NbTi Multicore Wire Layout for Low AC Loss and Stable Drawing
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Solution Overview
Problem
Conventional NbTi superconducting multicore wires face challenges in achieving low production costs, low AC loss, and high critical current due to issues with filament diameter, twist pitch, and stabilizing metal distribution, leading to instability and increased production complexity.
Innovation Solution
A NbTi superconducting multicore wire design featuring a core portion with a first copper alloy barrier layer, a filament assembly with multiple NbTi filaments embedded in a second copper alloy matrix, and a stabilizing layer, where the Ni and Mn content ratios in the copper alloys are optimized to reduce hysteresis and coupling losses, and the filaments are arranged in concentric circular shapes with varying diameters to enhance processability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the filament diameter is reduced to reduce hysteresis loss, then hysteresis loss decreases, but production cost increases
Solution Approach 1:
The patent applies local quality by using a two-layer copper alloy structure: CuNi alloy barrier layers with high electrical resistance are positioned at critical locations (around core portion and around filament assembly) to suppress coupling loss, while the matrix uses CuMn alloy with lower cost. This selective placement of high-performance materials only where needed reduces overall production cost while maintaining low hysteresis loss through optimized filament diameter
Solution Approach 2:
The patent employs composite materials by combining different copper alloys (CuNi and CuMn) with distinct properties in a multi-layer configuration. The CuNi barrier layers provide high resistance to suppress AC loss, while the CuMn matrix provides cost-effective stabilization. This composite approach allows the use of expensive high-performance materials only where necessary, reducing overall production cost while achieving low hysteresis loss
2Loss of energy
If CuNi alloy is disposed all over spaces around filaments and between filaments to reduce coupling loss, then coupling loss decreases, but production cost increases
Solution Approach 1:
The patent implements local quality by strategically positioning CuNi alloy barrier layers only at two critical locations: (1) around the core portion and (2) around the filament assembly. This selective placement targets the regions where coupling loss occurs most significantly, achieving effective coupling loss reduction while avoiding the need to fill all spaces with expensive CuNi alloy, thereby controlling production cost
Solution Approach 2:
The patent applies segmentation by dividing the stabilizing metal into distinct functional zones: CuNi alloy barrier layers at critical interfaces and CuMn alloy matrix in other regions. This segmentation allows the expensive CuNi material to be used only where it provides maximum benefit for reducing coupling loss, while less expensive CuMn material handles other stabilization functions, optimizing the cost-performance balance
3Power
If the outer diameter of the strand is increased to increase critical current capacity, then critical current capacity increases, but heat discharge becomes poor
Solution Approach 1:
The patent uses composite materials with different thermal and electrical properties: CuMn alloy matrix provides good thermal conductivity for heat discharge, while CuNi alloy barrier layers provide high electrical resistance for AC loss reduction. This composite structure allows the strand to achieve high critical current capacity through increased outer diameter while maintaining effective heat discharge through the thermally conductive CuMn matrix
Solution Approach 2:
The patent applies local quality by assigning different functional roles to different materials in the composite structure: CuMn alloy in the matrix handles thermal management and mechanical stabilization, while CuNi alloy at the barrier layers handles electrical isolation and AC loss reduction. This functional differentiation allows the strand to simultaneously achieve high current capacity and effective heat discharge
4Power
If the number of twisted wires is increased to increase critical current capacity, then critical current capacity increases, but mechanical rigidity decreases
Solution Approach 1:
The patent employs composite materials where the CuMn alloy matrix provides excellent mechanical strength and rigidity, allowing the use of fewer twisted wires (reducing complexity) while maintaining structural integrity. The CuNi barrier layers provide electrical isolation to reduce coupling loss. This material composition enables achieving high critical current capacity with simpler wire configurations that maintain mechanical rigidity
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
The design achieves low AC losses, high critical current density, and reduced production costs by optimizing the copper alloy compositions and filament arrangement, improving the wire's stability and processability while minimizing wire breaking during drawing.
Implementation Method 1
a first barrier layer arranged around the circumference of the core portion and composed of a first copper alloy including at least one element selected from Ni or Mn
Implementation Method 2
a coupling loss (including an eddy current loss) generated in a stabilizing metal portion formed of a normal conducting metal
Implementation Method 3
a NbTi superconducting multicore wire including: a core portion; a first barrier layer arranged around the circumference of the core portion
Implementation Method 4
the hysteresis loss in the NbTi filament portion can be suppressed by reducing a filament diameter
Data Source
AI summary
A NbTi superconducting multicore wire includes a core portion and a first barrier layer arranged around the core portion and composed of a first copper alloy including at least one element selected from Ni or Mn. A filament assembly arranged around the first barrier layer includes NbTi filament assemblies each including at least seven NbTi filaments, embedded in a matrix of a second copper alloy including at least one element selected from Ni or Mn. A second barrier layer is arranged around the filament assembly and composed of the first copper alloy, and a stabilizing layer arranged around the second barrier layer and composed of metal. The NbTi filaments are arranged in circular shapes each having a different diameter, centering on one NbTi filament, and NbTi filaments arranged in a circular shape in an outermost circle being arranged at approximately equal intervals along a circumferential direction.