Electron field emission from copper with various thicknesses of oxide film

A new, nondestructive method for electron field emission measurement is presented, which, in principle, completely avoids the need for deleterious multiple sparking of the surface required by previous workers and which allows electron field emission to be measured at its origin; i.e. with only a few electrons leaving the cathodes per second. The results obtained on oxide-covered copper cathodes with various controlled thicknesses differ markedly from those obtained by previous workers and conform more with modern interpretation.