A simple model for a buoyancy-driven dynamo in accretion discs ⋆

A model for the magnetic dynamo process in accretion discs is proposed that does not involve underlying turbulent motions. The key ingredient of the model is the magnetic buoyancy. Combined with Coriolis twist, the buoyant motions result in a backcoupling between azimuthal and radial components of the field. It is shown that for reasonable values of the free parameters of the model all three components of the magnetic field reach a stable saturation state consistent with the basic assumptions underlying the model.