Planar ion microtraps.

Planar quadrupole ion traps have been analysed through numerical and analytic solutions of Laplace's equation. These involve either one or more conducting rings or their analogs, a hole in one or more conducting sheets. The leading terms in the potential are harmonic, corresponding to the Paul trap, but with coefficients that reduce their efficiency and for some traps, the anharmonic terms can be suppressed to eighth order. Stable ion trapping is predicted for all electrode configurations possessing radial and axial symmetry