MAGNETIC-FIELD LINE RECONNECTION IN WEAKLY IONIZED PLASMAS

We present the results of theoretical studies of the magnetic held lin e reconnection in weakly ionized plasmas. We investigate the propagati on of small amplitude magnetohydrodynamic (MHD) waves near critical li nes of the magnetic field and show the occurrence of the pile-up of el ectric current. This magnetic collapse is described by self-similar so lutions that demonstrate the formation of singular structures in the v icinity of the magnetic field separatrix surfaces. We obtain the growt h rate of the tearing mode instability of the current sheet and presen t a solution of the Taylor problem for a slab of a weakly ionized plas ma. We have found the reconnection rate and the dimensionless paramete rs that describe the relative role of nonlinearity and dissipation eff ects near critical points. We present results of the MHD computer simu lation of two-loop coalescence that show the dependence of reconnectio n on the value of ion-neutral drift.