Chromospheric evaporation and pitch angle diffusion of trapped electrons in solar flare coronal loops

The peculiarities of time delays between the peaks of hard X-ray and microwave emissions within the framework of the trap-plus-precipitation model are studied. Using the continuity equation it has been shown that time delays strongly depend on the chromospheric evaporation in the case of the Coulomb pitch angle diffusion of trapped electrons into the loss-cone. Based on the obtained results the origin of time delays as well as the role of Coulomb collisions in flare coronal loops are discussed.