ELECTRICAL PHENOMENA OCCURRING AT THE SURFACE OF ELECTRICALLY STRESSED METAL CATHODES .2. 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.