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Fig. 2.10 An axisymmetric geometry modeled in the r-z plane [54].
In this work COMSOL MULTIPHYSICS has been used for simulating inductances, mutual
inductances, coupling factors, and the effects of metallic objects. In addition, the
accomplishment of the regulations according to the ICNRP have been assessed [55].
Although AC signals will really be applied over an inductor, a DC model may be sufficient
to calculate the inductance of a coil winding. This approximation implies that current
redistribution over the wire cross-section does not noticeably influence the inductance value.
This is true for most practical coils, with diameter dimensions normally much larger than the
diameter of the wire. In this case, (2.51) becomes:
1
(2.52)
2.8.2 Calculation of the Inductance of a Solenoid
A single rectangle can represent the winding cross-section of a solenoid as can be seen in
Fig. 2.11. Actually consisting out of multiple turns, an homogeneous current distribution can be
assumed over this cross-section. Hence, a constant current density Jφ is applied over it. Using
the vector potential definition and Stokes’s theorem [54], the magnetic flux enclosed by the
circular contour at (r, z) is:
,
24
2
,
(2.53)