Experimental study of a porous electrospray thruster with different number of emitter-strips

The electrospray thruster is becoming popular in space propulsion due to its low power and high specific impulse. Before this work, an electrospray thruster based on a porous emitter was developed. In order to achieve larger and more stable thrust, the thruster was redesigned, and the influence of the space between strips on thrust was studied. Four types of emitter were tested, and they had 1, 3, 4 and 14 emitter-strips on the emission surface of the same size respectively. According to the experimental results, the maximum extraction voltage and emission current of the four thrusters are different under stable operational conditions. The measured stable emission currents and extraction voltages were −500 μA/−5000 V, −1570 μA/−3800 V, −1200 μA/−3800 V, and −650 μA/−4500 V, respectively. Increasing the number of strips may not result in the emission current increasing, but changing the stable operational range of the emission current per strip and the extraction voltage. The maximum stable operational extraction voltages of 3 and 4 emitter-strips are lower than those of 1 and 14 emitter-strips, but the emission currents are higher than those of 1 and 14 emitter-strips. Time-of-flight mass spectrometry was used to analyze the mass distribution and obtain the performance of the thruster in the case of thrusters with 1 and 3 emitter-strips. Both of their plumes were composed of very small ion cluster (the pure-ion regime), and their thrusts were 80.1 μN, 219.2 μN with specific impulses of 5774 s, 5047 s, respectively.