ABSTRACT
Chemical contamination of surfaces can greatly affect the secondary electron yield (SEY). Experiments conducted at CERN, Geneve, Switzerland, found that surfaces after scrubbing have significant difference in SEY compared with surfaces before scrubbing The formula features an empirical surface condition parameter s, which one can obtain from the actual measurements of the SEY δ(E) of the surface material to be used. For spacecraft charging, perhaps a piece of test material with surface conditions identical to that used on the spacecraft can be used for measurement of SEY δ(E) under a simulated space condition in the laboratory. High-energy ion impact in space may also cause coarseness on surfaces, especially as time goes by. Atomic oxygen may change the chemical composition of the surface top layer. Atomic hydrogen bombardment at geosynchronous altitudes may remove the oxidized layer, but this has to be demonstrated in the laboratory under simulated condition together with theoretical support, which seems to be lacking at the time of writing.
