Electron Trapping Times and Trap Densities in Solar Flare Loops Measured with COMPTON and YOHKOH

Abstract

We measure energy-dependent time delays of ~20--200 keV hard X-ray (HXR) emission from 78 flares observed simultaneously with the Compton Gamma Ray Observatory and Yohkoh. Fast time structures ( < 1), but they also are subject to filling factors less than unity (when qe > 1). Our measurements provide comprehensive evidence that electron trapping in solar flares is governed in the weak-diffusion limit, i.e., that the trapping time corresponds to the collisional deflection time, while pitch-angle scattering by resonant waves seems not to be dominant in the 20--200 keV energy range. The measurements do not support a second-step acceleration scenario for energies