AR DESORPTION FROM OSRU COATED CATHODES (L6)

OsRu and other alloys are used as a top-layer on impregnated W thermio nic cathodes to obtain a high emission performance. We apply a cathode with a sputtered OsRu layer in cathode ray tubes (crt), Due to the sp uttering process Ar is incorporated in this layer. Part of this Ar des orbs into the crt on first heating. The Ar desorption mechanism has be en studied by thermal desorption spectrometry and the metal layer stru cture has been studied with a variable energy positron beam. It has be en found that no Ar bubbles are formed during deposition. Ar is partia lly released on heating by thermal-vacancy assisted diffusion at ca. 1 300 K from the W pellet, and at ca. 1100 K from the OsRu layer. At the same time Ar bubbles an formed in the OsRu layer that desorb at ca. 1 800 K.