THE NEUPERT EFFECT AND THE CHROMOSPHERIC EVAPORATION MODEL FOR SOLAR-FLARES

The Neupert effect is the name given to the apparent causal relationsh ip between hard and soft X-ray emissions observed in many solar flares . It is shown that the observed distributions of flare hard X-ray flue nce and soft X-ray flux are incompatible with the simple statement of the Neupert effect commonly found in the literature. The more fundamen tal energy relationship predicted by the chromospheric evaporation mod e! may also be incompatible with the observations unless a well-define d temperature-density scaling exists. Without such a scaling, addition al heating by an agent other than accelerated electrons (e.g., turbule nce) is necessary to explain the observations.