Thermionic and electrical properties of rhenium surface activated by yttria

A laboratory technology for creating rhenium cathodes activated by yttria has been developed, both completely covered with an activated layer and with local activation, when only part of the surface is covered with a layer. The application of yttria leads to a significant decrease in the work function of rhenium cathodes from 5.15 eV for pure rhenium to 3.4 eV for an activated surface. The elemental composition of the activated surface is represented only by yttrium and oxygen atoms with a small proportion of rhenium. Such cathodes are thermally stable at least up to $T$ = 2500 K, the calculated value of thermionic current at this temperature is $\sim$100 A/cm$^2$.