Evaporative cooling of flare plasma

Abstract

We investigate a one-dimensional loop model for the evaporative cooling of the coronal flare plasma. The important assumptions are that conductive losses dominate radiative cooling and that the evaporative velocities are small compared with the sound speed. We calculate the profile and evolution of the temperature and verify the accuracy of our assumptions for plasma parameters typical of flare regions. The model is in agreement with soft X-ray observations on the evolution of flare temperatures and emission measures. The effect of evaporation is to greatly reduce the conductive heat flux into the chromosphere and to enhance the EUV emission from the coronal flare plasma.