61st example file for CPO3D.
Illustration of the 'User-supplied near-axis electric field' option.
Here a central cylinder is split into 8 parts that can be used as a quadrupole, octupole or monopole (ie round) lens.
The 'related voltages' option is used so that the multipolarity of the lens can be easily changed.
With the values given above all 3 multipolarities are activated together, each with a voltage 1V.
The User-supplied routine is user3d.cpp. A read-only copy is in use3copy.cpp. The 2 files that are read by user3d.cpp are userfld1.dat and userfld2.dat, which are given in the footnotes to the data file.