Analysis of Ion Motion in Ion Cyclotron Resonance Cells

The detailed discussion of ion motion in ion cyclotron resonance cells forms the basis of any interpretation of experimental results. We show that the resonance frequency of (quasi-) cyclotron motion is a function of the ion's position in the cell, and that its drift velocity exhibits a similar dependence. These features of the motion are due to the complicated multipole structure of the electric field. In spite of this, we find simple expressions for the ion coordinates as functions of time.