Relaxation time of temperatures for completely ionized matter and radiation

The work is devoted to calculating the rate of energy exchange (relaxation time) between completely ionized matter and radiation, i.e. between electrons and photons. Calculations are conducted in a non-relativistic approximation for electrons, but arbitrary degree of their degeneration is taken into account. Initial stopping process cross sections are taken in quasiclassical and Born approximations, and then corresponding relation coefficients are derived for a wide range of the matter parameters: temperature T and degeneration parameter φ=exp (μ/kT) (μ-electron chemical potential). Difference of quasiclassical and Born approximations was insufficient with the exception of maximally strong degeneration φ>>1. For practical applications the obtained relaxation coefficients are extrapolated to the area of final differences T-T2, where T2 is the radiation temperature. Compton scattering process contribution is evaluated