The angular distribution of elastically scattered electrons and computed impact on collector performance

Data are presented for the angular distribution of energetic secondary electrons from two copper surfaces, one highly polished and the other roughened by ion sputtering. The incident electron beam varies from normal to grazing incidence, while secondary electrons within 20% of the incident energy are measured throughout the half sphere above the target surface. Relative to the polished surface, the sputtered surface exhibits a much reduced magnitude of secondary emission and a significantly different angular distribution. The application of this information to the design and operation of collectors is discussed.<>