Turbulent plasma flow, its energies, and structures: Velocity vortices, magnetic field cocoons, and plasmoids

¹ University of South Bohemia, Faculty of Science, Department of Physics, Branišovská 1760, CZ – 370 05 České Budějovice, Czech Republic
² Astronomical Institute of the Czech Academy of Sciences, Fričova 258, CZ – 251 65 Ondřejov, Czech Republic

^⋆ Corresponding author; pjelinek@prf.jcu.cz

Received: 9 February 2024
Accepted: 27 October 2024

Abstract

Context. Turbulent flows are believed to be present in the solar corona, especially in connection with solar flares and coronal mass ejections. They are supposed to be very effective processes in energy transportation and can contribute to the heating of the solar corona.

Aims. We study turbulence in reconnection outflows associated with flares and coronal mass ejections. We simulated the generation and evolution of the turbulent plasma flow and investigated its energies and formed plasma velocity and magnetic field structures.

Methods. For the numerical simulations, we adopted a three-dimensional (3D) magnetohydrodynamic (MHD) model, in which we solved a full set of the 3D time-dependent resistive and compressible MHD equations using the LARE3D numerical code.

Results. We numerically studied turbulence in the plasma flow in the model with the plasma parameters that could simulate processes in the magnetic reconnection outflows in solar flares. Starting from a non-turbulent plasma flow in the energetically closed system, we studied the evolution of the kinetic, internal, and magnetic energies during the turbulence generation. We found that most of the kinetic energy is transformed into the plasma heating (about 95%) and only a small part to the magnetic energy (about 5%). The turbulence in the system evolves to the saturation stage with the power-law index of the kinetic density spectrum, −5/3. Magnetic energy is also saturated due to its dissipation and reconnection in small and complex magnetic field structures. We show examples of the structures formed in studied turbulent flow: velocity vortices, magnetic field cocoons, and plasmoids.