MATERIALS FOR CLASSICAL AND HIGH-T-C SUPERCONDUCTING TAPES AND WIRES AT 4.2 K

For the next few years, the classical materials NbTi and Nb3Sn will st ill remain at the centre of interest for the construction of magnets o perating at temperatures between 1.8 and 4.2 K. Magnets operating in t he persistent mode at fields >20 T and laboratory magnets approaching 23 T can be envisaged in the near future, based on Nb3Sn and Nb3Al wir es. The actual situation of critical current densities as a function o f the applied field at 4.2 K is briefly reviewed. Considerably higher fields will be produced using insert magnets based on Bi(2212) and Bi( 2223) tapes, provided the mechanical properties can be improved.