Speaker
Description
Research on high-field all-superconducting magnets has garnered significant global attention in recent years due to their reduced size, lower cost, and enhanced convenience compared to hybrid magnet systems. These magnets play a pivotal role in various research fields, including material science, biological studies, and quantum computing. However, the fabrication of high-field superconducting magnets, particularly those using Nb3Sn superconducting wires, presents considerable challenges and requires meticulous care.
Since 2019, our team has embarked on designing and producing a 19T all-superconducting magnet with a bore diameter exceeding 70 mm. This magnet aims to serve as the background field system for investigating superconducting material properties for future fusion reactor. The project is a sub-component of the Comprehensive Research Facility for Fusion Technology (CRAFT) initiative, which seeks to establish a comprehensive laboratory equipped with capabilities related to superconducting materials, AC loss measurement, structural materials evaluation, thermal-hydraulic studies, non-destructive testing, and high-voltage research.
To ensure safety and feasibility, a stepwise research approach was adopted:
Initial Phase: Design and construct a 15 T low-temperature superconducting (LTS) magnet using Nb3Sn and NbTi wires, featuring a bore size larger than 70 mm.
Intermediate Phase: Attempt to increase the bore size to 150 mm. Concurrently, develop an insert magnet utilizing high-temperature superconducting (HTS) double-pancake coils with a 70 mm aperture.
Final Phase: Achieve the target by integrating the 15 T & 150 mm LTS outer magnet with a 5 T & 70 mm HTS insert magnet.
After nearly five years of dedicated research, we have successfully developed China's first 15 T & 77 mm LTS magnet, along with a compact version of the same specifications, and a custom-built 15 T & 150 mm LTS magnet. By combining these with a 5 T & 70 mm HTS insert magnet, the project objective was met in 2024. The resultant LTS + HTS all-superconducting magnet achieves a stable central magnetic field of 19.13 T, with an available measuring bore of 70.1 mm.
This paper reviews the development progress of high-field all-superconducting magnets within the CRAFT project. Although the target has been achieved, numerous challenges remain to be addressed for the stable operation of the home-made all-superconducting magnets. Specifically, improving the success rate in manufacturing all-superconducting magnets using brittle Nb3Sn superconducting wires is a critical issue that needs resolution. Addressing this challenge will significantly advance the development of high-field magnet technologies.
