Patent GB-251673-A (GB)
Title: Improvements in or relating to vacuum electric tube devices
IPC: H01J17/26
Filed: 1924-12-31
Abstract: 251,673. Robinson, E. Y., and Metro- Politan-Vickers Electrical Co., Ltd. Dec. 31, 1924. Low-pressure metallic-vapour apparatus. - In introducing vaporizable substances into the envelopes of vacuum electric devices, applicable to the introduction of getters for removin residual gases and of substances such as caesium increasing the electron emission of tungsten and other cathodes, a compound of the vaporizable substance together with a reducing agen therefor, is placed within a metallic container or upon a metallic member other than an electrode of the device, which container or member is located in the envelope of the device or in an extension thereof, and, after exhaustion of the envelope, is heated independently of the envelope or its extension to the reaction temperature to liberate the substance. A mixture of caesium chloride with calcium or magnesium may be placed in a nickel tube 14, Fig. 1, held by a wire 13 in an extension 10 of the enevlope 7 of a valve with two or more electrodes. The tube 14 is closed at the ends, for example, by pinching, and is seamless or. if seamed, has its adjacent edges welded together to allow the circulation of high-frequency currents. After ovening of the envelope 7 and exhaustion thereof through a tube 8 fused into the pin 5 in connection with a blow hole 9, the electrodes are heat-treated by high-frequency induction and the tube 14 is then heated independently of the electrodes by high-frequency induction to red-heat to form caesium and vaporize it into the envelope, the extension 10 being finally sealed off at 12 and removed and the envelope sealed off from the pump. Alternatively, the electrodes and the tube 14 may be heated after the envelope 7 has been sealed off from the pump. Magnesium or calcium may also be vaporized to serve to remove residual gases. The tube 14 may be located at other places in the envelope and may remain permanently therein, for example, it may be welded or clipped to the filament support 3, the envelope being then exhausted through a tube at the upper end 12 of the envelope. The tube 14 mav be welded or otherwise connected to the anode 1 or a nickel pocket 17, Fig. 3, may be welded to the anode 1 to form a container to receive the reaction mixture, the reaction being produced by heat treatment of the anode. The anode may also be heated by electron bombardment or heat radiation from the cathode or the container or member carrying the reaction mixture may be heated by direct electron bombardment from the cathode or by heat radiation from the cathode or other electrode or member carrying electric current, for example, a heating coil may be arranged within the envelope. Specifications 17416/13, [Class 39 (ii), Electric lamps, Incandescent], 195,440, 207,816, and 208,694 are referred to. The Provisional Specification describes also the direct heating of the reagents by high-frequency induction and the sealing of caesium in a glass capsule placed within the envelope and heated by high-frequency induction to cause the caesium to penetrate the capsule.