Element fractionation in the solar chromosphere driven by ionization-diffusion processes

An ionization-diffusion mechanism is proposed to understand the first ionization potential (FIP) fractionation as observed in the solar corona and the solar wind. The enrichment of the low-FIP elements (<10 eV) compared to the highFIP elements in a large variety of phenomena, as e.g. slow and fast wind or polar plumes, is explained. Also the special behaviour of the heavy noble gases becomes perceptive and the absolute fractionation, i.e. in relation to hydrogen, can be calculated and fits well to the measurements. Additionally the theoretical velocity-dependence of the fractionation will be used to determine the velocities of the solar wind in the chromosphere. The main achievement of this paper is the explanation of a great variety of fractionation-related phenomena on the basis of one single model.