Parametric instability of the helical dynamo
arXiv:physics/0703216 · doi:10.1063/1.2734118
Abstract
We study the dynamo threshold of a helical flow made of a mean (stationary) plus a fluctuating part. Two flow geometries are studied, either (i) solid body or (ii) smooth. Two well-known resonant dynamo conditions, elaborated for stationary helical flows in the limit of large magnetic Reynolds numbers, are tested against lower magnetic Reynolds numbers and for fluctuating flows (zero mean). For a flow made of a mean plus a fluctuating part the dynamo threshold depends on the frequency and the strength of the fluctuation. The resonant dynamo conditions applied on the fluctuating (resp. mean) part seems to be a good diagnostic to predict the existence of a dynamo threshold when the fluctuation level is high (resp. low).
37 pages, 8 figures
References in corpus (13)
- Generation of magnetic field by dynamo action in a turbulent flow of liquid sodium
- Detection of a flow induced magnetic field eigenmode in the Riga dynamo facility
- Magnetic Field Saturation in the Riga Dynamo Experiment
- Fluctuation dynamo and turbulent induction at low magnetic Prandtl numbers
- Numerical demonstration of fluctuation dynamo at low magnetic Prandtl numbers
- Towards an experimental von Karman dynamo: numerical studies for an optimized design
- Critical Magnetic Prandtl Number for Small-Scale Dynamo
- Influence of turbulence on the dynamo threshold
- Fluctuation of magnetic induction in von Kármán swirling flows
- Influence of electromagnetic boundary conditions onto the onset of dynamo action in laboratory experiments
- Wetting and particle adsorption in nanoflows
- The turbulent dynamo as an instability in a noisy medium
- Influence of inner and outer walls electromagnetic properties on the onset of a stationary dynamo
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- Energy oscillations and a possible route to chaos in a modified Riga dynamo
- Spherical single-roll dynamos at large magnetic Reynolds numbers
- Effects of radial conductivity variation on the Ponomarenko dynamo