charged particles in the Ring Trap. The outer ring is about 20 mm
in diameter, and the scene is illuminated with green laser light.
Trapped particles oscillate at 60 Hz, and this long-exposure photograph
shows tracks that delineate the path of each particle. The
particles all have like charges, so their mutual repulsion keeps them
apart, while at the same time trapping forces push the particles toward
the trap center. The resulting lattice-like structure is called a
Electrodynamic Ion Traps