Patent GB-477850-A (GB)
Title: Improvements in or relating to electron discharge devices
IPC: H01J21/02
Filed: 1936-07-06
Abstract: 477,850. Discharge devices. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. July 6, 1936, No. 18769. Convention date, July 5, 1935. [Class 39 (i)] A discharge tube has a straight cylindrical cathode with alternate emitting and non-emitting areas along its length, a cylindrical anode anc a grid interposed between the cathode and anode and arranged so that a grid conductor is in registry witl the non-limiting areas and openings in the grid are in registry with the emitting areas. As shown, emitting material 67 is arranged in a helical groove formed so as to leave a non- emitting helical strip 68 between the turns of the groove. The groove is filled to the surface with the emitting material. A helical grid 69 surrounds the cylindrical cathode with its turns in registry with the non-emit. ting strip. A cylindrical anode 70 may be formed with pockets by means of ribs 71 which are in alignment with the grid turns when the grid potential is not greater than the anode potential, but, when it exceeds the anode potential, the ribs are arranged in alignment with the spaces between the grid turns. The anode may be coated with lamp-black to reduce secondary emission. In a modification, Fig. 7 (not shown), two additional longitudinal non-emitting strips are formed, for example, by uncoated nickel rods lying along the cathode and maintained at zero potential. The side rods of two grids are in alignment with the uncoated rods. Specification 453,421 is referred to. The Specification, as open to inspection under Sect. 91, comprises a number of arrangements for producing and using beams from a cathode not formed with separate emitting and non-emitting areas. The conductors of an outer grid may be longitudinal wires in registry with the wires of an inner beamforming grid ; or the outer grid may consist of flat metal rings or a strip helix wound edgewise, the rings or turns being in registry with the turns of an inner helical grid. In other valves one grid consists of a helix and the other of longitudinal wires. In the arrangement shown in Fig. 11 (Cancelled) the emission from a cathode 35 is formed into two beams passing to an anode consisting of two trough-shaped parts 51 by an elliptical grid G at a negative potential having curved end plates 45. A slotted cylinder 47 at a positive potential surrounds the beams, and is surrounded by a slotted cylinder 50 which is at zero potential and acts as a secondary emission suppressor and as a re-focusing electrode. In the arrangement shown in Fig. 21 (Cancelled) the emission from a cylindrical cathode 35 is focused by two rods 90 to form two beams surrounded by a slotted cylinder 91 and passing to two rods 92 and a box-shaped electrode 93. As the negative bias on the rods 90 is decreased the current to the cylinder 91 increases, while the current to the electrodes 92, 93 remains constant. This arrangement may be used for producing a negative resistance effect in the circuit to the electrode 92 by maintaining the electrode 93 at a low positive, zero or negative potential. In the arrangement shown in Fig. 33 (Cancelled) a single beam from a cathode 35, produced by electrodes 110, 111, each having a single slot, is directed towards the overlapping edges of two plate electrodes 112, 113, connected oppositely with deflecting plates 114, 115. An increase of potential on the plate 112 and deflecting plate 114 causes the beam to be deflected towards the plate 115 with a resultant decrease in current to the plate 112. A screening grid 116 is arranged in front of the plates 112, 113. This subject-matter does not appear in the Specification as accepted.