GB301412A - Improvements in or relating to electric discharge tubes - Google Patents

Abstract

301,412. Dicker, S. G. S., (Naamlooze Vennootschap Philips' Gloeilampenfabrieken). Aug. 29, 1927. Low-pressure metallic-vapour apparatus. In mercury discharge tubes having an incandescent cathode, the mercury is so enclosed that it cannot flow on to the transmitting part of the tube, on which metal, used as a getter, is deposited, it being contained in the space surrounding the stem of the tube. A screen for this purpose is provided on the wall of the tube and extends round the stem of the tube or round the conductors or supports therein. In the discharge tube shown the cathode 2 is formed of a tungsten helix on which a nickel wire is wound, a coating of barium oxide being formed by precipitation of barium thereon. A small quantity of mercury 11 is maintained at the base of the tube by a screen 12 sealed to the wall 1 and surrounding the cathode conductors or support, the mercury thus being prevented' from passing into the body of the tube. Sealed into the wall are anodes 3, 4 and tubes 6, 7 by means of which a liquid or gas entering at 9 and leaving at 10 may be treated with ultraviolet rays. To enable this to-be done, the tube 6 is formed of quartz or glass which transmits the rays and the outer wall 1 and the admission tube 7 of ordinary glass. The discharge tube may contain argon or neon in addition to mercury vapour and be used for luminous purposes, and in its formation magnesium or barium is vaporized to remove detrimental gases or vapours.