An Equation of State for Helium

TL;DR

This paper presents a new helium equation of state (EOS) model that accurately predicts static and shock-wave data, incorporating phase transitions and electronic effects, primarily for astrophysical applications.

Contribution

A novel helium EOS combining solid and fluid phases with electronic effects, suitable for planetary and stellar modeling.

Findings

Excellent agreement with static and shock-wave data

Effective modeling of phase transitions and electronic effects

Applicable to planetary, stellar, and other astrophysical models

Abstract

This report describes a new equation of state (EOS) for helium. The PANDA code was used to construct separate EOS tables for the solid and fluid phases. The solid and fluid EOS were then assembled into a multiphase EOS table using the PANDA phase transition option. Contributions from thermal electronic excitation and ionization were also included in the model. The EOS gives very good agreement with all static and shock-wave data, except at temperatures below 20K, where further work is needed. This EOS was developed primarily for use in models of the giant planets, the sun, and stars but should be useful in other applications as well.