The characteristics and modeling of secondary electrons elastically scattered from collector surfaces

Previous research has shown that secondary electron emission can reduce collector performance and consequently, the performance of electron beam devices. While all secondaries can create problems, elastically scattered secondary electrons (sometimes called reflected primaries) are particularly important. Their high energies allow a greater probability of these electrons leaving the collector, re-entering the slow-wave circuit and producing unwanted signal distortion or signal oscillation. However, a complete analysis of the effects of elastically scattered secondary (ESS) electrons has not been possible because of the lack of quantitative data. For this reason, NASA Glenn Research Center measured the angular distributions of ESS electrons from three materials of interest: oxygen-free, high conductivity (OFHC) polished copper, OFHC copper textured by ion texturing and high purity isotropic graphite.