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Generalised magnetic polarizability tensors / Paul, Ledger

Mathematical Methods in the Applied Sciences, Volume: 41, Issue: 8, Pages: 3175 - 3196

Swansea University Author: Paul, Ledger

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DOI (Published version): 10.1002/mma.4809

Abstract

We present a new complete asymptotic expansion for the low‐frequency time‐harmonic magnetic field perturbation caused by the presence of a conducting (permeable) object as its size tends to zero for the eddy current regime of Maxwell's equations. The new asymptotic expansion allows the characte...

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Published in: Mathematical Methods in the Applied Sciences
ISSN: 0170-4214
Published: 2018
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URI: https://cronfa.swan.ac.uk/Record/cronfa38104
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Abstract: We present a new complete asymptotic expansion for the low‐frequency time‐harmonic magnetic field perturbation caused by the presence of a conducting (permeable) object as its size tends to zero for the eddy current regime of Maxwell's equations. The new asymptotic expansion allows the characterisation of the shape and material properties of such objects by a new class of generalised magnetic polarizability tensors, and we provide an explicit formula for their calculation. Our result will have important implications for metal detectors since it will improve small object discrimination, and for situations where the background field varies over the inclusion, this information will be useable, and indeed useful, in identifying their shape and material properties. Thus, improving the ability of metal detectors to locate landmines and unexploded ordnance, sort metals in recycling processes, and ensure food safety as well as enhancing security screening at airports and public events.
Keywords: asymptotic expansion, eddy currents, landmine detection, metal detectors, polarizability tensors
College: College of Engineering
Issue: 8
Start Page: 3175
End Page: 3196