Modeling of Butt Joint Composed of Nb₃Sn Cable-In-Conduit Conductors

Abstract

To evaluate butt joint fabrication technology of Nb 3 Sn cable-in-conduit (CIC) conductors, joint resistance and quench current were measured using a joint sample developed for the JT-60SA central solenoid (CS) coil. The measurements indicate that the butt joint fulfilled the design requirements. To simulate the butt joint characteristics, a one-dimensional numerical model simplifying the butt joint configuration was developed. Using the model, joint resistance and quench current of the butt joint were calculated. The calculations were in good agreement with the measurements. As a result, the model is valid for butt joint simulations.

Conductor and joint test results of JT-60SA CS and EF coils using the NIFS test facility

“…44 shows the measurement results of joint resistance. The measurements indicated that the performance of the pancake joint fulfilled the design requirement in which the joint resistance was less than 5 nΩ at 2 T [23].…”

“…37 and 38. The sample is hairpin-shaped and consists of two butt joints using the JT-60SA CS coil conductors [23,24]. The sample has a single inlet and double outlets for SHe.…”

Investigation into Quench Detection for a Multi-Stacked Pancake Coil Wound with Nb₃Sn CIC Conductors

“…All coils are wound with Nb 3 Sn CIC conductors. Each pancake coil is connected through butt joints [15][16][17] of the conductor. The number of coil winding layers is 52.…”

Investigation of long time constants of magnetic fields generated by the JT-60SA CS1 module

“…In Table 2, the specification of the CS conductor is listed. Each coil was connected through butt joints [8,9] of the conductors.…”

“…The conductor lengths of the model coil and the CS1 module were approximately 200 m and 2600 m, respectively. In the CS1 module, as described in Section 2, each pancake coil was connected using butt joint technology where two superconducting cables were connected through a 0.1 mm-thick-copper sheet by diffusion bonding [8,9]. Therefore, loop currents, which are supercurrents, cannot flow along the entire length of the CS1 module due to the resistance of the butt joint while holding coil current after coil excitation and degauss.…”