Technology challenges of 14 T whole-body superconducting MRI magnets —A target of high-field superconducting magnet technology for large scale applications in next decade

Abstract

This paper presents a brief review of the development trend of superconducting magnets in large scale applications towards high magnetic fields, depending on and pushing the Nb₃Sn wire technics' continuous improvement. The focus is on analysis of the technology challenges of 14 T whole-body superconducting magnets. Using the Bonze Nb₃Sn wires and on the base of a combination design of Nb₃Sn and NbTi coils, an electromagnetic conception design of a 14 T whole-body MRI magnet is presented, and the thermal stability and quench protection are analyzed by simulations. The critical issues on stress, joints as well as shimming of 14 T whole-body superconducting magnets are also discussed. According to the results, this paper believes: 1) Nb₃Sn wires are of the first important issue for 14 T whole-body superconducting magnets—the Bonze Nb₃Sn wire is of the best choice but the performance specifications of the current products need to be improved further to match the requirements; 2) quench protection of 14 T whole-body superconducting magnets is one of the most complicated technics that covers design of the copper to superconductor (Cu/SC) ratio, coordination of the operating current and coil inductances, subdivisions of passive protection circuits and quench triggering control of active protection, as well as the stray field limitation during the transient process.