Abstract
We propose a new planar single-channel shim coil for magnetic resonance imaging (MRI) permanent magnets. The coil design is based on the superposition of multiple circular currents and the stream function method. The designed shim coil was implemented for a permanent magnet with 1.0 T and a 90 mm gap. When the shim coil current was optimized, the magnetic field inhomogeneity decreased from 240 to 97 ppm (peak-to-peak) in the central cylindrical area (54.6 mm diameter, 60.0 mm height), demonstrating that the single-channel shim coil proposed here is a useful device for permanent narrow-gap magnets with complicated magnetic field distribution.