Adaptive Method for Gradient Coil Design

Method One of the obstacles in designing gradient coil is the general discretization procedure that approximates the continuous current densities by a number of current carrying conductors. The shape of the conductors’ layout determines the properties of the gradient coil such as the gradient strength, field quality characteristics inside the FoV, level of shielding, coil resistance, slew rate, etc. For a self-shielded gradient coil the level of the eddy currents is very sensitive to the discretization procedure and may result in distortions of the images. When designing the gradient coil it is important to be able to minimize the net thrust Lorentz force exerted on the coil due to the presence of the main magnet field which is sensitive to the position of the current carrying conductors. The common practice of a gradient coil design is to derive the continuous current densities that provide the desired characteristics of the gradient coil. It is sometimes difficult to find a continuous solution that satisfies the trade-offs. Depending on the magnet configuration the nullification of the thrust force can lead to an energy penalty or even to reversed current patterns on either of the primary and shield coils, which in fact lead to an energy/inductance penalty. Because of the proximity of the cold shield to the magnet’s coils, the forces on the cold shield due to the eddy currents could be big and should be reduced to avoid quenching. In this abstract we propose an adaptive method of design/discretization of the continuous current solution that allows satisfying the trade-offs for the gradient coil characteristics. We illustrate this adaptive method on an example of an X-gradient design. One can find coarse continuous solutions for the z-components ) (z f z of the current densities that yield good approximations of the desired coil characteris-