Technique to Collimate Ions in a Hall-Effect Thruster Discharge Chamber

High thrust-to-power ratio on Hall-effect thrusters allows for more efficient thrust generation and better overall performance. It allows Hall-effect thrusters to perform more thrust-intensive maneuvers such as orbit raising, thus saving the mass of a second engine purely for those maneuvers. This paper presents the initial performance measurements of aHall-effect thruster using in-channel electrodes to collimate ions in the discharge channel in order to increase thrust-to-power. The thruster is tested in the range of 100–300 V discharge voltage, at 9 and 20 A discharge current, and with 0–30 V electrode potential on krypton propellant. Xenon propellant is used briefly. A null-type, inverted pendulum thrust stand is used to acquire thrust measurements. Improvements of 3 mN=kW, 200 s specific impulse, and 4%anode efficiency are observedwith energized electrode, supporting the ion collimation hypothesis. Improvements exist primarily at low voltages (<200 V), which indicates a behavior different from the two-stage Hall-effect thruster. Extending the inner channel wall causes a tilt of the magnetic field and severely decreases performance. Plume and in-channel measurements to determine ion collimation are forthcoming.