Investigation of the Perveances and Beam Profiles of an Aperture Disk Emission System

Argon ion beams are used for determining experimentally the perveances and the associated beam profiles of a series of electrode structures consisting of coaxial aperture disks. The results are of particular interest in the design of ion sources. Since, fundamentally, there is little difference between electron guns and ion sources, the results should also be of interest in the design and study of electron guns. Electron guns producing convergent beams, and designed on the Pierce principle of rectilinear flow, require electrodes whose shape is not always easy to reproduce or the most convenient to use. If the principle of rectilnear motion is abandoned, it is found experimentally that the perveance in many cases is little affected by the adoption of the much simpler electrode system of coaxial aperture disks. Perveance is the ratio of the output current to the$\frac{3}{2}$ power of the input voltage.