Spatial charge in low density polyethylene irradiated with low dose gamma-ray

The research on the effect that radiation exerts on polymer insulation materials is indispensable for the improvement of safety in nuclear power generation, future nuclear fusion power generation and the expansion of space utilization, and it is important also as the technique for examining the electrical properties of polymer insulation materials themselves. However, in the case of carrying out irradiation at relatively low dose, the example of the research on the initial state of deterioration is few. Therefore, in this study, through the measurements of thermal pulse current, residual voltage, thermal stimulation currents, radiation-induced electrical conduction and other experiment, the behavior of spatial charges in the low density polyethylene irradiated with low dose gamma-ray was investigated. Gamma ray was irradiated at room temperature in the atmosphere at the dose rate of 200 Gy/h. The samples and the experimental method and the results are reported. In the irradiated samples, at a relatively low electric field of 0.1 MV/cm, hetero spatial charges were formed near both electrodes. In the irradiation of 0.2 - 5 kGy, either many carriers are generated or the mobility of carriers increases, which is one of the causes of initial deterioration. (K.I.)