GB268742A - Roentgen tube - Google Patents

Abstract

268,742. Siemens - Reiniger - Veifa Ges. fiir Medizinische Technik. April 3,1926, [Convention date]. R÷ntgen-ray tubes.- The anticathode of a R÷ntgen - ray tube is fitted with an apertured hood 1 impenetrable to R÷ntgen rays, the aperture 6 being provided with a window 10 of beryllium or other material transparent to R÷ntgen rays but giving rise to little R÷ntgen radiation under electron bombardment, and the cathode 23 is fitted with a shell 15 which surrounds and overlaps the end of the hood 1 adjacent the cathode and which is impenetrable by R÷ntgen rays as reach it and has an end wall 17, impenetrable by R÷ntgen rays issuing from the passage 13 of the hood 1. The tube emits only useful R÷ntgent rays and electrons are prevented from impinging on the glass and causing emission of gas. The hood 1 may be of copper turned on a lathe and may be held in good heat-conducting relation with the anticathode 2 by conical engaging surfaces 2<1> pressed together by tightening up screws and engaging conical recesses 4 in the anticathode 2. The flat window 10 wholly covers the part of the wall of the aperture on the anticathode side of its outer surface and is held in place by a screw ring 11. The passage 13 is narrow at its end, for example 8 mm. in diameter, and widens towards the anticathode to prevent electrons from the cathode striking the walls of the passage and to diminish R÷ntgen rays from these walls issuing from the window 10. The outer edge of the hood has a projecting ring 14 hindering the travel of electrons to the outer surface of the hood and absorbing weak R÷ntgen radiation from the end of the hood. The shell 15 may be of iron and the part 17 may carry a tubular extension 19 made resilient by slits and clamped by a ring 21 and screw 22 against a mica sheath on the cathode lead 18. The extension 19 has an enlarged bore 19<1> at the end near the cathode to space it away from the lead 18.