Prototype of Super-FRS Superconducting Dipole for FAIR Project of Germany Successfully Gone through Magnetic Field Test
Recently, the prototype of Super-FRS superconducting dipole for FAIR project of Germany has successfully gone through the magnetic field test by one expert testing group.
The Super-FRS superconducting dipole is a superferric superconducting magnet with the warm iron yoke. The coils are wound from multi-filamentary NbTi with a high percentage of copper to superconductor and operated in liquid helium temperature. The coils are positioned in the helium cryostat with the multi-layer insulation structure. The total weight of the magnet is about 50 tons. The FEM(Finite Element Method) tool has been used to design the magnet. The magnetic field distribution, the mechanical structure and the thermal performance were optimized with the professional software such as TOSCA, ANSYS and ADINA. The dipole has a wide good field region and high homogeneity. The passive air slot and chamfered removable poles guarantee that the magnetic field distribution is homogeneous at both low and high field level. The magnetic field measurements indicate that the field homogeneity is about ±2×10-4 at different magnetic field levels (0.16 T- 1.6 T), which is better than the targets of GSI. The whole experiment system, which consists of superconducting magnet, current supply, quench protection system, data acquisition and helium recovery system, has been tested and the main points of the results are as the follows: The vacuum of the cryostat is better than 3×10-4 Pa; The stability of the current supply is better than ±2×10-5.
The magnetic field distribution across the 400 mm good field region at different field levels
The success of the superconducting dipole has verified the design of the magnet system, including coils, cryostat and mechanical structure. A lot of experience has also accumulated in the design and fabrication of superconducting magnet system.
The project is supported by the Ministry of Science and Technology of China, the Major State Basic Research Development Program of China and GSI in Germany. Institute of Modern Physics, CAS is responsible for the design of the whole system, the magnetic field optimization and the development of the 50 tons lamination iron yoke. Institute of Plasma Physics, CAS is responsible for the development of superconducting coils and cryostat. Institute of Electrical Engineering, CAS contributes to the concept design of the superconducting coils.