Perturbation techniques in the problems of computational charged particle optics

摘要

Basing on perturbation technique, discussed are some urgent problems of computational charged particle optics including numerical evaluation of fringe fields and field perturbations caused by small deviation of the shape of electrodes from rotational or planar symmetry as well as aberrational analysis of charged particle beams in the most general tensor form. It is shown that perturbation technique, being combined with other numerical approaches such as the tau-variations method and generalized method of initial parameters variation, proves to be most promising for evaluation of mechanical tolerances and simulation of Coulomb repulsion effects and charged particles scattering upon a fine-structure grid.