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Intermittency in the homopolar disc-dynamo

N. Leprovost1 - B. Dubrulle2 - F. Plunian3

1 LPS/ENS, 24 rue Lhomond, F-75231 Paris cedex 05, France
2 DRECAM/SPEC/CEA Saclay, and CNRS (URA2464), F-91190 Gif sur Yvette Cedex, France
3 LEGI, B.P. 53, 38041 Grenoble Cedex 9, France

We study a modified Bullard dynamo and show that this system is equivalent to a non-linear oscillator subject to a multiplicative noise. The stability analysis of this oscillator is performed. Two bifurcations are identified, first, towards an łqłq intermittent\rq\rq state, where the absorbing (non-dynamo) state is no more stable but the most probable value of the amplitude of the oscillator is still zero, and, secondly, towards a łqłq turbulent\rq\rq (dynamo) state, where it is possible to define unambiguously a (non-zero) most probable value, around which the amplitude of the oscillator fluctuates. The bifurcation diagram of this system exhibits three regions, which are analytically characterized. Figs 7, Refs 27.

Magnetohydrodynamics 42, No. 2/3, 131-142, 2006 [PDF, 0.29 Mb]

Copyright: Institute of Physics, University of Latvia
Electronic edition ISSN 1574-0579
Printed edition ISSN 0024-998X