Temperature Dependence of Electron Emission in the Field Emission Region

The variation in field emission current as a function of the temperature of the emitter has been measured for tungsten over the range from 4.2^∘{}K to 400^∘{}K. The expected form of the temperature dependence of the emission current confirms the relationship previously postulated on theoretical grounds. This is j(T)=j(0)(KT/sinKT), where K is a constant depending on the work function and the field at the surface of the emitter. A current-increment method, in which the increase of current is plotted against the square of the temperature increase at constant field, gives a straight line whose slope permits surface field calculations more precise than heretofore possible by electron microscope measurement of tip radius.