Transient excitation of zonal flows by geodesic acoustic modes

Makoto Sasaki; K. Itoh; A. Ejiri; Y. Takase

doi:10.1088/0741-3335/51/8/085002

Transient excitation of zonal flows by geodesic acoustic modes

Makoto Sasaki, K. Itoh, A. Ejiri, Y. Takase

Research output: Contribution to journal › Article › peer-review

13 Citations (Scopus)

Abstract

Zonal flows (ZFs) are excited transiently by geodesic acoustic modes (GAMs) in toroidal plasmas. When GAMs have radially inward and outward propagating components, these components interact to excite the zero frequency modes (ZFs) transiently, in addition to exciting higher harmonics of GAM. A fluid model is used to study this transient excitation. The Reynolds stress is evaluated from the action conservation equation, and a set of equations to analyze nonlinear couplings among GAMs and ZFs is derived. GAMs are driven by the drift wave (DW) turbulence, and ZFs are transiently driven by nonlinear self-interaction of GAMs. The dependences of the peak amplitudes of ZFs on coupling coefficients are explained theoretically. A new energy path from the DW turbulence to ZFs is found under a situation in which there is only energy transfer from the DW turbulence to GAMs.

Original language	English
Article number	085002
Journal	Plasma Physics and Controlled Fusion
Volume	51
Issue number	8
DOIs	https://doi.org/10.1088/0741-3335/51/8/085002
Publication status	Published - 2009
Externally published	Yes

All Science Journal Classification (ASJC) codes

Nuclear Energy and Engineering
Condensed Matter Physics

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10.1088/0741-3335/51/8/085002

Cite this

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title = "Transient excitation of zonal flows by geodesic acoustic modes",

abstract = "Zonal flows (ZFs) are excited transiently by geodesic acoustic modes (GAMs) in toroidal plasmas. When GAMs have radially inward and outward propagating components, these components interact to excite the zero frequency modes (ZFs) transiently, in addition to exciting higher harmonics of GAM. A fluid model is used to study this transient excitation. The Reynolds stress is evaluated from the action conservation equation, and a set of equations to analyze nonlinear couplings among GAMs and ZFs is derived. GAMs are driven by the drift wave (DW) turbulence, and ZFs are transiently driven by nonlinear self-interaction of GAMs. The dependences of the peak amplitudes of ZFs on coupling coefficients are explained theoretically. A new energy path from the DW turbulence to ZFs is found under a situation in which there is only energy transfer from the DW turbulence to GAMs.",

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T1 - Transient excitation of zonal flows by geodesic acoustic modes

AU - Sasaki, Makoto

AU - Itoh, K.

AU - Ejiri, A.

AU - Takase, Y.

PY - 2009

Y1 - 2009

N2 - Zonal flows (ZFs) are excited transiently by geodesic acoustic modes (GAMs) in toroidal plasmas. When GAMs have radially inward and outward propagating components, these components interact to excite the zero frequency modes (ZFs) transiently, in addition to exciting higher harmonics of GAM. A fluid model is used to study this transient excitation. The Reynolds stress is evaluated from the action conservation equation, and a set of equations to analyze nonlinear couplings among GAMs and ZFs is derived. GAMs are driven by the drift wave (DW) turbulence, and ZFs are transiently driven by nonlinear self-interaction of GAMs. The dependences of the peak amplitudes of ZFs on coupling coefficients are explained theoretically. A new energy path from the DW turbulence to ZFs is found under a situation in which there is only energy transfer from the DW turbulence to GAMs.

AB - Zonal flows (ZFs) are excited transiently by geodesic acoustic modes (GAMs) in toroidal plasmas. When GAMs have radially inward and outward propagating components, these components interact to excite the zero frequency modes (ZFs) transiently, in addition to exciting higher harmonics of GAM. A fluid model is used to study this transient excitation. The Reynolds stress is evaluated from the action conservation equation, and a set of equations to analyze nonlinear couplings among GAMs and ZFs is derived. GAMs are driven by the drift wave (DW) turbulence, and ZFs are transiently driven by nonlinear self-interaction of GAMs. The dependences of the peak amplitudes of ZFs on coupling coefficients are explained theoretically. A new energy path from the DW turbulence to ZFs is found under a situation in which there is only energy transfer from the DW turbulence to GAMs.

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Transient excitation of zonal flows by geodesic acoustic modes

Abstract

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