THE COOLING AND CONDENSATION OF FLARE CORONAL PLASMA

ABSTRACT---- We investigate a model for the decay of flare heated coronal loops in which rapid radiative cooling at the loop base creates strong pressure gradients which, in turn, generate large (supersonic) downward flows. Hence, the coronal material cools and I'condenses'onto the flare chromosphere. The important features of this model which distinguish it from previous models of flare cooling are: (1) Most of the thermal energy of the coronal plasma may be lost by mass motion rather than by conduction or coronal radiationj (2) Flare loops are not isobaric during their decay phase, and large downward velocities are present near the footpoints (3) The differential emission measure q has a strong temperature dependence, q,l T3 "5. These results can account for recent observations of compact flare loops that are not consistent with the previous cooling models. /0 ' I ' r--- "-l _ _ _,,,, 1...- "Ir 4 I 1 I "- 1 I- i-IR..