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Publisher Summary This chapter addresses the problem of evaluating potential perturbations resulting from small deviations of the geometry and voltages of the electrodes that form the electron-optical system's boundary, also termed “the boundary variations,” from some ideal state, which is called “nominal.” This problem is the starting point and main issue for many charged particle optics problems, including mechanical tolerances computation, fringe effects evaluation, electron-optical system optimization. This chapter develops another, more versatile and numerically efficient perturbation approach based on direct variational analysis of the first-kind Fredholm integral equation. Fedorenko's variational scheme is used for varying the Dirichlet problem for Laplace equation in the general three dimensional (3D) case. This chapter concludes with the numerical approaches for accurate evaluation of potential perturbations caused by the locally strong 3D boundary perturbations of axisymmetric and planar nominal boundaries. |
