Material charging in space environment: experimental test simulation and induced conductive mechanisms

Dielectric materials used in space on satellite structure may have to cope with strong levels of charging under electron irradiation in space environment. This could lead to potential hazardous discharges and electric arcs and consequent anomalies on the satellite, such as electromagnetic disturbances or, in worst case, the destruction of some on-board systems. These materials need to be tested on-ground to assess their electric behaviour and predict any risk of failure in space environment. The SIRENE facility allows the simulation of geostationnary orbit electron environment and the evaluation of charging capabilities of material samples. We demonstrate, in this paper, that polyimide and polytetrafluoroethylene samples, commonly used in space, are submitted to potentially high radiation induced conductivity or resistivity and electrical ageing under radiation dose in this environment. These physical mechanisms can either reduce the charging level, as observed for polyimide, or dramatically enhance the electric surface potential and the charging kinetics, as seen on polytetrafluoroethylene, leading to high risk of discharge. Index Terms--Space materials, Electron irradiation, Dose Effect, Radiation Induced Conductivity (RIC)