Symmetries of cathode rays and segments
Reflection symmetries of voltages (see also general note on symmetries and reflections):
The symmetries in the reflection planes cannot be negative, because the space-charge cloud cannot have negative symmetry.
Reflection symmetries of rays (see also general note on symmetries and reflections):
The rays are automatically reflected in the relevant planes when space-charge is present.
Using minimum sector:
ADVICE: Confine the first set of rays (before reflections) to the smallest possible sector (for example if x = 0 and y = 0 are reflection planes in a 3D simulation, confine to the region of positive x and y). Otherwise unnecessary mesh points will be created, slowing down the calculation.