Charged Particl Optics: Theory and Simulation
   Project coordinator: Prof. Theo Zouros,
    Dept. of Physics, University of Crete
   Copyright 2010

   This project has been funded with support
   from the European Commission

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Useful SIMION tricks and other hard to find info.


Different color markers for different fly groups in the same fly:

In the Particle tab - Trajectory display change the color time marker to 15 (white). Then the markers use the color set for the trajectories in the Define initial fly parameters.


Regenerate PA's if dimensions in GEM have changed:

The Lua command regenerate() can be given either via a lua program or by giving this command in the command line of SIMION. This is useful in the case you have modified a gem file and then want to save it and refine it. The regenerate() command does exactly that.


Potential Array (PA) Scaling in GEM files

See link Potential Array (PA) Scaling


Change the size of the marker:

Use the "Size" field on the Trajectory Display panel on Particles tab to increase the marker size.


Screen dump of particular SIMION window view only: Put cursor on window of interest click and then hit



Lua control of electrode voltages in different instances in the workbench:

Answer: use the ion_instance reserved variable to differentiate electrodes with same number but in different instances. For example:

function segment.fast_adjust()
  if ion_instance == 1 then
    adj_elect01 = 20
    adj_elect02 = 30
  elseif ion_instance == 2 then
    adj_elect01 = 20
    adj_elect02 = sin(ion_time_of_flight)

For more information see How can a fast_adjust segment control electrodes in multiple arrays?


To compare values of SIMION pa and theory:

In the main (opening menu page of SIMION) Remove All PAs from RAM and load the ".pa0" file of your pa.

Then enter the following into the bottom SIMION command bar:

pa=simion.pas[1]; for y=30,60 do print(y, pa:potential(0,y,0), 0+((-600)-(0))/ln(60/30) * ln(y/30)) end

The output you get will look like this:

30        0        0
31        -28.380277755053        -28.383428867014
32        -55.859687813145        -55.865642634889
33        -82.493553548814        -82.502114249961
34        -108.33263087424        -108.34334738509
35        -133.42271068667        -133.43545280187
36        -157.80638552688        -157.82064350028
37        -181.52196344606        -181.53766201226
38        -204.60553522397        -204.62215070104
39        -227.0894767889        -227.10697395224
40        -249.00461463579        -249.02249956731
41        -270.37858466928        -270.39684540574
42        -291.23789048036        -291.25609630215
43        -311.60634322853        -311.62449545615
44        -331.50687545511        -331.52461381727
45        -350.96016568088        -350.97750043269
46        -369.98617924867        -370.0028162691
47        -388.602998686        -388.61895364147
48        -406.82810883686        -406.84314306758
49        -424.67741562398        -424.69154910401
50        -442.16631694961        -442.17935649972
51        -459.30888047795        -459.32084781779
52        -476.11873190155        -476.12947351954
53        -492.60837663564        -492.61791537281
54        -508.78992512088        -508.79814393297
55        -524.67455014521        -524.68147074968
56        -540.27305388165        -540.27859586945
57        -555.59546808616        -555.59965113373
58        -570.65145973968        -570.65423971143
59        -585.45007909758        -585.45147225199
60        -600        -600

This is a more direct way to evaluate the accuracy (without any particle tracing) by compare the potentials in the PA against the theoretical equation. This is a lua command and prints a table for the values of y=30 to 60 of the pa (0,y,0) entries and compares them to the theoretical result computed in the next column. Small differences between SIMION (left column) and theory (right column) are indicative of SIMIONs accuracy in this example. This a quick trick to compare simulation with theory and very useful in establishing the simulation accuracy of SIMIONs solution to the Laplace equation. The example is from a cylindrical mirror analyzer with R1=30 and R2=60 with V(R1)=0 and V(R2)=-600V having its y-axis along the interradial distance (see ).


Please send in your "discovery" as it will probably be useful to all.

Last Update: 19/10/12 10:37:49