Effect of flow damping on drift-tearing magnetic islands in tokamak plasmas

• Published in: Physics of plasmas Vol. 16; no. 7
• Main Authors: Fitzpatrick, R., Waelbroeck, F. L.
• Format: Journal Article
• Language: English
• Published: United States 01.07.2009
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DAMPING; MAGNETIC ISLANDS; MAGNETOHYDRODYNAMICS; NEOCLASSICAL TRANSPORT THEORY; SOUND WAVES; TOKAMAK DEVICES; WAVE PROPAGATION
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/1.3191719

A systematic fluid theory of nonlinear drift-tearing magnetic island dynamics in a conventional large aspect-ratio low- β circular cross-section tokamak plasma is derived from a set of single-helicity reduced neoclassical-magnetohydrodynamical equations which incorporate electron and ion diamagnetic flows, ion gyroviscosity, poloidal and toroidal flow damping, cross flux-surface momentum and particle transport, the sound wave, and the drift wave. The equations neglect the compressible Alfvén wave, electron inertia, the electron viscosity tensor, magnetic field-line curvature, and finite ion orbit widths. A collisional closure is used for plasma dynamics parallel to the magnetic field. The influence of various different levels of flow damping on the phase velocity of an isolated island, as well as the ion polarization term appearing in its Rutherford equation, are investigated in detail. Furthermore, it is found that, under certain circumstances, a locked island is subject to destabilizing ion polarization term to which a comparable isolated (i.e., rotating) island is not.