| abstract |
The invention relates to a cathode with a matrix body (1) impregnated with an alkaline earth compound, to the surface of which a cover layer (2, 3, 4) is applied, which contains high-melting metal such as, in particular, tungsten and scandium. A high emission at low operating temperature and, at the same time, a rapid recovery after ion bombardment and a long service life are achieved in that the cover layer contains at least two layers of different composition, a purely metallic layer (5, 6, 7) on the impregnated matrix body (1) is applied, which contains scandium and a high-melting metal such as, in particular, tungsten and / or rhenium, and that a metallic layer composed of a high-melting metal, such as in particular tungsten, is applied as the final layer. |