Round REBCO Wire Structure for High Current Density at Small Diameters
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Solution Overview
Problem
Current round REBCO superconductor wires face limitations in achieving high engineering current density (Je) levels when wound to small diameters, with Je levels typically around 400 A/mm2 at 20 T, which is insufficient for high magnetic field applications.
Innovation Solution
The development of a round superconductor wire fabrication method involving multiple superconductor tapes wound on a wire former, where each tape has varying thickness, width, or material composition, with the REBCO film positioned near the geometric center to minimize bending strains, and using different materials and thicknesses for stabilizers and substrates across layers to optimize current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If REBCO coated conductors are wound to small diameters to create round superconductor wires, then the wire geometry becomes suitable for accelerator magnet applications, but the engineering current density degrades significantly
Solution Approach 1:
The patent applies local quality by positioning the REBCO superconductor film at the geometric center of the round wire, creating a symmetric configuration where the film experiences minimal bending strain. This central positioning ensures that the superconductor material is located where mechanical stress is lowest during wire bending, thereby maintaining high critical current density while achieving the required round wire geometry for accelerator magnet applications
2Reliability
If the REBCO film is positioned at the geometric center of the tape, then bending strain tolerance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent employs asymmetry by using a symmetric tape configuration (with the REBCO film centered between stabilizer layers) to achieve asymmetric strain distribution characteristics during bending. This symmetric-centered design creates a neutral axis that passes through the REBCO film, resulting in minimal tensile and compressive strains on the superconductor during wire formation, thereby improving bending strain tolerance despite increased manufacturing complexity
3Reliability
If multiple superconductor tapes are wound in a multifilamentary architecture, then current density is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the round superconductor wire into multiple discrete REBCO-coated conductor tapes wound in concentric layers around a central core. Each tape is a separate superconducting element, and their collective arrangement creates a multifilamentary architecture that increases the overall engineering current density of the wire while maintaining manageable manufacturing processes through modular assembly
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves engineering current density levels of up to 1500 A/mm2 at 4.2 K, 20 T, significantly higher than traditional Nb3Sn superconductors, with improved tolerance to bending strain and potential for higher Je levels in future high-field applications.
Implementation Method 1
Round superconductor wires and methods of fabricating same, which, inter alia, achieve a round superconductor wire having improved current density in high magnetic field applications
Data Source
AI summary
A round superconductor wire and method for fabricating same are disclosed. Embodiments are directed to a round superconductor wire including at least two superconductor tapes wound on a wire former. Each superconductor tape includes: bottom stabilizer and silver layers; substrate disposed above the bottom silver layer; buffer film stack disposed above the substrate; superconductor film disposed above the buffer film stack; top silver layer disposed above the superconductor film; and top stabilizer layer disposed above the top silver layer. At least one of the bottom stabilizer layer, bottom silver layer, substrate, buffer film stack, superconductor film, top silver layer, or top stabilizer layer is of a different width, thickness, or material composition in one of the superconductor tapes than in another of the superconductor tapes. These and other embodiments achieve a round superconductor wire having improved current density in high magnetic field applications when made in small diameters.