Electron Cyclotron Resonance (ECR) Magnetometry with a Plasma Reservoir

TL;DR

This paper introduces a rapid, high-precision electron cyclotron resonance magnetometry method using plasma heating resonances in a Penning-Malmberg trap, enabling accurate magnetic field measurements crucial for fundamental physics experiments.

Contribution

It presents a novel, automated technique for measuring magnetic fields via plasma heating resonances, achieving sub-ppm accuracy and rapid scans for in situ applications.

Findings

Achieved magnetic field measurement accuracy better than 1 ppm.

Developed a quick plasma preparation method for temperature measurements.

Demonstrated high-precision in situ magnetometry for fundamental physics tests.

Abstract

The local magnetic field in a Penning-Malmberg trap is found by measuring the temperatures that result when electron plasmas are illuminated by microwaves pulses. Multiple heating resonances are observed as the pulse frequencies are swept. The many resonances are due to electron bounce and plasma rotation sidebands. The heating peak corresponding to the cyclotron frequency resonance is identified to determine the magnetic field. A new method for quickly preparing low density electron plasmas for destructive temperature measurements enables a rapid and automated scan of microwave frequencies. This technique can determine the magnetic field to high precision, obtaining an absolute accuracy better than $1\,\mathrm{ppm}$, and a relative precision of $26\,\mathrm{ppb}$. One important application is in situ magnetometry for antihydrogen-based tests of charge-parity-time symmetry and of the weak equivalence principle