[Table of Contents]

Plasma and Fusion Research

Volume 6, 1402017 (2011)

Regular Articles

Long Range Temperature Fluctuation in LHD
Shigeru INAGAKI1,2), Tokihiko TOKUZAWA3), Kimitaka ITOH2,3), Katsumi IDA2,3), Sanae-I. ITOH1,2), Naoki TAMURA3), Satoru SAKAKIBARA3), Naohiro KASUYA3), Akihide FUJISAWA1,2), Shin KUBO3), Takashi SHIMOZUMA3), Takeshi IDO3), Seiya NISHIMURA3), Hiroyuki ARAKAWA4), Tatsuya KOBAYASHI4), Masatoshi YAGI1,2), Kenji TANAKA3), Yoshio NAGAYAMA3), Kazuo KAWAHATA3), Shigeru SUDO3), Hiroshi YAMADA3), Akio KOMORI3) and LHD Experiment Group
1)
Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan
2)
Itoh Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580, Japan
3)
National Institute for Fusion Science, Toki 502-5292, Japan
4)
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga 816-8580, Japan
(Received 31 August 2010 / Accepted 11 January 2011 / Published 15 April 2011)

Abstract

We report a detailed correlation technique to identify the long-range temperature fluctuation in the Large Helical Device. Correlation hunting has successfully realized the observation of electron temperature fluctuations, which are characterized by their correlation length comparable to the plasma minor radius, with low frequency of ∼ 1-3 kHz, ballistic radial propagation (at a speed of ∼1 km/s, of the order of diamagnetic drift velocity), spatial mode number of m/n = 1/1 (or 2/1), and amplitude of ∼2% at the maximum. Bicoherence analysis confirmed their nonlinear coupling with local microscopic turbulent fluctuations. This long-range temperature fluctuation is a possible carrier of fast propagation in transport processes observed so far. We also comment on the theoretical interpretation.

Keywords

electron temperature fluctuation, correlation length, transient transport, toroidal plasma, modulational coupling

DOI: 10.1585/pfr.6.1402017

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This paper may be cited as follows:

Shigeru INAGAKI, Tokihiko TOKUZAWA, Kimitaka ITOH, Katsumi IDA, Sanae-I. ITOH, Naoki TAMURA, Satoru SAKAKIBARA, Naohiro KASUYA, Akihide FUJISAWA, Shin KUBO, Takashi SHIMOZUMA, Takeshi IDO, Seiya NISHIMURA, Hiroyuki ARAKAWA, Tatsuya KOBAYASHI, Masatoshi YAGI, Kenji TANAKA, Yoshio NAGAYAMA, Kazuo KAWAHATA, Shigeru SUDO, Hiroshi YAMADA, Akio KOMORI and LHD Experiment Group, Plasma Fusion Res. 6, 1402017 (2011).