Physics of static loop structures and scaling laws

The use of quasi-static models in the study of the physical processes occurring in the magnetic flux loops making up the visible, EUV and X-ray corona in solar active regions is considered. The quasi-static loop models are based on steady-state energy equations for a static plasma in a section of a symmetrical loop with specified boundary conditions, from which values of parameters such as loop length, pressure, maximum temperature and differential emission measure may be derived that are consistent with those observed. The models also provide insight into mechanisms controlling mass exchange between the chromosphere and the corona, and the role of changes in coronal heating in the loops in initiating the mass flows. Investigations into the properties of quasi-static models for coronal loops have also demonstrated the insensitivity of the loop longitudinal temperature-density structure to parameters characterizing hypothetical steady-state heating functions