Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps

TL;DR

This paper presents a novel NIST apparatus using permanent magnet-based Penning traps for the manipulation and spectroscopy of highly charged ions, enabling extended ion confinement and potential applications in various physics fields.

Contribution

It introduces a new Penning trap design with NdFeB permanent magnets for stable confinement of highly charged ions, demonstrating effective ion storage and manipulation capabilities.

Findings

Confined ions for about 1 second in room-temperature traps.

Achieved ion capture with improved magnetic field homogeneity.

Enabled charge-state evolution studies with fast detectors.

Abstract

A newly constructed apparatus at the National Institute of Standards and Technology (NIST) is designed for the isolation, manipulation, and study of highly charged ions. Highly charged ions are produced in the NIST electron-beam ion trap (EBIT), extracted through a beamline that selects a single mass/charge species, then captured in a compact Penning trap. The magnetic field of the trap is generated by cylindrical NdFeB permanent magnets integrated into its electrodes. In a room-temperature prototype trap with a single NdFeB magnet, species including Ne10+ and N7+ were confined with storage times of order 1 second, showing the potential of this setup for manipulation and spectroscopy of highly charged ions in a controlled environment. Ion capture has since been demonstrated with similar storage times in a more-elaborate Penning trap that integrates two coaxial NdFeB magnets for improved B-field homogeneity. Ongoing experiments utilize a second-generation apparatus that incorporates this two-magnet Penning trap along with a fast time-of-flight MCP detector capable of resolving the charge-state evolution of trapped ions. Holes in the two-magnet Penning trap ring electrode allow for optical and atomic beam access. Possible applications include spectroscopic studies of one-electron ions in Rydberg states, as well as highly charged ions of interest in atomic physics, metrology, astrophysics, and plasma diagnostics.