| 摘要 |
675,456. Making electric components. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Oct. 20, 1950 [Oct. 25, 1949], No. 25609/50. Class 83 (ii). [Also in Group XL (a)] A cathode for an electric discharge tube is internally provided with a supply of alkaline earth metal compounds, the wall of the cathode being constituted at least in part by a homogeneous, porous, sintered body of at least one of the high melting-point metals, tungsten, molybdenum, tantalum, hafnium, and columbium, and the pores of the porous body constituting the largest apertures in the wall of the cathode body, and is characterized in that the porous body is butt-welded to the remaining part of the cathode wall so as to form a supply chamber for the alkaline earth metal compounds. As shown in Fig. 1, the cylindrical, porous, hood 1 contains a supply of alkaline earth metal compounds 2 and is butt-welded to a molybdenum bush 3 along the circular edge 5, a heater 4 being housed in the bush 3. In Fig. 4, the porous body consists of an elongated, cylindrical tube 10 which is closed at one end, and at its open end has welded to it the flange 12 of a molybdenum bush 11 which extends into the tube 10 to form a housing for the materials 2. In Fig. 5 (not shown), a cylindrical, porous tungsten tube surrounds a molybdenum tube, the widened ends of which are butt-welded to the inner side of the porous tube, and in Fig. 6 (not shown), the junction between the tungsten and molybdenum tubes is formed by small rings welded to the tubes. In Fig. 8 (not shown) to obtain more uniform heating a molybdenum bush containing a heater is welded to each of the ends of the cathode, and in Fig. 9 uniform heating is achieved by providing a molybdenum tube 17 with an extension 18 which extends into the porous tungsten tube 1. In Fig. 10 (not shown), the heater is coated with insulating material and arranged in direct contact with the earth metal compounds. Fig. 11 shows a directly-heated cathode in which a porous tube 13 has welded to it two plates 21 provided with wires for connection to the supply. |
