Energy release and plasma heating by forced magnetic reconnection

Abstract

A simple model of forced magnetic reconnection in a force-free magnetic field is considered, which allows the calculation of the magnetic energy release during the current sheet reconnection. The dependence of this energy on characteristics of the magnetic configuration has been studied, and it was found that the released energy becomes very large when the field is near the marginal tearing stability. A persistent plasma heating provided by ongoing external driving and internal reconnection is most efficient when the time-scales of these processes are comparable. Possible implications of the obtained results for the problem of solar coronal heating are briefly discussed.

Particle acceleration in a transient magnetic reconnection event

“…It also shows that the total energy release is greater for smaller initial CS thickness Y 0 . Considering that this parameter determines the maximum value of force-free parameter α in the model (α max = 1/y 0 ), one can conclude that our results are in good agreement with the previous analytical works (Vekstein & Jain 1998;Jain & Vekstein 1999) showing similar dependence.…”

“…The rate at which the magnetic energy dissipates depends on the resistivity as dE m /dt ∼ η −0.6 1 (see Fig. 5), which is in a good agreement with the analytical estimations (Hahm & Kulsrud 1985;Vekstein & Jain 1998).…”

“…This occurs because of the energy input of the boundary displacement and is expected from the analytical model of forced reconnection. This phase corresponds to the "ideal" equilibrium in the analytical models, which include tangential magnetic field discontinuity and infinite current at the resonant surface (Hahm & Kulsrud 1985;Vekstein & Jain 1998). As the result of the current density enhancement, the reconnection starts in the central region, forming a rather long and thin diffusion layer with plasma inflow in the vertical direction and outflow in the horizontal direction (Fig.…”

“…This also has the advantage of eliminating global resistive diffusion, which occurs when resistivity is uniform. Furthermore, we consider forced magnetic reconnection (Hahm & Kulsrud 1985;Vekstein & Jain 1998;Jain et al 2005), whereby the reconnection in the initially stable configuration is triggered by a transient spatially varying displacement of the top and bottom boundaries. This is done by applying plasma flow perpendicular to these boundaries and periodic in the x-direction during the time τ p :…”

“…For this purpose, we consider the model of forced reconnection (Hahm & Kulsrud 1985;Vekstein & Jain 1998;Jain et al 2005) performing 2.5D MHD simulations of reconnection in initially stationary non-neutral Harris CS (Sect. 2).…”