Split-type magnetic field generator with wide homogeneous region

This paper discusses the homogeneity of a magnetic field generator for measurement of nuclear magnetic resonance (NMR). It shows that inhomogeneity is caused by an excess number of turns and a discrepancy from the design dimensions. A control circuit consisting of a pair of shim coils and a few Hall elements can improve the homogeneity. With it, a homogeneity of the magnetic field in the split coil of better than /spl plusmn/0.05% over 50 mm was obtained.