Rafidain Journal of Science

Abstract

The bipolar region is one of the most important factors in determining the effectiveness of a magnetic lens. Regarding the focus and optical qualities of the display devices, the optimal position of the polepiece and the most significant aspect of the magnetic electron lenses were the iron shrouds, where the magnetic field increases smoothly and uniformly with the highest possible value and has just one peak.  The goal of this study is to determine the position of the shroud tip relative to the axial axis (Z), where the tip of the polepiece is located at (Z = 0 mm). In practice, it has been seen that the optical properties of electron lenses have improved when the position of the polepiece iron shroud tip is separated by a distance of 180 mm. By extending the distance between the iron shroud and the polepiece face in the opposite direction of the coil, by removing or reducing magnetic flux leakage, it is possible to increase its performance. The axial magnetic field will then rise within the lens in a direction that prevents it from being lost. In this work, the FEMM and MELOP programs were used to investigate the lens' performance, axial magnetic field, and focal optical characteristics.