Xmpl3d27, 27th 'example' data file for CPO3D

Simplest unbalanced deflector

Superseded by the set of data files starting at xmpl3d33

The file was written when the memory and speed of PC's was much more limited than at present, so the available number of segments was small and the requested inaccuracies were fairly high to give a quick demonstration.

The relevant theory and description is given in F H Read, L A Baranova and N J Bowring, to be published (1997 or 1998)

Simple deflector plates are put at +/- x and +/- y. All have voltage 0, except the plate at +x, which has voltage 1.

They are enclosed by conical shields.

(A system of balanced deflectors could be obtained by changing the reflection symmetries from 0 1 1 0 to -1 1 1 0, and omitting some electrodes)

Deduced aberration coefficients, as function of the distance dy from the axis:

It is found that 0.01 is too small, 0.025 is alright, 0.05 is ultra-safe but slightly inaccurate (by 0.1pc).

Increase number of axis points from 50 to 200 (dy=0.025):

Then coefficients change by 0.1pc.

Deduced aberration coefficients:

D = 2.64332E+00

A = -2.49471E+01

C1= -1.98914E+00

C2= 3.01404E+02

Increase all y coordinates by a factor of 2:

D = 3.49798E+00

A = -1.49466E+01

C1= -2.63829E+00

C2= 1.18431E+02

Increase all y coordinates by a factor of 4:

D = 3.90810E+00

A = -5.74834E+00

C1= -2.95000E+00

C2= 1.52054E+01

Summary:

increase in y= 2 4

change in D= 1.323 1.478

change in A= 0.599 0.230

change in C2= 0.393 0.050

For the analysis programs see the set of miscellaneous programs.