Electrostatic behavior of dielectrics under GEO-like charging space environment simulated in laboratory

Due to their dielectric nature and under the effect of the different forms of radiation encountered in space, dielectrics accumulate electrical charges up to the point where electrostatic discharges may occur. To prevent and avoid harmful interference due to discharges, their behavior under irradiation must therefore be investigated in the laboratory before they are used in space applications. A current and widely used practice is to submit the tested materials to the bombardment of monoenergetic electron beams. Such a practice ignores the presence in space of a spectrum of electrons with energies reaching several MeV, and leads solely to surface charging and surface potentials generally higher than those really induced in space. The new approach consists in using in laboratory an electron source as similar as possible to the one existing in orbit. This paper describes the result obtained in the SIRENE facility, which was developed for simulating the spatial geostationary or MEO environment during great geomagnetic activity comparatively with monoenergetic irradiation. The range of available electrons in SIRENE goes from 10 to 400 keV. It points out the effect of the radiated induced conductivity. This paper provides results obtained on classical dielectrics as Teflon, Kapton and Duroid of different thickness under mono and multi-energetic irradiation at ambient temperature and at - 150 C. This paper showed also that even in the case of very low flux of high energy electrons, the surface voltage measured remains deeply affected. Based on those results the usual habit to use monoenergetic irradiation for qualification of space dielectrics should be reconsidered. For example surface voltage obtained of Teflon is lower than the one obtained on Kapton under the same irradiation condition.
資料番号: AA0049206008
レポート番号: JAXA-SP-05-001E