Chromospheric model. (a) shows the density and temperature structure of the chromosphere. (b) shows chromospheric ionization fractions for low FIP elements and (c) for high FIP elements. (d) shows the wave energy fluxes in each direction for the three waves in the closed loop model. (e) shows the ponderomotive acceleration (solid line) and the amplitude of slow mode waves induced by the Alfvén wave driver. (f) shows the fractionations resulting for selected elements relative to Mg. Gas pressure and magnetic field pressure are equal at about 1000 km, with magnetic field pressure dominating at higher altitudes.