Heating element for indirectly heated cathode and method for the manufacture of such an element

摘要

This heating element is constituted by a filament and a mixture, fritted at between 1700 DEG and 1800 DEG C., of alumina and less than 10% by weight of yttrium oxide. This mixture fills the space left free by the filament within the cylinder closed by an emissive disk forming the cathode.