部分电离稠密氦等离子体物态方程的自洽变分计算

稠密氦在高温高压下将会发生电离, 电离能会因为原子、离子以及电子之间的相互作用而降低. 考虑He，He⁺，He²⁺，e之间的相互作用, 通过粒子化学势平衡得到非理想的电离平衡方程，用自洽流体变分过程对方程求解, 进而对自由能求导获得体系的热力学状态参量. 模型计算结果与已有的实验和理论计算相一致. 用此模型预测密度10^-3—10^0.3 g/cm³和温度4—7 eV范围的物态方程, 获得了压力在500　GPa以内的理论数据. 计算表明粒子间的非理想相互作用引起的电离能降低是出现压致电离现象的主要原因，在高温高密度物态方程的计算中必须考虑粒子间非理想相互作用对电离能修正的影响. 关键词： 氦 物态方程 部分电离等离子体 自洽变分

Self-consistent variational calculation of the dense fluid helium plasma in the region of partial ionization

The dense fluid helium will be ionized under high pressures and temperatures. The ionization energy of helium will be lowered as the result of interactions between all particles of He, He⁺, He²⁺, and e. In this paper, the thermodynamic parameters are obtained from nonideal ionization equilibrium, taking into account the correlation contributions to the chemical potential which is determined self-consistently by the free energy function. The theoretical equation of state (EOS) is verified by shock compression experiments and other theoretical calculations. The EOS of dense helium plasma are predicted and the contributrions of interactions are discussed for the density and temperature range of 10^-3—10^0.3 g/cm³ and 4—7 eV, respectively. The calculations show that the pressure ionization is caused by the reduced ionization energy induced by the nonideal interactions, and the ionization energy should be corrected at high temperatures and densities.