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Input files
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ExVarL.png, LinearityL.png, RodQuad.SCR,RodQuad.xls, RodQuad025.EIN, RodQuad025.MIN, ..., RodQuad150.EIN,RodQuad150.MIN
Download RodQuad.zip
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Description
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Electrodes with hyperbolic surfaces are required for an ideal quadrupole electric field, but circular rods can give a good approximation. The purpose of this exercise is to find the best choice of the rod radius R compared to the central bore radius r0 (the minimum distance from the axis to an electrode tip). A set of 6 input files is used to check a range of values. Also included is a spreadsheet to investigate the comparitive linearity of the electric fields along the horizontal axis and a script for automatic generation of field scans for the six cases.
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Results
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For the choice R = r0, the electric field is almost perfectly linear with an amplitude within 0.7% of the value generating by a hyperbolic electrode with the same value of r0.
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Comments
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The results were applied in the tutorial Modeling quadrupole mass analyzers.
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