Electrostatic behaviour of space used materials in regard of internal charging met on spacecrafts

This paper is dedicated to the characterisation of charging behaviour of space used polymers in space electron environment. Spacecrafts are indeed submitted in Medium Earth Orbit (MEO) to severe fluxes of electrons with energies ranging from a few keV to several MeV. For qualification of materials used on satellites and the prediction of their electrostatic behaviour in space environment, it is therefore important to tests these materials in representative environment. These experiments have been carried out at ONERA, The French Aerospace Lab (Toulouse, France) in the SIRENE facility. Different polymers (PEEK, ETFE, Kapton®, polyurethane and silicone varnish, polyurethane based paint) have been characterised to extract the main electric parameter that steer their charging behaviour in space environment: the radiation induced conductivity (RIC). These materials have then been tested in representative environment so as to study the evolution of their conductivity and charging behaviour as a function of the received radiation dose (for low and high dose levels). From these experiments, it was possible to extract the physical parameters that steer RIC and assess numerically their charging levels in specific MEO environment.