GB615934A - Improvements relating to electron-discharge devices - Google Patents

Abstract

615,934. Electrode materials and processing. SOMMER, A. June 29, 1946, No. 19479. Class 39 (i)] In the manufacture of an electron discharge device having a photo-electric or secondary emitting electrode, the electrode comprising a metal deposit which has been exposed to air, is subjected to a discharge in hydrogen in order to reduce or substantially eliminate the deleterious effect which would result from such exposure, and then without further exposure to air is sensitized in vacuo. As applied to the manufacture of a photo-electric cell, antimony is deposited on a support which is subsequently sealed into the envelope to form a photoelectric cathode. The envelope is baked in vacuum at a temperature of between 250‹ and 300‹ C., and after cooling hydrogen is admitted to a pressure, for example of the order of 1/10 mm. of Hg. A discharge in the hydrogen is then effected by applying a potential, for example 500 volts, between the cathode and another electrode, the latter being at the higher potential, and maintained, for example one minute or less. The hydrogen is then removed from the envelope and while maintaining the vacuum sensitization is effected by admitting caesium to react with the antimony, there being no further baking before sensitization. In a modification, the discharge may be effected by a high-frequency oscillatory field. The invention may also be applied to electron multipliers having secondary emitting electrodes and to television transmission tubes having photocathodes or photo-sensitive mosaic screens.