Electronically excited states and their role in affecting thermodynamic and transport properties of thermal plasmas

The contribution of internal degrees of freedom to thermal-plasma properties has been investigated in a wide range of temperature and pressure. Thermodynamic functions have been calculated modelling in different ways the electronic levels of atomic species (ground-state, Debye-Hückel and confined-atom approximations). Frozen and reactive specific heats are strongly affected by electronic excitation whereas compensation effects smooth its influence on the total specific heat, i.e. the sum of frozen and reactive contributions. High-order Chapman-Enskog method has been applied to evaluate transport coefficients. The inclusion of electronically excited states have a twofold impact, reflecting the changes on thermodynamic properties and on transport cross sections of excited species. Results for atomic hydrogen, nitrogen and air plasmas are considered in this lecture.