22-27 September 2019
Hyatt Regency Hotel Vancouver
Canada/Pacific timezone

Tue-Mo-Po2.10-05 [77]: In-Field Current Transport Properties in Long Length IBAD-PLD REBCO Tapes under the Influence of Local Ic Variation

24 Sep 2019, 08:45
2h
Level 2 Posters 2

Level 2 Posters 2

Speaker

Takanobu Kiss (Kyushu University)

Description

Spatial homogeneity is one of the most important issues for practical applications of REBCO based magnets. Reel-to-reel Ic measurement is now widely used for the investigation of local Ic variation, however, these measurements are limited at low magnetif field around self-field and at 77 K in most cases, whereas practical operation condistions of superconducting magnets are higher magnetic field, B, and lower temperature, T. Furthermore, the relationship among the positional Ic variation, transport Ic and n-value in the long REBCO tapes is not yet fully understood.
In this study, we carried out spatially resolved Ic measurement in IBAD-PLD processed REBCO tapes under external magnetic field up to 5 T and down to 35 K by combining reel-to-reel contimuous measurement and in-field scanning Hall probe microscopy. We have also succeeded in measuring local n-value in the tape continuously with a spatial resolution of 1 mm. These measurements allow us to obtain deep insight into the controlling factors of B, T and position dependences of the current transport properties of REBCO tape. We confirmed good correlation between the measurements at low-field, 77 K and at in-field lower temperatures. Also, the positional dependence is almost independent from measurement conditions such as B and T. This strongly suggests that the B and T dependences are dominated by uniform flux pinning in a mesoscopic scale while the local Ic variation is mainly originated from current blocking obstacles in a macroscopic scale. Based on this understanding, we also propsed a multi-scale model to describe global current-voltage characteristics, i.e., transport Ic and n-value of long length REBCO tapes analytically. This is useful for describing properties in a long length magnet winding under practical operation condisions.
This work was supported by JSPS KAKENHI Grant Number 16H02334 and the New Energy and Industrial Technology Development Organization (NEDO).

Primary authors

Takanobu Kiss (Kyushu University) Kohei Higashikawa (Kyushu University) Mr Shohei Noda (Kyushu University) Mr Yukihisa Kumagai (Kyushu University) Takumi Suzuki (Kyushu University) Mr Kazutaka Imamura (Kyushu University) Mr wataru Hirata (Fujikura Ltd.) Shinji Fujita (Fujikura Ltd.) Dr Yasuhiro Iijima (Fujikura Ltd.) Dr Akira Ibi (AIST) Dr Takato Machi (AIST) Teruo Izumi (Advanced Industrial Science and Technology)

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