Uniformity Aspects of Superconducting MRI Magnet Developed by IHEP

A 1.5-T whole-body magnetic resonance imaging (MRI) magnet was designed and manufactured at the Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China. The designed field inhomogeneity is less than 50 parts per million peak-to-peak in a sphere with a diameter of 50 cm. Unfortunately, during the process, there are many different manufacturing errors that can generate field inhomogeneity. In this paper, the different manufacturing errors have been discussed, through the accurate calculation of the magnet, and we shall focus on the position offset while manufacturing. In addition, there are several methods that can be used in this situation, and the principle of each of these methods will be given. Finally, comparing with the measured data, the main reasons that lead to inhomogeneity were given in the MRI magnet.