“…Experimental investigations behind shock waves show that at low temperatures the rotational degrees of freedom of N2 tend towards equilibrium within only two mean free paths [17]. The results for thermal plasma also show that, despite the vibrational and electron nonequilibrium, the rotational degrees of freedom stay in the proximity of translational equilibrium [18]. As a result, 1 /Zrot,ij tends towards 1, making a conditional equation for Zrot,ij necessary.…”