Metamorphosis of helical magnetorotational instability in the presence axial electric current
arXiv:1410.1750 · doi:10.1103/PhysRevE.91.033014
Abstract
This paper presents numerical linear stability analysis of a cylindrical Taylor-Couette flow of liquid metal carrying axial electric current in a generally helical external magnetic field. Axially symmetric disturbances are considered in the inductionless approximation corresponding to zero magnetic Prandtl number. Axial symmetry allows us to reveal an entirely new electromagnetic instability. First, we show that the electric current passing through the liquid can extend the range of helical magnetorotational instability (HMRI) indefinitely by transforming it into a purely electromagnetic instability. Two different electromagnetic instability mechanisms are identified. The first is an internal pinch-type instability, which is due to the interaction of the electric current with its own magnetic field. Axisymmetric mode of this instability requires a free-space component of the azimuthal magnetic field. When the azimuthal component of the magnetic field is purely rotational and the axial component is nonzero, a new kind of electromagnetic instability emerges. The latter driven by the interaction of electric current with a weak collinear magnetic field in a quiescent fluid gives rise to a steady meridional circulation coupled with azimuthal rotation.
10 pages, 12 figures, final version
References in corpus (7)
- Experimental evidence for magnetorotational instability in a helical magnetic field
- Helical Magnetorotational Instability in Magnetized Taylor-Couette Flow
- How to circumvent the size limitation of liquid metal batteries due to the Tayler instability
- Destabilisation of hydrodynamically stable rotation laws by azimuthal magnetic fields
- Absolute versus convective helical magnetorotational instability in a Taylor-Couette flow
- A unifying picture of helical and azimuthal MRI, and the universal significance of the Liu limit
- Capacitance matrix technique for avoiding spurious eigenmodes in the solution of hydrodynamic stability problems by Chebyshev collocation method