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Phys. Rev. Lett. 98, 044502 (2007) [4 pages]

Generation of a Magnetic Field by Dynamo Action in a Turbulent Flow of Liquid Sodium

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R. Monchaux1, M. Berhanu2, M. Bourgoin3,*, M. Moulin3, Ph. Odier3, J.-F. Pinton3, R. Volk3, S. Fauve2, N. Mordant2, F. Pétrélis2, A. Chiffaudel1, F. Daviaud1, B. Dubrulle1, C. Gasquet1, L. Marié1,†, and F. Ravelet1,‡
1Service de Physique de l’Etat Condensé, Direction des Sciences de la Matière, CEA-Saclay, CNRS URA 2464, 91191 Gif-sur-Yvette cedex, France
2Laboratoire de Physique Statistique de l’Ecole Normale Supérieure, CNRS UMR 8550, 24 Rue Lhomond, 75231 Paris Cedex 05, France
3Laboratoire de Physique de l’Ecole Normale Supérieure de Lyon, CNRS UMR 5672, 46 allée d’Italie, 69364 Lyon Cedex 07, France

Received 25 October 2006; published 25 January 2007

See accompanying Physics Focus

We report the observation of dynamo action in the von Kármán sodium experiment, i.e., the generation of a magnetic field by a strongly turbulent swirling flow of liquid sodium. Both mean and fluctuating parts of the field are studied. The dynamo threshold corresponds to a magnetic Reynolds number Rm∼30. A mean magnetic field of the order of 40 G is observed 30% above threshold at the flow lateral boundary. The rms fluctuations are larger than the corresponding mean value for two of the components. The scaling of the mean square magnetic field is compared to a prediction previously made for high Reynolds number flows.

© 2007 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.98.044502
DOI:
10.1103/PhysRevLett.98.044502
PACS:
47.65.−d, 52.65.Kj, 91.25.Cw

*Present address: LEGI, CNRS UMR 5519, BP53, 38041 Grenoble, France.

†Present address: IFREMER, Laboratoire de Physique des Océans, CNRS UMR 5519, BP70, 29280 Plouzane, France.

‡Present address: Laboratory for Aero and Hydrodynamics, TU-Delft, The Netherlands.

 
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