Patent ID: 6158209
Filing Date: 2000-12-12
Classification: F03H,H01J,H05H

Abstract:
A closed electron drift plasma thruster comprising:an annular ionization and acceleration channel defined by pieces of insulating material having an opening at its downstream end;at least one hollow cathode disposed outside said annular channel and downstream therefrom;an annular anode concentric with the annular channel and disposed upstream from the opening of said channel, and at a distance therefrom;first and second ionizable gas feed means respectively associated with the hollow cathode and with the annular anode; anda magnetic circuit for creating a magnetic field in the annular channel, said magnetic circuit comprising a plurality of distinct magnetic field creating means a yoke, a peripheral magnetic circuit disposed axially outside the annular channel, and peripheral and central pole pieces connected to one another by said peripheral magnetic circuit and said yoke and disposed on either side of the annular channel to produce an essentially radial magnetic field in an outlet plane perpendicular to the axis of said annular channel;the thruster being characterized in that it further comprises:an essentially frustoconical flared magnetic pole piece open at both ends, coaxial about the axis of the annular channel, situated downstream from said outlet plane, and flaring downstream; andat least one additional peripheral magnetic circuit connecting the downstream end of said flared magnetic pole piece to the peripheral pole piece situated outside the auxiliary channel, the flared magnetic pole piece co-operating with the additional peripheral magnetic circuit and the pole pieces situated on either side of the annular channel to define the shape of the magnetic field downstream from the annular channel in such a manner as to constrain the ion beam emitted by the annular channel to remain within an essentially conical zone whose determined angle at the apex is defined by the angle at the apex of the flared pole piece.