Flexible HTS Current Lead Structure for Thermal Shrinkage and Bending

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Solution Overview

Problem

Existing HTS current leads face mechanical issues due to thermal shrinkage and bending strain, leading to cracks and reduced critical current, particularly in flexible designs.

Innovation Solution

An HTS current lead design comprising a plurality of HTS tapes, a braided sleeve, and a stabilizer material impregnated within a leak-tight sheath, allowing the lead to be reshaped by heating and cooling to maintain a desired configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If flexible HTS current leads are used to accommodate thermal shrinkage and mechanical movement, then adaptability is improved, but the HTS tape develops cracks and critical current is reduced due to bending strain

Engineering Contradiction:

Improveadaptability to thermal shrinkageVSAvoidcritical current performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The HTS current lead is segmented into multiple HTS tapes (typically 3-7 tapes) arranged in a cable configuration. Each tape can independently accommodate some thermal shrinkage and mechanical deformation, preventing any single tape from experiencing excessive bending strain that would cause cracks and critical current loss.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The current lead uses a composite structure combining HTS tapes with a stabilizer material matrix (such as epoxy or polymer). This composite construction allows the HTS tapes to maintain their superconducting properties while the stabilizer material provides mechanical support and flexibility, enabling the cable to bend without damaging the HTS tapes.

Inventive Principle:

Principle #40Composite materials

2Strength

If rigid HTS current leads are used to maintain structural stability, then strength is improved, but mechanical issues occur due to thermal shrinkage when the cryostat is cooled

Engineering Contradiction:

Improvestructural stabilityVSAvoidaccommodation of thermal shrinkage

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The current lead transitions from a rigid structure to a flexible dynamic structure that can adapt to thermal changes. The flexible cable construction with multiple HTS tapes and stabilizer material allows the lead to dynamically adjust its shape and accommodate thermal shrinkage of the cryostat during cooling cycles, preventing mechanical failure.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The current lead employs a flexible cable construction where HTS tapes are embedded in a flexible stabilizer material matrix. This flexible shell structure allows the current lead to bend and deform elastically during thermal cycling, accommodating cryostat shrinkage without causing mechanical damage to the HTS tapes.

Inventive Principle:

Principle #30Flexible shells and thin films

3Ease of operation

If HTS tape is bent with small radius to achieve flexibility, then ease of operation is improved, but the HTS tape develops cracks and critical current is reduced

Engineering Contradiction:

ImproveflexibilityVSAvoidcritical current performance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

By dividing the current lead into multiple HTS tapes rather than using a single thick tape, each individual tape experiences reduced bending stress. The segmented structure allows the cable to achieve flexibility through the collective bending of multiple thinner tapes, each within its safe bending radius limits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The composite construction of HTS tapes embedded in stabilizer material provides a minimum bending radius that protects the HTS tapes from excessive strain. The stabilizer material acts as a protective matrix that distributes and reduces the bending stress on individual HTS tapes, enabling flexibility while maintaining critical current performance.

Inventive Principle:

Principle #40Composite materials

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

The design provides structural stability and prevents damage from bending, maintaining high critical current performance by using a stabilizer material with a melting point above the HTS critical temperature but below its degradation temperature.

Implementation Method 1

a stabiliser material impregnating the HTS cable and the braided sleeve

Methodology Applied

Scientific EffectImpregnation: Absorption (physical)

Implementation Method 2

The HTS current lead is heated to a temperature above the meting point of the stabiliser material

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

The HTS current lead is allowed to cool while maintaining it in the desired shape

Methodology Applied

Scientific EffectSolidification: Freezing

Data Source

PatentUS20250316408A1Flexible HTS current leads

Publication Date: 2025.10.09 TOKAMAK ENERGY

AI summary

According to a first aspect, there is provide an HTS current lead. The HTS current lead comprises an HTS cable comprising a plurality of HTS tapes; a braided sleeve around the HTS cable; and a stabiliser material impregnating the HTS cable and the braided sleeve. The stabiliser material has a melting point above a critical temperature of the HTS tapes and below a thermal degradation temperature of the HTS tapes.