New generation of superconducting magnet for the production of Teslas with a reduced electical consumption – NOUGAT

A magnetic field is a very powerful thermodynamic parameter to influence the state of any material system. Consequently magnetic fields serve as an experimental tool in very diverse research areas like condensed matter physics, molecular physics, chemistry and, with increasing importance, in biology and biotechnology. Many magnetic field based research techniques are standard and can be done with conventional commercially available magnets and associated equipment (MRI-scanners, NMR and ESR spectrometers, conventional superconducting magnets, etc.) that can provide field up to 18-20 T.

To go beyond, very large infrastructures such as the LNCMI, a very large instrument of CNRS, are necessary. Indeed, the generation of intense magnetic fields requires the use of copper alloy based resistive coils with forced cooling which consume large amounts of electrical current and cooling water. Thus, the installed power at LNCMI is currently 24 MW in DC current and the annual consumption is about 20 GWh.

The increasing energy cost of operating high field magnets has strongly stimulated the interest in high Tc superconductors for magnetic field generation. The general interest of superconductors is that they can carry high current without dissipation by Joule effect. The specific interest of HTc superconductors (HTS) for high field generation is that at very low temperatures (below 20 K) and under high magnetic induction (> 20 T), they remain in the superconducting state while keeping a transport capacity of strong electrical currents. In fact, they offer opportunities for generating unimaginable magnetic fields between 25 and 50 T with conventional superconductors limited to 18-20 T. Many recent studies show the strong potential of coated conductor tapes made of REBaCu0 (RE = Rare Earth) superconductor. The lengths produced industrially and the transport critical currents have increased steadily over the decade and the mechanical properties of tapes based on a Hastelloy substrate have been proved remarkable.

The heart of our proposal is the fabrication of an HTS insert capable of providing at least 10 T at 4.2 K in a stable and protected manner in a background field of 20 T, to produce at least a total of 30 T. The background field will be produced by a resistive magnet available at the LNCMI. This combination provides a unique and original way to test HTS inserts at low-cost. The cost of a conventional 20 T LTS coil in a cold 150 mm configuration remains high ( greater than 4 M € ) , and the possible interactions between HTS and LTS coils is a huge risk as long as the operation of the HTS coil is not controlled. By focusing on the operation of an HTS insert fields at high magnetic field in a resistive environment, we eliminate this risk and concentrate our efforts on the validation tests of the protection modes of this insert.

We will rely on a structured approach integrating experimental and numerical modeling on critical aspects of design, whether material, mechanical, electromagnetic or cryogenic. Particular attention has to be paid to the protection of the magnet during transitions from the superconducting to the normal state (quench), a major lock for this type of applications.

Our ambition for this project is to develop the technology to design and produce forward superconducting magnets in the most demanding conditions, very high field at low temperature ( 4 - 20K ) for SMES , dipoles at CERN , inserts for high field to LNCMI or field sources on Xray (ESRF) or neutron (ILL and ESS) beam lines.