Relaxation and Heating Triggered by Nonlinear Kink Instability: Application to Solar Flares and Coronal Heating

Abstract

Energy release and particle acceleration in kink-unstable twisted coronal loops are discussed. If the magnetic field in a coronal loop is sufficiently strongly twisted, it may become unstable to the ideal kink instability. We present results of 3D MHD simulations which show that in the nonlinear phase of the instability, current sheets form in which magnetic reconnection rapidly dissipates magnetic energy. In the later phase, the current sheet fragments. The energy release is well-modelled by a helicity conserving relaxation to a minimum energy state. We exploit this in order to calculate a distribution of energy-release events, and show how this is relevant to the solar coronal heating problem. Using test particle approach coupled with 3D MHD simulations, we also show how the electric fields associated with the fragmented currents sheet can efficiently accelerate charged particles. This has implications for the origin of high-energy particles in solar flares.