HTS Wire Joint Layout for High-Current Superconductor Connections
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Solution Overview
Problem
Current methods for connecting high-temperature superconducting (HTS) wires, such as the melting diffusion method and bulk connection methods, face challenges in achieving high current capacity and require lengthy heat treatment processes, limiting their effectiveness for applications like MRI and NMR devices.
Innovation Solution
The connection of HTS wires is achieved through a method where multiple joint portions are formed along the longitudinal direction of the wires, with each joint having a specific shape and size ratio, allowing for increased current capacity by arranging bulk bodies in parallel, enabling higher current flow without the need for prolonged heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the melting diffusion method is used to connect REBCO superconducting wires, then the electric resistance is reduced below the soldering method, but a long heat treatment for one week or longer is required to increase the current capacity
Solution Approach 1:
The connection structure is divided into multiple joint portions (first joint portion and second joint portion) arranged in parallel between the superconducting wires. Each joint portion has a different aspect ratio (L/W), with the first joint portion having L/W ≤ 0.5 and the second joint portion having L/W > 0.5. This segmentation allows different joint portions to contribute differently to current capacity, enabling high current capacity without requiring prolonged heat treatment.
2Productivity
If joining methods using a bulk are used to connect HTS wires, then the connection time is reduced and mechanical strength is improved, but the current capacity is not sufficient
Solution Approach 1:
Multiple joint portions are merged in parallel between the superconducting wires. The first joint portion with L/W ≤ 0.5 and the second joint portion with L/W > 0.5 work together to provide both rapid connection (short heat treatment time) and high current capacity. The parallel arrangement of joint portions with different aspect ratios allows the system to achieve both short connection time and high current capacity simultaneously.
3Reliability
If a single joint portion is used to connect superconducting wires, then the structure is simple, but the current capacity is limited
Solution Approach 1:
Different joint portions are designed with different local qualities in terms of aspect ratio. The first joint portion has L/W ≤ 0.5 (more compact), while the second joint portion has L/W > 0.5 (more elongated). This local differentiation in geometry allows each joint portion to contribute differently to the overall current capacity, enabling the system to achieve high current capacity without excessive 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
This approach significantly enhances the current capacity of HTS wire connections, allowing for currents up to 100 amperes at 77 K and no magnetic field, and up to 200 amperes at 4.2 K with a magnetic field, making it suitable for long HTS wire applications in persistent current mode.
Implementation Method 1
the superconducting layers are heated to their melting point while being pressed to bring them into contact with each other, so that a part of the contacted superconducting layers in the thickness direction is subjected to melt diffusion to join the superconducting wires
Implementation Method 2
connects a HTS layer and a HTS bulk body by melting the HTS bulk body and performing crystal growth using the HTS layer serving as a seed crystal
Implementation Method 3
melting the HTS bulk body and performing crystal growth using the HTS layer serving as a seed crystal
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
In a high-temperature superconducting (HTS) wire connection assembly in which HTS wires each including a HTS layer are connected to each other, a first HTS wire and a second HTS wire that face each other are connected to each other at a plurality of joint portions separated from each other along a longitudinal direction of the first HTS wire and the second HTS wire. Each of the plurality of joint portions may preferably have any one of a rectangle shape, a rounded rectangle shape, and an ellipse shape, and it is preferable to satisfy 0.1 < L/W < 1.5, and is more preferable to satisfy 0.25 < L/W < 0.75 when a length in the longitudinal direction of the HTS wire is taken as L and a length in a width direction of the HTS wire is taken as W. It is also preferable that W and/or L monotonously increase from upstream side toward downstream side along the longitudinal direction of the wire.