Abstract
Turbulence, magnetic reconnection, and shocks can be present in explosively unstable plasmas, forming a new electromagnetic environment, which we call here turbulent reconnection, and where spontaneous formation of current sheets takes place. We will show that the heating and the acceleration of particles is the result of the synergy of stochastic (second order Fermi) and systematic (first order Fermi) acceleration inside fully developed turbulence. The solar atmosphere is magnetically coupled to a turbulent driver (the convection zone), therefore the appearance of turbulent reconnection in the solar atmosphere is externally driven. Turbulent reconnection, once it is established in the solar corona, drives the coronal heating and particle acceleration.
Highlights
In the 80’s, the link between the spontaneous formation of current sheets inside fully developed turbulence and the evolution of unstable current sheets to fully developed turbulence has been established with the use of 2D numerical simulations of the MHD equations [1, 2]
Onofri et al [32] numerically solved the incompressible, dissipative, magnetohydrodynamics (MHD) equations in dimensionless units in a three-dimensional Cartesian domain, with kinetic and magnetic Reynolds numbers Rv = 5000 and RM = 5000. They set up the initial condition in such a way as to have a plasma that is at rest, in the frame of reference of the computational domain, permeated by a background magnetic field sheared along the xdirection, with a current sheet in the middle of the simulation domain
Parker [12] was the first to realize that the spontaneous formation of magnetic current sheets in the solar corona is a natural consequence of the magnetic link between the turbulent convection zone and the solar atmosphere [13, 44]
Summary
In the 80’s, the link between the spontaneous formation of current sheets inside fully developed turbulence and the evolution of unstable current sheets to fully developed turbulence has been established with the use of 2D numerical simulations of the MHD equations [1, 2]. Turbulence is externally driven by the convection zone, and the spontaneous formation of a turbulent reconnecting environment has been analyzed in several articles [12, 13, 14, 15, 16, 17, 18]. In the first section we pose the question: How the three well known non linear MHD structures appearing in many astrophysical and laboratory plasmas, i.e. Turbulence, Current Sheet(s), and Shocks, can lead asymptotically to turbulent reconnection.
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