Patent ID: 7208864
Filing Date: 2007-04-24
Classification: H01J

Abstract:
1. An oxide cathode for an electron gun comprising a cathodo-emissive layer basically made of alkaline earth oxides or of a mixture of such oxides, a metallic substrate having a top face onto which the cathodo-emissive layer is deposited, and a bottom face opposite to said top face, containing a plurality of reducing agents which are able to reduce said oxides under conditions of operation of said electron gun, said plurality including a first reducing agent Mg and a second reducing agent Si or Al, wherein: on the said top face, the Mg weight concentration is superior to 0.005%, the second reducing agent weight concentration is inferior or equal to 0.025%, and the refractory metals weight concentration is inferior or equal to 3%, where so-called refractory metals are selected from the group consisting of W, Mo, Re, on the said bottom face, the Mg weight concentration is inferior to the Mg weight concentration on the said top face, and the second reducing agent weight concentration is superior to the second reducing agent weight concentration on the said top face and superior to 0.02%, the thickness E of the said metallic substrate is inferior or equal to 100 μm.