Title :
Design criteria for active shielding of inhomogeneous magnetic fields for biomagnetic applications
Author :
Urankar, Laxmikant ; Oppelt, Ralph
Author_Institution :
Res. Labs., Siemens AG, Erlangen, Germany
fDate :
7/1/1996 12:00:00 AM
Abstract :
General analytical expressions for the field attenuation and the reaction factor for a spherical active compensated cabin are theoretically derived. The shielding effect of various materials and their thickness on external magnetic disturbances as well as the retroactive effect on the locally generated compensating fields of the compensating coils are then analyzed. A numerical evaluation of the analytical expressions developed is made and directives for practical measures are derived. Comparison with the experimental results obtained from the measurement of shielding properties of an equivalent cubic cabin is made. The so-determined design criteria are then discussed in detail.
Keywords :
biological effects of fields; biological techniques; biomagnetism; closed loop systems; coils; compensation; magnetic shielding; magnetic variables control; active shielding; analytical expressions; biomagnetic applications; biomagnetic research; clinical use; compensating coils; design criteria; equivalent cubic cabin; external magnetic disturbances; field attenuation; general analytical expressions; inhomogeneous magnetic fields; locally generated compensating fields; negative feedback closed loop system; numerical evaluation; reaction factor; retroactive effect; shielding effect; spherical active compensated cabin; thickness; Aluminum; Biomagnetics; Coils; Control systems; Eddy currents; Frequency; Magnetic analysis; Magnetic field measurement; Magnetic materials; Magnetic shielding; Aluminum; Electromagnetic Fields; Equipment Design; Ferric Compounds; Materials Testing; Models, Theoretical; Surface Properties;
Journal_Title :
Biomedical Engineering, IEEE Transactions on
