(19)
(11) EP 0 157 634 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
08.01.1986 Bulletin 1986/02

(43) Date of publication A2:
09.10.1985 Bulletin 1985/41

(21) Application number: 85302311

(22) Date of filing: 02.04.1985
(84) Designated Contracting States:
DE FR GB IT NL SE

(30) Priority: 02.04.1984 US 595789

(71) Applicant: VARIAN ASSOCIATES, INC.
 ()

(72) Inventor:
  • Green, Michael Curzon
     ()

   


(54) Tungsten-iridium impregnated cathode


(57) Porous agglomerates (14) are made from pure tungsten by sintering fine particles together and mechnically breaking down the mass to form some agglomerates (14) considerably larger than the particles. These agglomerates (14) are mixed with fine iridium powder (18) and sintered to form a porous mass. The mass is machined to the cathode shapes (10') and impregnated with an alkaline earth aluminate (18). The large agglomerates (14) alloy with the iridium only on their outer surface. Their pure tungsten interior provides the surfaces to reduce the alkaline earth oxide to the metal which activates the cathode.





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