Role of soft-iron impellers on the mode selection in the von kármán-sodium dynamo experiment.
A crucial point for the understanding of the von Kármán-sodium (VKS) dynamo experiment is the influence of soft-iron impellers. We present numerical simulations of a VKS-like dynamo with a localized permeability distribution that resembles the shape of the flow driving impellers. It is shown that the presence of soft-iron material essentially determines the dynamo process in the VKS experiment. An axisymmetric magnetic field mode can be explained by the combined action of the soft-iron disk and a rather small alpha effect parametrizing the induction effects of unresolved small scale flow fluctuations.
Giesecke
André
A
Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden, Germany. a.giesecke@fzd.de
Stefani
Frank
F
Gerbeth
Gunter
G