Temporal evolution of an energetic electron population in an inhomogeneous medium: Application to solar hard X-ray bursts

Energetic electrons accelerated during solar flares can be studied through the hard x-ray emission they produce when interacting with the solar ambient atmosphere. In the case of the nonthermal hard x-ray emission, the instanteous x-ray flux emitted at one point of the atmosphere is related to the instantaneous fast electron spectrum at that point. A hard x-ray source model then requires the understanding of the evolution in space and time of the fast particle distribution. The physical processes involved here are energy losses due to Coulomb collisions and pitch angle scattering due to both collisions and magnetic field gradients