0000000000873856
AUTHOR
Franck Plunian
showing 4 related works from this author
Instability of the homopolar disk-dynamo in presence of white noise
2006
International audience; 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, whic…
Influence of electromagnetic boundary conditions onto the onset of dynamo action in laboratory experiments
2009
We study the onset of dynamo action of the Riga and Karlsruhe experiments with the addition of an external wall, the electro-magnetic properties of which being different from those of the fluid in motion. We consider a wall of different thickness, conductivity and permeability. We also consider the case of a ferro-fluid in motion.
Intermittency in the homopolar disk-dynamo
2006
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 \lq\lq 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 \lq\lq 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 characteri…
Intermittency in the homopolar dynamo
2005
URL: http://www-spht.cea.fr/articles/s05/152 Rigas Jurmala, Rigas Jurmala, Latvia, June 27 - July 1st, 2005; 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'' 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'' (dynamo) state where it is possible to define unambiguously a (non-zero) most probable value around which the amplitude of the oscillator fluctuates. The …