電子線を照射した各種ポリマーの内部帯電現象

The spacecraft like a communication or a broadcasting satellite flying in GEO (Geostationary Earth Orbit) is always exposed to plasma and/or radioactive-rays such as alpha-, beta- and gamma-rays. When the dielectric materials, in which the spacecraft is wrapped to keep temperature in it stable, are irradiated by the high energy electron beam, sometimes an unexpected accident due to an electrostatic discharge happens. The accident sometimes causes a serious mission error of the spacecraft. However, there remain many unknown factor about a charge accumulation in dielectric materials by irradiation of electron beam. Therefore, we need to measure the charge distribution in the bulk of dielectric materials. We have been developing a system for measuring such a charge distribution in dielectric materials using pressure wave propagation method. Using this system, we tried to measure the charge distribution under electron beam irradiated Low Density Polyethylene, Polyethylene Terephthalate, Polycarbonate, Polyethylene Naphthalate in addition to Polyimide and PTFE (PolyTetraFluoroEthylene) films which are used as a thermal control layer or a optical solar reflector of spacecrafts. We observed accumulation behavior of charge in each sample, survey relationship with each sample's molecular structure. As a result, It's believed that charging characteristics of insulating material is linked to benzene ring in each sample's molecular structure.
資料番号: AA0063997025
レポート番号: JAXA-SP-07-030