Anodic plasma in Hall thrusters

In this paper plasma dynamics and ionization of propellant gas are modeled within the anode holes used for gas injection of a Hall thruster. Under conditions of anode coating with dielectric material, the discharge current should close within these holes, which results in ionization and formation of plasma jets emanating from the openings. The model shows that gas ionization inside the anode holes is very significant. For instance, the electron density increases by two orders of magnitude under certain conditions. The potential drop in the anode region which includes the electrostatic sheath inside the hole and potential drop along the hole might be positive or negative, depending on the anode hole radius.