Abstract: An electron discharge device, such as a photomultiplier tube, has an evacuated envelope with an alkali-antimonide photoemissive cathode therein. A thermionic emission-reduction coating is disposed within the envelope. The coating alloys with the constituents of the photoemissive cathode to reduce thermionic emission. The thermionic emission reduction coating is formed preferably of indium; however, indium oxide may also be used.

Abstract: A photomultiplier tube comprises an evacuated envelope having therein a photocathode, an anode and a high speed electron multiplier. The electron multiplier includes a primary dynode having a substantially parallel electron permeable member spaced from the primary dynode and disposed between the photocathode and the primary dynode. The electron permeable member also extends between the primary dynode and a plurality of secondary dynodes and accelerates secondary electrons from the primary dynode towards an input secondary dynode. Steering means disposed between the electron permeable member and the secondary dynodes direct the secondary electrons toward the input secondary dynode. Optional electron permeable second members, spaced from and disposed parallel to the secondary dynodes are operated at a potential midway between the adjacent dynode and the next succeeding dynode to accelerate the secondary electrons towards the anode.

Abstract: An electron discharge tube comprises an evacuated envelope, a photocathode within the envelope and a primary dynode having an active portion substantially coplanar with the photocathode. The active portion of the dynode has an oxide secondary emitting surface. A substantially uniform layer of an alkali antimonide compound is formed on substantially all of the oxide secondary emissive surface of the dynode.

Abstract: An electron discharge tube includes an evacuated envelope comprising a photocathode, an anode, a primary dynode and a secondary dynode for propagating and concatenating electron emission from the photocathode to the anode. A focusing electrode is disposed between the photocathode and the dynodes. The focusing electrode is capable of generating an electric field for focusing the electron emission between the photocathode and the primary dynode and also between the primary dynode and the secondary dynode. The focusing electrode has a planar surface that is reflective to light transmitted through the photocathode so that some of the transmitted light is returned to the photocathode to increase the responsivity of the tube.