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Title: Drift-tearing magnetic islands in tokamak plasmas

Abstract

A systematic fluid theory of nonlinear magnetic island dynamics in conventional low-{beta}, large aspect-ratio, circular cross-section tokamak plasmas is developed using an extended magnetohydrodynamics model that incorporates diamagnetic flows, ion gyroviscosity, fast parallel electron heat transport, the ion sound wave, the drift wave, and average magnetic field-line curvature. The model excludes the compressible Alfven wave, geodesic field-line curvature, neoclassical effects, and ion Landau damping. A collisional closure is used for plasma dynamics parallel to the magnetic field. Two distinct branches of island solutions are found, namely the 'sonic' and 'hypersonic' branches. Both branches are investigated analytically, using suitable ordering schemes, and in each case the problem is reduced to a relatively simple set of nonlinear differential equations that can be solved numerically via iteration. The solution determines the island phase velocity, relative to the plasma, and the effect of local currents on the island stability. Sonic islands are relatively wide, flatten both the temperature and density profiles, and tend to propagate close to the local ion fluid velocity. Hypersonic islands, on the other hand, are relatively narrow, only flatten the temperature profile, radiate drift-acoustic waves, and tend to propagate close to the local electron fluid velocity. The hypersonic solution branchmore » ceases to exist above a critical island width. Under normal circumstances, both types of island are stabilized by local ion polarization currents.« less

Authors:
;  [1]
  1. Institute for Fusion Studies, Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)
Publication Date:
OSTI Identifier:
21069963
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 15; Journal Issue: 1; Other Information: DOI: 10.1063/1.2829757; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALFVEN WAVES; ASPECT RATIO; ELECTRIC CURRENTS; ELECTRONS; HEAT TRANSFER; IONS; LANDAU DAMPING; MAGNETIC FIELDS; MAGNETIC ISLANDS; MAGNETOHYDRODYNAMICS; MATHEMATICAL SOLUTIONS; NEOCLASSICAL TRANSPORT THEORY; NONLINEAR PROBLEMS; PHASE VELOCITY; PLASMA; PLASMA DENSITY; PLASMA DRIFT; SOUND WAVES; TOKAMAK DEVICES; WAVE PROPAGATION

Citation Formats

Fitzpatrick, R, and Waelbroeck, F L. Drift-tearing magnetic islands in tokamak plasmas. United States: N. p., 2008. Web. doi:10.1063/1.2829757.
Fitzpatrick, R, & Waelbroeck, F L. Drift-tearing magnetic islands in tokamak plasmas. United States. https://doi.org/10.1063/1.2829757
Fitzpatrick, R, and Waelbroeck, F L. 2008. "Drift-tearing magnetic islands in tokamak plasmas". United States. https://doi.org/10.1063/1.2829757.
@article{osti_21069963,
title = {Drift-tearing magnetic islands in tokamak plasmas},
author = {Fitzpatrick, R and Waelbroeck, F L},
abstractNote = {A systematic fluid theory of nonlinear magnetic island dynamics in conventional low-{beta}, large aspect-ratio, circular cross-section tokamak plasmas is developed using an extended magnetohydrodynamics model that incorporates diamagnetic flows, ion gyroviscosity, fast parallel electron heat transport, the ion sound wave, the drift wave, and average magnetic field-line curvature. The model excludes the compressible Alfven wave, geodesic field-line curvature, neoclassical effects, and ion Landau damping. A collisional closure is used for plasma dynamics parallel to the magnetic field. Two distinct branches of island solutions are found, namely the 'sonic' and 'hypersonic' branches. Both branches are investigated analytically, using suitable ordering schemes, and in each case the problem is reduced to a relatively simple set of nonlinear differential equations that can be solved numerically via iteration. The solution determines the island phase velocity, relative to the plasma, and the effect of local currents on the island stability. Sonic islands are relatively wide, flatten both the temperature and density profiles, and tend to propagate close to the local ion fluid velocity. Hypersonic islands, on the other hand, are relatively narrow, only flatten the temperature profile, radiate drift-acoustic waves, and tend to propagate close to the local electron fluid velocity. The hypersonic solution branch ceases to exist above a critical island width. Under normal circumstances, both types of island are stabilized by local ion polarization currents.},
doi = {10.1063/1.2829757},
url = {https://www.osti.gov/biblio/21069963}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 1,
volume = 15,
place = {United States},
year = {Tue Jan 15 00:00:00 EST 2008},
month = {Tue Jan 15 00:00:00 EST 2008}
}