xmpl3d18, 18th 'example' data file for CPO3D

Multiple focussing of hemispherical deflection analyzer.

The HDA is set up as in test3d01.dat. Six rays move in the xz plane. The first three start from y = -1, with angles of 0, +/-0.1 rad and with an energy of 1 eV, and the next three with an energy of 1.05 eV. The focal points of the 2 sets are specified as y = 1 and 1.1 respectively.

(This simulation has 2D symmetry, and so is solved faster by CPO2D, see the file xmpl2d16.)

The file was written when the memory and speed of PC's was much more limited than at present, so the available number of segments was small and the requested inaccuracies were fairly high to give a quick demonstration.

Detailed description:

The initial voltages on the spheres are 1.6667 and 0.6, and the initial step sizes for the voltages are specified as 0.01 and 0.005 respectively. After 5 iterations the best voltages are found to be 1.668 and 0.598. A larger number of segments is required to obtain the more accurate result given by using CPO2D with file xmpl2d16.dat.