Bistability between a stationary and an oscillatory dynamo in a turbulent flow of liquid sodium - Berhanu, M. and Gallet, B. and Monchaux, R. and Bourgoin, M. and Odier, Ph. and Pinton, J. -F. and Plihon, N. and Volk, R. and Fauve, S. and Mordant, N. and Petrelis, F. and Aumaitre, S. and Chiffaudel, A. and Daviaud, F. and Dubrulle, B. and Ravelet, F.
JOURNAL OF FLUID MECHANICS 641, 217-226 (2009)
Abstract : We report the first experimental observation of a bistable dynamo
regime. A turbulent flow of liquid sodium is generated between two disks
ill the von karman geometry (VKS experiment). When one disk is kept at
rest, bistability is observed between a stationary and an oscillatory
magnetic field. The stationary and oscillatory branches occur in the
vicinity of a codimension-two bifurcation that results from the coupling
between two modes of magnetic field. We present an experimental study or
the two regimes and study in detail the region of bistability that we
understand ill terms of dynamical system theory. Despite the very
turbulent nature of the flow, the bifurcations of the magnetic field are
correctly described by a low-dimensional model. In addition, the
different regimes are robust; i.e. turbulent fluctuations do not drive
any transition between the oscillatory and stationary states in the
region of bistability.