Saturation of Magnetorotational Instability through Magnetic Field Generation

Abstract

The saturation mechanism of Magneto-Rotational Instability (MRI) is examined through analytical quasilinear theory and through nonlinear computation of a single mode in a rotating disk. We find that large-scale magnetic field is generated through the alpha effect (the correlated product of velocity and magnetic field fluctuations) and causes the MRI mode to saturate. If the large-scale plasma flow is allowed to evolve, the mode can also saturate through its flow relaxation. In astrophysical plasmas, for which the flow cannot relax because of gravitational constraints, the mode saturates through field generation only.

9 pages, 10 figures to appear in ApJ, Jun 2009, 10 v698

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• Global MHD simulations of stratified and turbulent protoplanetary discs. I. Model properties
• Global magnetohydrodynamical models of turbulence in protoplanetary disks I. A cylindrical potential on a Cartesian grid and transport of solids
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Cited by in corpus (18)

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• Helicity-Flux-Driven Alpha Effect in Laboratory and Astrophysical Plasmas
• Large scale dynamo action precedes turbulence in shearing box simulations of the magnetorotational instability
• On the Anisotropic Nature of MRI-Driven Turbulence in Astrophysical Disks
• The weakly nonlinear magnetorotational instability in a local geometry
• Radially Dependent Large Scale Dynamos in Global Cylindrical Shear Flows and the Local Cartesian Limit
• The weakly nonlinear magnetorotational instability in a global, cylindrical Taylor-Couette flow
• Persistent mysteries of jet engines, formation, propagation, and particle acceleration: have they been addressed experimentally?
• Near-cancellation of up- and down-gradient momentum transport in forced magnetized shear-flow turbulence
• A non-local magneto-curvature instability in a differentially rotating disk
• Evolution of the magnetorotational instability on initially tangled magnetic fields
• The impact of magnetic fields on momentum transport and saturation of shear-flow instability by stable modes
• Onset of Plasmoid Reconnection during Magnetorotational Instability
• Quasi-two-dimensional nonlinear evolution of helical magnetorotational instability in a magnetized Taylor-Couette flow
• Momentum transport from current-driven reconnection in astrophysical disks
• A generalized effective potential for differentially rotating plasmas
• Low magnetic-Prandtl number flow configurations for cold astrophysical disk models: speculation and analysis