For discussion see the other paper from a paper in Proc CPO6 (B. Lencova, NIM-a 519) on comparison of FEM and BEM. The geometry of the lens was taken from Kasper (AIEP 116 from 2001). The same lens also analyzed Becker on CPO6 (see also www.egunigun.com).
Geometry
Mesh selection is complicated for this type of lens because the geometry of the polepiece is rather triangular. Nevertheless, with a slight overkill in the number of mesh points in the vicinity of the polepiece the accuracy of axial flux density is high enough. This example clearly shows the advantage of using graded mesh and automeshing procedure, because the user does not have to select anything else but the density of mesh points in the region (either in horizontal or vertical direction, the other direction adjusts automatically) and by using default q-factor.
Flux density in magnetic circuit of one pole lens and B(z) on axis. Borders are 1 m from the lens.
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