Electromotive force due to magnetohydrodynamic fluctuations in sheared rotating turbulence
Authors: J. Squire and A. Bhattacharjee
Abstract: This article presents a calculation of the
mean electromotive force arising from general small-scale
magnetohydrodynamical turbulence, within the framework of the
second-order correlation approximation. With the goal of improving
understanding of the accretion disk dynamo, effects arising
through small-scale magnetic fluctuations, velocity gradients,
density and turbulence stratification, and rotation, are included.
The primary result, which supplements numerical findings, is that
an off-diagonal turbulent resistivity due to magnetic
fluctuations can produce large-scale dynamo action - the
magnetic analogue of the "shear-current" effect. In addition,
consideration of α effects in the stratified regions of
disks gives the puzzling result that there is no strong prediction
for a sign of α, since the effects due to kinetic and
magnetic fluctuations, as well as those due to shear and rotation,
are each of opposing signs and tend to cancel each other.
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Submitted to: Physical Review E
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