First-order finite-Larmor-radius effects on magnetic tearing in pinch configurations
- Center for Magnetic Self-Organization and Center for Plasma Theory and Computation, 1150 University Avenue, Madison, Wisconsin 53706 (United States)
The linear and nonlinear evolution of a single-helicity tearing mode in a cylindrical, force-free pinch are investigated using a fluid model with first-order finite-Larmor-radius corrections. Linear results computed with the nimrod[nonideal magnetohydrodynamics (MHD) with rotation, open discussion] code [Sovinec et al., J. Comput. Phys. 195, 355 (2004)] produce a regime at small {rho}{sub s} where the growth rate is reduced relative to resistive MHD, though the Hall term is not significant. The leading order contributions from ion gyroviscosity may be expressed as a drift associated with {nabla}B{sub 0} and poloidal curvature for experimentally relevant {beta}=0.1, S{approx}10{sup 5}-10{sup 6} force-free equilibria. The heuristic analytical dispersion relation, {gamma}{sup 4}({gamma}-i{omega}{sub *gv})={gamma}{sub MHD}{sup 5} where {omega}{sub *gv} is the gyroviscous drift frequency, confirms numerical results. The behavior of our cylindrical computations at large {rho}{sub s} corroborates previous analytic slab studies where an enhanced growth rate and radially localized Hall dynamo are predicted. Similar to previous drift-tearing results, nonlinear computations with cold ions demonstrate that the Hall dynamo is small when the island width is large in comparison with the scale for electron-ion coupling. The saturation is then determined by the resistive MHD physics. However, with warm ions the gyroviscous stress supplements the nonlinear Lorentz force, and the saturated island width is reduced.
- OSTI ID:
- 21537635
- Journal Information:
- Physics of Plasmas, Vol. 18, Issue 4; Other Information: DOI: 10.1063/1.3571599; (c) 2011 American Institute of Physics; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DISPERSION RELATIONS
DRIFT INSTABILITY
ELECTRON-ION COUPLING
EVOLUTION
LARMOR RADIUS
MAGNETOHYDRODYNAMICS
PLASMA
PLASMA SIMULATION
TEARING INSTABILITY
COUPLING
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
MECHANICS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PLASMA MICROINSTABILITIES
SIMULATION