I am facing some problems in Simulating linear rf trap in Simion. I made four cylindrical rods. and made TOF spectrometer with the einzel lens, defined some particles originating from the center of the trap and detecting them. but when I draw contour lines on the rods, putting same voltage, 100 V on each rod[Contour lines for rods at 100 V12, the contour lines are not symmetric. this is the reason why ions are diverging too much. I am attaching some photos which show how I made the rods, PE surface view, and ion trajectories and contour lines.
Could anyone tell me how to properly make the rods? I also tried using .gem files to make the rods.