2000/07/28 by Axel Brandenburg, Kandaswamy Subramanian
Physics and Astronomy · #astro-ph
published as Astron. Astrophys. 361, L33-L36 (2000) · 4 pages, 5 figures
arxiv created 2000/07/28 · arxiv updated 2009/12/01
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.