Electrical phenomena occurring at the surface of electrically stressed metal cathodes. II. Identification of electroluminescent (k-spot) radiation with electron emission on broad area cathodes

For pt.I see ibid., vol.12, p.2229 (1979). The results are reported of experiments designed to isolate both electron emitting areas and electroluminescent (k-spot) regions on broad area copper cathodes exposed to high electric fields. The results show that electroluminescence is always observed in the region of an electron-emitting site when the emission current exceeds about 10 -7 A. Furthermore the random intensity fluctuations of the emission current correspond identically with the k-spot light intensity fluctuations. These observations are evidence that electron-emitting sites found on broad area cathodes are associated with semiconducting type impurities located at grain boundaries, or other defects in metal electrode surfaces.