GB1398678A - High-voltage installations - Google Patents

Abstract

1398678 Cold cathode tubes ROBERT BOSCH GmbH 6 July 1973 [10 July 1972] 32430/73 Heading HID [Also in Divisions F1 and H2] A high voltage gas filled switch comprises anode 3, and cathode 2 with lateral extension 7, the discharge being initiated when movable control electrode 4 is positioned adjacent the extension. Electric potentials, rates of voltage rises, and dimensions are given. Electrode bodies 9, 10 may be Fe-Co-Ni alloy and at least in the free end region, coatings 11, 12 (e.g. not readily atomizable zirconium nitride) may be applied by plasma spraying for instance. Extension 7, at least on the surface, is a low work function, conductive material (e.g. Cu). Gas filling may be noble gas, for example Ar and nitrogen in a 1 : 1 to 20 : 1 vol. ratio, with <10<SP>-4</SP>% oxygen and water contamination. Gas pressure may be 0À5 to 10 bars. Tube 14 may be glass or quartz. Control electrode 4 may be Cu, Al or steel and may include at least a section of poor electrically conducting material (19) (Fig. 3, not shown) or dielectric constant >10 (e.g. sintered barium titanate). Conductive holder (18) may be provided. Insulating tube 20 inhibits discharge between electrodes 2 and 4. More than one switch may be included in a two cylinder internal combustion engine with spark plugs (21), (Fig. 4, not shown). The switches may be combined in a single tube, individual discharge gaps protected at least partly from mutual influence by insulating barriers. Photographic flashlight application is also disclosed.