Ramping loss and mechanical response in a no-insulation high-temperature superconducting layer-wound coil and intra-layers no-insulation coil

The layer-wound coil has a great potential in nuclear magnetic resonance and magnetic resonance imaging owing to the better spatial homogeneity of the magnetic field. However, high-temperature superconducting (HTS) coil wound by no-insulation (NI) layer-wound technique has been verified with a long field delay time. A new method named the intra-layer no-insulation (LNI) winding technique has been proposed to reduce the charging delay time of the coil. This paper is mainly to study and compare the ramping loss and mechanical characteristics of the layer-wound coil and LNI coil. The results indicate that the total ramping loss can be significantly reduced by using the LNI winding method. The effects of the ramping rate of power supply current and the contact resistivity on the ramping loss are also discussed in the paper. Furthermore, the stress distributions in the layer-wound coil and LNI coil are compared, where the cooling process and Lorentz force are both considered. It can be found that the copper sheet of the LNI coil experiences relatively higher stress than its (RE)Ba₂Cu₃O_x (REBCO) conductor layer. Meanwhile, the magnitude of stress generated in the REBCO conductor of the LNI coil is slightly different from that of the layer-wound coil.

     

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