%0 Journal Article
%T Large scale dynamos with ambipolar diffusion nonlinearity
%A Axel Brandenburg
%A Kandaswamy Subramanian
%J Physics
%D 2000
%I arXiv
%X It is shown that ambipolar diffusion as a toy nonlinearity leads to very similar behaviour of large scale turbulent dynamos as full MHD. This is demonstrated using both direct simulations in a periodic box and a closure model for the magnetic correlation functions applicable to infinite space. Large scale fields develop via a nonlocal inverse cascade as described by the alpha-effect. However, because magnetic helicity can only change on a resistive timescale, the time it takes to organize the field into large scales increases with magnetic Reynolds number.
%U http://arxiv.org/abs/astro-ph/0007450v2