RHQT JR Nb3Al conductors developed for nuclear fusion devices

Three kinds of stabilized rapid-heating, quenching and transformation annealing (RHQT) Nb3Al round wires have been developed for nuclear fusion devices; the Ag internally stabilized Nb matrix, the Cu internally stabilized Ta matrix and Cu ion-plated/electroplated wires. The critical current densities Jc of Nb3Al filaments are almost the same as the conventional Cu clad stabilized flat-wire, as long as the Jc is optimized by mechanical deformation of wire after quenching but before the final transformation annealing. To demonstrate the applicability of RHQT Nb3Al wire to nuclear fusion devices, we have trial manufactured a cable-in-conduit conductor (CICC) using the Ag internally stabilized round strands and confirmed the critical current of CICC to be nearly the same with the strain-free designed one.