The invention relates to a Hall effect plasma thruster including a main annular ionization and acceleration channel (120) having an open downstream end (129), at least one cathode, an annular anode that is concentric with the main annular channel (120), a pipe and a dispenser for feeding an ionizable gas into the channel (120), and a magnetic circuit for generating a magnetic field in the main annular channel (120). The main annular channel (120) includes portions of inner (127) and outer (128) annular walls located in the vicinity of the open end and (129) each including an assembly of conductive or semiconducting rings (150) juxtaposed in the form of blades separated by thin layers of insulation (152).