How can a 22-pole ion trap exhibit 10 local minima in the effective potential?

TL;DR

This study measures the distribution of trapped OH$^-$ ions in a 22-pole trap, revealing 10 local minima in the potential due to symmetry breaking caused by electrode displacement, supported by numerical simulations.

Contribution

It demonstrates the presence of 10 local minima in a 22-pole ion trap's potential, attributed to electrode displacement, and correlates experimental data with simulations.

Findings

Observation of 10 local minima in the trap potential

Agreement with ideal 22-pole effective potential

Electrode displacement explains symmetry breaking

Abstract

The column density distribution of trapped OH$^-$ ions in a 22-pole ion trap is measured for different trap parameters. The density is obtained from position-dependent photodetachment rate measurements. Overall, agreement is found with the effective potential of an ideal 22-pole. However, in addition we observe 10 distinct minima in the trapping potential, which indicate a breaking of the 22-fold symmetry. Numerical simulations show that a displacement of a subset of the radiofrequency electrodes can serve as an explanation for this symmetry breaking.