Modeling and validation of nonlinear voltage-current characteristics of ITER PF joint sample tested in SULTAN facility

Abstract The ITER Poloidal Field (PF) coils are wound into double pancakes with NbTi cable-in-conduit conductors, which connected by joints in shaking hands lap-type configuration. operating pulsed mode a maximum current of 55 kA and peak magnetic field 6.4 T, utilizing electromagnetic load on the conductors joints. A series PF qualification joint samples modified praying configuration is measured SULTAN facility. For some samples, nonlinear voltage-current ( VI ) characteristic observed during assessment resistance. growth resistance versus B × I product larger than what expected from magneto-resistant copper contribution. Two non-homogeneous contact models developed combined to quantitatively evaluate reason for behavior combination relevant power dissipation redistribution joint. simulations reveal that, particular pre-qualification PFJEU2 sample variation up 3.5 nΩ, most probable widely spread defective connection between sole shim. force involves separation effect mechanically electrically weakly parts, resulting varying depending transport background field. hypothesis validated an experiment similar PFJEU3 post-mortem examination sample.