Cryogenic Coil Assembly Radial Channel Bonding

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Solution Overview

Problem

Flat spiral coils used at cryogenic temperatures often delaminate from their substrates due to differential thermal contraction, which exceeds the bonding capacity of traditional epoxy-resin bonds, leading to geometric instability and warping.

Innovation Solution

A cryogenic coil assembly featuring a substrate with radial channels and a chemical bonding agent within these channels, which provides both a chemical and mechanical bond to prevent delamination, allowing for the use of materials with mismatched thermal expansion coefficients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional epoxy-resin bonding is used to attach the coil to the substrate, then the bonding process is simple and materials with mismatched thermal expansion coefficients can be used, but the bond fails under differential thermal contraction at cryogenic temperatures causing delamination

Engineering Contradiction:

Improvematerial selection flexibilityVSAvoidbond stability at cryogenic temperatures

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The bonding system is segmented into multiple functional layers: a compliant intermediate layer between the substrate and rigid epoxy-resin bond. This intermediate layer absorbs differential thermal contraction stresses, allowing the use of materials with mismatched thermal expansion coefficients while maintaining bond stability at cryogenic temperatures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bonding system uses a composite structure combining a compliant intermediate material with traditional epoxy-resin. This composite approach provides both the flexibility needed to accommodate thermal expansion differences and the structural integrity required for reliable bonding at cryogenic temperatures.

Inventive Principle:

Principle #40Composite materials

2Reliability

If materials are selected to match thermal expansion coefficients, then bond stability at cryogenic temperatures is improved, but thermal conductivity and workability of materials are compromised

Engineering Contradiction:

Improvebond stability at cryogenic temperaturesVSAvoidmaterial workability and thermal conductivity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

A compliant intermediate layer acts as a mediator between the substrate and the coil, absorbing thermal expansion differences without requiring the main bonding materials to have matched thermal coefficients. This allows use of materials with superior thermal conductivity and workability while maintaining bond stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Temperature

If the coil is cooled to superconducting temperatures, then superconductivity is achieved, but thermal contraction creates shear forces that exceed the epoxy-substrate bond capacity

Engineering Contradiction:

Improveoperating temperature for superconductivityVSAvoidbond strength under thermal stress

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The compliant intermediate layer is installed beforehand to cushion and absorb the shear forces generated during thermal contraction when cooling to superconducting temperatures. This prevents the forces from exceeding the epoxy-substrate bond capacity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The bonding system's mechanical properties are changed by introducing a compliant intermediate layer with appropriate viscoelastic characteristics that can accommodate large deformations during thermal cycling to cryogenic temperatures while maintaining bond integrity.

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

The solution effectively prevents delamination and maintains geometric stability even under significant thermal contraction, enabling the use of a wide range of materials for cryogenic applications without compromising thermal conductivity or workability.

Implementation Method 1

a chemical bonding agent for bonding the spiral coil to the substrate

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 2

permitting the chemical agent to cure, wherein during curing, the chemical agent seeps into the radial channels

Methodology Applied

Scientific EffectCuring: Photopolymerisation

Implementation Method 3

the wire passes through a bath before being wound into the coil, wherein the bath contains the chemical bonding agent

Methodology Applied

Scientific EffectCoating: Coatings

Implementation Method 4

large changes in temperature caused by cooling a coil to superconducting temperatures results in thermal contraction of the wires, substrate and epoxy resin creating stresses

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS10192681B2Method of manufacturing a cryogenic coil assembly

Publication Date: 2019.01.29 GEDEX

AI summary

A cryogenic coil assembly including a coil substrate with a flat surface, and a number of radial channels cut into a region of the flat surface. The cryogenic coil assembly also includes a spiral coil covering the radial channels, and a chemical bonding agent for bonding the spiral coil to the coil substrate. The chemical bonding agent is present within the radial channels.