Ultra-High Field NMR Magnets with Multifilament High Temperature Superconductors - PROJECT SUMMARY We propose to develop a new technology pathway towards 1.5 GHz 1H NMR, by building a 28.2 T (1.2 GHz 1H)/1ppm, all-superconducting NMR demonstrator magnet using coils of the High-Temperature Superconductors (HTS) Bi-2212 (Bi2Sr2CaCu2Ox) and Bi-2223 ((Bi,Pb)2Sr2Ca2Cu3Ox) nested inside an existing wide-bore, 12 T Low-Temperature Superconductor (LTS) magnet. The novelty of our proposal is that the primary HTS conductor technology will be Bi-2212, made using a process we have developed with DOE High Energy Physics support. In contrast to existing commercial HTS NMR magnet technology that is reliant on REBCO (REBa2Cu3O7-δ) tape conductor, Bi-2212 is a round, genuinely multifilament and isotropic conductor that does not suffer from the very large screening current induced stresses and error fields of the large width, single filament REBCO coated tape conductors. It is also presently made in 3-4 times longer lengths than REBCO, making it more appropriate for our long-term goal of creating magnets for 1.5 GHz 1H/ 35.3 T NMR spectroscopy, where 40-60% of the field must be provided by the HTS insert magnets. To make our proposal compatible with R01 funding possibilities, we pair two inner Bi-2212 coils with a larger diameter Bi-2223 coil as the HTS insert magnet. This strategy has two advantages: (i) we have more than 2 km of Bi-2223 and more than 3 km of Bi-2212 conductor available at no added cost to this project; and (ii) we can use the two HTS conductors to generate almost 60% of the total field as would be needed for going to 1.5 GHz magnets. The following capabilities available at the National High Magnetic Field Laboratory (NHMFL) enable the proposal: (a) A 212 mm bore, high-homogeneity LTS magnet supported by the Oxford Instruments (OI) team that built it; (b) a unique over-pressure heat treatment furnace (OPHT) facility for reaction of the Bi-2212 coils at the scale needed for NMR magnets; and (c) the essential expertise of NHMFL scientists and engineers with experience building high field magnets and magnetic resonance equipment for biological and biomedical applications. Successful demonstration of ultra-high-field NMR technology will meet the aggressive challenge of 1.3-1.5 GHz NMR articulated by the 2013 National Academy Panel assessing U.S. high magnetic field needs.
