Statistical theory of the equation of state for 2D Coulombic gas near its critical point

The van der Waals equation of state for the 2D Coulombic gas is constructed within the dipole fluid approximation. The dependence of the dipole moment for a single ionic pair on temperature and density is taken into account. The critical values of temperature and density are determined. It is shown that the density dependence of dipole moments of ionic pairs leads to main variations of the critical parameters. The applicability region of the dipole fluid approximation is considered.