA, Ichihiro YAMADA and LHD Experimental Group, Plasma Fusion Res. 3, S1032 (2008).