Ion number density profile as a function of the cometary distance (normalized to the cometocentric distance at the surface, r_c) for the equilibrium between the attenuated solar flux through the coma (referred to here as different values of the optical depth at the cometary surface) and the e⁻ -ion dissociative recombination rate (see Eq. (19)). The solid black line corresponds to the density profile without photoabsorption and the dashed line to the cometary surface. Increasing τ_c is similar to increasing the outgassing rate. These profiles depend on neither U_n nor α as they have been scaled accordingly.