Atomic Partition Function
In this chapter, the statistical thermodynamic concepts described in the previous chapter will be applied to atomic species and to their plasma mixtures. Emphasis will be given to the translational and internal contributions to partition function, to their derivatives as well as to thermodynamic properties of single species. The mixture properties are then analyzed after the introduction of a simplified Saha equation for describing the equilibrium composition of an ionized system. Hydrogen is considered as a case study and the problem of the cutoff of the atomic partition function is introduced leaving to Chap. 8 a more detailed description.