Thermal instability of a current sheet as the origin of the cool coronal loops

The problem of the stability of a neutral current sheet against small perturbations having their wave vector parallel to the current is solved in the MHD approximation. Radiative energy losses may serve to split the sheet into a system of relatively cool, dense filaments aligned parallel to the magnetic field. This process corresponds to the condensation mode of thermal instability, and could be responsible for the cool, dense arched loops often observed in the solar corona