For a couple of decades, electric propulsion systems, and especially plasma thrusters, have been increasingly used on spacecraft. Their very low fuel consumption enables tremendous reductions of launching mass, which comes with significant costs reductions. “All electric” telecommunication satellites, that use plasma thrusters for GTO to GEO transfers, are more and more common. During such a manoeuver, which takes about 6 month to be performed, thrusters operate almost continuously. This leads to spacecraft direct or indirect exposure to a heavy ions plasma (Xe / Kr) with energies from dozens to hundreds of electronvolts. This may cause sputtering of exposed surfaces, and induce contamination by sputtering products.

Sputtering yield, as well as sputtered particles emission directions of common materials (metals / SiO2 for instance) is well known. However, there is virtually no data concerning polymers. These materials are however widely used on spacecraft for different application (electrical, thermal, mechanical). During these talk, we will present sputtering behaviour and characteristics (yield, sputtered particles emission directions) for different spacecraft polymers: Kapton, PEEK and PTFE.

Mass spectrometer measurements, performed during the tests, indicated that molecules (e.g. C2F4) , and molecular fragments (CF, C2F3) were emitted during erosion. This is quite unexpected, as sputtering phenomena are known to occur at atomic scale. During this talk, we will describe and discuss a new erosion mechanism for polymers, relying on sputtering induced desorption of broken chains.