MgB2 Superconducting Wire Structure for Stable Coil Connections

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Solution Overview

Problem

MgB2 superconducting wire connections face challenges in achieving both ease of superconducting connection and thermal stability, particularly when copper is involved in the connection process, which can lead to mechanical strength impairment and hinder effective bonding between wires.

Innovation Solution

A superconducting wire structure comprising elemental MgB2 wires incorporated into a first metal, such as iron or niobium, without copper in the region between the wires, ensuring no gaps are generated during heating, thereby maintaining mechanical strength and enhancing thermal stability by using iron or copper as low resistivity materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If copper is used in the connection process of MgB2 wires, then thermal stability is improved, but mechanical strength is impaired and bonding between wires is hindered

Engineering Contradiction:
Improvethermal stabilityVSAvoidmechanical strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention extracts copper from the connection portion of the MgB2 wire, eliminating it from the region where wires are bonded together. This removal prevents copper from interfering with the bonding process and maintaining mechanical strength, while copper can still be present in other parts of the wire structure to provide thermal stability benefits.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention applies different material compositions to different regions of the wire structure. The connection portion has a copper-free composition optimized for bonding and mechanical strength, while other regions may contain copper for thermal stability, creating local quality variations that resolve the contradiction.

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If copper is polished physically or chemically to improve connection, then bonding is enhanced, but the process becomes complex and copper on the inner side remains unpolished

Engineering Contradiction:
Improvebonding processVSAvoidpolishing process
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

By extracting copper from the connection portion entirely, the invention eliminates the need for complex polishing processes to remove copper oxides or prepare copper surfaces. The bonding process becomes simpler since the connection region contains only MgB2 and matrix materials that can be directly bonded without extensive surface preparation.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If copper is present in the container during connection heating, then thermal stability is maintained, but gaps are generated and mechanical strength is reduced

Engineering Contradiction:
Improvethermal stabilityVSAvoidgap formation
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The invention extracts copper from the container or connection environment during the heating process, preventing copper from participating in reactions that generate gaps. This ensures precise bonding without gap formation while thermal stability can be maintained through alternative means or copper present in non-connected regions.

Inventive Principle:
Principle #2Taking out (Extraction)

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 allows for improved superconducting characteristics and thermal stability by preventing copper reactions and maintaining mechanical integrity, enabling effective and stable connections between MgB2 wires.

Implementation Method 1

One of the features of the MgB2 superconductor is a high critical temperature of approximately 39 K, making it possible to maintain the superconducting state without involving cooling to the liquid helium temperature of 4.2 K

Methodology Applied
Scientific EffectSuperconductivity: Superconductivity

Implementation Method 2

What is common to substantially all the connecting methods is that the end portions of two wires to be connected together are put in a container and heated

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP3327733B1Superconducting wire, superconducting coil, MRI and nmr
Publication Date: 2023.11.22 HITACHI LTD
  • EP3327733B1 patent drawingFigure 1~2
  • EP3327733B1 patent drawingFigure 3~4
  • EP3327733B1 patent drawingFigure 5~7

AI summary

It is an object of the present invention to provide an MgB2 wire helping to achieve compatibility between the ease with which superconducting connection is effected and thermal stability. A superconducting wire according to the present invention includes: an elemental wire formed of MgB2; and a first metal not reacting with Mg. In a section orthogonal to the longitudinal direction of the superconducting wire, the region extending from the center of the superconducting wire to the installation position of the elemental wire is formed by the elemental wire and the first metal.