Electrical conductivity and magnetic permeability of magnetohydrodynamic turbulent plasma of the Sun
Рубрика:
| 1Kryvodubskyj, VN 1Astronomical Observatory, Taras Shevchenko National University of Kyiv, 04053, Kyiv, Ukraine |
| Kinemat. fiz. nebesnyh tel (Online) 2024, 40(3):53-70 |
| https://doi.org/10.15407/kfnt2024.03.053 |
| Язык: Ukrainian |
Аннотация: Background. In the framework of classical MHD, the magnetic fields on the Sun, due to the high inductance caused by the large size of the fields and the high gas-kinetic electrical conductivity of the plasma, are characterized by huge theoretically calculated time intervals of their ohmic dissipation. This is in striking contrast to the observed rapid changes in the structure of solar magnetism. In order to solve this contradiction, the search for new methods of studying magnetized plasma becomes relevant. Involvement of researchers in the consideration of turbulent motions in the plasma ended with the creation of macroscopic MHD, in the framework of which there is a significant decrease in electrical conductivity and magnetic permeability, which leads to a decrease in the calculated time of reconstruction of global magnetic fields. The purpose of this study is to calculate the coefficients of turbulent electrical conductivity and turbulent magnetic permeability of the solar plasma; to analyze changes in the spatio-temporal evolution of the global magnetism of the Sun considering these parameters.Methods. Macroscopic magnetohydrodynamics, which studies the behavior of global electromagnetic and hydrodynamic fields in turbulent plasma.Results. For models of the photosphere and the SСZ the distribution along the solar radius was calculated of the next parameters: coefficients of kinematic ν, magnetic νm and turbulent σT viscosities, hydrodynamic Re and magnetic Rm Reynolds numbers, gas-kinetic σ and turbulent σT electrical conductivities, and turbulent magnetic permeability μT. The theoretically calculated parameters have the following values: ν = 0.2...10 cm2/s, νm = 6*108...8*102 cm2/s, νТ = 1011...1013 cm2/s, Re = 5*1011...5*1013, Rm = 104...1010, σ = 1011...4*1016 CGS, σT = 109...4 *1011 CGS, μT = 10–2...4*10–5. It is relevant that σT << σ, and μT << 1.Conclusions. Our calculated turbulent magnetic diffusion DT = c2/4πσTμT turned out to be 4 to 9 orders of magnitude higher than the magnetic viscosity coefficient νm = c2/4πσ, which is responsible for the ohmic dissipation of magnetic fields. As a result, it becomes possible to theoretically explain the observed rapid reconstruction of magnetism on the Sun. The radial inhomogeneity of the turbulent viscosity νТ and the condition μТ << 1, revealed by us, testify to the strong macroscopic diamagnetism of the solar plasma. In the lower part of the SCZ, the turbulent macroscopic diamagnetism performs the role of “negative magnetic buoyancy” and thereby contributes to the formation of a magnetic layer of a stationary toroidal magnetic field BS ≈ 3000…4000 G near the bottom of the SCZ. |
| Ключевые слова: electrical conductivity, macroscopic MHD, magnetic activity of the Sun, magnetic fields, magnetic permeability, turbulence, turbulent diamagnetism |
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