Mass flows and the ionization states of coronal loops

A basic assumption in the analysis of EUV and X-ray solar emission is that the plasma is in ionization equilibrium. The effects of mass flows on the ionization state of solar plasma have been investigated in order to check the validity of ionization equilibrium. Solar coronal loop models with a steady state flow as described by Antiochos (1984) are considered. The number densities of carbon ions have been determined for four loop models that cover a range of densities and flow velocities. The results show evidence of nonequilibrium ionization effects even for velocities of only a few km/s at the loop top and 10 times less at the base, with densities ranging from 10 to the 8th to 10 to the 10th/cu cm between the top and the footpoints. The importance of these results for the analysis of EUV and X-ray solar emission is discussed. 20 references.