부산대학교 도서관

Recent electrical insulation design under severe environment such as low air-pressure and/or high radioactive rays is required for the application to higher altitude and/or high radiation area. Under such environment, deteriorations of insulation materials due to the charge accumulation are concerned. With respect to radiation, the charging phenomena in the materials by the high energy charged particles beams, such as electrons and photons, give rise to the electric field enhancement which may cause breakdown of materials, and the power electronics equipment may become inoperable. In this paper, therefore, the experimental results of physical analyses and direct current breakdown characteristics to evaluate deterioration of the insulation materials caused by proton beam irradiation. Three results were obtained from our works. Firstly, the degree of oxidation deteriorations due to proton beam irradiations inside the insulation materials, which have some metal oxide fillers, were smaller than the material surfaces. Secondly, in the insulation materials before and after proton beam irradiations, there was no large change in the space charges and electric field distributions under applying direct current voltage. Finally, the changes of breakdown electric field strengths were generally small with proton beam irradiation current density for the above two reasons. However, the degradations such as oxidative degradations by XPS (X-ray photoelectron spectroscopy) analyses were indicated. Therefore it is necessary to evaluate the long-term breakdown characteristics in our next works.