The Emission and Electrophysical Features of an Yttria-Coated Iridium Cathode

Resumo

A laboratory technology for manufacturing iridium–yttrium cathodes, which are totally or locally coated with yttria, was developed. A technique for determining the emissivity on the iridium surface was proposed and its value was determined: 0.6 at a wavelength of 665 nm. The work function of such film cathodes was determined: eφ = 3.4 eV. The temperature range of the cathode operation under the conditions of a medium vacuum was established, and it was shown that this operation is efficient only for Т ≥ 1600 K. A physical model for describing this process is proposed. The high thermal stability of yttria-based cathodes, which can withstand heating at Т = 2500 K for hours without degradation, is shown.