GB625283A - Improvements in rectifying electric discharge tubes - Google Patents

Abstract

625,283. Thermionic power converters. PHILIPS LAMPS, Ltd. Sept. 20, 1946, No. 28255. Convention date, March 6, 1943. [Class 39 (i)] In a gas and/or vapour-filled rectifier having two or more anodes and an incandescent cathode provided within a screen, the product pd of the distance d from each anode to the cathode screen and the pressure p is less than the value at the minimum of the Paschencurve, and the cathode screen and any other screens present in the tube are fitted to inhibit the passage of charge-carriers from one anode space to another. Preferably, the diameter of the front surface of the anodes is at least four times the distance from the anodes to the screen and at least four times the diameter of the apertures in the cathode screen for the discharge to pass, and the product pd is between 0.15.10<-3> and 15.10<-3> mm. cm. In one tube having three anodes, the anodes 4, Fig. 1, consist of chrome-iron boxes each having a layer of carbonized iron 14 as a front surface and mounted opposite apertures 13 in the cathode screen 3. The anodes may be cooled by natural circulation of air or by forced cooling. The cathode screen is mounted insulatingly on the cathode leads 5, and is closely surrounded by the envelope wall 1. The anodes 4 are shielded from each other by cylindrical screens 17 closely adjacent to the cylindrical surfaces formed by glass parts 16. In another form, one anode is arranged opposite a flat end of the cylinder forming the cathode screen, and the other anodes are arranged circumferentially, the front surfaces of these anodes being curved to conform with the surface of the cylinder. The discharge apertures are covered by screens 18, Fig. 3, each having a separate lead and which may be given positive potentials with respect to the cathode screen. Specification 508,190 is referred to.