Self-similar solutions for high-energy density radiative transfer with separate ion and electron temperatures

We consider a non-equilibrium plasma radiatively heated by an external source in the high-energy density regime. It is shown that self-similar solutions resembling the classic Marshak wave exist for the ion and electron temperatures, if the electron–ion coupling coefficient scales inversely proportional to either the time from when the heating begins or to the square of the distance from the surface of the plasma. We discuss how such a coupling coefficient may arise, and demonstrate that these solutions are also useful for verifying simulation codes that treat radiation–electron–ion coupling in high-energy density plasmas.