Features of the effective potential formed by multipole ion trap

Here we present a new model of the effective field in multielectrode ion traps. The proposed method involves averaging over radio frequency oscillations, through which we derive stationary equations of ion motion in the trap. We apply our approach to the 22-pole trap and compare the resulting potential distribution with both numerical calculations and experimental data. We show that the multipole trap with 2n electrodes excluding quadrupole traps has n points of stable quasi-equilibrium. We also calculate the stability diagram for the 22-pole trap, the main features of which can also be described by the proposed method. The proposed approach is of importance for particle trap dynamics analysis and mass-to-charge selection techniques.