Superconducting Joint for Bi-2212 Wire Eliminating Ohmic Losses

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Solution Overview

Problem

Conventional soldered electrical joints in high-temperature superconducting (HTS) conductors, such as Bi-2212 round wire, introduce ohmic losses that lead to heat generation, instability, and premature quenching in high-field magnet systems, making them impractical for commercial production and limiting the operational stability of superconducting magnets.

Innovation Solution

A method for establishing superconducting electrical joints between Bi-2212 conductor segments using a chemically compatible joint forming material and high-temperature heat treatment, which is compatible with the high-pressure conditions required for Bi-2212 conductor formation, allowing for the creation of longer HTS conductors with negligible ohmic resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If conventional soldered electrical joints are used to connect HTS conductor segments, then the conductors can be joined to form longer lengths, but ohmic losses occur that generate heat and reduce system stability

Engineering Contradiction:
Improveconductor lengthVSAvoidohmic loss
Core Design Contradiction:
Length of stationary objectVSLoss of energy

Solution Approach 1:

The invention changes the electrical resistance parameter of the joint from resistive (conventional soldered) to superconducting by using a superconducting material for the joint forming material. This allows the joint to maintain zero or near-zero resistance at operating temperatures, eliminating ohmic losses while enabling conductor connection.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite structure where a superconducting material (such as NbTi or Nb3Sn) is combined with the HTS conductor segments (Bi-2212). The superconducting joint forming material creates a composite joint that maintains superconducting properties across the connection point, resolving the contradiction between joining conductors and maintaining low resistance.

Inventive Principle:
Principle #40Composite materials

2Length of stationary object

If conventional soldered electrical joints are used, then conductors can be connected, but heat generation leads to premature quenching and loss of superconducting properties

Engineering Contradiction:
Improveconductor lengthVSAvoidsuperconducting stability
Core Design Contradiction:
Length of stationary objectVSReliability

Solution Approach 1:

The invention changes the thermal and electrical parameters of the joint by using superconducting material, which has zero resistance and therefore generates no heat at operating conditions. This eliminates the heat generation problem that leads to quenching, while maintaining the ability to connect conductor segments for extended lengths.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The superconducting joint forming material is designed to be consumed or transformed during the heat treatment process, creating a permanent superconducting bond. The joint material serves its purpose during manufacturing and then becomes part of the permanent superconducting structure, ensuring long-term reliability.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Length of stationary object

If resistive joints are used in high-field magnet systems, then conductors can be joined, but constant power supply is required to maintain operating current, increasing system complexity and cost

Engineering Contradiction:
Improveconductor lengthVSAvoidpower supply system
Core Design Contradiction:
Length of stationary objectVSDevice complexity

Solution Approach 1:

The invention changes the electrical resistance parameter of the joint to superconducting levels, enabling the magnet system to operate in persistence mode. Once charged, the superconducting joints maintain current without external power, eliminating the need for complex constant power supply systems and electronic control loops.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The superconducting joints enable the magnet system to be self-sufficient after initial charging. The persistent current mode allows the system to maintain its operating state without external intervention or complex control systems, as the superconducting joints prevent current decay naturally.

Inventive Principle:
Principle #25Self-service

4Length of stationary object

If conventional joining methods are used, then conductors can be connected, but ohmic losses alter current distribution over time, requiring field compensation measures

Engineering Contradiction:
Improveconductor lengthVSAvoidcurrent distribution stability
Core Design Contradiction:
Length of stationary objectVSStability of the object's composition

Solution Approach 1:

The invention changes the resistance parameter of the joint to superconducting levels, which prevents ohmic losses that would otherwise alter current distribution over time. This maintains stable current distribution and magnetic field characteristics without requiring field compensation measures.

Inventive Principle:
Principle #35Parameter changes

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 enables the formation of superconducting joints that maintain low losses and stability, allowing HTS magnets to operate in 'persistence' with minimal current decay, reducing the need for constant power supply and field compensation, and enhancing the practicality and efficiency of high-field magnet systems.

Implementation Method 1

subjecting the first Bi-2212 conductor segment and the second Bi-2212 conductor segment to a superconducting heat treatment effective to establish the superconducting properties of the first Bi-2212 conductor segment and the second Bi-2212 conductor segment and to substantially simultaneously create a superconducting joint

Methodology Applied
Scientific EffectSuperconductivity: Superconductivity

Data Source

PatentUS9966167B1Superconducting joint for high-temperature superconducting Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8+x </sub>(Bi-2212) wire
Publication Date: 2018.05.08 FLORIDA STATE UNIV RES FOUND INC

AI summary

The present invention provides a system and method for producing superconducting joints between superconductive segments of a Bi-2212 high-temperature superconducting (HTS) conductor, thereby eliminating the heat generating resistive joints that are commonly known in the art for connecting two or more smaller Bi-2212 conductive segments to create an Bi-2212 conductor of adequate length.