Self-consistent stationary MHD shear flows in the solar atmosphere as electric field generators

0434761 - ASÚ 2015 RIV FR eng J - Journal Article
Nickeler, Dieter Horst - Karlický, Marian - Wiegelmann, T. - Kraus, Michaela
Self-consistent stationary MHD shear flows in the solar atmosphere as electric field generators.
Astronomy & Astrophysics. Roč. 569, September (2014), A44/1-A44/10. ISSN 0004-6361. E-ISSN 1432-0746
R&D Projects: GA ČR GA13-24782S; GA ČR GAP209/12/0103
Institutional support: RVO:67985815
Keywords : magnetohydrodynamics * Sum : flares * Sun : corona
Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics
Impact factor: 4.378, year: 2014

Within a physically simplified, but exact mathematical model, we study the electric currents and corresponding electric fields generated by shear flows. Methods: Starting from exact and analytically calculated magnetic potential fields, we solved the nonlinear MHD equations self-consistently. By applying a magnetic shear flow and assuming a nonideal MHD environment, we calculated an electric field via Faraday's law. The formal solution for the electromagnetic field allowed us to compute an expression of an effective resistivity similar to the collisionless Speiser resistivity. We find that the electric field can be highly spatially structured, or in other words, filamented. The electric field component parallel to the magnetic field is the dominant component and is high where the resistivity has a maximum. The electric field is a potential field, therefore, the highest energy gain of the particles can be directly derived from the corresponding voltage. In our example of a coronal post-flare scenario we obtain electron energies of tens of keV, which are on the same order of magnitude as found observationally. This energy serves as a source for heating and acceleration of particles.
Permanent Link: http://hdl.handle.net/11104/0238769