Development and large volume production of extremely high current density YBa2Cu3O7 superconducting wires for fusion

TLDR

Fusion power density scales with the fourth power of magnetic field, and second‑generation high‑temperature superconductor wires deliver high engineering current densities at high fields, yet achieving consistent high performance, large‑scale supply, and low cost remains a key challenge. The authors report a reproducibly high engineering current density in practical YBCO wires containing Y₂O₃ nanoparticles, delivered within nine months to a commercial fusion customer in the largest‑volume order yet seen. They achieve this by formulating YBCO without the traditionally required c‑axis correlated nano‑columnar defects, challenging the prevailing belief that such defects are essential for high in‑field performance. The simplified formulation enables robust, scalable manufacturing, producing large volumes of consistently high‑performance wire and reducing HTS wire prices to levels acceptable for fusion and broader commercial use.

Abstract

Abstract The fusion power density produced in a tokamak is proportional to its magnetic field strength to the fourth power. Second-generation high temperature superconductor (2G HTS) wires demonstrate remarkable engineering current density (averaged over the full wire), J E , at very high magnetic fields, driving progress in fusion and other applications. The key challenge for HTS wires has been to offer an acceptable combination of high and consistent superconducting performance in high magnetic fields, high volume supply, and low price. Here we report a very high and reproducible J E in practical HTS wires based on a simple YBa 2 Cu 3 O 7 (YBCO) superconductor formulation with Y 2 O 3 nanoparticles, which have been delivered in just nine months to a commercial fusion customer in the largest-volume order the HTS industry has seen to date. We demonstrate a novel YBCO superconductor formulation without the c -axis correlated nano-columnar defects that are widely believed to be prerequisite for high in-field performance. The simplicity of this new formulation allows robust and scalable manufacturing, providing, for the first time, large volumes of consistently high performance wire, and the economies of scale necessary to lower HTS wire prices to a level acceptable for fusion and ultimately for the widespread commercial adoption of HTS.