A method for activating an electron-emitting multi alkali - cathode layer

摘要

1442405 Photocathodes RCA CORPORATION 9 Nov 1973 [11 Dec 1972] 52143/73 Heading H1D A photocathode is formed by exposing a Sb layer successively to Cs, K and Na vapour, the exposure to Cs being stopped before the photosensitivity reaches a peak, preferably at a very low value. The layer is maintained at 240‹ C. and exposure to K and Na is stopped when the photosensitivity reach a maximum in each case. The process is carried out in a photomultiplier tube containing sources of Cs, K and Na. The tube is initially baked at 300‹ C. and evacuated to remove impurities. The cathode may be secondary emissive.