Speakers
Description
Building upon the successful development of 26.86 T @ 30 mm and 16.6 T @ 100 mm fully REBCO high temperature superconducting (HTS) magnets, we have initiated the research and development of an 800 MHz NMR magnet with a 54 mm room-temperature bore. High-field HTS magnets face significant challenges during operation, such as pronounced screening current effects, which lead to poor magnetic field stability and localized stress concentration. As a preliminary step to address these issues, we have designed and constructed a 400 MHz small-scale NMR magnet based on REBCO conductors. The magnet consists of 26 double pancake coils, designed to operate at a current of 247 A, generating a central magnetic field of 9.4 T. The coils are wound with a standard inner diameter of 38 mm, with those near the center employing a notch structure to enhance field homogeneity, achieving a uniformity of 4.1 ppm over a 10 mm DSV. To mitigate magnetic field drift, a metal-co-wound no-insulation winding technique was adopted, and a localized adhesive impregnation method is planned to secure the coils, further improving the long-term stability of the magnetic field. This paper comprehensively presents the magnet design, magnetic field optimization, coil fabrication and assembly, as well as performance testing at 4.2 K. It also provides an in-depth analysis of operational characteristics, offering essential theoretical and practical insights for the development of 800 MHz HTS NMR magnet.
