Critical fields and growth rates of the Tayler instability as probed by a columnar gallium experiment

Abstract

Many astrophysical phenomena (such as the slow rotation of neutron stars or the rigid rotation of the solar core) can be explained by the action of the Tayler instability of toroidal magnetic fields in the radiative zones of stars. In order to place the theory of this instability on a safe fundament it has been realized in a laboratory experiment measuring the critical field strength, the growth rates as well as the shape of the supercritical modes. A strong electrical current flows through a liquid-metal confined in a resting columnar container with an insulating outer cylinder. As the very small magnetic Prandtl number of the gallium-indium-tin alloy does not influence the critical Hartmann number of the field amplitudes, the electric currents for marginal instability can also be computed with direct numerical simulations. The results of this theoretical concept are confirmed by the experiment. Also the predicted growth rates of the order of minutes for the nonaxisymmetric perturbations are certified by the measurements. That they do not directly depend on the size of the experiment is shown as a consequence of the weakness of the applied fields and the absence of rotation.

8 pages, 5 figures, accepted by ApJ

References in corpus (7)

• On magnetic instabilities and dynamo action in stellar radiation zones
• White dwarf spins from low mass stellar evolution models
• Experimental evidence for Tayler instability in a liquid metal column
• Kink instabilities in jets from rotating magnetic fields
• Non-axisymmetric instability of axisymmetric magnetic fields
• Breakdown of chiral symmetry during saturation of the Tayler instability
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Cited by in corpus (6)

• Numerical simulation of the Tayler instability in liquid metals
• The angular momentum transport by unstable toroidal magnetic fields
• Stability and instability of hydromagnetic Taylor-Couette flows
• Astrophysical and experimental implications from the magnetorotational instability of toroidal fields
• On the possibility of helicity oscillations in the saturation of the Tayler instability
• Gravity's role in taming the Tayler instability in red giant cores