High-Specific-Impulse Electrostatic Thruster with Argon Propellant

摘要

In this study, an electrostatic thruster was newly developed, in which a diverging magnetic field with a cusp arounda cathode was applied by using two solenoid coils. The effects of the magnetic field strength on thrust performanceunder a similar applied-magnetic-field configuration were investigated. Because of its light weight and lower price,argon was used as a propellant. By increasing the magnetic field strength, the thrust efficiency was improved owing tothe suppression of the discharge current while an almost constant thrust was maintained. A specific impulse of 3800 swith thrust efficiency greater than 30% was obtained; the corresponding mass-averaged exhaust velocity exceededthe value by full-potential electrostatic acceleration of singly charged ions. From the thrust performance, ion beamcurrent, and ion energy distribution function that were experimentally measured under the representative operationcondition, 32% of the ion beam current and 43% of the total thrust were evaluated as the contribution of doublycharged ions.