Thermodynamic properties and plasma phase transition of xenon at high pressure and high temperature

By using recent Padé approximations for the Coulombic contribution and hard-core, Van der Waals and polarisation approximations for the atomic contribution, the thermodynamic functions for the nonideal xenon plasma are constructed. These formulae cover a large range of pressure and temperature. Single ionisation is studied by minimising the free energy with respect to the particle numbers. A second critical point is predicted. The coexistence line for the corresponding first order phase transition (weakly ionised plasma - strongly ionised plasma), the lines indicating the soft transition to a higher degree of ionisation at overcritical temperatures, as well as the border of the coexistence area are presented. The influence of the different interactions on the critical data is discussed.