The mechanism of multi-anode electrode geometry applied to vacuum arc thruster

Abstract

A multi-anode electrode geometry suitable for vacuum breakdown is proposed in this paper. This electrode geometry forms a unique electric field distribution based on its anode configuration which is different from the conventional electrode geometry. There exists a region A between the insulated-anode and the remote-anode where the electric field vector has opposite directions. The existence of region A directly affects the movement of electrons in the initial stage of the discharge, thereby changing the process of vacuum breakdown. The variation of discharge process affects the generation and propagation mechanism of plasma, forming a plasma plume in favor of the propulsion performance of thrusters. The photograph of plasma plume and the electron density spatial distribution of plasma plume preliminarily prove the pinch effect of multi-anode electrode geometry on the radial diffusion of plasma. In the optimization of remote-anode of multi-anode electrode geometry, the variation of the distance of cathode and remote-anode (short for D) is found to affect the pinch effect. Through the reduction of D, the directional jet effect of the multi-anode electrode geometry is enhanced under the same discharge parameters. Applying it to the VAT (multi-anode VAT) and comparing it with the VAT based on conventional electrode geometry (conventional VAT), it is found that the propulsion performance of multi-anode VAT is superior to conventional VAT, and it is further promoted with the decrease of D. Under the same discharge parameters, the impulse bit and the thrust-to-power ratio of the multi-anode VAT is able to be increased by a factor of 26 and 2.88 respectively compared with the conventional VAT. Theoretical analysis and investigation of propulsion performance validate the potential application advantages of the multi-anode VAT in the field of nanosatellite propulsion.