MT27, 27th International Conference on Magnet Technology

In-field evaluation of REBCO superconducting joint

WED-PO2-613-09

17 Nov 2021, 10:30

2h

Fukuoka Convention Center

Poster WED-PO2-613 Joints between Superconductors

Speaker

Kensuke Kobayashi (National Institute for Materials Science)

Description

The superconducting joint is one of key technologies to evolve high temperature superconducting (HTS) conductors and their applications. Various joint techniques have been proposed in these years [1]. To evaluate developed joint efficiently, we developed a resistance evaluation system for superconducting joints [2]. The system consists of a superconductor sample with a joint, a copper coil to inject (induce) current to the sample, and a superconducting magnet for external fields applied to the joint. Using this system, joint resistance (R${}_j$) ranging 10${}^{-15}$-10${}^{-7}$ Ω can be quantitatively evaluated as a function of injected current (I${}_i$${}_n$) magnitude, temperature, and external magnetic field. In addition, I${}_c$ and T${}_c$ of the joint can be evaluated. In this paper, we report the evaluation results of the REBCO superconducting joint [3]. At 4.2 K without external field, R${}_j$ stayed ~10${}^{-14}$ Ω at I${}_i$${}_n$ up to ~300 A. This indicates that the I${}_c$ of the joint is sufficiently larger than 300 A. At 77 K, I${}_i$${}_n$ of ~150 A rapidly decreased to ~116 A and evaluated R${}_j$ was ~10${}^{-12}$ Ω. This higher R${}_j$ is considered to be due to a high load factor of ~100% at the joint. R${}_j$ at 4.2 K showed almost no dependence on external field ranging 0 ≤ B ≤ 3 T. Even at 77 K and 3 T, the junction carried I${}_c$ of ~17 A and R${}_j$ was ~10${}^{-12}$ Ω. This work is based on results obtained from a project commissioned by JST-Mirai Program Grant Number JPMJMI17A2, Japan.

[1] G. D. Brittles et al., Supercond. Sci. Technol. 28, 093001 (2015).
[2] K. Kobayashi et al., IEEE Trans. Appl. Supercond. 30, 9000204 (2020).
[3] K. Ohki et al., Supercond. Sci. Technol. 30, 115017 (2017).

Presentation materials

WED-PO2-613-09_kobayashik_revised.pdf