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200keV saturated lens of a TEM |
The data similar to those Tsuno used in 1986 ICEM conference in Japan are used. This example is used to demonstrate the accuracy of EOD and its LENS module.
- Data contain 80000 mesh points
- 3 excitations of a lens (15000, 15500 and 16000 Aturns)
- computation will take 22 s on 3 GHz PC. This is a large difference to typical computation time of 1 night for 1 lens excitation with 6000 mesh points in 1986!
The same data but with saving only the result of the last excitation are used to check the computation error with a built-in procedure in EOD. The accuracy (i.e. the error of B(z) close to its maximum) is around 0.01 %, and the computation time is just 240 s.
Geometry
The geometry of the lens is shown at the left. The 2 mm gap has 40 mesh lines in the gap, polepiece radius has 1 mm has 20 mesh lines between the axis and the polepiece. There are in total 355 mesh points in z direction, 79165 mesh points in total, the q factor is 1.025.
Lens saturation
Field accuracy
The plot shows in blue the axial flux density (maximum 3.30 T) and in red the error estimate (the difference between the computations a mesh with 80000 points and with 320000 points at the mesh points of the older mesh – see papers from 2002-2004). The red curve is magnified 10000 times and the error is between +0.28 mT and –0.25 mT.
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