[Table of Contents]

Plasma and Fusion Research

Volume 6, 2401082 (2011)

Regular Articles

Observation of Nonlinear Coupling between Low Frequency Coherent Modes and Background Turbulence in LMD-U
Tatsuya KOBAYASHI, Shigeru INAGAKI1,2), Hiroyuki ARAKAWA, Stella OLDENBÜRGER2), Makoto SASAKI1,2), Yoshihiko NAGASHIMA2,3), Takuma YAMADA2,3), Satoru SUGITA, Masatoshi YAGI1,2), Naohiro KASUYA2,4), Akihide FUJISAWA1,2), Sanae-I. ITOH1,2) and Kimitaka ITOH2,4)
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka 816-8580, Japan
1)
Research Institute for Applied Mechanics, Kyushu University, Fukuoka 816-8580, Japan
2)
Itoh Research Center for Plasma Turbulence, Kyushu University, Fukuoka 816-8580, Japan
3)
Graduate School of Frontier Sciences, The University of Tokyo, Tokyo 277-8561, Japan
4)
National Institute for Fusion Science, Toki 509-5292, Japan
(Received 7 December 2010 / Accepted 10 May 2011 / Published 12 July 2011)

Abstract

A solitary wave like fluctuating structure is observed in the Large Mirror Device-Upgrade (LMD-U) under relatively high neutral pressure conditions. Ion saturation current fluctuations are measured and Fourier and wavelet power spectra are calculated. Temporal behavior of fluctuation power and strength of nonlinear coupling of low frequency coherent mode and background turbulence in a specific frequency region is analyzed. This is achieved using wavelet spectral and bispectral analyses with conditional averaging.

Keywords

linear plasma, drift wave, turbulence, bispectral analysis, wavelet analysis, nonlinear coupling

DOI: 10.1585/pfr.6.2401082

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This paper may be cited as follows:

Tatsuya KOBAYASHI, Shigeru INAGAKI, Hiroyuki ARAKAWA, Stella OLDENBÜRGER, Makoto SASAKI, Yoshihiko NAGASHIMA, Takuma YAMADA, Satoru SUGITA, Masatoshi YAGI, Naohiro KASUYA, Akihide FUJISAWA, Sanae-I. ITOH and Kimitaka ITOH, Plasma Fusion Res. 6, 2401082 (2011).