Improvements in and relating to directly-heated cathodes for electric disharge devices

摘要

506,150. Thermionic cathodes. BRITISH THOMSON-HOUSTON CO., Ltd. Nov. 23, 1938, No. 34063. Convention date, Nov. 23, 1937. [Class 39 (i)] A directly-heated cathode for electron discharge devices is formed by a plurality of individual conducting wires or ribbons which are either woven directly onto a core wire or woven together and then spirally wound onto a core wire. Suitable metals for the wires or ribbons are molybdenum, tungsten, nickel and copper, and different metals may be used for the individual wires or ribbons in order to combine mechanical strength with a low work function or to eliminate the stresses set up by the expansion on heating by choosing metals with suitable coefficients of thermal expansion. The woven construction gives a good hold for the oxide coating.