| 摘要 |
An impregnated cathode comprising three layers: a very thin emitting surface layer of metal such as an alloy of tungsten with a high fraction of an activating metal of the platinum group to provide low workfunction; an underlying, thin buffer layer of porous tungsten alloyed with a fraction of activating metal, to retard diffusion loss of activating metal from the emitting layer; and a substrate of porous tungsten impregnated with barium aluminate.
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