Scandate cathodes, state of the art

The author reviews the different solutions regarding scandate cathodes, describes the technology, and compares and discusses the results obtained in various laboratories. It is pointed out that the technology of scandate cathode types is well advanced and many solutions exist, such as the classical impregnation of a porous tungsten matrix with 4-1-1 or 5-3-2 to which a certain amount of Sc/sub 2/O/sub 3/ is added, or by pressing and sintering mixed matrix pellets of tungsten and scandium oxide and impregnating them with 4-1-1 or 5-3-2 or by coating the surface of the impregnated cathode with a complex coating of a metal and scandium oxide. The main difficulty encountered so far is the good reproducibility of the mixed matrices. The results for scandium mixed matrices and cathodes impregnated with BaCa aluminates containing scandium oxide are very similar. The top layer cathodes are more difficult to realize. >