Double Focusing of Charged Particles with a Wedge-Shaped, Non-Uniform Magnetic Field

Abstract

The pole faces of a wedge‐shaped magnet can be shaped so as to reduce the image distance for simultaneous horizontal and vertical focusing, and thereby increase the intensity at the image. The field inside the magnet is assumed to behave as r⁻ⁿ, where r is the distance from the center of curvature of the normal path and n is a constant parameter. Equations are obtained for the image distance for double focusing, and the results of calculations for several representative cases are shown. It is shown that by appropriate choice of the non‐uniform field, the image distance can be appreciably reduced in all cases of interest.