The software suite CIELAS2 provides rapid interactive calculation of trajectories and electron-optical properties for particle beams in systems of 2-D geometry. Behaviour near a thermionic cathode is modelled accurately even when the mesh spacing is too coarse to show the potential minimum. The displacement of trajectories by asymmetric or symmetric pertubations of electrodes can be displayed. The operation of PC-compatible computers has been enhanced to allow the program to be run on widely-available hardware.