In this paper the magnetic field is computed as the superposition of two contributions: B = B-0 + Delta B. The vacuum field Bo due to the coil currents can be obtained with extreme accuracy using analytical methods. The field Delta B, due to the magnetizing currents in the iron or other perturbations like eddy currents in passive conductors, is computed numerically. The splitting yields a very high accuracy in all cases in which \Delta B\ much less than \B-0\. The method, based on a calibration of the numerical results, is shown to be similar, but less expensive than perturbation techniques and reduced potential approaches. The effect of the outer magnetic shield on the field produced by an air core magnet for magnetic resonance is studied and compared to the analytical solution available for a particular shield geometry. An example of application is also shown for a dynamic case in the presence of eddy currents.
ACCURATE COMPUTATION OF ELECTROMAGNETIC-FIELDS IN THE PRESENCE OF CONDUCTING AND MAGNETIC-MATERIALS
MARTONE, Raffaele
1995
Abstract
In this paper the magnetic field is computed as the superposition of two contributions: B = B-0 + Delta B. The vacuum field Bo due to the coil currents can be obtained with extreme accuracy using analytical methods. The field Delta B, due to the magnetizing currents in the iron or other perturbations like eddy currents in passive conductors, is computed numerically. The splitting yields a very high accuracy in all cases in which \Delta B\ much less than \B-0\. The method, based on a calibration of the numerical results, is shown to be similar, but less expensive than perturbation techniques and reduced potential approaches. The effect of the outer magnetic shield on the field produced by an air core magnet for magnetic resonance is studied and compared to the analytical solution available for a particular shield geometry. An example of application is also shown for a dynamic case in the presence of eddy currents.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
