Investigation of Current Redistribution in Multifilamentary REBCO Tapes With Bridges

Filamentisation of superconducting tapes is an effective way to reduce alternating current (AC) losses in REBCO-coated conductors. However, current redistribution in filamented tapes may be a challenge, as local defects in individual filaments may lead to reduced performance. A remedy for this is the introduction of periodically spaced short bridges, or non-filamentized sections in the superconductor layer. The purpose of these segments is to facilitate a rerouting of current to even out the consequences of any defects in individual filaments. Multifilamentary REBCO tapes were fabricated starting from SUBRA's three-dimensionally structured Hastelloy substrate, onto which the buffer and superconductor were deposited by THEVA using large-scale industrial processes. We tested the current-voltage properties and evaluated local voltages by soldering voltage contacts onto individual filaments. A numerical model was developed using COMSOL Multiphysics [17] to simulate current sharing through bridges and within filamented sections. Our results show that bridge length could be reduced from the current 10 mm to approximately 1 mm without compromising redistribution performance. The simulations suggest that current redistribution over distance alone is less effective than using bridges, even at distances approaching 20 cm. Experimental measurements qualitatively confirmed these predictions, showing improved voltage characteristics due to bridges, although quantitative differences remain and warrant further investigation.