The research group has previously proposed dimethyl ether (DME) as a promising alternative propellant for arcjet thrusters, given the toxicity and handling difficulties associated with hydrazine, which is widely used in current systems. However, the use of DME has been accompanied by the formation of soot on the cathode and nozzle surfaces during operation, leading to discharge instabilities that hinder reliable performance. To mitigate this issue, the researchers investigated the effect of adding nitrous oxide (Formula: see text) to the DME propellant, aiming to promote oxidative reactions that suppress soot formation. Experimental results demonstrated that increasing the proportion of Formula: see text in the mixture to a moderate extent significantly reduced soot deposition on the electrodes, thereby stabilizing the discharge and enhancing thrust performance. In particular, a Formula: see text mass ratio of 6:4 yielded the most favorable results, with no observable soot accumulation and without the excessive oxidation damage seen at higher Formula: see text ratios on the cathode or nozzle, within the tested duration of 90 s. Reaction pathway analysis and experimental diagnostics revealed that reactive species, such as OH, O, and Formula: see text, generated during the thermal decomposition of Formula: see text, played a key role in suppressing soot formation.
Yamamoto et al. (Sun,) studied this question.