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Description
High-temperature superconducting (HTS) Twisted-Stacked-Tape-Cable (TSTC) conductors have been developed for use in high-field magnets, particularly those needed for compact, high-field fusion tokamaks. TSTC conductors generally contain a large number of simply-stacked RE-Ba2Cu3O7-x (RE=rare earth) (REBCO) coated conductors inserted into helical channels in a round former. Multiple versions have been proposed by several labs throughout the world, for both DC and pulsed-field applications. The inductance of each tape in the TSTC depends on its position relative to the cable centerline. A large variation among the tape inductances could cause current in the cable to distribute nonuniformly when current is changed at high rates. For instance, current ramp rates of several kilo-Amperes per second occur during pulsed-field applications, such as in fusion or accelerator magnets.
In this paper, we develop an analytical model of the behavior of a TSTC conductor during transient operation, during which the current distribution in the cable is determined chiefly by inductive effects rather than by the distribution of the tape-to-terminal resistances at the cable ends. The model is principally directed towards determining the self-field transport current losses in the cable during fast ramping. The modelled results are then compared with experimental data measured at the MIT Superconducting Magnet Test Facility during the test of magnet prototypes wound using Commonwealth Fusion System’s PIT-VIPER TSTC conductor.
Acknowledgement: This work was sponsored by Commonwealth Fusion Systems of Devens, MA.
