Emission Microscopy and Auger Spectroscopy of Impregnated Cathodes. [Abstract only]

Vacuum Devices [Proc. Conf.], Cambridge, England, Mar. 1980. SEM and Auger micrographs of impregnated-W cathodes show that patches of impregnant material remain on the surface after activation and may evaporate only slowly during life. When poisoned by about 50% (either by chemisorption or by ion bombardment) patches of emission appear. The life time of this material may be hundreds of hours or only a few hours depending on the amount of sputtering by residual gas ions. Thicker material is more resistant to poisoning. These observations help to explain the variablity of cathodes early in their life.--R.E.