Polarimetric study of space charge distribution in dielectric materials

The kinetics of alternation of the profile of a space charge (SC) in transparent dielectrics in the process of their irradiation, is investigated. The phenomenon of optic anisotropy of dielectrics in the SC field is used. 100x100x50 mm samples made of polymethylmetacrylate are selected for investigation. The LU-40 accelerator is used as a source of high-energy electrons. Sample irradiation is carried out by a wide (diameter of approximately 6 cm) electron beam with the energy of 16 MeV and the average current of 2.4 μA. When the given exposure expires, the accelerator switches on; after that the lighting lamp and the camera are switched on. The servey time of one frame, is 30 sec. The characteristic interference images of sample initial state and its state after irradiation with the exposure of 15, 30, 45 and 60 s are presented. The data obtained show that exposure increase brings about the increase in SC concentration. The zone of maximum concentration shifts to the side of the irradiated surface, which is caused by the deceleration of injected electrons in the SC field