Deep minima in stellar dynamos

We study a Cartesian analogy for a solar dynamo model to investigate systematically a dynamo model limited by the back reaction of the Lorentz force on the differential rotation. In particular, we investigate intermittent behaviour found at low turbulent magnetic Prandtl numbers tau, and determine empirical scaling laws with tau. We find this class of models to be incapable of producing extended periods of "normal" behaviour separated by occasional "grand minima" - rather the behaviour is a mirror image, with occasional "grand maxima". Further we find the existence of solar-like torsional oscillations to be incompatible with low magnetic Prandtl number intermittent regimes.