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06:42
Magnetically Induced Rotating Rayleigh-Taylor Instability
Published on: March 3, 2017
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Magnetorotational decay instability in Keplerian disks
Yuri Shtemler1, Edward Liverts1, Michael Mond1
1Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
Physical Review Letters
|January 31, 2014
Summary
The magnetorotational instability (MRI) in astrophysical disks saturates via three-wave interactions, transferring energy to stable waves. This leads to bounded MRI oscillations and growth in other waves, creating a new magnetorotational decay instability.
Area of Science:
- Plasma physics
- Astrophysical fluid dynamics
Background:
- The magnetorotational instability (MRI) is crucial for angular momentum transport in accretion disks.
- Understanding MRI saturation mechanisms is key to modeling astrophysical phenomena.
Purpose of the Study:
- To introduce and analyze the saturation of MRI in thin Keplerian disks.
- To explore the role of three-wave resonant interactions in MRI dynamics.
Main Methods:
- Derivation of a second-order Duffing amplitude equation for the MRI.
- Formulation of two first-order equations for interacting stable waves.
- Analysis of solutions to understand energy transfer and instability evolution.
Main Results:
- The MRI exhibits bounded, bursty nonlinear oscillations.
- Linearly stable slow Alfvén-Coriolis and magnetosonic waves experience unbounded growth.
- A novel phenomenon termed 'magnetorotational decay instability' is identified.
Conclusions:
- Three-wave resonant interactions provide a natural saturation mechanism for MRI.
- This mechanism generalizes the classical plasma decay instability to astrophysical contexts.
- The identified instability impacts the understanding of turbulence and transport in accretion disks.
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