Design of a biplanar gradient coil using a genetic algorithm.

A biplanar z-gradient coil has been designed using a genetic algorithm, and its efficiency for producing a gradient along the axis of a solenoid magnet compared to that of a conventional Maxwell coil set. Coils of 21.8 cm by 20.9 cm area and 10 cm separation give 0.37 m Tm-1 A-1 with standard and maximum deviations of 2.6 and 13.1% of this value over an optimised cuboid region of 12 by 15 by 1.8 cm. The experimentally useable linear volume extends beyond this to 50% of the separation between the planes. Design data are also given for a transverse gradient set.