Sputtering yield and nanopattern formation study of BNSiO2 (Borosil) at elevated temperature relevance to Hall Effect Thruster

Abstract

Lower sputtering yield of the discharge wall material is a crucial parameter for the performance of Hall Effect Thruster (HET). In this article, we report the sputtering yield of HET wall material BNSiO2 (borosil) at elevated temperature ∼ 600 °C using quartz crystal microbalance (QCM). We observe a linear increase in the sputtering yield with temperature and it remains stable during long duration experiments using Xe ions. Two different crystallographic orientations of borosil give a slight variation in the yield. The higher yields for higher operating temperatures is proposed to be due to the thermal spike nature. Microscopic surface morphology shows only different grains of BNSiO2, however high resolution nanoscopic view reveals the formation of nanoripple like structures over different grains. The periodicity of such features increases with ion dose (sputtering time) and temperature in the range of 70–190 nm. Local curvature dependent erosion plays crucial role in such pattern formation.