The Relationship Between the Lengths of the Pole and the Iron Arm in the Design of the Electronic Magnetic Snorkel- Lens

The dipole region is one of the most important factors in determining the effectiveness of a magnetic lens. The optimum position of the pole and the most important aspect of magnetic electron lenses are the iron covers, which are used to study the concentrations and optical properties of the display devices, where the magnetic field increases smoothly and uniformly at the highest possible value and with only one peak. The main objective of this study is to determine and reach a relationship between the length of the tip of the iron arm relative to the length of the axial magnetic pole (Z), where the pole tip was chosen at (Z = 0 mm). In practice, it was observed that the optical properties of the electron lenses showed a significant improvement when the length of the tip of the iron arm and the length of the magnetic pole were changed. The opposite of the coil as it was noted that it is possible to increase its performance by removing or reducing the magnetic flux leakage so that the axial magnetic field will then rise inside the lens in a direction that prevents its loss. The designers’ choice is when preparing the lens along the iron arm based on extensive studies and choosing an appropriate length of the pole that determines the desired function of the lens or what is known as the optical system. In this work, a relationship was established between the length of the electrode and the length of the iron arm, and FEMM and MELOP programs were used to verify the performance of the lens, the axial magnetic field as well as the focal optical properties.