On the role of MHD turbulence in the decrease of electric conductivity of plasma in the active magnetic area of the Sun

1Krivodubskij, VN
1Astronomical Observatory of Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2019, 35(3):34-43
Start Page: Solar Physics
Language: Russian

To overcome the difficulty of effective dissipation of currents in electromagnetic flare model associated with the high gas-kinetic conductivity of solar plasma, we draw attention to the possibility of a local decrease in the conductivity in places of highly developed MHD-turbulence near the neutral lines of photospheric magnetic configurations. We proposed the concept of redistribution of electrical conductivity, which is based on the following physical effects and the conditions known from observations in the solar atmosphere: 1. Reducing of the electrical conductivity parameter (increasing of the resistivity) in a turbulent medium. 2. Magnetic suppression of turbulence under the influence of strong magnetic fields. 3. Excitation of a large-scale electric field by macroscopic plasma motions in the photosphere in the presence of a magnetic field (photospheric dynamo). 4. The observing spatial inhomogeneous structure of magnetic configurations in the vicinity of sunspot groups, which leads to the formation of current layers with zero (neutral) magnetic fields lines. The values of the MHD turbulent conductivity near neutral magnetic lines in the photosphere that we calculated turn out to be almost 3 orders of magnitude smaller than the values of the usual gas-kinetic conductivity in the places of strong magnetic fields in the vicinity of sunspots. Significantly reduced conductivity in the areas of highly developed MHD turbulence can contribute here to accelerated Joule current dissipation, whose energy is consistent with the characteristics of thermal flares.

Keywords: магнитные поля, солнечные вспышки, солнечные пятна, турбулентная электропроводность, электрические токи

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