This is from the "_TRAP" group.prg example in SIMION 7.0. This uses a user program to demonstrate motions of groups of ions in an ion trap. Ions form patterns and shells due to charge repulsion and gas cooling (simulated by Stoke's law).
3-D view of trap.
Adjusting Fly parameters.
Dynamic potential energy view.
Particle motion. Note: heavy ions have the largest shell.