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The interrelation of hard X-ray (HXR) emitting sources and the underlyingphysics of electron acceleration and transport presents one of the majorquestions in high-energy solar flare physics. Spatially resolved observationsof solar flares often demonstrate the presence of well-separated sources ofbremsstrahlung emission, so-called coronal and footpoint sources. Usingspatially resolved X-ray observations by the Reuven Ramaty High Energy SolarSpectroscopic Imager (RHESSI) and recently improved imaging techniques, weinvestigate in detail the spatially resolved electron distributions in a fewwell-observed solar flares. The selected flares can be interpreted as having astandard geometry with chromospheric HXR footpoint sources related tothick-target X-ray emission and the coronal sources characterised by acombination of thermal and thin-target bremsstrahlung. Using imagingspectroscopy techniques, we deduce the characteristic electron rates andspectral indices required to explain the coronal and footpoint X-ray sources.We found that, during the impulsive phase, the electron rate at the looptop isseveral times (a factor of 1.7-8) higher than at the footpoints. The resultssuggest that a sufficient number of electrons accelerated in the looptopexplain the precipitation into the footpoints and imply that electronsaccumulate in the looptop. We discuss these results in terms of magnetictrapping, pitch-angle scattering, and injection properties. Our conclusion isthat the accelerated electrons must be subject to magnetic trapping and/orpitch-angle scattering, keeping a fraction of the population trapped inside thecoronal loops. These findings put strong constraints on the particle transportin the coronal source and provide quantitative limits on deka-keV electrontrapping/scattering in the coronal source.

Implications for electron acceleration and transport from non-thermal electron rates at looptop and footpoint sources in solar flares