Speakers
Description
Neoscan Solutions is currently building the 14T HTS MRI magnet for whole-body MR imaging and spectroscopy, under the supervision of a magnet committee formed by the DYNAMIC consortium, i.e. seven research institutes and medical centers in the Netherlands who will be using the system. The magnet will be sited at the Radboud University in Nijmegen. It offers an 82 cm wide warm bore for MRI of human subjects [1].
Previously, a concept study had shown that such type of magnet seems feasible with respect to its critical currents in an ambient field of up to 16.2 T in the magnet coils, at up to 20 K temperature [2]. The proposed magnet is unshielded, conductively cooled, and does not use any liquid He. The core magnet is accessible by removing the lids of the cryostat. Its pancake coils are not casted and but can be unwound for repair or reconfiguration. A conductor layout yielding a highly homogeneous central field has been proposed; the stresses in the core magnet have shown to be within the limits of the conductor, and a cooling concept and methods for quench protection have been devised. An HTS magnet appears an attractive concept in ultra-high field (UHF) MRI, since it could offer resilience against heating of the magnet induced by the gradient fields used for image encoding. The magnet currently under construction will offer a temperature safety margin of about 15 K before reaching its Ic limit. In comparison, temperature safety margins are significantly lower in LTS magnets for imaging of humans at fields above 10T.
Here we present how the magnet and associated simulations have been improved compared to the original concept: (i) the rationale for choosing REBCO over BSCCO; (ii) a new mechanical model of the magnet coil inner forces, taking into account three different coil materials and coil confinement; (iii) the choice of coil co-winding material for improving passive quench protection, experimental data of shoot-out testing; (iv) electrical and mechanical properties of its joints. The finalized cryostat is shown. Furthermore, the strategy for experimental validation of the magnet design and its construction will be presented and discussed.
[1] Bates S, Dumoulin SO, Folkers PJM, Formisano E, Goebel R, Haghnejad A, Helmich RC, Klomp D, van der Kolk AG, Li Y, Nederveen A, Norris DG, Petridou N, Roell S, Scheenen TWJ, Schoonheim MM, Voogt I, Webb A. (2023). A vision of 14 T MR for fundamental and clinical science. MAGMA. 36(2):211-225. doi: 10.1007/s10334-023-01081-3. Epub 2023 Apr 10. PMID: 37036574; PMCID: PMC10088620.
[2] Li Y, Roell S (2021). Key Designs of a Short-bore and Cryogen-free High Temperature Superconducting Magnet System for 14 T Whole-Body MRI. Superconductor Science and Technology. 34. 10.1088/1361-6668/ac2ec8.
