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arXiv · 1011.4029

High Magnetic Shear Gain in a Liquid Sodium Stable Couette Flow Experiment; A Prelude to an alpha-Omega Dynamo

Stirling A. Colgate·Hui Li·Vladimir Pariev·John Finn·Howard Beckley·Jiahe Si·Joe Martinic·David Westpfahl·James Slutz·Cebastian Westrom·Brianna Klein·Paul Schendel·Cletus Scharle·Travis McKinney·Rocky Ginanni·Ian Bentley·Timothy Mickey·Ragnar Ferrel
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Abstract

The $Ω$-phase of the liquid sodium $α$-$Ω$ dynamo experiment at NMIMT in cooperation with LANL has successfully demonstrated the production of a high toroidal field, $B_ϕ \simeq 8\times B_r$ from the radial component of an applied poloidal magnetic field, $B_r$. This enhanced toroidal field is produced by rotational shear in stable Couette flow within liquid sodium at $Rm \simeq 120$. The small turbulence in stable Taylor-Couette flow is caused by Ekman flow where $ (δv/v)^2 \sim 10^{-3} $. This high $Ω$-gain in low turbulence flow contrasts with a smaller $Ω$-gain in higher turbulence, Helmholtz-unstable shear flows. This result supports the ansatz that large scale astrophysical magnetic fields are created within semi-coherent large scale motions in which turbulence plays only a smaller diffusive role that enables magnetic flux linkage.

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Stirling A. Colgate, Hui Li, Vladimir Pariev, John Finn, Howard Beckley, Jiahe Si, Joe Martinic, David Westpfahl, James Slutz, Cebastian Westrom, Brianna Klein, Paul Schendel, Cletus Scharle, Travis McKinney, Rocky Ginanni, Ian Bentley, Timothy Mickey, Ragnar Ferrel. 2010-12-01. High Magnetic Shear Gain in a Liquid Sodium Stable Couette Flow Experiment; A Prelude to an alpha-Omega Dynamo. https://doi.org/10.1103/physrevlett.106.175003

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