The Magneto-Rotational Decay Instability in Keplerian Disks

Abstract

The saturation of the magnetorotational (MRI) instability in thin Keplerian disks through three wave resonant interactions is introduced and discussed. That mechanism is a natural generalization of the fundamental decay instability discovered five decades ago for infinite, homogeneous and immovable plasmas. The decay instability relies on the energy transfer from the MRI to stable slow Alfv'en-Coriolis (AC) as well as magnetosonic (MS) waves. A second order forced Duffing amplitude equation for the initially unstable MRI as well as two first order equations for the other two waves are derived. The solutions of those equations exhibit bounded bursty nonlinear oscillations for the MRI as well as unbounded growth for the linearly stable slow AC and MS perturbations, thus giving rise to the magneto-rotational decay instability (MRDI).

4 pages, 3 figures

References in corpus (6)

• On the Saturation of the Magnetorotational Instability via Parasitic Modes
• A weakly nonlinear analysis of the magnetorotational instability in a model channel flow
• Hall equilibrium of thin Keplerian disks embedded in mixed poloidal and toroidal magnetic fields
• Non-Dissipative Saturation of the Magnetorotational Instability in Thin Disks
• Spectral and algebraic instabilities in thin Keplerian discs under poloidal and toroidal magnetic fields
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Cited by in corpus (2)

• Resonant instability of the nonlinearly-saturated magnetorotational mode in thin Keplerian discs
• Explosive magnetorotational instability in Keplerian disks