Two-temperature equation of state for aluminum and gold with electrons excited by an ultrashort laser pulse

Abstract

A short laser pulse converts metal into a two- temperature state with the electron temperature higher than the ion temperature. To describe the electron contributions to the total internal energy and pressure arising as a result of electron heating, we develop the new analytic approxi- mation formulae for two-temperature thermodynamics of metal. Those approximations are based on quantum cal- culations performed with density functional theory (DFT) packages. DFT calculations provide the internal energies and pressures for densities of the order of solid-state den- sity and for electron temperatures up to 55 kK. The new analytic approximations give a better accuracy in hydrody- namic simulation of laser-matter interaction and should be used instead of the less accurate expressions based on the Fermi model of ideal electron gas, which is widely used for two-temperature states of metal.