“…Different relations in the literature were derived to describe the ionization and dissociation reactions and the main models include Potapov's method, 30 method of van de Sanden et al, 31 Gibbs free energy minimization method, 45,46 as well as the kinetic model. 47 For the law of mass action, two main derivations, respectively, by Potapov's method and method of van de Sanden et al are developed in previous literature. Using the argument that in the extreme cases of very high and very low electron number density, the dissociation and ionization laws must not depend on h ¼ T h /T e , the same expressions as those of van de Sanden et al are 26 Gleizes et al, 27 and Andr e et al, 49 respectively, presented their own derivations of the excitation temperature.…”