Unified Treatment of Small- and Large-Scale Dynamos in Helical Turbulence

Abstract

Helical turbulence may provide the key to the generation of large-scale magnetic fields. Turbulence also generically leads to rapidly growing small-scale magnetic fields. These two processes are usually studied separately. We give here a unified treatment of both processes, in the case of random fields, incorporating also a simple model nonlinear drift. We uncover an interesting plausible saturated state of the small-scale dynamo and a novel analogy between quantum mechanical (QM) tunneling and the generation of large-scale fields. A field generated by the small-scale dynamo, can ``tunnel'' to produce large-scale correlations, which in steady state, correspond to a force-free ``mean'' field.