Progress in research and development for high temperature and lowtemperature superconductors

It is noted that the most significant result in the development of Nb-Ti conductors in the last few years is the attainment of the critical current density J_c(5 T, 4.2 K)=(3-4)×10⁹ A/m² in industrial lots of wires. This value is close to the upper limit for traditional thermomechanical treatments with low-temperature annealing. New results on Nb₃Sn and other A-15 compounds have been obtained using methods that overcome some weak points of the bronze process. However, the bronze technology will remain the most suitable for large-scale production. Active work on the first stage of HTSC (high-temperature superconductor) development has produced some promising results. Critical current density values at 4.2 K and 77.3 K have been obtained in bulk samples such that practical applications of HTSC in high current technologies can be seriously considered