Equation of State and Constitutive Models for Numerical Simulations of Dust Impacts on the Solar Probe

Abstract

This report presents new EOS and strength models for use in numerical hydrocode simulations of dust impacts on the NASA solar probe space vehicle. This spacecraft will be subjected to impact at velocities up to 300 km/s, producing pressures as high as 100 TPa and temperatures as high as 200 eV. Hence the material models must treat a variety of physical and chemical phenomena, including solid-solid transitions, melting and vaporization, chemical reactions, electronic excitation and ionization. The EOSPro code is used to develop tabular EOS that include these effects. The report discusses the theoretical methods used to create the new EOS tables and constitutive models for six materials--Al2O3, two porous carbon materials, fused SiO2, a silicone elastomer, and germanium--which will be used in the thermal protection shield (TPS) and solar cells, the components most vulnerable to dust impacts. It also presents the results of hydrocode simulations of dust impacts on the TPS and on glass targets. It discusses the importance of radiation contributions to the EOS and the importance of reactions between Al2O3 and carbon during impacts. It makes recommendations for additional work, including experiments for testing the accuracy and reliability of the hydrocode simulations as well as for improving and calibrating the material models.