[Table of Contents]

Plasma and Fusion Research

Volume 5, S2053 (2010)

Regular Articles

Turbulence Response in the High Ti Discharge of the LHD
Kenji TANAKA, Clive MICHAEL1), Leonid VYACHESLAVOV2), Hisamichi FUNABA, Masayuki YOKOYAMA, Katsumi IDA, Mikiro YOSHINUMA, Kenichi NAGAOKA, Sadayoshi MURAKAMI3), Arimitsu WAKASA3), Takeshi IDO, Akihiro SHIMIZU, Masaki NISHIURA, Yasuhiko TAKEIRI, Osamu KANEKO, Katsuyoshi TSUMORI, Katsunori IKEDA, Masaki OSAKABE, Kazuo KAWAHATA and LHD Experiment Group
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan
1)
UAKEA Fusion Association, Culham Science Center, Oxfordshire OX14 3 DB, United Kingdom
2)
Budker Institute of Nuclear Physics, 630090, Novosibirsk, Russia
3)
Department of Nuclear Engineering, Kyoto University, Kyoto 606-8501, Japan
(Received 30 December 2009 / Accepted 24 March 2010 / Published 10 December 2010)

Abstract

A high ion temperature (Ti) was achieved using a combination of perpendicular and parallel injected neutral beams in the Large Helical Device (LHD). Microturbulence spatial profiles in a high-Ti discharge were measured by two-dimensional phase contrast imaging (2D-PCI) through almost the entire vertical central chord. The 2D-PCI microturbulence spectral ranges covered wavenumbers (k) of 0.1-1 mm−1 and frequencies (f) of 20-500 kHz. The ion thermal conductivity (χi) increased in the entire region with increasing Ti. However, the difference between the experimental and neoclassical values of χi became smaller at ρ < 0.5, where ρ is the normalized position, in the high-Ti phase. Increasing fluctuation was not observed at this location, suggesting improved ion energy transport in this region. On the other hand, at ρ > 0.5, χi deviated from the neoclassical value due to enhancement of the experimental χi and reduction in the neoclassical χi by a positive radial electric field. Increasing turbulence was observed at ρ = 0.6-0.8, with fluctuations likely propagated to the ion diamagnetic direction in the plasma frame, suggesting that the observed turbulence degrades the ion energy transport at this location in the high-Ti phase.

Keywords

LHD, turbulence, phase contrast imaging, ion temperature gradient mode, neoclassical transport

DOI: 10.1585/pfr.5.S2053

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This paper may be cited as follows:

Kenji TANAKA, Clive MICHAEL, Leonid VYACHESLAVOV, Hisamichi FUNABA, Masayuki YOKOYAMA, Katsumi IDA, Mikiro YOSHINUMA, Kenichi NAGAOKA, Sadayoshi MURAKAMI, Arimitsu WAKASA, Takeshi IDO, Akihiro SHIMIZU, Masaki NISHIURA, Yasuhiko TAKEIRI, Osamu KANEKO, Katsuyoshi TSUMORI, Katsunori IKEDA, Masaki OSAKABE, Kazuo KAWAHATA and LHD Experiment Group, Plasma Fusion Res. 5, S2053 (2010).