Quantification of coupling between two-dimensional low-frequency magnetic fields and a spherical model of biological substance

This article analyzes the current density distribution induced in a spheric al biological model exposed to a two-dimensional external magnetic field, c onsidering the phase difference. To date, the current density induced in bi ological subjects by low-frequency magnetic fields has been analyzed assumi ng a uniform or nonuniform magnetic field in space, but there have been few studies considering the phase difference between the external magnetic fie ld components. This study intends to investigate the induced current densit y distribution at an arbitrary point in the subject and calculates the indu ced current density on the model surface for the case where a spatially uni form magnetic field is impressed on a uniform medium model, considering the phase difference. It is found that the synthesized induced current density is greatly affected by the relation between the angle formed by the induce d current components as determined by the position in the model and the pha se difference of the external magnetic field components. When the external magnetic fields are in phase or have a 180 degrees phase difference, there exists a point where the induced current is zero. It is also shown that the synthesized induced current density distribution depends on the phase diff erence. Lastly, an analysis is performed with the ground under an ultrahigh -voltage transmission line as the external magnetic field environment, and it is shown that the synthesized induced current density may differ greatly depending on the position on the model surface and the position in relatio n to the transmission line. (C) 2000 Scripta Technica.