Features of Hypothetical Plasma Phase Transition in Interiors of Saturn and Jupiter

Abstract: Anomalous features for hypothetical Plasma Phase Transitions (PPT), which is expected to occur in mixed hydrogen-helium plasma in interior of Jupiter and Saturn, are under discussion. The characteristics of the Coulomb and density corrections (the so-called non-ideality corrections) are reconstructed for hydrogen-helium plasma in the vicinity of phase coexistence boundary of this PPT in version of Saumon and Chabrier, using tabular data for hydrogen-helium EOS of Saumon, Chabrier and VanHorn and some general thermodynamic relations. Two previously unknown characteristics of the studied PPT have been estimated based on these results: (i) -- the jump of the electrostatic potential across the phase boundary of PPT (Galvani potential), and (ii) -- the scale of non-congruency for this PPT (the differences in chemical composition of the coexisting hydrogen-helium phases), which could be expected in H2/He mixture at typical parameters of plasma in interior of Jupiter and Saturn. While the first effect -- the potential of phase boundary -- turned out to be within the typical scale of contact electrochemical potentials, $\Delta \varphi$ ~ 1-2 eV, the second quantity -- the PPT non-congruency -- proved to be considerable under Saturn and Jupiter conditions.