Wednesday

Since the Sweet-Parker reconnection model was first proposed in 1957, it has been firmly established that magnetic reconnection is a crucial process in the solar corona, especially for flares and coronal heating. Further, the theory of MHD reconnection has been explored extensively, both mathematically and with the use of numerical simulations. Despite major progress being made, several challenges in the field remain unsolved. In this talk, we examine whether previous models and simulations of reconnection, many of which were limited to 2.5D or relatively low magnetic Reynolds numbers (Rm) by necessity, can be extrapolated to the fully 3D and high-Rm solar corona. We find that 3D MHD simulations have recently exceeded a parameter threshold where magnetic reconnection is qualitatively different to classical models. In the new high-Rm regime, which is presumably more realistic, reconnection is intrinsically both 3D and turbulent. This is due to the development of 3D nonlinear instabilities and field line wandering that are enabled by the additional spatial degree of freedom combined with high-Rm. We present a 3D MHD simulation of a reconnecting current sheet in the high-Rm regime which achieves fully 3D turbulent reconnection that is self-generated from initially slow 2.5D Sweet-Parker reconnection. We also share some innovative analysis used to investigate how 3D instabilities seed field line stochasticity, and how the reconnection layer evolves once it has become stochastic.