The design, construction, and characterization of a High Temperature Superconducting (HTS) magnet is described. The design stage has involved the development of computer software for the calculation of the critical current of a solenoid wound from anisotropic HTS conductor. This calculation can be performed for a variety of problems including those involving magnetic materials such as iron. by the incorporation of finite element electromagnetic analysis software. This has enabled the optimization of the magnet's performance. The HTS magnet is wound from 190 m of silver-matrix Bi2Sr2Ca2Cu3O10 powder-in-tube. tape conductor supplied by Intermagnetics General Corporation (IGC). The dimensions are 70 mm bore and 70 mm length, and it consists of 728 turns.. Iron end-plates were utilized in order to reduce the radial magnetic field, and consequently increase the performance by similar to20%. The magnet has been operated in liquid cryogens and has achieved engineering current densities of 900 A cm(-2) at 77 K and 6680 A cm(-2) at 4.2 K. The HTS magnet has been operated by conduction-cooling on a mechanical refrigerator at various temperatures in the range 12 to 50 K. The thermal stability in this relatively low cooling-power system has been assessed. An engineering current density of 5600 A cm(-2) was achieved at 12 K.

Root and branch change has resulted at the UK's principal high magnetic field facility since the abandonment of multi-MW water-cooled magnets in 1997. Ultra-high-field pulsed magnets now centerd in a new dedicated magnet suite. Continuous fields are provided by superconducting magnets up to 21.5 T. Unique work on high-T-c materials should push this up to 25 T and beyond. (C) 2001 Elsevier Science B.V. All rights reserved.

An experimental study of multicore Bi(2223)/Ag tapes, roll-sintered by different methods and subjected to bending and tension stresses has been performed. The tapes, of various technological histories, were bent and tensioned and subsequently the transport current was measured at each stressed state. Comparison of degradation curves shows that applied rolling may influence the sensitivity of Bi-2223 filaments against the mechanical stress. The existence of transverse microcracks caused by intermediate rolling leads to a higher sensitivity of the tape to bending. A lowering of critical current degradation was observed for two-axially rolled tapes having a higher filament density and better homogeneity prior to sintering treatment.

We describe the development of magnet coils constructed using high-temperature superconducting tapes (2212 and 2223 BSCCO/Ag) from a variety of sources. The applications area for these coils are as high-field inserts for superconducting magnets, at or near 4.2 K, and as a source of ampere – turns (at 77 K) for iron circuits. The latter application is illustrated with a coil built for a successful demonstration of attraction levitation using direct control of the magnet current to maintain a fixed airgap.

We describe two versions of a simple device that enable the J/sub c/ (B,T,/spl epsi/) characterisation of a <40 mm diameter single loop of HTS tape. The loop is mounted on a cylinder that is slit longitudinally at regular intervals around its circumference. Strain is applied by forcing a conical plug into the tapered bore of the cylinder which expands evenly as a consequence. The strain is measured by a strain gauge glued to the surface of the tape. The advantage of this configuration is that it enables insertion in the small bores of the highest field superconducting magnets and thus permits access to fields levels not easily available in more traditional linear pulling devices. Also the loop configuration is more representative of the coil geometry encountered in magnet applications. Representative data are presented and discussed critically.