EVOLUTION OF FORCE-FREE ELECTRIC CURRENTS IN THE SOLAR ATMOSPHERE

The new 3-D numerical model studying evolution of force-free electric currents in the solar atmosphere is presented. The initial dipole magn etic field is considered in a simplified active region. Starting from a low electric current, which penetrates the photosphere, and increasi ng the current intensity, the path of force-free electric current and the corresponding magnetic field are computed. The virtual mirror curr ent representing the effect of the inertial photosphere is considered. The single and the multiple current paths are compared. For the singl e path case, it was found that an arch-shape electric current is shear ed with the increasing current intensity, then screwed into a current loop with the helical structure and when the electric current generate s a magnetic field greater than the initial dipole magnetic field the current path becomes unstable. During all this process the current pat h moves upwards. Although the multiple current paths show more complex internal structures of electric currents, the global aspect of these processes remains the same. The relevance of this modelling for proces ses in the solar atmosphere is discussed.