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Intermittency in the homopolar disk-dynamo

Nicolas Leprovost·Bérengère Dubrulle·Franck Plunian
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Abstract

We study a modified Bullard dynamo and show that this system is equivalent to a nonlinear oscillator subject to a multiplicative noise. The stability analysis of this oscillator is performed. Two bifurcations are identified, first towards an `` 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 `` 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.

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Nicolas Leprovost, Bérengère Dubrulle, Franck Plunian. 2006-07-24. Intermittency in the homopolar disk-dynamo. https://arxiv.org/abs/nlin/0506050

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