Pinch sheets and reconnection in astrophysics

Magnetic reconnection processes involving the formation and destruction of pinch current sheets in plasma are a universal phenomenon typical of both laboratory and space plasmas. In current sheets a rapid dissipation of the magnetic field is possible in conditions of high conductivity and large scales of the plasma. This effect results from specific features of the flow near the null lines of the magnetic field, which lead to increases in the magnetic field gradient until dissipative effects become significant. As a result of magnetic reconnection processes, a change occurs in the magnetic field topology: initially independent magnetic fluxes become connected. It is also suggested that current sheets can accumulate excess magnetic energy as compared with the energy of the potential magnetic field.