  This paper presents an improved version of the previously proposed
self-consistent drift-diffusion-reaction model correcting for non-physical
behavior at longer time scales. To this end a novel boundary condition is
employed that takes into account the effect of tertiary electrons and a fully
dynamic trap-assisted generation-recombination mechanism is implemented.
Sensitivity of the model with respect to material parameters is investigated
and a calibration procedure is developed that reproduces experimental
yield-energy curves for uncharged insulators. Long-time charging and yield
variations are analyzed for stationary defocused and focused beams as well as
moving beams dynamically scanning composite insulators.
