Development of Bi-2212 conductors and magnets for high-magnetic-field generation
Abstract:Bi-2212 is a very interesting superconductor from the point of view of high-magnetic-field generation because it has an extraordinarily high upper critical field. This paper reviews recent remarkable progress on Bi-2212/Ag superconductors and their applications to high-field magnets. Bi-2212/Ag multifilamentary and multilayer tape conductors with excellent performance in high fields were developed by the application of a powder-in-tube method and a coating method, respectively. High Jcvalues of (1.5-3) × 105A cm-2in a field of 30 T at 4.2 K were obtained for both multifilamentary and multilayer tapes. Pancake-type magnets were fabricated with these Bi-2212 tapes. The combination of Bi-2212 magnets and an 18 T conventional superconducting magnet generated a world record of 23.4 T at 4.2 K. A Bi-2212 magnet having a practical size of clear bore of 61 mm was also fabricated. This magnet generated 3 T in a backup field of 18 T at 4.2 K with a total field of 21 T. This 21 T magnet system has been operated many times since 28 September 1998, and the magnet system is now being used for experiments such as the Jc-Bmeasurements of superconductors. These results clearly demonstrate that a Bi-2212 conductor is very promising for high-field applications. One of the interesting applications of a high-field superconducting magnet is a high-field NMR spectrometer. The electric field versus current density (E-J) characteristics and the persistent-current mode of magnet operation are discussed in connection with the NMR.
Document Type: Miscellaneous
Publication date: January 1, 2000