2009/11/05 by Dhrubaditya Mitra, Simon Candelaresi, Piyali Chatterjee +2 · 2 citations
Biochemistry, Genetics and Molecular Biology · Environmental Science · Physics and Astronomy · #Climate variability and models #Geomagnetism and Paleomagnetism Studies #Solar and Space Plasma Dynamics #astro-ph.EP #astro-ph.SR
paper · pdf · doi:10.1002/asna.200911308
published as Astron. Nachr. 331, 130-135 (2010) · 6 pages 5 figures
arxiv created 2009/11/05 · openalex publication_date 2009/12/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Abstract We use direct numerical simulations of forced MHD turbulence with a forcing function that produces two different signs of kinetic helicity in the upper and lower parts of the domain. We show that the mean flux of magnetic helicity from the small‐scale field between the two parts of the domain can be described by a Fickian diffusion law with a diffusion coefficient that is approximately independent of the magnetic Reynolds number and about one third of the estimated turbulent magnetic diffusivity. The data suggest that the turbulent diffusive magnetic helicity flux can only be expected to alleviate catastrophic quenching at Reynolds numbers of more than several thousands. We further calculate the magnetic helicity density and its flux in the domain for three different gauges. We consider the Weyl gauge, in which the electrostatic potential vanishes, the pseudo‐Lorenz gauge, where the speed of light is replaced by the sound speed, and the ‘resistive gauge’ in which the Laplacian of the magnetic vector potential acts as a resistive term. We find that, in the statistically steady state, the time‐averaged magnetic helicity density and the magnetic helicity flux are the same in all three gauges (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)