Patent ID: 8635850

Claim:
An electron cyclotron resonance thruster comprising: a plasma chamber comprised of non-magnetic conducting material, with at least a portion of said plasma chamber being electrically conducting; a source of ionizable propellant gas in fluid communication with said plasma chamber; at least one first magnet disposed to generate a magnetic field in said chamber, coaxial with the long axis of said chamber; a microwave generator; means for coupling microwaves comprising a waveguide from said generator to an entry window provided in said chamber in order to ionize neutral propellant gas electrons in said propellant present within said chamber, said microwaves serving to excite said electrons, resulting in said excited electrons ionizing at least a portion of said propellant within said chamber, thereby generating a plasma; at least one electrode disposed to be in electrical contact with the electrically conducting portion of said chamber; a power supply connected to said electrode serving to bias said chamber wall to a positive electrical bias voltage, wherein said positively biased chamber exerts an electrostatic force on positive ions in said plasma serving to accelerate said positive ions; and wherein said chamber has an exit aperture without a grid through which said accelerated positive ions exit from said chamber; and at least one second magnet disposed in the region proximal to said chamber exit aperture and oriented along the long axis of said chamber, to generate a downstream shaping magnetic field; wherein said downstream shaping magnetic field is oriented to accelerate said positive ions, shape the plume, act as an energy filter, or a combination of the foregoing.