MgB2 Sintered Wire Connector for Stable Superconducting Joints
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Solution Overview
Problem
Existing methods for connecting superconducting wires using magnesium diboride (MgB2) face issues such as low critical temperature limitations, mechanical fragility, and reaction interference from stabilizing materials, leading to suboptimal conduction characteristics and potential wire separation due to thermal strain.
Innovation Solution
A superconducting wire connector and method that involves forming a sintered body containing MgB2 by exposing the outer peripheral surfaces of the superconducting cores within a metal container, removing the metal sheath at intermediate portions to prevent stabilizing material reactions, and heat-treating the raw materials to achieve high conduction characteristics without length differences that could cause warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If superconducting solder is used to connect MgB2 superconducting wires, then superconductive connection is achieved, but the operating temperature is limited to below 10K due to the low critical temperature of the solder
Solution Approach 1:
The invention extracts and removes the limiting factor (superconducting solder with low critical temperature) from the connection system. Instead of using solder, the patent directly connects MgB2 superconducting wires through a metal tube, eliminating the temperature limitation imposed by solder's critical temperature while maintaining superconductive connection reliability.
Solution Approach 2:
The invention uses a composite connection structure consisting of a metal tube containing multiple MgB2 superconducting wires that are in direct contact with each other. This composite structure enables superconductive connection without relying on solder, allowing operation at temperatures up to the MgB2 critical temperature (approximately 39K).
2Reliability
If superconducting wires are inserted into a metal tube for connection, then superconductive connection is achieved, but mechanical fragility and wire separation occur due to thermal strain
Solution Approach 1:
The invention applies preliminary action by inserting the superconducting wires into the metal tube and establishing their positions before the superconductive connection process. The wires are pre-positioned and secured within the tube, which prevents mechanical fragility and separation during subsequent thermal cycling and operation.
Solution Approach 2:
The metal tube acts as a flexible protective shell that constrains and protects the superconducting wires. This tube structure provides mechanical strength while allowing thermal expansion and contraction, preventing wire separation due to thermal strain during operation.
3Strength
If stabilizing materials are present in the superconducting wires, then wire strength is improved, but reaction interference occurs during heat treatment that degrades conduction characteristics
Solution Approach 1:
The invention extracts and removes the harmful stabilizing materials from the superconducting wire structure before the heat treatment process. By eliminating these materials that cause unwanted reactions with MgB2, the patent prevents degradation of conduction characteristics while maintaining the necessary mechanical strength through the wire construction.
Solution Approach 2:
The invention performs preliminary removal of stabilizing materials before the heat treatment process. This preliminary action prevents the harmful reactions that would otherwise occur during heat treatment, ensuring high conduction characteristics are achieved while the wire maintains its structural integrity.
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 high conduction characteristics with reduced variation and prevents wire separation from the sintered body due to thermal strain, enabling stable superconductive connections at higher operating temperatures.
Implementation Method 1
charging a mixed powder of magnesium and boron into the container, and pressurizing and heat-treating the mixed powder. In patent document 2, the mixed powder of magnesium and boron charged in the container is heat-treated to produce a sintered body of MgB2 between the superconducting wires.
Implementation Method 2
heat-treating the raw materials to achieve high conduction characteristics
Implementation Method 3
Magnesium diboride (MgB2) is a superconductor having a higher critical temperature than NbTi, Nb3Sn, and the like. MgB2 does not require cooling using liquid helium, and freezer cooling can be used for it.
Data Source
AI summary
A superconducting wire connector includes superconducting wires and a sintered body containing MgB2. The superconducting wires are connected by the sintered body. At least one of the superconducting wires includes a superconducting core having a first outer surface. The sintered body is in contact with the first outer surface. A method of connecting superconducting wires by a sintered body containing MgB2 includes exposing a superconducting core of at least one of the superconducting wires by removing a portion, positioned in the middle in a longitudinal direction of the at least one of the superconducting wires, of a metal sheath disposed around the superconducting core, disposing the at least one of the superconducting wires through a container, filling the container with a raw material of MgB2, and forming the sintered body being in contact with an outer surface of the superconducting core by sintering the raw material filled in the container.