Speaker
Description
The High Field Magnet Laboratory of the Radboud University in Nijmegen has been building a 45 T hybrid magnet system over the last 10 years. The 12.3 T Nb3Sn CICC outsert coil has been wound and further processed by the National High Magnetic Field Laboratory in Tallahassee FL, USA. The coil is placed in a separate enclosure and will be operated at 4.5 K in an atmosphere of 1 bar of helium gas. Binary HTS/Cu-HEX current leads have been placed at some distance from the magnet, and are connected with a 4 meter long NbTi superconducting busbar to the magnet coil. The bus bar and the HTS section of the current leads are surrounded by the 1 bar helium gas atmosphere over their entire lengths as well, thus reducing the risk of high-voltage discharges that can occur in vacuum.
Significant forces may act on the superconducting outsert coil when the 32.7 T resistive insert magnet would fail, such as through partial burn-out. We have implemented novel solutions for the axial and radial support of the outsert magnet to sustain these forces comfortably.
The superconducting magnet is cooled with a forced flow of supercritical helium delivered by a helium refrigerator. The combination of the cryogenic distribution box and the refrigerator was extensively tested and shows that the cooling and guarding procedures in principle are adequate, and can be programmed into the Valve Box Control System, that will supervise the cryogenic operation of the hybrid magnet.
At present, assembly and integration of the outsert magnet system is completed, all auxiliary systems are commissioned and in place. After repair of several leaks in internal helium sub-systems, the magnet cryostat will be closed soon. The first cool-down of the outsert magnet of the Nijmegen 45 T hybrid magnet is expected in the second half of this year. In this paper, we briefly summarize the main design concepts and the system’s status.
