DIRECT OBSERVATION OF THE TURBULENT emf AND TRANSPORT OF MAGNETIC FIELD IN A LIQUID SODIUM EXPERIMENT

Journal Article · Sat Nov 10 04:00:00 EST 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/759/2/80· OSTI ID:22086432

Rahbarnia, Kian; Brown, Benjamin P; Clark, Mike M; Kaplan, Elliot J; Nornberg, Mark D; Rasmus, Alex M; Taylor, Nicholas Zane; Forest, Cary B ^[1]; Jenko, Frank; Limone, Angelo ^[2]; Pinton, Jean-Francois; Plihon, Nicolas; Verhille, Gautier ^[3]

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1. Department of Physics, University of Wisconsin-Madison, 1150 University Ave, Madison, WI 53706 (United States)
2. Max-Planck-Institut fuer Plasmaphysik (IPP), EURATOM Association, D-85748 Garching (Germany)
3. Laboratoire de Physique de l'Ecole Normale Superieure de Lyon, CNRS and Universite de Lyon, F-69364 Lyon (France)

For the first time, we have directly measured the transport of a vector magnetic field by isotropic turbulence in a high Reynolds number liquid metal flow. In analogy with direct measurements of the turbulent Reynolds stress (turbulent viscosity) that governs momentum transport, we have measured the turbulent electromotive force (emf) by simultaneously measuring three components of velocity and magnetic fields, and computed the correlations that lead to mean-field current generation. Furthermore, we show that this turbulent emf tends to oppose and cancel out the local current, acting to increase the effective resistivity of the medium, i.e., it acts as an enhanced magnetic diffusivity. This has important implications for turbulent transport in astrophysical objects, particularly in dynamos and accretion disks.

• OSTI ID: 22086432
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 759; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCRETION DISKS
ASTROPHYSICS
CORRELATIONS
ELECTRIC CURRENTS
ELECTROMOTIVE FORCE
LIQUID METALS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MEAN-FIELD THEORY
REYNOLDS NUMBER
SODIUM
STRESSES
TURBULENCE
VECTORS
VELOCITY
VISCOSITY