There are a variety of applications that utilize superconducting magnets in order to capitalize on their unique ability to create extremely high magnetic fields. The NMR (Nuclear Magnetic Resonance) and MRI (Magnetic Resonance Imaging) machines of today utilize such superconducting magnets for this very reason. Currently, high-field superconducting magnets are manufactured using commercially available superconducting wire such as niobium-titanium (NbTi) or niobium-tin (Nb3Sn).
- NbTi systems operate at a critical temperature of 10 Kelvin (K) and can achieve magnetic field strengths up to 15 Tesla (T).
- More expensive magnets, made of Nb3Sn, can reach magnetic field strengths up to 25 T. Nb3Sn is most often used in devices operating at 4.2 K in order to intensify the superconductor performance and attain high magnetic fields. Unfortunately, Nb3Sn based superconducting wire is also more difficult to manufacture and handle when compared to NbTi based wire.
NMR and MRI device manufacturers look towards advances in superconducting technologies to improve the overall performance of their systems by dramatically increasing the magnetic fields while reducing size. High demand for a robust, high performance and low cost superconducting wire has spurred rapid development of a next generation alternative. In the last 10 years, new second generation (2G) Rare Earth, Barium, Copper Oxide (ReBCO) superconducting materials have been proven to drastically increase magnetic field strengths, especially at low temperatures. These advanced ReBCO based superconductors now provide an excellent alternative to NbTi and Nb3Sn based materials.
- When operating in temperatures from 4.2K to 20K, ReBCO materials offer outstanding performance with magnetic fields well above 50T.
- STI’s Conductus® wire has been successfully tested at high-field and low temperatures and approved for use in NMR and MRI devices.
Hundreds of meters of Conductus® wire is coiled and placed into the inner magnetic core, which operates at 77K, in conjunction with an outer coil made of traditional NbTi or Nb3Sn superconducting wire. This combination optimizes both performance and cost of the system.
- NbTi and Nb3Sn superconducting wire is currently mass produced in quantities of 100’s of thousands of kilometers a year, and therefore is cost optimized.
- The primary cost benefit of Conductus® operating at 77K vs. NbTi and Nb3Sn operating at 4.2K is the elimination of liquid helium for cooling. Liquid Helium currently costs more than 5X the liquid nitrogen used for Conductus® solutions. In addition, that price differential is expected to increase significantly over the next several years.
- While more costly, Conductus® wire can significantly reduce machine/magnet size, increase magnetic field strength 2-3X and allow for operation in less expensive cooling mediums. These tradeoffs make Conductus® wire a viable alternative to other technologies.