Limits of the weakly coupled field assumption for low conductivity electromagnetic induction tomography

• Autorzy: Yin W. , Peyton A. J. , Zysko G. , Dekdouk B.
• Języki publikacji: EN

Abstrakty

EN

In medical or low conductivity electromagnetic induction tomography, a low frequency approximation (i.e. neglecting the diffusion effect) can significantly simplify the forward and inverse solutions. However, this approximation normally leads to the over prediction of the amount of eddy currents induced by the transmitter coil, and hence to an overestimation of the secondary voltage measured on the receiver coil. The reason is because the penetration of the field into the object is not correctly described and the skin effect is ignored. In effect, the theory assumes that the signal is coming from a larger-than-actual volume. This paper uses an exact analytical solution for a coil(s) near a stratified media derived from a full wave theory to evaluate the skin effect at a range of frequencies and compares it with a simple model which omits the skin effect. The error due to the approximation is evaluated and the highest frequency at which the approximation holds valid to within a defined error range is ascertained.

Słowa kluczowe

EN

non-destructive evaluation; eddy current; tomography; high frequency; low conductivity; skin effect

• Wydawca: Wydawnictwo Politechniki Łódzkiej
• Czasopismo: Zeszyty Naukowe. Elektryka / Politechnika Łódzka
• Rocznik: 2009
• Tom: z. 114
• Strony: 75--79
• Opis fizyczny: Bibliogr. 6 poz.

Twórcy

autor

Yin W.

autor

Peyton A. J.

autor

Zysko G.

autor

Dekdouk B.

• School of Electrical and Electronic Engineering, University of Manchester, UK,

Bibliografia

• BINNS R, LYONS A.R.A. PEYTON A.J., PRITCHARD W. D.N., (2001), Imaging molton steel flow profiles, Measurement Science and Technology, Vol. 12, pp. 1132 -1138.
• DODD C.V, DEEDS W.E., (1968), Analytical solutions to eddy-current probe-coil problem, Journal of Applied. Physics., Vol. 39, pp. 2829-2839.
• GRIFFITHS H, (2001), Magnetic induction tomography, Measurement Science and Technology, Vol. 12, pp. 1126-1131.
• KORZHENEVSKY A, SAPETSKY S, (2001), Visualisation of the internal structure of extended conducting objects by magnetoinduction tomography. Bulletin of Russian Academy of Sciences: Physics, Vol. 65, pp. 1945-1949.
• MERWA R., HOLLAUS K., OSZKAR B., SCHARFETTER H., (2004), Detection of brain oedema using MIT: a feasibility study of the likely sensitivity and detectability. Physiological Measurement, Vol. 25, pp. 347-354.
• PEYTON A, MACKIN R, GOSS D, WAN-DAUD W, CRESCENZO E, SAUNDERS N, TAPP H, (2003), Addressing the difficulties in using inductive methods to evaluating human body composition, Biométrie Humaine et Anthropologie, Vol. 21, pp. 63-71.