GB559515A - Improved method of forming anodes in current-converting tubes - Google Patents

Abstract

559,515. Discharge converters. PHILIPS LAMPS, Ltd. (Naamlooze Vennootschap Philips' Gloeilampenfabrieken). Oct. 14, 1941, No. 13228. Drawings to Specification. [Class 39 (i)] The anodes of converters are treated to minimize back-ignition by subjecting them to a glow discharge in a gaseous medium under constant conditions of pressure and current density, until the occurrence of back ignition as indicated by a device responsive thereto has ceased for a time sufficient to ensure that further back ignitions are not to be expected under the conditions of the treatment. The current density and voltage conditions during the forming operation are in excess of those occurring in the normal working for which the converter is rated. The gas filling may be any of the rare gases, nitrogen, hydrogen, oxygen, or mercury vapour, or mixtures thereof. and the pressure not less than 0.3 m.m. of mercury. The anodes treated may be of graphite, or more homogeneous composition such as mixtures of carbon graphite or carbides which have been sintered or baked together with bonding agents such as clay or bituminous substances ; the treatment may also be applied to aluminium or carbonized nickel anodes. Alternating or direct current may be used, and the treatment may be applied in the envelope of the rectifier, or in a separate envelope. The gas pressure may be reduced by utilizing a magnetic field to lengthen the path of the electrons and so increase the degree of ionization and the intensity of the glow discharge current, as described in Specification 488,886. The glow discharge may be used simultaneously with an arc discharge. The subjectmatter is identical with that of Specification 601,870, [Group XL (a)].