Abstract: The impact of the electric-propulsion plasma sputtering onto the insulation layer of C55 wire has exerted a great significance on the spacecraft safety, and the conductor with damaged insulation layer can cause short circuit of gas breakdown or between conductors. These impacts seriously reduce the reliability of the on-orbit operation for aircraft. In order to study the relevant sputtering mechanism, a sputtering test of polytetrafluoroethylene (C55 wire insulation material) by Xe plasma is conducted. Specifically, the quartz crystal microbalance (QCM) is employed to measure the solid sputtering yield of the target, the electronic weighing balance is employed to measure the total sputtering yield of the target, and the field emission scanning electron microscope is used to measure the element composition of the QCM surface collection and the exhaust gas of the vacuum chamber. Based on the above measurement data and its variation rule, the sputtering products and relevant mechanism of Xe plasma on polytetrafluoroethylene is deduced. The results show that, as the incident energy of ions increasing, different sputtering products can be generated, that only -［CF2］- long-chains (solid state) is generated with the incident energy less than 10eV, and that both the -［CF2］- short-chains and the -［CF2］- long-chains are generated. During the entire increase in incident energy, the sputtering yield of solid objects first increases, then decreases, and then increases again, and this trend is probably related to the different monotonicity between the long-chain -［CF2］- detachment velocity and cleavage velocity. The present study reveals the plasma-polytetrafluoroethylene sputtering mechanism that has a high correlation with the sputtering products and conducts a remarkable influence on the sputtering yield.Finally, this study can provide the theoretical foundation for the subsequent research of plasma-polytetrafluoroethylene sputtering yield simulation model.

Key words: electric-propulsion plasma, polytetrafluoroethylene, gaseous sputtering product, sputtering mechanism, sputtering test