Thrust vector control of Hall thrusters using asymmetrical gas injection

We present an experimental validation of thrust vector control in a Hall thruster by using asymmetrical gas injection into the thruster discharge channel. We detail the design and operation method of a gas distributor divided into three compartments, each fed by a dedicated mass flow controller. Low power Hall thruster (273 W) was operated, and its plume diverted using uneven gas injection via the mass flow controllers. Axial and lateral thrust were measured to assess thrust vector magnitude and direction. We show that the visual plume deflection is approximately in line with the thrust vector. We show that the direction of thrust could be manipulated in the range of -11° to + 7.3° in the cathode plane, when the positive angles are on the cathode side. Additionally, the thrust and specific impulse are reduced by up to 20% when total mass flow rate is preserved while the efficiency may drop to less than half of the nominal (straight) thrust direction. The thrust and specific impulse are reduced by up to 45% when maintaining a constant anode power while the efficiency may drop to less than half. We also showed that for a constant total mass flow rate, anode power may increase by as much as 80% due to an increase in discharge current at deflection angles greater than + 5°, corresponding to gas starvation in the discharge channel closest to the cathode. On the other hand, large discharge current oscillations, Id,rms/Id > 50%, were observed at deflection angles larger than -10°, when most gas is injected in the discharge channel closest to the cathode. This study validates the possibility to control the thrust vector, to a limited degree, using asymmetrical gas injection into the discharge channel.