Superconducting Wire Joint Structure for Thermal Cycling Stability
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Solution Overview
Problem
Existing superconducting wire connections experience peeling and bending deformation due to thermal expansion and contraction, leading to reduced contact area and increased resistance.
Innovation Solution
Thicken the base material of at least one superconducting wire to create a thicker joint portion, using materials with similar thermal expansion coefficients to minimize deformation and enhance rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two superconducting wires are joined by removing protective layers and applying MOD solution, then connection resistance is reduced compared to soldering, but peeling and bending deformation occur due to thermal expansion differences between oxide superconducting layer and base material
Solution Approach 1:
The base material is designed with non-uniform thickness: thicker at the joint portion where two superconducting wires are connected, and thinner at other portions. This local thickness variation compensates for thermal expansion differences and prevents peeling deformation at the connection interface while maintaining overall structural integrity
Solution Approach 2:
The thickness parameter of the base material is specifically optimized at the joint portion to be greater than at other portions. This parameter change addresses the thermal expansion mismatch between the oxide superconducting layer and base material, preventing peeling and bending deformation during thermal cycling
2Strength
If the base material thickness is increased at the joint portion, then rigidity and resistance to thermal deformation are improved, but manufacturing complexity increases
Solution Approach 1:
Rather than uniformly increasing the entire base material thickness, only the joint portion is made thicker. This localized approach provides the necessary rigidity and thermal deformation resistance at the critical connection area while minimizing the overall material usage and manufacturing complexity
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 connection structure effectively suppresses peeling and bending, maintaining stable superconductivity even with repetitive thermal cycling.
Implementation Method 1
A superconducting wire on which an oxide superconducting layer is formed on the base material made of metal (hereinafter may be referred to simply as 'superconducting wire'), due to the electrical current loss being low
Implementation Method 2
due to the difference in each thermal expansion coefficient of the oxide superconducting layer and the base material made of metal, from repetitive changes of thermal expansion and thermal contraction by heat cycling
Data Source
Figure 1~2
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AI summary
A structure for connecting high temperature superconducting wires according to an embodiment includes: a first superconducting wire 3 and a second superconducting wire 4 which are two high temperature superconducting wires respectively having a band-shaped base material 1 consisting of metal or alloy, and an oxide superconducting layer 2 formed on a surface side of the base material 1; and a joint portion 6 containing a superconducting connection portion 5 formed between the first superconducting wire 3 and the second superconducting wire 4, the joint portion joining the first superconducting wire 3 and the second superconducting wire 4 in a positional relationship facing the surfaces of the first and second superconducting layers 2, 2, which are the oxide superconducting layers of each of the first and second superconducting wires 3, 4, are opposed to each other. In a base material 1 of at least one superconducting wire 3 among the first and second superconducting wires 3, 4, a first portion 7 constituting the joint portion 6 is thicker than a second portion 8 that does not constitute the joint portion 6 in the same base material 1.