Stability and dynamics of ion rings in linear multipole traps

TL;DR

This paper investigates the formation, stability, and normal mode spectra of ion rings and tubular structures in linear multipole traps, revealing how trap geometry influences ion arrangements and their dynamical properties.

Contribution

It provides a detailed analysis of the stability conditions and normal modes of ion rings and tubes in multipole traps, highlighting the impact of the number of poles on structure formation.

Findings

Single-ring structures depend on the number of poles.

Tubular structures form with ions arranged in a triangular lattice.

Normal mode spectra are characterized for different lattice constants.

Abstract

Trapped singly-charged ions can crystallize as a result of laser cooling. The emerging structure depends on the number of particles and on the geometry of the trapping potential. In linear multipole radiofrequency traps, the geometry of the radial potential can lead to the formation of single-ring structures. We analyse the conditions and stability of single rings as a function of the number of poles. For larger numbers of ions the rings form tubes in which the arrangement of the ions corresponds to a triangular lattice folded onto a cylinder. The stability of these tubular structures is numerically studied for different lattice constants and their normal mode spectrum is determined.