The global plasma model is discussed in Chapter 10.2 of Lieberman & Lichtenberg (2005)
The code here is an extension to a multi-species plasma
The first version of the code is for an Ar/Xe plasma. The two species have been hard-coded into the code.
The code has been verified against the examples in Lieberman, Section 10.2. The agreement is approximate. This is most likely because of differences in the calculated electron temperature (and thus rates and energy losses).
The neutrals model and that of ion-ion plasma remains to be implemented.