Charge transport and behavior analysis with electron irradiated (PMMA)

A method for studying the space charge distribution and transport was applied to poly-methyl-methacrylate (PMMA) polymer material. The specimens were submitted to electron irradiations using a scanning electron microscope (SEM). The method helps in estimating the charge distribution (or quantity) and the trapping processes during and after the electron irradiation. The mechanisms of trapped charge involve several parameters related to the electronic injection, the characteristics of the insulator and the effects of the trapped charge itself. For that purpose, an arrangement adapted to the SEM for measuring the leakage and displacement currents have been designed and implemented. The properties of the dynamic trapping of PMMA and the constants of charge processes were evaluated. Many physical phenomena such as charging-discharging processes, surface conduction, etc... were outlined, and by controlling the irradiation conditions, various types of surface discharging (flashover phenomenon) behavior were observed.