Metamorphosis of helical magnetorotational instability in the presence of axial electric current

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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.
Original languageEnglish
Article number033014
JournalPhysical Review E
Volume91
DOIs
Publication statusPublished - 2015

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Electric Current
electric current
Magnetic Field
electromagnetism
magnetic fields
Taylor-Couette Flow
Axial Symmetry
Liquid Metal
Linear Stability Analysis
Collinear
Prandtl number
Numerical Stability
Free Space
Couette flow
Interaction
External Field
liquid metals
Disturbance
Liquid
disturbances

Bibliographical note

© 2015 American Physical Society.

Keywords

  • axial symmetry
  • Taylor-Couette flow
  • electromagnetic instability

Cite this

Metamorphosis of helical magnetorotational instability in the presence of axial electric current. / Priede, Janis.

In: Physical Review E, Vol. 91, 033014, 2015.

Research output: Contribution to journalArticle

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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.",
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