Impregnated cathode surface investigations by SFM/STM and SEM/EDX

The surfaces of 411-impregnated S-cathodes have been investigated by SFM/STM (= scanning force microscopy and scanning tunnelling microscopy) and SEM/EDX. The S-cathodes of different origin consist of a tungsten matrix (20% porosity) and are impregnated with 4BaO · CaO · Al2O3 (abbreviation: WI-cathodes). Surface structure and topography and elemental constituents of the partly contaminated tungsten surface have been identified. A comparison between non-activated and activated WI-cathodes is given. The specific advantages and the resolution limits of both characterization tools are discussed.