Space- Charge effect in the Design of electron gun using immersion lens under high and low finite magnification condition Space- Charge effect in the Design of electron gun using immersion lens under high and low finite magnification condition

الملخص

Abstract
A computerized investigation has been carried out on the design of an
electron gun taken into consideration space-charge effect under high and low
finite magnification condition.
The Finite element method (FEM) used in the solution of Poison's
equation for determine the axial potential distribution of the immersion lens,
paraxial ray equation was solved and the optical properties for this lens are
calculated.
The work has been focused on the effect of current beam on the
spherical and chromatic aberration and to find the best value of the current
which gives accepted value of aberration in the present of space-charge.