Study on the ablation of a pulsed plasma thruster with a non-volatile liquid propellant

Perfluoropolyether (PFPE), as a non-volatile liquid propellant for pulsed plasma thrusters (PPTs), has exhibited potential for inhibiting carbon deposition compared with polytetrafluoroethylene (PTFE). However, previous investigations have not focused on the ablation process of PPTs when using PFPE. In this study, ablation and the formation of carbon deposition were assessed based on ablated product analysis, element distributions, long-duration exposure images and emission spectroscopy. The results showed that the ablated products of PTFE were mainly CF and CF₂, with a small amount of C, while PFPE was more likely to evaporate or generate molecules with large molecular weights. Carbon deposition on the ablated surface of PTFE was confirmed by the element distribution, while no obvious carbon deposition was found on the ablated surface of the porous ceramic. Carbon deposition was inevitable when using PTFE as a propellant according to the ablated products. The current density near the anode on the ablated surface of the propellant was low, and carbon could not be ablated in a timely manner; thus, carbon deposition easily occurred. For PFPE, the discharge arc was evenly distributed on the ablated surface, which could limit deposition.