Xmpl2d48, 48th 'example' data file for CPO2D
Sputter ion source
This is a very simple design, intended only to show the capabilities of CPO2DS.
The number of trajectories is small, as is the number of space-charge iterations.
See also the analogous 3D example, xmpl3d78.dat.
Cs+ ions originate near a spherical sputter ion surface of radius 25.4 mm. They are attracted to a small flat surface that has an applied voltage -5 kV, and that is situated 5.6 mm beyond the centre of the spherical surface. The beam of Cs+ ions is focused to a diameter of approximately 0.5 mm.
Each Cs+ ion produces an average of 0.5 C- ions (this number, and all the other numbers, are chosen by the User).
The initial energy distribution of the C- ions is Maxwellian, with kT = 5 eV. The initial angular distribution of the C- ions is Lambertian (these distributions are chosen by the User, from the available options in CPO2DS).
The C- ions travel back towards the sputter ion source, where most of them pass through a hole of diameter 5 mm. (If ions fail to pass through the hole they hit the spherical sputter surface and in the present version of CPO2DS they then produce more C- ions, but these remain in the vicinity of the sputter surface and so do not affect the performance.)
The outer radius of the emitting surface is 17.96 mm and so the emitting area is 1214 mm^2. The current density has been chosen to be 1.E-5 mA/mm^2 (this is the value in the above data file of the 'initial current density' and also the 'final maximum current density'). Therefore the emitted current is 1.214E-2 mA = 12.14 micro-Amp. When the current is increased by a factor of 10 (by using the space-charge repeat option in CPO2DS) signs of space-charge expansion of the beams appear. But it must be emphasised again that the present simulation is very simple.