The Determination and Use of Mean Electron Flux Spectra in Solar Flares

Hard X-ray spectra in solar ares provide information on electron accelera- tion and propagation processes. We here point out that the inference of these processes involves two distinct steps: rst, the model-independent deconvolution of the hard X-ray spectrum to obtain the eectiv e mean electron spectrum F (E) in the source; and second, the model-dependent interpretation of this mean spec- trum in terms of physical processes operating in that source. Thus, the mean electron spectrum is a natural \middle ground" on which to compare the pre- dictions of models with observations, and we urge the presentation of results, both from analysis of photon spectra and from modeling of candidate physical processes, in the form of F (E) spectra. We consider the constraints that various source models impose on F (E) and we present explicit forms for an illustrative F (E) corresponding to the injection of a power-law spectrum of electrons into a thick target of nonuniform ionization level.