RESEARCH AND DEVELOPMENT OF LOW-POWER HALL THRUSTERS WITH CIRCULAR-CROSS-SECTIONAL DISCHARGE CHAMBER, AND ITS INNER PHYSICAL PROCESSES

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Effects of magnetic field configuration in Hall thrusters with circular cross-sectional discharge chambers were examined using TCHT-3A and TCHT-3B series Hall thrusters. The results showed that by adjusting the position of peak of radial magnetic flux density the thrust performance was improved. As the position of peak of radial magnetic flux density shifts downstream, the ion loss to the wall and electron current to the anode decrease. However, propellant utilization also decreases because of neutral diffusion. Hence, the optimal position of peak exists.Plume measurements of Hall thruster with circular cross-sectional discharge chamber, named TCHT-2, were carried out. Ion current density measurement showed that the plume divergent angle was not sensitive to propellant mass flow rate and that the propellant utilization decreased as the mass flow rate decreased. Ion energy measurement using RPA indicated that the efficiency of acceleration decreased at low mass flow rate. From the electron temperature and plasma potential distribution inside the discharge chamber obtained by a double probe, the ionization/acceleration region is located at which strong radial magnetic field exists.The miniature Hall thruster TCHT-3A showed that thrust performance declined with scaling down by increase of ion loss. By applying strong radial magnetic field at the downstream region, miniature Hall thruster TCHT-3B achieved higher thrust performance than TCHT-3A did at low power level. It has efficiency (26-39%) in the power range 80-170W.