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Title: Excitation of macromagnetohydrodynamic mode due to multiscale interaction in a quasi-steady equilibrium formed by a balance between microturbulence and zonal flow

Abstract

This is the first numerical simulation demonstrating that a macromagnetohydrodynamic (macro-MHD) mode is excited as a result of multi-scale interaction in a quasi-steady equilibrium formed by a balance between microturbulence and zonal flow based on a reduced two-fluid model. This simulation of a macro-MHD mode, a double tearing mode, is accomplished in a reversed shear equilibrium that includes zonal flow and turbulence due to kinetic ballooning modes. In the quasi-steady equilibrium, a macroscale fluctuation that has the same helicity as the double tearing mode is a part of the turbulence. After a certain period of time, the macro-MHD mode begins to grow. It effectively utilizes free energy of the equilibrium current density gradient and is destabilized by a positive feedback loop between zonal flow suppression and magnetic island growth. Thus, once the macro-MHD appears from the quasi-equilibrium, it continues to grow steadily. This simulation is more comparable with experimental observations of growing macro-MHD activity than earlier MHD simulations starting from linear macroinstabilities in a static equilibrium.

Authors:
;  [1]
  1. National Institute for Fusion Science, Toki 509-5292 (Japan)
Publication Date:
OSTI Identifier:
20974908
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 4; Other Information: DOI: 10.1063/1.2716669; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BALLOONING INSTABILITY; CURRENT DENSITY; EQUILIBRIUM; EQUILIBRIUM PLASMA; EXCITATION; FLUCTUATIONS; FREE ENERGY; INTERACTIONS; MAGNETIC ISLANDS; MAGNETOHYDRODYNAMICS; PLASMA SIMULATION; REVERSED SHEAR; TEARING INSTABILITY; TURBULENCE

Citation Formats

Ishizawa, A., and Nakajima, N.. Excitation of macromagnetohydrodynamic mode due to multiscale interaction in a quasi-steady equilibrium formed by a balance between microturbulence and zonal flow. United States: N. p., 2007. Web. doi:10.1063/1.2716669.
Ishizawa, A., & Nakajima, N.. Excitation of macromagnetohydrodynamic mode due to multiscale interaction in a quasi-steady equilibrium formed by a balance between microturbulence and zonal flow. United States. doi:10.1063/1.2716669.
Ishizawa, A., and Nakajima, N.. Sun . "Excitation of macromagnetohydrodynamic mode due to multiscale interaction in a quasi-steady equilibrium formed by a balance between microturbulence and zonal flow". United States. doi:10.1063/1.2716669.
@article{osti_20974908,
title = {Excitation of macromagnetohydrodynamic mode due to multiscale interaction in a quasi-steady equilibrium formed by a balance between microturbulence and zonal flow},
author = {Ishizawa, A. and Nakajima, N.},
abstractNote = {This is the first numerical simulation demonstrating that a macromagnetohydrodynamic (macro-MHD) mode is excited as a result of multi-scale interaction in a quasi-steady equilibrium formed by a balance between microturbulence and zonal flow based on a reduced two-fluid model. This simulation of a macro-MHD mode, a double tearing mode, is accomplished in a reversed shear equilibrium that includes zonal flow and turbulence due to kinetic ballooning modes. In the quasi-steady equilibrium, a macroscale fluctuation that has the same helicity as the double tearing mode is a part of the turbulence. After a certain period of time, the macro-MHD mode begins to grow. It effectively utilizes free energy of the equilibrium current density gradient and is destabilized by a positive feedback loop between zonal flow suppression and magnetic island growth. Thus, once the macro-MHD appears from the quasi-equilibrium, it continues to grow steadily. This simulation is more comparable with experimental observations of growing macro-MHD activity than earlier MHD simulations starting from linear macroinstabilities in a static equilibrium.},
doi = {10.1063/1.2716669},
journal = {Physics of Plasmas},
number = 4,
volume = 14,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}