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: The photomultiplier tube comprises an evacuated envelope having therein a photocathode, an anode, a plurality of spaced apart dynodes for propagating and concatenating electron emission from the photocathode to the anode and a pair of substantially parallel support spacers of insulating material to support the dynodes and the anode. A chrome oxide layer is disposed on the support spacers adjacent to the dynodes and the anode. The chrome oxide layer has a resistance of at least about 10.sup.12 ohms per square to about 10.sup.15 ohms per square. A Nichrome coating overlies an inter-electrode region extending along the concatenating path of the electron emission from the dynodes to the anode. The Nichrome coating has a resistance of greater than 10.sup.6 ohms per square but less than the resistance of the chrome oxide layer.

Abstract: An improved electron discharge device comprises an evacuated envelope having therein a photoemissive cathode for providing photoelectrons in response to radiation incident thereon, an electron multiplier, including a primary dynode spaced from the cathode, and a focusing assembly disposed between the cathode and the multiplier. A thermionic electron control plate is disposed between the focusing assembly and the multiplier to prevent thermionic electrons from the focusing assembly from impinging on the primary dynode, while permitting the passage of photoelectrons to the primary dynode. The control plate overlies the primary dynode and is contiguous therewith.

Abstract: A method of processing a bialkali-antimonide photoemissive cathode to remove trace quantities of alkali metal impurities is disclosed. The cathode is formed by heating alkali vapor sources comprising the chromates of two alkali materials which include trace impurities of two other alkali materials of higher vapor pressures than the aforementioned two alkali materials to sufficiently high temperatures to produce alkali vapors. The temperature of the substrate onto which the various alkali vapors condense is maintained at a sufficiently high temperature for a sufficiently long period of time to drive off the trace quantities of the higher vapor pressure other alkali materials from the substrate. Additionally, after the alkali vapor sources are heated to temperatures sufficient to vaporize the alkali chromates therein, the temperatures of the sources are lower and maintained at sufficient levels to accelerate the removal of reduced alkali vapors from the sources and from the photomultiplier tube.

Abstract: An improved electron discharge device comprises an evacuated envelope having at least one alumina ceramic insulator member. Within the device is a source of electrons, and an electron multiplier assembly including an anode. A high resistance material is diffused into the ceramic insulator to reduce luminescence within the insulator. The method of diffusion includes the steps of applying an opaque coating of a high resistance material to a surface of the ceramic insulator member and then firing the member in a reducing atmosphere at a temperature within the range of about 1500.degree. C. to 1550.degree. C. until the high resistance material diffuses into the surface of the member forming a diffusion region.

Abstract: An electron tube having an evacuated envelope includes therein an insulating substrate with a photoemissive cathode thereon. The cathode comprises a plurality of discrete substantially isolated photoemissive regions. A plurality of spaced apart conductive strips are disposed on the substrate and interconnect each of the photoemissive regions.

Abstract: A planar mesh structure that facilitates forming into a non-planar mesh structure comprises a peripheral support ring lying in a plane with a plurality of first members and a plurality of second members lying in the plane. The first members comprise substantially concentric, spaced-apart mesh rings of progressively decreasing diameter disposed within the peripheral support ring. The plurality of second members extend generally inwardly from the peripheral support ring and terminate at the innermost of the first members. The second members intersect the first members disposed between the peripheral support ring and the innermost first member to form, with the intersected first members, a plurality of apertures. In one embodiment, the second members are generally arcuately shaped and lie in a first plane with the support ring and the first members.

Abstract: A photomultiplier tube comprises an evacuated envelope having a generally cylindrical sidewall with a faceplate closing one end of the envelope. A conductive coating is disposed on a portion of the sidewall adjacent to the faceplate. A photocathode is formed on the faceplate and on a portion of the conductive coating. An electron multiplier assembly including a plurality of electrodes is spaced from the photocathode. A plurality of leads extend from the electrodes to a plurality of terminals in a base attached to the tube. A resilient electrical contact member is connected to a terminal in the base for applying a potential to the photocathode. The electrical contact member has a pair of support tabs at the opposite ends of the member. The tabs are affixed to the multiplier assembly so that the contact member assumes a substantially arcuate shape which contacts and conforms to a large area of the conductive coating on the sidewall of the envelope.

Abstract: A photomultiplier tube includes an evacuated envelope having therein a photocathode, an anode and an electron multiplier disposed between the cathode and the anode for propagating and concatenating electrons along a path therebetween. The electron multiplier and the anode are supported by a pair of oppositely-disposed support plates. At least one aperture which extends along at least a portion of the electron path is formed in each plate. A pair of focusing shields may be spaced from the exterior surface of each of the support plates. The focusing shields are disposed adjacent to the apertures in the support plates and extend longitudinally along the electron path to provide a transverse focusing field which prevents substantially all of the electrons from impinging on the interior surface of the support plates.

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: A photomultiplier tube comprises an electron multiplier assembly including a pair of oppositely-disposed insulative support spacers. A plurality of elements including an ultimate dynode and an anode are affixed to the support spacers. The ultimate dynode comprises a relatively inflexible multilateral hollow member having two plane-face surfaces lying at an acute angle to one another and terminating at a lower transverse edge. The ultimate dynode includes dynode mounting tabs extending from opposing ends thereof for affixing the ultimate dynode to the support spacers. The anode includes a substantially flat electron permeable mesh portion spaced from one of the plane-face surfaces of the ultimate dynode. Anode mounting tabs extend from opposing ends thereof for affixing the anode to the support spacers. Electrical leakage isolation slots are formed in the support spacers to increase the electrical leakage path length across the support spacers between the ultimate dynode and 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.

Abstract: An electron emissive surface portion on one of a series of electrodes includes a cross-sectional contour substantially characterized by a superimposed undulating line of curvature which includes a plurality of interconnected arcuate regions.