Marcotte F, Gallet B, Pétrélis F, Gissinger C. Enhanced dynamo growth in nonhomogeneous conducting fluids.
Phys Rev E 2021;
104:015110. [PMID:
34412215 DOI:
10.1103/physreve.104.015110]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/22/2021] [Indexed: 11/07/2022]
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 and Proctor (2013) to show that swapping the distributions of conductivity and permeability and changing u→-u leaves the dynamo threshold unchanged. This allows one to make connections between a priori unrelated dynamo studies. Finally, we discuss the possibility of observing such an effect both in laboratory and astrophysical settings.
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