Next-Generation Advanced MOCVD for Long REBCO Tapes

Abstract

REBCO tapes exhibit considerable potential for application in high magnetic field devices such as compact fusion reactors and particle accelerators; next-generation electric machines such as high-efficiency industrial motors and high-power wind turbine generators; and electric aircraft. Our group had previously demonstrated an advanced metal organic chemical vapor deposition (A-MOCVD) method to produce 50-meter-long REBCO tapes with film thickness over 4 µm in a single pass, and a uniform critical current ( I_c ) over 1,750 A/12 mm at 65 K, 0.25 T. Further, for high magnetic field applications, 40-meter-long tapes have been made by A-MOCVD with an I_c over 4,000 A/12 mm at 4.2 K and 13 T, as well as over 1,400 A/12 mm at 20 K and 20 T. A laminar vapor path design in the A-MOCVD reactor enabled the growth of thick REBCO films with a high precursor-to-film conversion efficiency up to 45% (4x the conversion efficiency of conventional MOCVD of REBCO tapes). Subsequent advancements in the A-MOCVD process enabled simultaneous deposition of REBCO films on both sides of a double-sided buffered substrate, in a single pass. This yielded double-sided, 30-cm-long REBCO tapes with 3.4-µm-thick films on each side, which showed I_c over 530 A/4 mm at 20 K, 20 T. This paper reports our recent work on next-generation A-MOCVD design to scale up double-sided REBCO tapes to long lengths, with superior performance and an increased precursor-to-film conversion efficiency beyond 70%. Tape heating and precursor delivery methods incorporated in the new design aims to facilitate the scale-up of A-MOCVD for multi-track deposition for higher tape throughput.