The Effect of Cross-Section Area of Electron Beam on the Aberration of Einzel Electrostatic Lens

A theoretical study by using computer model is presented by fitting an axial electrostatic potential distribution to polynomial function of fourth order from which the paraxial ray equation is solved to obtain the trajectory of particle that satisfy the suggested potential function. The distribution of the axial potential up or on the lens of length (22mm) has been carried out using Laplace equation by using Finite element method. , the results are obtained for Cs and Cc normalized in terms of the results showed low value of spherical and chromatic aberration comparing with other searches about ( 2.42) for spherical aberration and ( 0.03) of chromatic aberration, of this study showed small values of spherical and chromatic aberration, with values of area of which considered as ( 3mm2).