Structural Design and Analysis of 14 T Animal MRI Superconducting Magnet

Abstract

High field magnetic resonance imaging (HF-MRI) systems can achieve higher image resolution and sensitivity, resulting in better image quality and more biological information, which has significant value in life science and clinical medicine applications. The development of HF-MRI system depends on the development of high field superconducting magnet. HF-MRI superconducting magnet needs to solve problems such as high magnetic field uniformity requirements, large stray field range, high coil electromagnetic stress, and shrinkage stress in low-temperature systems. This article introduces the design and optimization process of 14 T at 175 mm warm bore size animal MRI superconducting magnet. We used a nonlinear multiobjective programming algorithm to simultaneously optimize warm bore space (diameter 175 mm), magnetic field homogeneity and the stray magnetic field (5 Gauss line) for a 14 T MRI magnet. The spatial position, electromagnetic density, and electromagnetic stress of different coils are obtained, and the design stability of magnet coil is evaluated using coil loading ratio and current safety margin. In addition, the magnet coil former is designed, and the finite element method is used to perform mechanical simulation analysis on the coil former. The optimization results show that the warm bore of the magnet is 175 mm, and the homogeneity of the magnet design is 1.1 ppm at 60 mm DSV, magnet stray field (5 Gauss line) is 2.9 m in the axial direction, and 2.4 m in the radial direction from the center of the magnetic field. The minimum safety margin of the magnet coil is 10.6%, and the maximum hoop stress of the magnet coil is 225 MPa. The magnet meets the design requirements and provides necessary reference for the engineering prototype of the 14 T animal MRI superconducting magnet.