A Feasibility Study of an Optimization-Based Active Field Uniformity Compensation Method for Superconducting Magnets

In order to enhance the quality of measurement results of various scientific instruments, such as magnetic property measurement systems, magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR) and others, a spatially uniform magnetic field is required at the magnetic center. However, the measured field uniformity is usually worse than that in the design result due to the manufacturing errors of a superconducting magnet system. Therefore, spatial field uniformity compensation is needed to reduce the effects of manufacturing errors on field uniformity. Conventional field compensation methods require recursive routines of field mapping and compensation coil current adjustments, which lead to a less effective time-consuming process. In this study, a recently developed active field compensation algorithm employing pattern search, an optimization theory, will be introduced. A MATLAB code for active compensation coil current calculations with pattern search was developed, and six compensation coil designs and field distribution calculations with and without the proposed method were also carried out to compare the results. The test results demonstrate the feasibility of the proposed field compensation method for superconducting magnets.