Identification of a non-axisymmetric mode in laboratory experiments searching for standard magnetorotational instability

Abstract

The standard magnetorotational instability (SMRI) is a promising mechanism for turbulence and rapid accretion in astrophysical disks. It is a magnetohydrodynamic (MHD) instability that destabilizes otherwise hydrodynamically stable disk flow. Due to its microscopic nature at astronomical distances and stringent requirements in laboratory experiments, SMRI has remained unconfirmed since its proposal, despite its astrophysical importance. Here we report a nonaxisymmetric MHD instability in a modified Taylor-Couette experiment. To search for SMRI, a uniform magnetic field is imposed along the rotation axis of a swirling liquid-metal flow. The instability initially grows exponentially, becoming prominent only for sufficient flow shear and moderate magnetic field. These conditions for instability are qualitatively consistent with SMRI, but at magnetic Reynolds numbers below the predictions of linear analyses with periodic axial boundaries. Three-dimensional numerical simulations, however, reproduce the observed instability, indicating that it grows linearly from the primary axisymmetric flow modified by the applied magnetic field.

15 pages, 16 figures

References in corpus (10)

• High Reynolds number Taylor-Couette turbulence
• Hydrodynamic turbulence cannot transport angular momentum effectively in astrophysical disks
• Experimental observation and characterization of the magnetorotational instability
• Experimental evidence for magnetorotational instability in a helical magnetic field
• Stability and angular-momentum transport of fluid flows between corotating cylinders
• Helical Magnetorotational Instability in Magnetized Taylor-Couette Flow
• Numerical simulations of the Princeton magneto-rotational instability experiment with conducting axial boundaries
• Observation of a Free-Shercliff-Layer Instability in Cylindrical Geometry
• Observation of axisymmetric standard magnetorotational instability in the laboratory
• A non-local magneto-curvature instability in a differentially rotating disk

Cited by in corpus (8)

• Characterization of Quasi-Keplerian, Differentially Rotating, Free-Boundary Laboratory Plasmas
• Taylor-Couette flow for astrophysical purposes
• A non-local magneto-curvature instability in a differentially rotating disk
• A generalized effective potential for differentially rotating plasmas
• Parametric Survey of Nonaxisymmetric Accretion Disk Instabilities: Magnetorotational Instability to Super-Alfvénic Rotational Instability
• Laboratory modeling of MHD accretion disks
• Structure and Dynamics of Magneto-Inertial, Differentially Rotating Laboratory Plasmas
• Non-ideal stability analysis of differentially rotating plasmas with global curvature effects