Magnetic reconnection in kinked coronal loops

The resistive dissipation process triggered by the non linear development of the kink instability in a coronal loop is investigated using a three-dimensional MHD code in cylindrical geometry. An equilibrium flux tube carrying a zero net axial current is considered. The magnetic field lines are locally twisted in the central region and inertially anchored at the two photospheric end-plates. When the twist exceeds a critical value, the loop becomes kink unstable and an intense electric current concentration develops along the loop length (Baty et al. 1998). It is found that the system settles into a steady state where a magnetic reconnection of field lines consistent with the SweetParker model occurs, in spite of the three dimensional character of the present process. In particular, the Ohmic dissipation rate scales as the square root of the resistivity. The reconnection can release more than 50 percent of the free magnetic energy stored in the initial equilibrium. Consequences for the coronal activity are presented.