Analysis of charging characteristics of a 500 MHz HTS-LTS series NMR magnet with an intra-layer no-insulation HTS layer-wound coil structure

The intra-layer no-insulation (LNI) layer-wound coil has the advantages of high spatial magnetic field homogeneity and a smaller number of joints, as well as the ability of self-protection during quench, which has great potential in making MRI or NMR superconducting magnet. In this paper, a 500 MHz NMR magnet connected in series by a high temperature superconducting (HTS) magnet and a low temperature superconducting (LTS) magnet was designed, fabricated, and tested at a low field for homogeneity, in which the HTS magnet is an LNI layer-wound coil structure. And a helical equivalent circuit model of the 500 MHz HTS-LTS NMR magnet coupled with the stacked homogenization T-A and mechanical model is established, which agrees with the experimental results. This paper provides a sufficient numerical analysis of the charging characteristics of the HTS-LTS series magnet, including magnetic field homogeneity, current distribution, loss distribution, screening current induced stress, etc. And this paper provides valuable insights into the ramping behavior of the HTS-LTS series magnet, which can be useful for practical charging experiments.