SIMULATION OF INSULATOR CHARGING BY A NARROW ELECTRON-BEAM

We are dealing with the problem of the charge distribution within an i nsulator (present application: SiO2) which is bombarded by a narrow el ectron beam. The electron trajectories within the sample are simulated via a single diffusion Monte-Carlo method. A mathematical model is pr oposed for the potential and the charge density. The development of an electric field, a potential and the broadening of the incident beam a re taken into account. These two last distributions appear to have a p rominent effect. It is shown that the charge distribution tends to a d ouble layer; the shape and thickness of positive and negative distribu tions are given.