EOS of helium and hydrogen and its application to astrophysics

With the shock compression experiments in the Mbar regime [1, 2, 3] extensive investigations were performed on the equation of state (EOS) for hydrogen. One major application of this EOS is the modelling of gaseous planets like Jupiter. These planets consist basically of hydrogen and helium. We extended our chemical models, developed earlier [4], to a hydrogen-helium mixture. For a typical fraction of 15% of helium in a hydrogenhelium mixture we show the pressure isotherms in Fig. 1. The effect of helium is to be seen at larger densities above 1 g/cm. The model is based on fluid variational theory (FVT) using effective pair potentials [4]. We extended this model to a three-component model for the species hydrogen atom and molecule and helium atom [5].