**4. Method for the characterization of the charging state of dielectrics**

In insulator material, the charges can be injected through interfaces, via an applied voltage, or created by irradiation via energetic particles. For instance, incident electrons, as they slowdown, can generate pairs of electrons and holes. These charge carriers can recombine, be trapped or move as a result of diffusion and/or field conduction. Concurrently, some of the electrons can be emitted from the sample surface and a distribution of trapped charges may develop within the irradiated volume. In our case, experiments are carried out using the electron beam of a SEM. The experimental set up, described below, provides means for measuring the evolution of the net amount of trapped charges Qt, which characterize the charging state of the insulator. For this purpose, we use the Induced Current Measurements "ICM" method (called also the Displacement Current Measurements), which we have recently improved (Zarbout et al., 2008, 2010).
