Relationships between Thrust Performance and Plasma Characteristics in the Vicinity of Acceleration Channel Wall of a Hall Thruster

For a Hall thruster, the influences of discharge channel wall material on thrust performance and plasma characteristics in the vicinity of the channel wall were investigated. In this study, THT-III 1-kW class Hall thruster was operated with three dielectric channel walls of BN, BNAlN and BNSiN. Discharge current and thrust were measured; specific impulses and thrust efficiencies were evaluated. The plasma potential, channel wall potential, electron temperature and electron number density were measured with an electrostatic single probe. The process of ion generation and acceleration in a Hall thruster was discussed with measured results. The thrust performances were affected by nature of the channel walls. Measured plasma characteristics suggested that the channel wall material affected an ionization region and ion wall losses in the channel, resulting from secondary electron emission. The difference of discharge current between channel materials was considered to be caused by the difference of current density near the inner channel wall.