Usage of Bi-HTS in High Field Magnets

Abstract

At present, superconducting high field magnets built up of metallic Low Temperature Superconductors (LTS) like NbTi and ternary/quaternary Nb 3 Sn are near to the upper limit of achievable field strength. Fields above approx. 23 T seem to be only reachable with LTS-HTS hybrid configurations consisting of an outer LTS section and a High Temperature Superconductor (HTS) insert. Commercially available Bi-HTS wires were investigated for their application in high field facilities like the HOMER II system with the goal of 25 T and in new generations of NMR magnets of 1000 MHz and above. Therefore the superconducting properties of the HTS wires were examined at 4.2 K in magnetic fields up to 10 T. The voltage-current relation was examined resistively using a high resolution four-point measurement technique. The dependence of the critical current and the n-value on the winding diameter, on the field alteration (increasing/decreasing), and on the field orientation to the wire is presented and discussed.

Manufacture and Test of a 5 T Bi-2223 Insert Coil

“…In conjunction with our results obtained in earlier investigations of the AMSC wire (see [2], [5], and [7]) following can be stated.…”

“…Due to the reinforcement by two layers of stainless steel soldered on both sides, the AMSC tapes used provide a unique combination of properties: High critical currents and high -values associated with a high tensile strength to withstand the hoop stress occurring in a magnet without degradation of the superconducting properties. A detailed study of the physical properties and the suitability of the AMSC tapes for high field insert magnets is given in [5]. More information Lower curve: extrapolated I (B) data measured for a comparable AMSC tape in perpendicular field orientation [5].…”

“…A detailed study of the physical properties and the suitability of the AMSC tapes for high field insert magnets is given in [5]. More information Lower curve: extrapolated I (B) data measured for a comparable AMSC tape in perpendicular field orientation [5]. Both curves lie well above the rated current of 150 A for the HTS insert.…”