AN INVERSE APPROACH TO THE DESIGN OF MRI MAIN MAGNETS

We present a new method for the design of MRI main magnets, based on a variational approach with constraints introduced by Lagrange multipli ers. The extrema are located with a combination of analytical and nume rical techniques. This method has been tested in the design of nonshie lded and actively-shielded magnets. Several representative designs are given. The method is very flexible, having been applied also to the i nvestigation of gradient coils, and could be adapted to the design of other static and quasi-static field systems. It may also be used to co nsider alternate geometries.