Thermodynamics and transport properties of thermal plasmas: the role of electronic excitation

摘要

The role of electronic excited states in affecting the thermodynamic and transport properties ofthermal plasma is investigated in the temperature range [300-100 000 K] and in the pressurerange [1-103 atm] for hydrogen and [10-2-103 atm] for nitrogen. Thermodynamic functionshave been calculated modelling in different ways the electronic levels of atomic species(ground-state, Debye—Hiickel and confined-atom approximations). Frozen and reactivespecific heats as well as isentropic coefficients are strongly affected by the electronicexcitation whereas compensation effects smooth its influence on the total specific heat, i.e. thesum of frozen and reactive contributions. Higher-order approximations of the Chapman—Enskog method have been used to evaluate transport coefficients, includingelectronically excited states as separate species. The importance of a state-to-state approach tocalculate transport coefficients is presented taking into account the strong dependence oftransport cross sections on the principal quantum number. Results for hydrogen, nitrogen andair plasmas are widely discussed.