Nearest-neighbor effects in hot and dense plasmas: Thermodynamic properties

A model for describing the influence of the nearest-neighbor interaction on the thermodynamic properties of plasmas is presented. This model is a generalization of the Thomas-Fermi model to cylindrical symmetry. The model was applied to the calculation of the electric potential of a pair of identical ions. An iron plasma at an ion density of 10²³ cm^-3 at a range of temperatures of practical interest was used to illustrate the predictions of the model. The ionization-potential reduction, the ion-pair free energy, and the average distance to the nearest neighbor were calculated. Our results indicate that the inclusion of the nearest-neighbor interaction predicts a plasma which is slightly more compressible than predicted by the spherically symmetric Thomas-Fermi model.