Hypersonic drift-tearing magnetic islands in tokamak plasmas

Journal Article · Sat Dec 15 00:00:00 EST 2007 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2811928· OSTI ID:21072692

Fitzpatrick, R; Waelbroeck, F L ^[1]

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1. Institute for Fusion Studies, Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)

A two-fluid theory of long wavelength, hypersonic, drift-tearing magnetic islands in low-collisionality, low-{beta} plasmas possessing relatively weak magnetic shear is developed. The model assumes both slab geometry and cold ions, and neglects electron temperature and equilibrium current gradient effects. The problem is solved in three asymptotically matched regions. The 'inner region' contains the island. However, the island emits electrostatic drift-acoustic waves that propagate into the surrounding 'intermediate region', where they are absorbed by the plasma. Since the waves carry momentum, the inner region exerts a net force on the intermediate region, and vice versa, giving rise to strong velocity shear in the region immediately surrounding the island. The intermediate region is matched to the surrounding 'outer region', in which ideal magnetohydrodynamic holds. Isolated hypersonic islands propagate with a velocity that lies between those of the unperturbed local ion and electron fluids, but is much closer to the latter. The ion polarization current is stabilizing, and increases with increasing island width. Finally, the hypersonic branch of isolated island solutions ceases to exist above a certain critical island width. Hypersonic islands whose widths exceed the critical width are hypothesized to bifurcate to the so-called 'sonic' solution branch.

• OSTI ID: 21072692
• Journal Information: Physics of Plasmas, Vol. 14, Issue 12; Other Information: DOI: 10.1063/1.2811928; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BIFURCATION
CHARGED-PARTICLE TRANSPORT
CONFINEMENT
ELECTRIC CURRENTS
ELECTRON TEMPERATURE
ELECTRONS
EQUILIBRIUM
ION ACOUSTIC WAVES
IONS
MAGNETIC ISLANDS
MAGNETOHYDRODYNAMICS
PLASMA
PLASMA DRIFT
PLASMA FLUID EQUATIONS
POLARIZATION
SHEAR
SOUND WAVES
TEARING INSTABILITY
TOKAMAK DEVICES
VELOCITY