Critical performance of a Nb3Sn Rutherford cable insert coil for 14 T MRI magnet

The Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) has been engaged the conceptual design and prototype coil development for the main coil of the whole-body 14 T magnetic resonance imaging (MRI) superconducting magnet since 2017. In order to improve the thermal and mechanical stability of the coil, a type of conductor called Rutherford cable-in-channel (RIC) will be used in the main coil of the 14 T MRI magnet system. The Rutherford cable is the core component of the RIC conductor. Assessing the electromagnetic performance of the Rutherford cable under operating conditions allows prediction and evaluation of the performance of RIC conductors and 14 T MRI magnets. In order to verify the critical performance of the Rutherford cable, a 2-layer, 2-turn (2 × 2) insert coil was manufactured and tested under a WM3 (maximum magnetic field of 20 T) resistive magnet at the High Magnetic Field Laboratory of the Chinese Academy of Science (CHMFL). The insert coil reaches a critical current of 3489.2 A with n-value of 24.39 after 12 times of quench training under a 14 T background field. The joint resistance is around 20 nΩ. The design, fabrication, testing and analysis of 2 × 2 insert coil will be presented in this paper.