The influence of anode position and structure on cusped field thruster

Abstract

A cusped field thruster is a kind of electric propulsion device using multi-stage cusped fields to realize plasma discharges and produce thrust. A previous study showed that plasma discharges in this thruster are non-uniform. In this work, a multi-annulus anode is used to measure the radial distribution of anode current density at different anode positions. The experimental results reveal that some electrons may reach the anode along the axis after they accelerate from the final cusp regardless of the anode positions. To further validate this idea and find out the mechanism of this central path along the axis, the central part of the anode is replaced with ceramics. This results in an increase in the total current with larger contributions at larger radii. The current oscillations also get larger. This brief letter is helpful to further understand the movement of electrons in cusped field thrusters and provide guidance on reducing the non-uniform degree of current density.