Time-resolved space charge measurements during electronic irradiation

Since many years, the behavior of dielectric materials is studied for the energy transportation or space applications. In our case, the Pulsed Electro Acoustic (PEA) method is selected to determine the space charges distribution in polymers submitted to an electron beam. In this work, the PEA measurements in non-contact mode during electronic irradiation are made to evaluate the charge injection dynamic. The measurements are realized with different irradiation conditions as different electronic fluxes and kinetic energies. Then a long relaxation step is performed to monitor the evolution of the injected space charges trapped in the bulk. The results concerning the relaxation phase are discussed in particular to try to explain the appearance of positive charge carriers at the sample surface.