title: Role of soft-iron impellers on the mode selection in the von kármán-sodium dynamo experiment.
abstract: 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.
authors.affiliation: Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden, Germany. a.giesecke@fzd.de
authors.forename: André
authors.initials: A
authors.lastname: Giesecke
authors.forename: Frank
authors.initials: F
authors.lastname: Stefani
authors.forename: Gunter
authors.initials: G
authors.lastname: Gerbeth