Thruster Relevant Material Sputter Investigations
Аuthors*, **, ***
Leibniz Institute of Surface Modification,
AbstractSputtering is an important process in the application of electric propulsion devices. For instance, the extraction grids of gridded ion thrusters are subject to grid erosion by charge-exchange ions, which works towards an increase of the accelerator grid hole diameter and limits the thruster lifetime, or the acceleration channel walls of Hall Effect ion thrusters are suffering from strong erosion by ions from the discharge plasma itself. One of the challenges facing further application of electric thrusters for space missions is the establishment of valid lifetime predictions. For the modelling, reliable sputter yield data are required, which, however, are often not available in the required energy and angular dependency for the ion-material combination under consideration. Especially sources of errors in sputter yield measurements like the influence of the background pressure, the roughness of the starting surface and the role of knowledge of the primary ion beam properties will be discussed in this short paper. Beside this an idea to surface modification of Titanium is given and assessed. Measurement strategy for isolating material like BN is short outlined and preliminary data are announced. More complete descriptions for metals and isolator sputter yield measurements of the Leibniz-Institut für Oberflächenmodifizierung (IOM) group are given in special papers [1, 2, 3].
Keywords:sputtering; electric propulsion; Xenon low energy sputtering; titanium; carbon-carbon; BN; gridded ion thruster; Hall effect thruster; silver connectors; low energy broad beam ion sources