Commissioning Tests of the 43+T Grenoble Hybrid Magnet

The Grenoble Hybrid magnet is a modular user platform based on resistive and superconducting technologies. It will produce various high DC magnetic field and flux configurations ranging from 43 T in 34 mm diameter with 24 MW of electrical power to 9 T in 810 mm diameter, when the superconducting coil is used alone. Thanks to the ongoing upgrade of the electrical power installation at LNCMI-Grenoble to 30 MW, the opportunity to increase the total field significantly above 45 T was anticipated for the superconducting part and will require an optimization of the resistive inserts. The large-bore “outsert” coil of the Grenoble hybrid magnet is based on a specifically developed Nb-Ti/Cu superconducting conductor. The magnet cryostat with its support structure includes an eddy-current shield and is connected via a cryogenic line to a cryogenic satellite, fed by a fully dedicated 150 l/h He liquefaction plant. All parts have been built, tested and delivered to LNCMI-Grenoble, where integration and final assembly were successfully completed. The commissioning tests of the overall system started in 2022. Progress is reported together with the main problems encountered and solved, such as successful cooling of the superconducting coil down to 1.85 K with pressurized superfluid He. The first powering cycles and tests of the magnet safety systems are described with gradual current increases in the superconducting coil alone and then combined with the powering of resistive inserts as well as the initial precise magnetic characterizations using a
¹
H NMR probe.