Comparison of the time-domain electromagnetic field from an infinitesimal point charge and dipole source
Zhou Nan-Nan1,2, Xue Guo-Giang1, and Wang He-Yuan2
1. Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Science, Beijing 100029, China.
2. College of science, Liaoning University of Technology, Jinzhou 121001, China.
Abstract An electromagnetic field is generated through the accelerating movement of two equal but opposite charges of a single dipole. An electromagnetic field can also be generated by a time-varying infinitesimal point charge. In this study, a comparison between the electromagnetic fields of an infinitesimal point charge and a dipole has been presented. First, the time-domain potential function of a point source in a 3D conductive medium is derived. Then the electric and magnetic fields in a 3D homogeneous lossless space are derived via the relation between the potential and field. The field differences between the infinitesimal point charge and the dipole in the step-off time, far-source, and near-source zones are analyzed, and the accuracy of the solutions from these sources is investigated. It is also shown that the field of the infinitesimal point charge in the near-source zone is different from that of the dipole, whereas the far-source zone fields of these two sources are identical. The comparison of real and simulated data shows that the infinitesimal point charge represents the real source better than the dipole source.
This work is supported by Chinese National Programs for Fundamental Research and Development (No.2012CB416605), the National Natural Science Foundation of China (No. 41174090), and Development Project of National Key Scientific Equipment (No. ZDYZ2012-1-05-04).
About author: Zhou Nan-Nan received his BS in geophysics from Ocean University of China, in 2008. Currently, he is enrolled in the PhD program of the Institute of Geology and Geophysics, CAS. His research interests are in the theory and application of large-size transient electromagnetic methods.
Cite this article:
ZHOU Nan-Nan,XUE Guo-Qiang,WANG He-Yuan. Comparison of the time-domain electromagnetic field from an infinitesimal point charge and dipole source[J]. APPLIED GEOPHYSICS, 2013, 10(3): 349-356.
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