Efficient and consistent methodology for the calculation of population densities, partition functions, and thermodynamic properties of ideal and weakly non-ideal multicomponent plasma mixtures in the P-T phase space
A set of nonideal Saha equations, for multicomponent plasma mixtures, can be derived from the conditions of the minimization of the free energy function in the ionization processes. Population densities derived from the solution of this set of equations subjected to electro-neutrality and conservation of nuclei are fully consistent with the thermodynamic properties derived from the same free energy function and, therefore, can be used to calculate these properties. Depending on the degree of complexity of the free energy function, nonideal Saha equations are obtained with different forms of nonideality corrections. In most practical situations, the problem of solving the resulting system of coupled nonlinear Saha equations, subjected to the above mentioned constraints, in the pressure-temperature (P-T) phase space, is found to be effectively a one-dimensional nonlinear problem i.e., solving a single transcendental equation. The methodology and algorithm presented herein are based on "the chemical picture," with all thermodynamic properties derived self-consistently from the free energy function, and on the mapping of the resulting set of governing equations into a one-variable zero-search. The algorithm is successful for most practical models for nonideality corrections to the free energy function, which are fully reflected in the derived nonideal Saha equations as lowering of ionization potentials, corrected equation of state, and truncated partition functions. The ease and efficiency of the introduced algorithm allows, with significant simplicity, the computations of population densities of all plasma species (neutral, ionized, and excited) up to maximum ionization states equal to the atomic numbers of the involved elements with minimal computational work. It also considers an extensive database of energy levels of the excited states. The algorithm is analytically known to be safe, fast, efficient, and solves the problem to the machine accuracy. It shows no numerical instabilities, no convergence problems, and no accuracy limitations or lack-of-change problems, which have been repeatedly reported in the literature. A nontrivial problem is worked out and presented in detail showing the effectiveness of the present methodology. For completeness, a criterion for the validity of the assumption of local thermodynamic equilibrium is applied to the results of the sample problem showing regions of the pressure-temperature phase space over which the assumption is valid.
Electronic excitation and isentropic coefficients of high temperature planetary atmosphere plasmas
In this paper, we have discussed the effects of electronically excited states of atomic species in affecting the isentropic coefficients of plasmas, focusing on mixtures representing the atmospheres of Jupiter, Mars, and Earth. General behaviors have been rationalized on the basis of simplified approaches. The contribution of the electronically excited states has been evidenced by comparing results obtained considering only the ground state and those obtained using either Fermi or Griem cutoff criteria.
Influence of electric fields on friction electrification between metals and borosilicate glass
Abstract In a cylindrical geometry, electric fields were applied through the entire contact area between the sliding metal and the glass surface. The maximum electric charges developed on the metal were measured and plotted against the applied voltage producing the field. The metals were high-purity nickel and gold. The borosilicate glass was Pyrex, brand 7740. The experiments with nickel, which has a work function greater than that of the glass, were performed in 10 −7 mm Hg vacuum. The experiments with gold, with a work function smaller than that of glass, were carried out in air at atmospheric pressure. The results show that: 1. 1) There is both asymmetry and a reversed slope portion in the charge vs. voltage plot. 2. 2) For a certain range of reversing fields, the electric charge developed on the nickel is always negative and the charge on gold is always positive.