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Open AccessArticle

Mean-Field Dynamo Model in Anisotropic Uniform Turbulent Flow with Short-Time Correlations

1
Department of Physics, Lomonosov Moscow State University, Moscow 119991, Russia
2
Space Research Institute RAS (IKI), Moscow 117997, Russia
3
Moscow Center of Fundamental and Applied Mathematics, Moscow 119991, Russia
4
Department of Physics, Moscow State University, Branch in Baku, Baku AZ 1143, Azerbaijan
5
IZMIRAN, Troitsk 142191, Russia
*
Author to whom correspondence should be addressed.
Galaxies 2020, 8(3), 68; https://doi.org/10.3390/galaxies8030068
Received: 2 August 2020 / Revised: 12 September 2020 / Accepted: 14 September 2020 / Published: 19 September 2020
The mean-field model is one of the basic models of the dynamo theory, which describes the magnetic field generation in a turbulent astrophysical plasma. The first mean-field equations were obtained by Steenbeck, Krause and Rädler for two-scale turbulence under isotropy and uniformity assumptions. In this article we develop the path integral approach to obtain mean-field equations for a short-correlated random velocity field in anisotropic streams. By this model we analyse effects of anisotropy and show the relation between dynamo growth and anisotropic tensors of helicity/turbulent diffusivity. Considering particular examples and comparing results with isotropic cases we demonstrate several mean-field effects: super-exponential growth at initial times, complex dependence of harmonics growth on the helicity tensor structure, when generation is possible for near-zero component or near-zero helicity trace, increase of the averaged magnetic field inclined to the initial current density that leads to effective Lorentz back-reaction and violation of force-free conditions. View Full-Text
Keywords: MHD-dynamo; mean-field model; short-correlated velocity field; method of functional integrals; uniform plasma anisotropy; tensors of helicity and turbulent diffusivity MHD-dynamo; mean-field model; short-correlated velocity field; method of functional integrals; uniform plasma anisotropy; tensors of helicity and turbulent diffusivity
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Yushkov, E.V.; Allahverdiyev, R.; Sokoloff, D.D. Mean-Field Dynamo Model in Anisotropic Uniform Turbulent Flow with Short-Time Correlations. Galaxies 2020, 8, 68.

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