GB841130A - Improvements in or relating to electron gun assemblies - Google Patents

Abstract

841,130. Velocity-modulated tubes ; cathode ray tubes. M-O VALVE CO. Ltd. Feb. 11, 1959 [April 24, 1958], No. 13116/58. Class 39(1). An electron gun assembly comprises a plurality of electrode components each of which includes at least one laminar part 5, 13, 14, Fig. 1, which has formed in it a plurality of slots 15, Fig. 2, inwardly extending from its periphery, all the laminar parts being arranged parallel to each other, by means of a plurality of insulating elongated support members 19 disposed with their lengths perpendicular to the lamina parts and having slots which correspond with the slots in the laminar parts. Each of the slots 15 in the laminar parts comprise two inwardly extending sides parallel to each other and to a diametral plane which intersects a third edge, joining the two sides, at a point off-set from its centre thus ensuring that the two sides are of different lengths. The length of the shorter side is greater that its distance from the diametral plane. The elongated members may be in the form of strips or, as shown, they may be cylindrical, in which case their radii are equal to the length of the shorter-slot-side, and the rods are provided with segmental slots 20 so that they fit into the laminar slots as shown in Fig. 2. The rods are disposed symmetrically about the gun axis when the lamina parts are of annular form. A preferred embodiment describes the gun for use in a travelling wave tube which comprises indirectly heated cathode 1, Fig. 1, mounted on tube 2 supported by clip 3 from a tubular heat shielding member 4. This member is connected to the titanium annulus 5 which has central portion 7 bent back towards the cathode and forms a focussing electrode which operates at cathode potential. The second annulus 13 is secured to one end of the cathode heating member 8, and the third titanium annulus 14 constitutes the anode. The annuli are provided with three apertures 18, Fig. 2, housing bushes 25, Fig. 1, through which alignment rods 22 pass. The support rods 19 are then fitted into the slots 15 in the annuli and the assembly is inserted into a tubular part 21, which may form part of the envelope of the device. The gun arrangement is stated also to be suitable for use in klystrons and cathode ray tubes.