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), JE, 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 JE in practical HTS wires based on a simple YBa2Cu3O7 (YBCO) superconductor formulation with Y2O3 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.
Highlights
The fusion power density produced in a tokamak is proportional to its magnetic field strength to the fourth power
In this article we demonstrate very high engineering current density in practical 2G high temperature superconductivity (HTS) wires based on a simple YBCO superconductor formulation with Y 2O3 nanoparticles
We fabricated the wire on a strong Hastelloy C276 substrate with a buffer layer architecture based on MgO textured using ion beam assisted deposition and with the HTS layer grown by pulsed laser deposition (PLD), as explained in the Methods section
Summary
The fusion power density produced in a tokamak is proportional to its magnetic field strength to the fourth power. 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 for the widespread commercial adoption of HTS. Engineering current density of 700 A/mm[2] at 20 K, 20 T is essential for the magnet system of the prototype commercial fusion device SPARC1 8, which is being designed and constructed by a collaboration of MIT and Commonwealth Fusion Systems (CFS) This target was a significant challenge when first announced, because even the best laboratory samples could barely reach that performance. Our concept for developing HTS wire with high in-field performance suitable for large volume, low cost manufacturing was the following:
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