On properties of Velikhov-Chandrasekhar MRI in ideal and non-ideal plasma

Abstract

Conditions of Velikhov-Chandrasekhar magneto-rotational instability in ideal and non-ideal plasmas are examined. Linear WKB analysis of hydromagnetic axially symmetric flows shows that in the Rayleigh-unstable hydrodynamic case where the angular momentum decreases with radius, the MRI branch becomes stable, and the magnetic field suppresses the Rayleigh instability at small wavelengths. We investigate the limiting transition from hydromagnetic flows to hydrodynamic flows. The Rayleigh mode smoothly transits to the hydrodynamic case, while the Velikhov-Chandrasekhar MRI mode completely disappears without the magnetic field. The effects of viscosity and magnetic diffusivity in plasma on the MRI conditions in thin accretion discs are studied. We find the limits on the mean free-path of ions allowing MRI to operate in such discs.

arXiv comment10 pages, 7 figures, MNRAS in press; figures 1-5 corrected, reference added

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• On the appearance of non-local MRI in Keplerian accretion discs
• Sustained turbulence and magnetic energy in non-rotating shear flows
• Revised Conditions for MRI due to Isorotation Theorem
• Study of MRI in stratified viscous plasma configuration
• Coexistence of Magneto-Rotational and Jeans Instabilities in an Axisymmetric Nebula
• Shearing box simulations in the Rayleigh unstable regime