Conductive Micro-Paths for Current Sharing Between REBCO Tapes in High-Tc Superconducting Conductors to Improve Stability

The REBa
₂
Cu
₃
O
_y
(REBCO, RE: Rare Earth) is expected to be applied to fusion magnets, and various REBCO conductors with a high current capacity has been developed for the fusion magnets by stacking the REBCO tapes. A disadvantage of REBCO conductors is that the buffer layer prevents current sharing between the tapes, reducing conductor stability. In this study, we propose conductive micro-paths where the current is shared between the REBCO tapes in order to improve the stability of conductors. We fabricated the conductive micro-paths in REBCO tapes by using a UV pulsed laser and an Ag sputtering method, and evaluated them. Furthermore, we investigated the current sharing between tapes at 77 K with two REBCO tapes with conductive micro-paths. As a result, in REBCO tapes with conductive micro-paths, the current was shared through these paths between the REBCO tapes at
$1.1 < I/{I_{\bf{c}}} < 1.15$
and was successfully bypassed the damaged area.