Search

The high amplitude pulse current during Hall thruster start-up is an important source of electromagnetic interference, which impacts the safety and reliability of the propulsion system. The characteristics of the pulse current, including the pulse current's integrated area, peak value, and transient time, are studied experimentally and theoretically under different Hall thruster discharge parameters. Results show that the pulse current's integrated area is determined by the atom density in the channel before Hall thruster start-up; the effects of coil current on the peak value and transient time of the pulse current are negligible. As the discharge voltage and mass flow rate increase, the pulse current peak value increases, the pulse current duration is inversely proportional to the discharge voltage and directly proportional to the mass flow rate. [ABSTRACT FROM AUTHOR]

A kilowatt-order Hall effect thruster with a variable channel, the HET72-VC, is proposed. The discharge channel consists of an inner divergent annular segment and a cylindrical segment near the exit. A discharge comparison experiment was conducted on this thruster, in which the propellant gas is supplied along the axial direction and along the channel centerline. The results show that under the condition of gas supply along the channel centerline, both the current utilization and propellant utilization are higher, the plume divergence angle is smaller, the ion energy distribution curve moves to the high-energy portion, and the overall discharge performance, including the thrust and anode efficiency, is improved. A theoretical analysis shows that these results are attributed to the change in the ionization and acceleration characteristics caused by the different gas supply directions. The HET72-VC is demonstrated to be able to operate stably at an electric power of 2.5 kW; compared with those Hall effect thrusters with the same outer diameter or flow area of the channel, its thrust density and power density are both greatly improved. This provides a new perspective for the development of a high-power Hall effect thruster with a compact structure. [ABSTRACT FROM AUTHOR]

In order to develop multi-mode thrusters for all-electric propulsion spacecraft, a double-stage Hall thruster is designed and investigated experimentally. By applying two independent non-emissive electrodes and a double-peaked magnetic field in the double-stage Hall thruster, the propellant can be ionized in the first stage and then accelerated in the second stage. Experiment results revealed that double-stage discharge effectively improves thruster performance in high specific impulse working mode by reducing the electron current. A one-dimensional model is used to discuss the effects of discharge parameters on ionization distribution theoretically. As a conclusion, ionization distribution (in terms of position and length) in high specific impulse mode (mode I) is significantly different compared to high-thrust working mode (mode F). This double-stage Hall thruster provides a double-stage discharge in mode I to enhance the ionization in the channel and a single-stage discharge in mode F to reduce the ion wall-loss, achieving high efficiency in both working modes. [ABSTRACT FROM AUTHOR]