Shielding and energy advantages of capped elliptical coil structures
Finnerty M, Chen X, Baig T, Eagan T, Petropoulos L, Edelstein W, Brown R
Case Western Reerve University
We have designed a capped actively shielded gradient coil on an elliptical coil form. Compared to conventional uncapped elliptical and cylindrical gradients, our design substantially reduces the fringe fields, the associated eddy currents in the inner bore and consequent acoustic noise power. In addition, there is a good reduction in magnetic energy. The fringe fields are reduced 70%, largely because of the end caps, and the magnetic energy is lessened because of the reduced cross sectional area. The magnetic energy is reduced, relative to cylindrical designs, by 35% for the z-gradient and 19% for the transverse gradients.