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http://dx.doi.org/10.9714/psac.2021.23.4.039

Design of ferromagnetic shims for an HTS NMR magnet using sequential search method  

Yang, Hongmin (Kunsan National University)
Lee, SangGap (Korea Basic Science Institute)
Ahn, Minchul (Kunsan National University)
Publication Information
Progress in Superconductivity and Cryogenics / v.23, no.4, 2021 , pp. 39-43 More about this Journal
Abstract
This study deals with the ferromagnetic shims design based on the spherical harmonic coefficient reduction method. The design method using the sequential search method is an intuitive method and has the advantage of quickly reaching the optimal result. The study was conducted for a 400 MHz all-REBCO magnet, which had difficulty in shimming due to the problem of SCF (screening current induced field). The initial field homogeneity of the magnet was measured to be 233.76 ppm at 20 mm DSV (Diameter Spherical Volume). In order to improve the field homogeneity of the magnet, the ferromagnetic shim with a thickness of 1 mil to 11 mil was constructed by a design method in which sequential search algorithm was applied. As a result, the field homogeneity of the magnet could be significantly improved to 0.24 ppm at 20 mm DSV and 0.05 ppm at 10 mm DSV.
Keywords
ferromagnetic shimming; NMR magnet; sequential search method; shimming design;
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