Transitional regime in the start-up process of conventional Hall thrusters

The operation of conventional Hall thrusters in laboratory experiments shows an anomalous start transient characterized by an increase of the discharge current along several minutes. In this study we correlate the appearance of the transitional regime with the presence of gas impurities within the thruster, which is previously exposed to the atmosphere. Water, Nitrogen, and Hydrogen seem to be the most important residual traces responsible of the phenomena. The physical mechanisms behind the transitional regime are studied through different experiments, and the results show the relevant role of the plasma-wall interaction.