http://arxiv.org/abs/1911.06611
The influence of fluctuating conductivity on the coefficients known from the mean-field electrodynamics is considered. If the conductivity fluctuations are assumed as uncorrelated with the turbulent velocity field then only the effective magnetic diffusivity of the fluid is reduced and the decay time of a large-scale magnetic field is increased. If the fluctuations of conductivity and flow are correlated in a certain direction then an additional diamagnetic pumping effect results transporting magnetic field in opposite direction to the resistivity flux vector $\langle \eta’\vec{u}’\rangle$. Even for homogeneous turbulence fields in the presence of rotation an $\alpha$ effect appears. With the characteristic values of the outer Earth core or the solar convection zone, however, the dynamo number of the new $\alpha$ effect never reaches supercritical values to operate as an $\alpha^2$-dynamo.
G. Rüdiger, M. Küker and P. Käpylä
Mon, 18 Nov 19
22/48
Comments: 11 pages, 4 figures
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