The simplest model for non-congruent fluid_fluid phase transition in Coulomb system

30th International Conference on Interaction of Intense Energy Fluxes with Matter

Stroev, N.E.^1 ; Iosilevskiy, I.L.^1

Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13, Moscow

125412, Russia^1

关键词: Analytical approximation;    Congruent phase transitions;    Equation of state;    Extreme temperatures;    Fluid-fluid phase transition;    High temperature heating;    Ionized electrons;    Temperature diagram;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/653/1/012078/pdf
DOI  :  10.1088/1742-6596/653/1/012078

来源: IOP

【 摘 要 】

The simplest model for non-congruent phase transition of gas-liquid type was developed in frames of modified model with no associations of a binary ionic mixture (BIM) on a homogeneous compressible ideal background (or non-ideal) electron gas/BIM(∼)/. The analytical approximation for equation of state equation of state of Potekhin and Chabrier of fully ionized electron-ionic plasma was used for description of the ion-ion correlations (Coulomb non-ideality) in combination with "linear mixture" (LM) approximation. Phase equilibrium for the charged species was calculated according to the Gibbs-Guggenheim conditions. The presently considered BIM(∼) model allows to calculate full set of parameters for phase boundaries of non-congruent variant of phase equilibrium and to study all features for this non-congruent phase transition realization in Coulomb system in comparison with the simpler (standard) forced-congruent evaporation mode. In particular, in BIM(∼) there were reproduced two-dimensional remarkable ("banana-like") structure of two-phase region P - T diagram and the characteristic non-monotonic shape of caloric phase enthalpy-temperature diagram, similar to the non-congruent evaporation of reactive plasma products in high-temperature heating with the uranium-oxygen system. The parameters of critical points (CP) line were calculated on the entire range of proportions of ions 0 Tand Xp. Finally, it is clearly demonstrated the low-temperature property of non-congruent gas-liquid transition - "distillation", which is weak in chemically reactive plasmas.