A Simple Relationship for High Efficiency-Gradient Uniformity Trade-offs in Multi-Layer Asymmetric Gradient Coils

H. Sanchez Lopez, F. Liu, A. Trakic, S. Crozier School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Queensland, Australia Introduction: This study details the design trade-offs available for asymmetric gradients and particularly investigates both scaling laws and appropriate relaxation factors useful in the design process. Recently a linear function interrelating coil diameter and DSV with the shortest length high performance symmetric gradient coils has been presented [1]. It is well-known that relaxing the magnetic field quality is one of the ways to obtain gradient coils with high figure of merit M=(ηρ1)/L. It is not clear, however, how this relaxation factor is related with DSV size, coil length and radius to produce maximal M. In this work, we have studied the influence of DSV, coil length and radius, relative axial offset position of DSV and target gradient field uniformity over the figure of merit in multi-layer asymmetric transverse gradient coils. A simple linear function that defines the optimal coil length to produce a maximum figure of merit given a DSV size, coil radius, axial offset position and introduced uniformity error is obtained.