Electrical double layer potential characteristics in porous electrospray thruster

Porous ionic liquid electrospray thrusters have the characteristics of high specific impulse and self-neutralization of plume. Electrochemical reaction is one of the main lifetime-limiting factors. In this study, a porous electrospray thruster with a 499-emitter array is adopted. The electrical double layer (EDL) potential under different emission conditions is analyzed. Experimental results demonstrate that the average rate of the EDL potential variation exhibits positive correlations with both voltage and bipolar switching frequency. The average rate in the positive mode is generally higher than that in the negative mode. Prolonged operation induces continuous accumulation of the EDL potential in the positive mode, eventually triggering electrochemical reactions and establishing a non-equilibrium state under bipolar switching operation. This investigation provides experimental insights for optimizing operational parameters and mitigating electrochemical reactions in porous ionic liquid electrospray thrusters.