A novel joint-less coil: promising unprecedented magnetic field stability to solve the persistent current mode issue in 2G-HTS magnet application

Abstract

Abstract Closed coils fabricated using second generation high temperature superconducting (2G-HTS) coated conductors (CCs) are promising for superconducting magnets, which operating in persistent current mode (PCM) such as magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) systems. However, the fabrication and application of superconducting joints for 2G-HTS CCs still pose a significant challenge. This paper reports a PCM joint-less 2G-HTS coil for capturing magnetic fields, which is called ‘Four Pancake Coil (FPC)’. A novel winding method was developed to form four pancake structure and effectively solved the closed-loop problem of 2G-HTS magnets. Meanwhile, the FPCs generated a 70.4 mT central magnetic field at 77 K and lasted for 57 d with a magnetic field drift rate of only 0.065 ppm h−1, which can satisfy the requirements of MRI magnets. In addition to the closed-loop characteristics of the FPC, the stacked magnet also provides expandability and ease of maintenance exchange. These advantages make it highly promising for the development of closed-loop 2G-HTS magnets.