Disabling the recalculation of surface charges due to the presence of space-charges.


In space-charge simulations the surface charges are influenced by the space charges and therefore CPO3DS recalculates the surface charges between iterations, unless the option to disable the recalculation of surface charges is used. This option is accessed in /databuilder/sources of rays/advanced options/. It can be used only with the space-charge tube method, and is relevant to the pulsed beam option.


If this option is not used then CPO3DS uses all the charges in all the space-charge tubes for the recalculation, irrespective of their time information. In some pulsed-beam simulations it will be better to disable the recalculation, in others not. The user should try both -and will usually find that there is very little difference. If there is a difference then it might be argued that it is better not to disable the recalculation, since for a pulsed beam the surface charges will respond to the local space-charge which is approximately represented locally by the whole space-charge.