I'll bet those particles have a short orbital period. sad to read the end of mission is less than 4 years away. our capable robot friend is still giving us fantastic images and wonderful science. wish it could keep going for another decade or more.
This image in comparison to http://www.ciclops.org/view_media/37585/F-Ring-Zoo raises the question, to what extent is there uniformity of motion of the particles in the F ring? Is the separation a result of the motion by Prometheus or is the converse true instead where this image is actually depicting a magnetic force causing the periodic collisions.