Reconnection of magnetic field lines near critical points

A review of theoretical studies and computer simulations of the plasma dynamics near critical points of the magnetic field is presented. The global characteristics of reconnection of the magnetic field lines and vortex lines are discussed. Examples of typical patterns of the magnetic field near critical points are presented. The propagation of MHD waves and the formation of singularities near null lines and separatrix surfaces are discussed. Nonlinear regimes of the plasma dynamics are described, and exact solutions of the MHD equations in which the Hall effect is taken into account are presented. The magnetic reconnection in the frame of the electron magnetohydrodynamics model is also discussed. The results of computer simulations of the current sheet formation near null lines and separatrices of the magnetic field are presented. The nonadiabatic motion and the acceleration of charged particles near critical points are discussed.