The structure of a QSE trap and the pseudopotential above electrodes. (a) The cross-sectional view of the QSE trap. The ion is to be trapped in the potential trap near the center of the figure. The lowest energy path for the ion to escape the trap is through the saddle point in the pseudopotential directly above. The difference in pseudopotential between the center of the trap and this escape point represents the trap depth. (b) The top view of the QSE trap, which consists of five electrode rails, two DC electrodes, two RF electrodes, and one ground electrode. The origin point is illustrated above. The parameters a, b, d, l, and w define the dimensions of the electrodes.