Open AccessEquation of State of Classical Systems of Charged Particles
Author(s) -
Stephen G. Brush,
H. E. DeWitt,
John G. Trulio
Publication year - 1962
Language(s) - English
Resource type - Reports
DOI - 10.2172/1122805
Subject(s) - spheres , hard spheres , range (aeronautics) , coulomb , ionization , ion , equation of state , electrolyte , charged particle , physics , atomic physics , classical mechanics , thermodynamics , quantum mechanics , materials science , electron , electrode , astronomy , composite material
Recent developments in the classical theory of fully ionized gases and strong electrolyte solutions are reviewed, and are used to discuss the equation of state at high temperature and low densities. The pressure is calculated using the ring-integral approximation, and quantitative estimates of higher correction terms are given. The effect of short-range repulsive forces is shown by comparing the results with two kinds of potential functions: hard spheres of diameter a, and "soft" spheres for which the short-range potential cancels the Coulomb potential at the origin, and decreases exponentially with distance. It is found that the use of either type of potential extends the range of validity of the ring integral approximation to considerably higher densities and lower temperatures. Since there is little difference in the results for the hard spheres and the soft spheres in this range, the latter is investigated more extensively since it is more easily handled by analytical methods. The expressions derived for the free energy of a system of charged particles can also be used in ionization equilibrium calculations, and the effect of electrostatic interactions on the equilibrium concentrations of various kinds of ions is indicated