GB221547A - Improvements in and relating to methods and apparatus for maintaining gaseous conduction discharges - Google Patents

Abstract

221,547. British Thomson-Houston Co., Ltd., (General Electric Co.). June 6, 1923. Vacuum tubes.-In a gaseous lamp in which the discharge consists substantially of the positive column, the discharge space between the electrodes is confined to a tube of substantially the same cross-section as both electrodes but is in communication with the surrounding bulb. The main electrodes are spaced at a distance greater than the striking distance for low potential, and means responsive to low potential are arranged to ionise the gas and to allow positive column discharge to begin. The ionising means may consist (1) of a short gap in parallel with the main gap which gives a barely-visible discharge; (2) of radioactive materials, or (3) of tungsten helices forming all or part of the main electrodes and giving some kind of ionising discharge at low potential. Three constructions of the auxiliary-gap type are described. The first comprises a bulb 1 containing rare gases, in which are mounted main electrodes 5, Fig. 1, which are in series with a limiting resistance 9. The electrodes 5 are enclosed in a transparent tube 6 of length greater than its diameter, and they have extensions 7 which form the auxiliary gap and are themselves slidingly fitted in a tube 8. In a modification, the auxiliary gap is exterior to and at a distance from the main gap, the tube 6 having closed ends and a central opening. In the construction shown in Fig. 3, electrodes 7 are placed adjacent one or both main electrodes, the discharge tube 12 having extensions -enclosing the electrodes and communicating at 13 with the interior of the bulb. The tubes 8 are preferably sealed at the ends remote from the electrodes 5, but otherwise are of such length as to confine the discharge thereto. The electrodes are made of or treated with material of high electron emissivity. A lamp is described in which the electrodes 5 are ¥" apart and the electrodes 7 are 1-32" apart. Other figures for pressures and dimensions are also stated.