Performance improvements of IFM Nano Thruster with highly focused ion beam generated with a compact electrostatic lens module

Abstract

The requirements for electric propulsion systems suitable for scientific missions are becoming increasingly stringent. This includes, in particular, the reduction of the beam divergence and the alignment accuracy of the thrust vector. Therefore, a modular electrostatic lens module has been developed by using an ion trajectory simulation model which considers the ion produced space charge. The focus module can be mounted on an IFM Nano Thruster with equal side length of 100 mm and it works for the entire operation envelope without increasing the electronics complexity. Experimental beam diagnostics measurements and performance analyses are carried out on an IFM Nano Thruster laboratory model with and without attached focus module. The results show an improvement in thrust and specific impulse of up to 30%. In addition, the beam divergence half-angle is drastically reduced down to < 20° half-angle and a high thrust vector accuracy of < 0.9° is achieved. In addition, the focus module significantly reduces the droplet contamination angle. With this design evolution, the IFM Nano Thruster is becoming a suitable candidate for highly complex scientific missions, such as NGGM.