Program used when simulating systems in which electrons start with low energies (for example from a cathode) and finish with energies that are orders of magnitude higher (for example 100kV).
See notes on using a cathode with a high voltage anode.
This program is called prog20.f90 and is supplied with the CPO package, together with a compiled version that can be activated by the command ‘prog20’.
The program is useful when simulating systems in which electrons start with low energies (for example from a cathode) and finish with energies that are orders of magnitude higher (for example 100kV). It is then sometimes necessary to divide the system into low and high energy halves, with the following steps:
(1) Find the boundary charges for the whole system and then output the potentials distribution at a test plane that is between the low energy and high energy parts.
(2) Use the program below, or something similar, to generate the segments (and their applied potentials) of an electrode that can be used to physically separate the two parts.
(3) Set up the first part of the system, terminated by the new electrode. The overall potential distribution in the first part should now be the same as it was when the whole system was used.
(4) Trace rays up to the new electrode, and output information on the rays at a test plane that coincides with the new electrode.
(5) Set up the second part of the system, terminated by the new electrode, and use the ray output information from the previous step to start rays from the new electrode.
It might be necessary to iterate this process if space-charges are present.
Other variations of this procedure might be necessary to give accurate results -for example by using two new electrodes, on either side of the middle test plane, the one inside the first part being used to terminate the second part and vice-versa.
(1) read grid of potentials from an output file produced by CPO3D and called tempin.dat,
(2) output into tempout1.dat the segment data in form suitable for use in an input data file,
(3) output into tempout2.dat the list of applied potentials, also for use in an input data file.
No checks are applied.