Electron Emission from Thoriated Tungsten

Constants of the electron emission from a monatomic layer of thorium on tungsten at temperatures from 1000° to 2000°K.—The electron emission for a monatomic layer of thorium on tungsten is best represented for zero field strength by the relation $I=3\mathrm{}{T}^2{\epsilon }^{-\frac{30,500}{T}}$, where $I$ is expressed in amps/${\mathrm{cm}}^2$. The emission was measured for different states of activation of the filament. If we let $\theta$ be the fraction of surface covered with thorium, then for $\theta <0.95\mathrm{}$ (approximately) $log{A}_{\theta }$ varies linearly with $b_{\theta }$ where the emission for the given surface is represented by $I=A_{\theta }{T}^2{\epsilon }^{-\frac{b_{\theta }}{T}}$. It is also pointed out that the emission for a monatomic film of thorium on tungsten is greater than that observed for metallic thorium.