Flexible Thermal Radiation Shield for Superconducting Magnet Assembly

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Solution Overview

Problem

Conventional thermal radiation shielding methods for superconducting magnets in MRI systems are cumbersome, time-consuming, and can increase heat-load due to electrical conductivity issues, especially when applying foil or laminate coatings to complex shapes, and additional 4K shields are costly and heavy.

Innovation Solution

A flexible, self-supporting radiation shield made of low-emissivity coated polymer material, such as double-aluminised PET, is placed between the cryogen vessel or magnet structure and the conventional thermal radiation shield, eliminating the need for surface coatings and reducing assembly complexity while maintaining low in-plane thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If foil or laminate coatings are applied to thermal radiation shields, then thermal radiation shielding is improved, but assembly complexity and time increase due to complex shapes

Engineering Contradiction:
Improvethermal radiation heat-loadVSAvoidassembly complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent uses a flexible radiation shield made of thin film material with low emissivity coating that can conform to complex magnet geometries without requiring rigid structures or complex assembly procedures. The flexible nature allows easy installation while maintaining effective thermal radiation shielding.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The flexible radiation shield is designed as a simple, lightweight component that can be easily replaced if needed, reducing the impact of assembly complexity. The thin film construction makes it inexpensive and simple to install compared to rigid coated shields.

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

2Object-affected harmful factors

If foil or laminate coatings are applied to thermal radiation shields, then thermal radiation shielding is improved, but heat-load increases due to electrical conductivity issues

Engineering Contradiction:
Improvethermal radiation shieldingVSAvoidheat-load
Core Design Contradiction:
Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The flexible thin film radiation shield uses a low emissivity coating on a flexible substrate that provides effective thermal radiation shielding without the electrical conductivity problems associated with traditional foil coatings. This reduces eddy current losses and associated heat-load in the presence of time-varying magnetic fields.

Inventive Principle:
Principle #30Flexible shells and thin films

3Object-affected harmful factors

If additional 4K shields are added, then thermal radiation shielding is improved, but weight and cost increase

Engineering Contradiction:
Improvethermal radiation shieldingVSAvoidshield weight
Core Design Contradiction:
Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

The flexible radiation shield provides effective thermal radiation shielding with minimal weight due to its thin film construction. It eliminates the need for heavy rigid 4K shields while maintaining shielding effectiveness through its low emissivity coating and flexible design that can conform to the magnet geometry.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The radiation shield uses a composite structure combining a flexible substrate with a low emissivity coating layer, providing effective thermal radiation shielding with minimal weight. This composite approach replaces heavy single-material shields with a lightweight multi-layer construction.

Inventive Principle:
Principle #40Composite materials

4Object-affected harmful factors

If conventional thermal radiation shields are used, then radiation protection is provided, but cool-down time increases due to mass

Engineering Contradiction:
Improvethermal radiation protectionVSAvoidcool-down time
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The flexible thin film radiation shield has minimal mass compared to conventional rigid shields, allowing the magnet system to cool down much faster while still providing effective thermal radiation protection. The thin film construction reduces thermal mass without sacrificing shielding capability.

Inventive Principle:
Principle #30Flexible shells and thin films

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 flexible shield effectively reduces thermal radiation heat-load by floating to an intermediate temperature, minimizing radiation emission towards the cold surface, and is quicker to assemble and lighter in mass, reducing overall system heat-load and cool-down time.

Implementation Method 1

The thermal radiation shield 16 acts to prevent thermal radiation from the outer vacuum chamber from reaching the cryogen vessel

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

The flexible shield effectively reduces thermal radiation heat-load by floating to an intermediate temperature, minimizing radiation emission towards the cold surface

Methodology Applied
Scientific EffectThermal floatation:

Implementation Method 3

A flexible, self-supporting radiation shield made of low-emissivity coated polymer material, such as double-aluminised PET

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 4

maintaining low in-plane thermal conductivity

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP3884290B1A self-supporting flexible thermal radiation shield for a superconducting magnet assembly
Publication Date: 2024.08.14 SIEMENS HEALTHCARE LTD
  • EP3884290B1 patent drawingFigure 1
  • EP3884290B1 patent drawingFigure 2
  • EP3884290B1 patent drawingFigure 3~4

AI summary

A self-supporting flexible shield for location between a warm surface (16) and a cold mass (10, 12) so as to substantially enclose the cold mass, wherein the self-supporting flexible shield comprises a shaped plastic sheet with a low emissivity coating on both of its sides.