Optimized design of uniform-field coils system with a large uniform region by particle swarm optimization algorithm

In this paper, a novel electromagnetic coil design method is proposed, which has a large uniform region for calibrating array optically pumped magnetometers (OPMs). The weighted Tikhonov regularization method, whose weight matrix is optimized by particle swarm optimization, is to balance the field error distribution in the uniform region. The cube coils system with a 25 cm side length can produce uniform fields in a cube uniform region with a 15 cm side length. The simulation result shows that the maximum field error epsilon(max) of the cube coils system is 1% in the uniform region, which is greatly reduced compared with Ruben's coils system(4.8%) and bi-planar coils system (22.7%). Due to the optimized weight matrix, the errors of the coils are mainly distributed in the range of 0-0.5%. The testing results were consistent with simulation results. The result of calibration experiment proves the superiority of cube coil in this application.