Cuts along the ecliptic coordinate planes through the simulated density cubes for particles of size 0.072 μm at different epochs. The years have been chosen to select a representative case in the defocussing phase (2020), the focussing phase (2030), and a transitional phase (2036). The Sun is in the centre. The ISD density is colour coded: dark blue: no ISD particles reach this region of space; green, yellow, and red colours represent density enhancements with respect to the initial density at 50 AU. The projection of the original flow direction (at 50 AU) is shown in the upper left corner of each plot.