Problems in the analysis of plasma collector probes

The surface layer analysis of collector probes after exposure in plasma experiments may often be obscured by a variety of effects, many of which are usually underestimated or ignored. Examples obtained by RBS and PIXE analysis of various types of carbon probes are used to illustrate some of the problems. However, the investigation and discussion should also have consequences for other analysis techniques and materials. In particular, it is questionable whether the fluxes of chemically active elements, notably oxygen, are measurable with collector probes at all.