GB894673A - Improvements in electric discharge tubes for high voltages - Google Patents

Abstract

894,673. Thermionic valves. PHILIPS ELECTRICAL INDUSTRIES Ltd. July 24, 1958 [July 27, 1957], No. 23877/58. Class 39 (1). An electric discharge tube has an anode 8, a thermionic cathode 7 and a heater (not shown) for the cathode, a mica member 16 holding said anode and cathode electrodes in spaced relationship and providing an insulating path between the electrodes, two conductive members 9 positioned on the mica member in said path, and two insulated conductors 11 and 12 disposed between the heater and the cathode 7, one insulated conductor being connected to one conductive member and the other insulated conductor being connected to the other conductive member. The members 9 acquire a potential intermediate those of the heater and cathode by induction in the conductors 11 and 12, and enable the tube to withstand very high potentials between the anode and cathode without having to increase disproportionately the lengths of the insulation paths across the mica member 16. In the tube shown there are two mica members 16, the conductive members 9 on the lower mica being connected to those on the upper mica by rods 13, one of which supports a getter holder 15. The members 9 may be plates arranged as shown at right angles to the mica surface or may be metal layers arranged in narrow lines on the surface. Each mica 16 has two vents 17 to increase the lengths of the insulating paths. The conductors 11 and 12 comprise metal core wires coated with insulating material such as aluminium oxide and wound helically in opposite directions. The tube may be connected in a diode limiter arrangement for a cathode-ray tube deflection system (Fig. 1, not shown).