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Article Dans Une Revue EPL - Europhysics Letters Année : 2007

Magnetic field reversals in an experimental turbulent dynamo

Michaël Berhanu
François Daviaud
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Résumé

We report the first experimental observation of reversals of a dynamo field generated in a laboratory experiment based on a turbulent flow of liquid sodium. The magnetic field randomly switches between two symmetric solutions B and -B. We observe a hierarchy of time scales similar to the Earth's magnetic field: the duration of the steady phases is widely distributed, but is always much longer than the time needed to switch polarity. In addition to reversals we report excursions. Both coincide with minima of the mechanical power driving the flow. Small changes in the flow driving parameters also reveal a large variety of dynamo regimes.
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Dates et versions

hal-00492334 , version 1 (15-06-2010)

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Michaël Berhanu, Romain Monchaux, Stéphan Fauve, Nicolas Mordant, François Pétrélis, et al.. Magnetic field reversals in an experimental turbulent dynamo. EPL - Europhysics Letters, 2007, 77 (5), pp.59001. ⟨10.1209/0295-5075/77/59001⟩. ⟨hal-00492334⟩
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