Ray parameters for cathodes

The parameters of the rays from cathodes also have to be carefully chosen.

Each step of each ray becomes a source of charge  The total number of steps therefore has to be kept as small as possible in order to avoid excessive computing times.

The step lengths should be small at the start of a ray  -use the cathode depth as a guide.

The later step lengths should be larger, using the advanced option to change the step lengths

If space-charge tubes are being used then the advaced option to change their diameters should be used.