TY - JOUR
T1 - Experimental study of nonlinear processes in edge turbulence of toroidal plasmas
AU - JFT-2M Group
AU - CHS Group
AU - Nagashima, Yoshihiko
AU - Hoshino, Katsumichi
AU - Nagaoka, Kenichi
AU - Shinohara, Kouji
AU - Fujisawa, Akihide
AU - Uehara, Kazuya
AU - Kusama, Yoshinori
AU - Ida, Katsumi
AU - Yoshimura, Yasuo
AU - Okamura, Shoichi
AU - Matsuoka, Keisuke
AU - Ejiri, Akira
AU - Takase, Yuichi
AU - Itoh, Kimitaka
AU - Yagi, Masatoshi
AU - Itoh, Sanae I.
N1 - Funding Information:
We are grateful to Dr. T. Ido, Prof. A. Fukuyama and Prof. P.H. Diamond for useful discussions. This work was carried out under the collaboration program between the Univ. of Tokyo and Naka Fusion Research Establishment of JAERI, and in the collaboration programmes of National Institute for Fusion Science and of Research Institute for AppliedMechanics, Kyushu University. This work was partially supported by Grant-in-Aid for Specially-Promoted Research (16002005) of MEXT Japan [Itoh project], by the 4-2-4 program of Kyushu University, by the collaboration programmes of the Research Institute for Applied Mechanics of Kyushu University and of National Institute for Fusion Science, and Grant-in-Aid for Scien-tific Research (15206106). The authors also appreciate the support of all members of the JFT-2M Group, and all members of the CHS group in carrying out the experiments.
PY - 2006
Y1 - 2006
N2 - This paper presents experimental studies of nonlinear processes between meso-scale structures and turbulent fluctuations, by use of bispectral analysis, in the edge region of toroidal plasmas. In ohmically heated plasmas of the JFT-2Mtokamak, the drift wave-zonal flow system is investigated by observation of the potential fluctuations. The total bicoherence is composed of two components, i.e., the peak at the geodesic acoustic mode (GAM) frequency and broadband distribution. The biphase is also obtained, which indicates the phase angle of coherent interaction between GAM oscillations and broadband fluctuations. Bispectral functions (e.g., magnitude and phase) give an order-of-estimate agreement for the drift wave-zonal flow systems. Bicoherence analysis is also applied to the edge plasmas of the high-confinement mode (H-mode) of the Compact Helical System (CHS). In the case of CHS plasmas, nonlinear couplings in a system composed of coherent global magneto-hydrodynamic (MHD) oscillations and broadband fluctuations (up to hundreds kHz range) have been observed. Bispectral analysis enhances our understanding of the self-regulation systems of various toroidal plasmas in which strong turbulence and meso-scale structures coexist.
AB - This paper presents experimental studies of nonlinear processes between meso-scale structures and turbulent fluctuations, by use of bispectral analysis, in the edge region of toroidal plasmas. In ohmically heated plasmas of the JFT-2Mtokamak, the drift wave-zonal flow system is investigated by observation of the potential fluctuations. The total bicoherence is composed of two components, i.e., the peak at the geodesic acoustic mode (GAM) frequency and broadband distribution. The biphase is also obtained, which indicates the phase angle of coherent interaction between GAM oscillations and broadband fluctuations. Bispectral functions (e.g., magnitude and phase) give an order-of-estimate agreement for the drift wave-zonal flow systems. Bicoherence analysis is also applied to the edge plasmas of the high-confinement mode (H-mode) of the Compact Helical System (CHS). In the case of CHS plasmas, nonlinear couplings in a system composed of coherent global magneto-hydrodynamic (MHD) oscillations and broadband fluctuations (up to hundreds kHz range) have been observed. Bispectral analysis enhances our understanding of the self-regulation systems of various toroidal plasmas in which strong turbulence and meso-scale structures coexist.
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U2 - 10.1585/pfr.1.041
DO - 10.1585/pfr.1.041
M3 - Article
AN - SCOPUS:85034629075
VL - 1
JO - Plasma and Fusion Research
JF - Plasma and Fusion Research
SN - 1880-6821
M1 - 041
ER -