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Abstract #3933

Eigenmode Analysis of Eddy Currents and Eigenmode Coil Design

Michael Stephen Poole1, Hector Sanchez Lopez1, Stuart Crozier1

1School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, QLD, Australia

Modelling gradient-induced eddy currents using eigenmode analysis reveals a set of non-interacting modes with characteristic exponential decays. These combine in conventional gradient coils to produce an eddy current that changes its magnitude and spatial form in time. This causes gradient pre-emphasis techniques to be ineffective over the whole imaging region. We propose, and demonstrate by simulation, that the eddy currents can be made more amenable to pre-emphasis by suppressing all but one mode. At the same time the primary field must match the field generated by this mode.