Photon-Flux Saturation in Large Solar Flares

We use the spectral and spatial resolution of RHESSI to explore the behavior of electron fluxes and their associated currents in large solar flares, including the Halloween events of October-November 2003. The incident electron spectra at the flaring footpoints are derived from the RHESSI photon spectra. Spectral images are used to determine an upper limit as well as a spectrally-averaged estimation for the footpoint area. We find that, over a wide range of flare X-ray magnitudes, the integrated fluxes above 20 keV asymptotically approach a limiting value, suggesting some form of saturation in the particle production in flares. We discuss the implications of these results in terms of the assumed model of a stable non-thermal electron beam.