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

Developments in shock-wave experimental techniques have allowed Megabar pressure range in dense fluid to be probed. It has been shown that the dissociation of the molecule and ionization of the atom become operative under such ultrahigh pressures. The dense fluid helium will be ionized in high pressures and temperatures. The ionization energy of helium will be lowered due to the interactions among all particles of He, He+, He2+, and e. The ionization degree is 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 composition of dense helium can be calculated with given densities and temperatures. The equations of state of dense helium plasma are predicted in the density and temperature range of 0