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  • Open Access

Free-induction-decay magnetometer for pulsed eddy current testing

Zixuan Xiao, Kaiwen Yi, Zejia Lin, and Xiang Peng*

  • *Contact author: xiangpeng@pku.edu.cn
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Phys. Rev. Research 8, 023180 – Published 18 May, 2026

DOI: https://doi.org/10.1103/6j4p-fs75

Abstract

Pulsed-eddy-current testing (PECT) is a highly efficient active detection technique used in nondestructive testing of conductive structures, transient electromagnetic exploration for mineral resources, and the detection of unexploded ordnance. To directly measure the induced magnetic field and improve the sensitivity of PECT systems, we use a free-induction-decay (FID) atomic magnetometer instead of pickup coils, enabling improved detection of weak low-frequency signals. The FID magnetometer employs an enhanced-optical-pumping scheme and an instantaneous phase-retrieval method, achieving a noise floor of 0.45 pT/Hz and bandwidth of 4.2 kHz. The synchronized magnetic-pulse pumping scheme not only significantly amplifies the spin polarization of the atomic ensemble to strengthen the FID signal and improve sensitivity, but also induces eddy-current magnetic fields in nearby metallic conductors. Using instantaneous phase retrieval, we extract the pulsed-eddy-current magnetic fields from the FID signal and determine their characteristic time constant (τ). The FID magnetometer is validated for measuring pulsed-eddy-current magnetic fields generated by multiple metals, including copper, aluminum, zinc, and lead. This work demonstrates the potential of the FID magnetometer for applications in magnetic induction tomography and remote-field eddy-current testing.

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Phys. Rev. Research 8, 023180– Published 18 May, 2026
  • Received 15 December 2025
  • Accepted 20 April 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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