Enhanced dynamo growth in nonhomogeneous conducting fluids

Abstract

We address magnetic-field generation by dynamo action in systems with inhomogeneous electrical conductivity and magnetic permeability. More specifically, we first show that the Taylor-Couette kinematic dynamo undergoes a drastic reduction of its stability threshold when a (zero-mean) modulation of the fluid's electrical conductivity or magnetic permeability is introduced. These results are obtained outside the mean-field regime, for which this effect was initially proposed. Beyond this illustrative example, we extend a duality argument put forward by Favier \& Proctor {(2013)} to show that swapping the distributions of conductivity and permeability and changing $u\to -u$ leaves the dynamo threshold unchanged. This allows one to make connections between {\it a priori} unrelated dynamo studies. Finally, we discuss the possibility of observing such an effect both in laboratory and astrophysical settings.

References in corpus (7)

• Generation of magnetic field by dynamo action in a turbulent flow of liquid sodium
• High Reynolds number Taylor-Couette turbulence
• On the magnetic fields generated by experimental dynamos
• Anelastic spherical dynamos with radially variable electrical conductivity
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• Axisymmetric dynamo action is possible with anisotropic conductivity
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Cited by in corpus (1)

• Fast and Furious dynamo action in the anisotropic dynamo