Turbulent dynamo as a result of non-coherent overlap of localized magnetic field perturbations

Statistical properties of a statistically homogeneous random magnetic field in a viscous diffusive fluid are derived from the evolution of a single blob of the magnetic field. It is shown that, although the magnetic field of a single blob decreases in time, the volume occupied by the magnetic field and its energy increase; this is the cause of the magnetic field growth in a homogeneous medium. We also get an exact expression for the increment of the magnetic field in the generalized (not time-inversible) Kraichnan model. (paper)