GB478926A - Improvements in or relating to electric discharge tubes - Google Patents

Abstract

478,926. Discharge apparatus. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. April 21, 1937, No. 11443. Convention date, April 23, 1936. [Class 39 (i)] An electric discharge tube comprises two or more independent vacuum vessels which are each provided with at least one metallic tubular extension which is closed at or near its end by a metallic foil or tag, the vessels being con. nected by arranging the tag of one exten. sion of one vessel close to or engaging the tag of one extension of a second vessel, hermetically interconnecting the two extensions, for example by soldering, and finally per. forating the tags. In the X-ray tube shown in Fig. 1, the anode and cathode are contained in separate metal compartments 1, 2 respectively, provided with extensions 9, 10 closed by metal foils 11, 12, as shown in detail in Fig. 2. The foils may be of constantan, 50 microns thick. The compartments are evacuated independently, and possibly the cables 7, 8 are connected up and their insulating collars 5, 6 sealed into the glass re-entrant stems by hardening material. The extensions 9, 10 are fitted together, the air trapped between 11, 12 passing out through hole 13. The joint 14 and hole 13 are sealed, for example, by solder, and the foils are perforated by passing a beam of electrons at 100-200 kilovolts through them. A window 32 for the X-rays is provided. Discharge tubes having' intermediate tubular electrodes may be made in the same way, each electrode being in two parts closed by foils. The foils may be perforated mechanically, as shown in Fig. 3, in which the extension 9 has an extensible corrugated portion 15 surrounding a hollow tubular mandrel 17 with a sharpened end, sliding in the member 16. A nut 21 enables the corrugated portion to be compressed, when the tubular mandrel, which has a shoulder 18 pressed against the end of extension 9 by a spring 19, is driven forward through the foils 11, 12. To prevent possible blocking of the mandrel by the detached foils, the mandrel is given an inclined edge which is rounded in the region 23. The foils are thus not completely severed but are bent back against the wall of extension 10 and lie in the recess 31 in the mandrel. The construction may be applied to cathode - ray tubes. To remove gases liberated during the perforation of the foils, a getter may be placed in one of the compartments preferably in the field-free space within the cathode shield.