Transient electromagnetic field in magneto-viscous medium |
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| Authors: | Felix M Kamenetsky George M Trigubovich |
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| Institution: | aL.-M.-University of Munich, Dpt. of the Earth and Environmental Sciences, Section Geophysics, Germany;bSNIIGGIMS of Novosibirsk, Russia |
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| Abstract: | When using Transient Geo-Electromagnetics (TEM) unusually slow decaying transients are sometimes observed in the absence of well-conductive objects. Many researchers explain this phenomenon by presence of material with magneto-viscous or superparamagnetic (SPM) properties. The analysis of electromagnetic (EM) field equations in conductive SPM medium is suggested in the present paper. It is shown that in a simplest case of small size single-domain magnetic particles with relative higher potential barrier energy, the SPM-medium is characterized by a very slow decaying exponential transient magnetic field, the level of which is much more as compared to that of due to non-magnetic medium of the same conductivity. This situation is traced up to the late transient time like 0.1 s and more. SPM and Induction fields are in the near zone additive. They depend in a different way on the superparamagnetic and electric properties of the SPM-medium. They also depend in different ways on the transient time and on the size of the transmitter–receiver configuration. These characteristics make it possible to recognize the presence of SPM-effect and to separate these fields. |
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| Keywords: | Electromagnetics Frequency dispersion Equations of the EM field Superparamagnetismus Magneto-viscous semi-space Separation of SPM |
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