GB502596A - Improvements in or relating to x-ray tubes - Google Patents

Abstract

502,596. R÷ntgen-ray tubes. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. Aug. 17, 1938, No. 24237. Convention date, Aug. 20, 1937. [Class 39 (i)] In an X-ray tube the anode 4 comprises a mass of metal, e.g. copper, a refractory impact disc 5, Fig. 1, e.g. of tungsten, and is blackened over a large part (at least 75 sq. cm.) of its outer surface 6, this part being arranged opposite a metal tube wall 1 which is insulated from the anode and cathode so as to withstand high-tension, and the direct connection between anode and tube end and external supply conductor is of such poor heat conductivity that the quantity of heat that it conducts away is low, compared with the heat radiated by the anode, the insulating tube ends and also the external metal parts serving to connect the current leads to the electrodes, being surrounded by an insulating protective body which has fixed to it a high tension cable. The wall 1 of ferrochrome is provided with a lead layer 7 and a protective metal wall 9 which may have cooling fins 39. The thin ends 64, 65 of the wall are sealed into glass' end-pieces 2, 3, on which are mounted the hoods 11, 12 by means of lead oxide, moulding asphalt, or sealing wax 16. Each hood comprises two fluted interlocking members 13, 15; the member 15 carries the cable connection, coated externally with metal, e.g. by spraying, and may be connected to the wall 1 or 9 by a screw 17 which may fix the parts, or by engaging an annular slot render them relatively rotatable. The metal coating may be omitted if the insulation is thick enough. Both wall 1 and metallic coating are earthed. The anode is carried by a thin-walled ferro-chrome tube 19 on a fluted disc 20, made of the material sold under the Registered Trade Mark "Calit," and which, together with a metal heat shield 38 is mounted on the end of the wall 1. The shield 38 may be of copper, and the surface of the anode facing it may be blackened. The lead 21 from the anode is taken to a disc 26 sealed in the member 2, and thence to the conductor 18. The cathode 23 and focusing device 22 are carried by a similar tube 25 on a similar disc 24, and the leads 27, 28 are taken to a metal ring 29 and hood 30, mutually insulated by a glass ring 31, and which are engaged by bush 32 and plunger 33 respectively. The tubular lead 34 from the bush 32, and the central lead 35 from the plunger 33 are separated by a rubber casing 36. The assembly at the cathode end of the tube is otherwise similar to that at the anode end. In a modification, the anode 45, Fig. 2, is carried by a thin-walled metal tube 48, on a massive copper member 49 provided with a shielding enlargement 51. A further screen 50 is provided. The cathode 53 is connected at one end to a tungsten plate, and its lead at the other end passes through the plate. Screens 60 and 61 protect this end of the tube from heat and electron bombardment. Insulating hoods are provided in the modification also, and a lead sheath and metal protecting member may be provided on the metal wall 11.