HTS Magnets at the Frontier of Science and Technology

Recent large-scale improvements in technical performance and production capacity of HTS materials, principally REBCO tape and Bi-2212 round wire, are enabling extension of magnet technology to magnetic fields of 20 T and well beyond. This has enormous potential benefit for both scientific and economic reasons in many applications of superconductor technology. In this roundtable discussion, three experts in the fields of NMR/MRI, High Energy Physics, and Magnetic Confinement Fusion are brought together to discuss the expansion of the scientific and technical horizons enabled by HTS technology. and to compare and contrast how the technology is being used in these particular applications.

Nuclear magnetic resonance (NMR) has been widely used in chemical, biochemical, and biological research, where high field magnets are playing central roles. Currently, most NMR magnets are made of low-temperature superconductors, typically a combination of NbTi and Nb3Sn. Although the last upgrade of LTS NMR magnet field was 23 T (1 GHz of 1H NMR frequency) in 2010 by the Bruker BioSpin, the higher field has been desired by the NMR user community. It is widely agreed among magnet engineers that high-temperature superconductor (HTS) capable of generating a field far greater than 23 T will play an increasingly indispensable role in >1 GHz NMR magnet. Yet, technical challenges, especially protection of HTS magnet and field inhomogeneity by screening currents, need to be overcome for widespread use of HTS in GHz-class NMR magnets. In this discussion, key technical challenges and state-of-the-art technologies in HTS NMR magnets are briefly introduced together with the latest achievements in HTS NMR magnets.

Likewise, in the field of High Energy Physics (HEP) NbTi and Nb3Sn superconducting magnets have been key to major particle physics and nuclear physics colliders including the Tevatron, RHIC, HERA, and LHC. The 8.33 T NbTi accelerator dipole magnets underpin the LHC at CERN, enabling the discovery of the Higgs Boson and the ongoing search for physics beyond the standard model of high energy physics, whereas Nb3Sn magnets are a key to a high-luminosity upgrade of the LHC that aims to increase the luminosity of the LHC by a factor of 5-10. In this discussion, we examine how emerging HTS conductor and magnet technologies can extend scientific space into higher fields (> 20T) and higher temperature for frontier accelerator facilities, and how HTS conductors can meet the severe requirements in terms critical current, magnetization, stress management, and quench protection. 

The recent commercial availability of high-temperature superconductors (HTS), specifically second-generation HTS REBCO coated conductors, at the scale and performance required to build high-field magnets represents a breakthrough opportunity to accelerate fusion energy. Many of the key fusion energy performance metrics in a tokamak, the leading fusion energy concept, scale as the strength of the magnetic field available to confine the plasma to the third or fourth power. One of the most important consequences of this fact is that increasing the magnetic field in a tokamak enables a dramatically smaller device to demonstrate net-energy production. A reduction in size is accompanied by important reductions in cost, timeline, and organizational complexity required to construct and operate the device, enabling a net-energy fusion device to be constructed at university or private company scale through innovative private funding models. The first step in this pathway – now actively underway at several institutions and companies – is to demonstrate the large-bore, high-field REBCO superconducting magnet technology at suitable scale for fusion systems. Part of this panel discussion will look at the game-changing advantages of high magnetic field fusion physics and engineering and some of the efforts underway to pursue this accelerated pathway to fusion energy. 

Additional keywords: BSCCO, NMR, High Energy Physics accelerators, nuclear fusion