Accurate computation of magnetic lenses with FOFEM

First-order finite element method (FOFEM) is used for computations of rotat ionally symmetric magnetic electron lenses with saturated materials. An ove rview of local and global errors in the axial Aux density distribution in t he first-order finite element method is given, and the coefficient computat ion in FOFEM providing the best axial fields are shown. The quality of comp uted results is illustrated on several typical problems. It is shown that w ith graded dense mesh accurate results can be obtained fast and with small memory requirements. (C) 1999 Elsevier Science B.V. All rights reserved.