Persistent Critical Current Measurement for REBCO Superconducting Wires

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional methods for evaluating superconductor quality and performance, such as critical current, are inadequate for applications like MRI and SMES, as they do not account for persistent current modes, which are crucial for the operation of these magnets.

Innovation Solution

A method and system for measuring superconducting critical current in persistent mode by using a closed-loop superconductor assembly, cooling it below the superconducting critical temperature, removing the magnetic field to initiate a persistent current, and measuring the variation in magnetic fields as temperature increases, allowing calculation of the persistent critical current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional critical current measurement methods are used, then the measurement process is simple and straightforward, but the measurement results do not accurately reflect the superconductor's performance in persistent mode applications

Engineering Contradiction:

Improveaccuracy of superconductor quality evaluationVSAvoidcomplexity of measurement system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

A pickup coil is introduced as an intermediary element to indirectly measure the persistent current in the superconducting loop. The pickup coil couples magnetically with the loop, allowing the current measurement without direct electrical contact, thus enabling accurate persistent mode measurement while maintaining system simplicity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces conventional electrical measurement methods with a magnetic coupling approach. By using magnetic field interaction between the superconducting loop and pickup coil, the system avoids complex electrical connections and achieves accurate measurement of persistent current through electromagnetic induction

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If conventional critical current parameters are used for magnet applications, then the evaluation process is straightforward, but the parameter does not reflect the actual operating conditions of persistent mode magnets

Engineering Contradiction:

Improvereliability of wire quality evaluation for MRI and SMESVSAvoidease of quality control in manufacturing

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the measurement parameter from conventional critical current (defined by electric field threshold) to persistent critical current (defined by magnetic flux conservation). This parameter change makes the measurement relevant to actual magnet operating conditions while maintaining a relatively simple measurement process through magnetic coupling

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The superconducting loop is first cooled below its critical temperature to establish the persistent current state before measurement. This preliminary cooling action ensures the superconductor is in the appropriate state for accurate persistent mode measurement, improving reliability without significantly complicating the manufacturing process

Inventive Principle:

Principle #10Preliminary action

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 provides a more accurate evaluation of superconductor quality and performance, particularly relevant for MRI and SMES applications, by measuring current levels in persistent mode, which is closer to real-world operational conditions, thereby improving the characterization and manufacturing of REBCO superconducting wires and tapes.

Implementation Method 1

lowering a temperature of the assembly below a superconducting critical temperature

Methodology Applied

Scientific EffectSuperconductivity: Superconductivity

Implementation Method 2

measuring a variation of a second magnetic field in the assembly in response to the increasing temperature

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10401393B2Method for determining persistent critical current of superconducting materials

Publication Date: 2019.09.03 UNITED STATES OF AMERICA THE AS REPRESENTED BY THE SEC OF THE ARMY

AI summary

A method of measuring superconducting critical current in persistent mode using superconducting closed loops which allow the persistent current to flow without any joints. This persistent critical current is different than traditional resistive critical current that is the upper limit of the superconducting current carrying capacity, and provides the information about the range of critical current in persistent mode that is more close to applications in MRI, SMES, and Maglev operations. The measurement can be used as a quality control method in the manufacturing process and a piece of crucial information to magnet manufacturers for the design and fabrication of magnet. The superconducting materials include the second generation superconducting wires (coated conductors) based on Rare Earth (RE) Barium Copper Oxide superconducting material (REBa.sub.2Cu.sub.3O.sub.6+x, REBCO), or any other type of superconducting wires that can be manufactured in the form of tape.