NONLINEAR DYNAMICS IN FORCED RECONNECTION

Forced reconnection in a current-carrying two-dimensional resistive ma gneto-fluid is explored in a slab geometry. The time development of th e two-dimensional processes that occur is studied numerically. Perturb ation of the wall during a few Alfven times generate ideal megnetohydr odynamics (MHD) waves that propagate towards the neutral layer and gen erate a current layer along it. The formation of the current sheet nea r the X point and the vortex motion inside the island are analysed in the nonlinear regime. In this phase the current in the X point of the generated island grows exponentially with time while it is still gover ned by ideal MHD. After having reached a maximum the current decreases sharply. This maximum and the subsequent decrease are determined by r esistivity and the narrowing of the local current profile, which is an ideal effect. The current distribution becomes that of a sheet curren t, especially for low values of the resistivity. Eventually a quasi-st ationary state is reached in which current and vorticity are localized along the separatrix.