Fast and Furious dynamo action in the anisotropic dynamo

TL;DR

This paper demonstrates that anisotropic electrical conductivity or magnetic permeability can induce fast dynamo action in large magnetic Reynolds number regimes, with growth rates increasing infinitely under certain shear conditions.

Contribution

It reveals that anisotropic properties enable rapid magnetic field amplification in differential rotation scenarios, extending understanding of dynamo mechanisms.

Findings

Anisotropic conductivity/permeability leads to fast dynamo action.

Magnetic growth rate increases with magnetic Reynolds number.

Infinite shear results in unbounded growth rates.

Abstract

In the limit of large magnetic Reynolds numbers, it is shown that a smooth differential rotation can lead to fast dynamo action, provided that the electrical conductivity or magnetic permeability is anisotropic. If the shear is infinite, for example between two rotating solid bodies, the anisotropic dynamo becomes furious, meaning that the magnetic growth rate increases toward infinity with an increasing magnetic Reynolds number.