Design and Optimization of the Irregular Shaped Permanent Magnet With High Homogeneity in the Magnetic Recoil Spectrometer System

The magnetic recoil spectrometer (MRS) system was established and optimized for precisely measuring the absolute neutron energy spectrum in high-resolution implosion experiments at the High Magnetic Field Laboratory of the Chinese Academy of Sciences (CHFML). The MRS system generates an irregular magnetic field that is wedge-shaped relative to the trajectory of the incident particle, and the magnetic field map in the wedge-shaped region determines the performance of the MRS prototype. To improve magnetic intensity and obtain a high uniformity magnetic field in the pole gap, a 3D method was introduced to create a closed magnetic circuit instead of the traditional magnet. The optimized magnet system is lighter, more compact, uses fewer magnet materials. Additionally, the uniform region was expanded, reaching a magnetic field of 0.98T with a 20 mm pole gap. The magnetic deviation on the symmetric surface is less than 0.006 T. This paper provides a detailed introduction to the 3D-type method, comparing with the traditional magnets. It discusses the advantages and challenges and presents potential diversified structures based on 3D methods for the future.