2D MHD Simulations of Multiple Shocks and Turbulence in the Reconnection Jet

S. Tanuma (Kyoto Univ.) and K. Shibata

The satellites such as Yohkoh and RHESSI observe the hard X- and
gamma-ray emissions from high energy particles at the impulsive solar
flares. The origin of them, however, is not known. In this paper,
we suggest that the internal shocks are created in the reconnection
jet and that they are possible site of particle acceleration. We
examine how the magnetic reconnection creates the multiple shocks, by
performing two-dimensional resistive magnetohydrodynamic
simulations. As the results, we find that the current sheet becomes
thin by tearing instability, and it collapses to Sweet-Parker current 
sheet. Tearing instability occurs again in the thin sheet, and creates
many plasmoids. The fast reconnection starts immediately after the
plasmoid-ejection, which are created by the secondary tearing
instability. During the fast reconnection, internal shocks are created
in the reconnection jet due to the non-steady plasmoid-ejection by the
secondary tearing instability. This situation is a turbulent
reconnection. We suggest that the multiple shocks, which are created
in the reconnection jet, accelerate the high energy electrons.