Electron Emission from Thoriated Tungsten

Abstract

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