Abstract
In this study, performance characteristics of the medium-power (1-3 kW) Hall thruster THT-VI, developed in Osaka Sangyo University, were measured using special gases of carbon dioxide, methane and ammonia as original materials in planets and satellites in the Solar System; that is, propellant can be supplied just on the planets and satellites, although only a heavy gas of xenon is used with higher performance; argon is also used as alternative propellants. Performances with CO2, NH3 and Ar were much lower than those with Xe. The present magnetic field optimized with Xe is not suitable for molecular and light atomic propellants because of poor ionization and acceleration with the Xe-optimized magnetic field. In molecular and light atomic gases, an axially-uniform or widely-stronger magnetic field is preferable for enough ionization and ion acceleration with longer length inside the acceleration channel. As a result, the Hall thruster THT-VI with an improved magnetic field, which was strengthened and flatter in the acceleration channel, was stably operated with CO2 and Ar. For Ar, the thrust after improvement ranged from 20 to 30 mN at input powers of 1-1.8 kW and the specific impulse from 1,000 to 1,700 sec. As for CO2, the thrust was 9.5 to 15 mN at 650-1150 W and the specific impulse 200 to 300 sec, although the performances were still low. Furthermore, pre-ionization by additional discharge in an upstream region of the acceleration channel is expected to be effective for enhancement of ion production and acceleration. The Hall thruster THT-VI with auxiliary electrodes inside the acceleration channel was successfully operated with CO2, resulting in 12.7 mN of thrust and 432 s of specific impulse.
https://ror.org/01h2m4f20 
