Photolithographic Fabrication of Multifilamentary Superconducting Tapes With Reduced AC Losses for Cable Fabrication

Reducing alternating current (AC) losses arising in high-temperature superconducting (HTS) tapes is crucial for their efficient operation in environments with alternating or varying magnetic fields. This study focuses on developing multifilamentary HTS tapes with reduced AC losses by introducing striations through a photolithography process. Tapes with varying numbers of striations were fabricated and tested to assess their impact on critical currents and AC loss performance. The most promising design was further evaluated in a cable-like configuration by winding onto a non-conducting core. The quality of the filaments was characterized using scanning electron microscopy (SEM), confirming complete disruption of the REBCO (rare-earth barium copper oxide) layer within the grooves and ensuring proper filament isolation. Critical current and AC loss measurements were conducted to comprehensively evaluate the overall performance of the tapes. Striation into 10 filaments reduced AC losses by approximately 7–19 times compared to an unstriated tape, depending on the applied magnetic field amplitude. This improvement, however, was accompanied by an approximately 50% reduction in critical current, which may limit potential applications. Tapes with fewer filaments offered a more balanced compromise, achieving significant AC loss reduction while retaining a higher fraction of the critical current. Furthermore, winding of the tape did not substantially lower the critical current but provided an additional reduction in AC losses, highlighting the suitability of this approach for cable fabrication. Overall, the photolithography method proved to be effective and reproducible approach for fabricating multifilamentary structures.