A novel design methodology for Nth order, shielded longitudinal coils for NMR

A new method is presented for the design of nuclear magnetic resonance (NMR) shim coils. The design methodology is the simulated annealing of the conductor positions, where the error function to minimize contains spherical harmonic field errors and other coil properties. This very flexible method allows pure, compact, low-inductance coils to be designed. Active magnetic shielding has been incorporated in the design process, enabling these coils to be used for rapid, pulsed experiments without the generation of deleterious eddy currents. The details for longitudinal coil designs are presented here. A shielded Z(0) coil was built to test the design process and demonstrated good correlation with theoretical predictions.