Magnetohydrodynamic simulation of reconnection in turbulent astrophysical plasmas

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Turbulence is prevalent in large-Reynolds-number astrophysical plasmas, such as the Solar corona, where it is believed to enhance energy conversion rates through magnetic reconnection beyond classical predictions. Due to the challenge of simulating turbulence alongside large-scale plasma behavior, magnetic reconnection is analyzed through the average properties of turbulence. A Reynolds-averaged turbulence model is proposed, where turbulence is self-sustained and generated by large-scale field inhomogeneities. This model is employed in large-scale MHD numerical simulations that solve the evolution equations of energy and cross-helicity alongside MHD equations. Findings indicate that turbulence can either enhance or suppress magnetic reconnection, depending on its timescale; when calculated self-consistently, reconnection is consistently enhanced. The study also examines the effects of strong guide magnetic fields, which are common in the solar corona, on turbulent reconnection. It is found that a finite guide field can slow reconnection due to residual helicity counteracting the turbulence's enhancing effects. Further investigations using high-resolution simulations of plasmoid-unstable current sheets underscore the critical role of turbulence in achieving rapid reconnection.