Rate coefficients and ion populations

The same modelling is used here for other elements routinely observed in the solar transition region: N, Ne, Mg, Si, and S. The modelling includes the effects of higher densities suppressing dielectronic recombination and populating long lived, metastable levels; the presence of metastable levels typically causes effective ionization rates to increase and recombination rates to decrease.

Processes induced by the radiation field, namely photoionization and photoexcitation, have been included, along with charge transfer, which occurs when electrons are exchanged during atom-ion and ion-ion collisions. The resulting ion balances are shown, and indicate significant changes compared to the frequently employed coronal approximation. The effect on level populations within ions caused by photoexcitation is also assessed.