| 摘要 |
<p>39 A thermionic cathode, the material of which is substantially high-melting metal such as W, Mo, Ta, Nb, Re and/or C, consists of a very fine-grained mechanically stable support layer, a series of layers considerably enriched with emissive material, in general from the scandium group especially from the group of rare earth metals, preferably with Th or compounds thereof and a thermally stable preferentially oriented coating layer. All the layers are provided via the gaseous phase, for example, CVD methods, on a substrate formed according to the desired cathode geometry. The subsrate is removed after termination of the deposition.</p> |
