Optimisation of Nb3Sn cable-in-conduit superconductors for application to pulsed tokamak coils

Cable-in-conduit conductors in pulsed tokamak applications have design requirements imposed by the tokamak operation: typically ana operating temperature dependant on the AC losses and pulse time, the field by the tokamak performance and a quench discharge time by the coil voltage limits. The void fraction of helium in the cable is determined by mechanical and thermal stability considerations. It is then possible to maximise the cable space current density for a given temperature margin and strand properties, using the procedure in the companion paper `Parametric Study of Cost Functions in Cable-in-Conduit-Conductors´. Nb ₃Sn strands can typically offer high loss, low jc. The sensitivity of the cable design to the choice of strand is discussed with reference to the quantity of strand and the achievable current density