  Using a model of particle acceleration and transport in solar flares, we
investigate the height distribution of coronal electrons by focusing on the
energy-dependent pitch-angle scattering. When pitch-angle scattering is not
included, the peak heights of loop-top electrons are constant, regardless of
their energy, owing to the continuous acceleration and compression of the
electrons via shrinkage of magnetic loops. On the other hand, under pitch-angle
scattering, the electron heights are energy dependent; intermediate energy
electrons are at a higher altitude, whereas lower and higher energy electrons
are at lower altitudes. This implies that the intermediate energy electrons are
inhibited to follow the shrinking field lines to lower altitudes because
pitch-angle scattering causes efficient precipitation of these electrons into
the footpoint and their subsequent loss from the loop. This result is
qualitatively consistent with the position of the above-the-loop-top hard X-ray
(HXR) source that is located above coronal HXR loops emitted by lower energy
electrons and microwaves emitted by higher energy electrons. Quantitative
agreement with observations might be achieved by considering primary
acceleration before the onset of loop shrinkage and additional pitch-angle
scattering via wave-particle interactions.

Solar and Stellar Astrophysics;Plasma Physics