Pseudo-critical point in anomalous phase diagrams of simple plasma models

31st International Conference on Equations of State for Matter

Chigvintsev, A.Yu.^1 ; Iosilevskiy, I.L.^1,2 ; Noginova, L.Yu.^3

Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region

141700, Russia^1

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

125412, Russia^2

Russian State Agrarian University - Timiryazev Moscow Agricultural Academy, Timiryazevskaya 49, Moscow

127550, Russia^3

关键词: Anomalous phase;    Boundary values;    Common features;    Critical isotherms;    Equation of state;    Model components;    Pseudo-critical points;    Wigner crystallization;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/774/1/012019/pdf
DOI  :  10.1088/1742-6596/774/1/012019

来源: IOP

【 摘 要 】

Anomalous phase diagrams in subclass of simplified ("non-associative") Coulomb models is under discussion. The common feature of this subclass is absence on definition of individual correlations for charges of opposite sign. It is e.g. modified OCP of ions on uniformly compressible background of ideal Fermi-gas of electrons OCP(∼), or a superposition of two non-ideal OCP(∼) models of ions and electrons etc. In contrast to the ordinary OCP model on non-compressible ("rigid") background OCP(#) two new phase transitions with upper critical point, boiling and sublimation, appear in OCP(∼) phase diagram in addition to the well-known Wigner crystallization. The point is that the topology of phase diagram in OCP(∼) becomes anomalous at high enough value of ionic charge number Z. Namely, the only one unified crystal- fluid phase transition without critical point exists as continuous superposition of melting and sublimation in OCP(∼) at the interval (Z12). The most remarkable is appearance of pseudo-critical points at both boundary values Z = Z1≈ 35.5 and Z = Z2≈ 40.0. It should be stressed that critical isotherm is exactly cubic in both these pseudo-critical points. In this study we have improved our previous calculations and utilized more complicated model components equation of state provided by Chabrier and Potekhin (1998 Phys. Rev. E 58 4941).