  We carried out detailed analysis of X-ray and radio observations of a simple
flare loop that occurred on 12th August 2002, with the impulsive hard X-ray
(HXR) light curves dominated by a single pulse. The emission spectra of the
early impulsive phase are consistent with an isothermal model in the coronal
loop with a temperature reaching several keVs. A power-law high-energy spectral
tail is evident near the HXR peak time, in accordance with the appearance of
footpoints at high energies, and is well correlated with the radio emission.
The energy content of the thermal component keeps increasing gradually after
the disappearance of this nonthermal component. These results suggest that
electron acceleration only covers a central period of a longer and more gradual
energy dissipation process and that the electron transport within the loop
plays a crucial role in the formation of the inferred power-law electron
distribution. The spectral index of power-law photons shows a very gradual
evolution indicating a quasi-steady state of the electron accelerator, which is
confirmed by radio observations. These results are consistent with the theory
of stochastic electron acceleration from a thermal background. Advanced
modeling with coupled electron acceleration and spatial transport processes is
needed to explain these observations more quantitatively, which may reveal the
dependence of the electron acceleration on the spatial structure of the
acceleration region.
