Multi-Shell Magnetic Shielded Room for Low Residual Fields
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Solution Overview
Problem
Existing multi-shelled magnetically shielded rooms face limitations in achieving a better shielding effect and reducing residual magnetic fields due to the inherent remanent magnetic stray field of shielding materials, which is not optimally demagnetized by the complex room geometry.
Innovation Solution
The use of different soft magnetic alloys for outer and inner shells, where the outer shell has a higher maximum permeability and the inner shell has a higher initial permeability, along with the inclusion of non-magnetic conductive shells for additional shielding at higher frequencies, optimizes the shielding factor and reduces residual fields by selecting materials based on the field strength exposure of each shell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple shells of the same highly permeable material are used, then the shielding factor is improved through multiplicative effect, but the residual field cannot be sufficiently reduced due to remanent magnetic stray fields
Solution Approach 1:
The patent applies different soft magnetic materials with different permeability characteristics to different shells. The outer shell uses a material with higher maximum permeability (μmax1) while the inner shell uses a material with higher initial permeability (μi2). This local differentiation optimizes each shell's contribution to shielding while minimizing remanent fields, resolving the contradiction between achieving high shielding factor and reducing residual magnetic fields.
Solution Approach 2:
The patent employs composite material construction by combining different soft magnetic alloys in a multi-shell configuration. Each shell is made from a specifically selected soft magnetic material with tailored permeability properties, creating a composite shielding system that achieves both high shielding factor and low residual field through the synergistic effect of material differentiation.
2Reliability
If more shells are added to improve shielding, then the shielding factor increases, but the device complexity and material usage increase
Solution Approach 1:
Instead of uniformly increasing the number of shells, the patent applies local quality by differentiating material properties within a multi-shell structure. This allows optimization of shielding performance through material selection rather than simply adding more shells, thereby improving shielding factor while controlling device complexity.
Solution Approach 2:
The patent changes material parameters (permeability characteristics) rather than only changing structural parameters (number of shells). By selecting materials with different μi and μmax values for different shells, the patent achieves enhanced shielding factor while avoiding the linear increase in complexity that would result from simply adding more identical shells.
3Reliability
If highly permeable materials are used for all shells, then the shielding factor is maximized, but the residual field reduction is limited by the materials' remanent properties
Solution Approach 1:
The patent applies local quality by assigning different soft magnetic materials with different permeability characteristics to different shells. The outer shell uses material with higher maximum permeability while the inner shell uses material with higher initial permeability. This differentiation allows each shell to contribute optimally to shielding while minimizing remanent field generation, resolving the contradiction between maximizing shielding factor and reducing residual field.
Solution Approach 2:
The patent uses composite material construction with multiple soft magnetic alloys having different magnetic properties. This composite approach enables the shielding system to achieve both high shielding factor and effective residual field reduction by combining materials whose complementary permeability characteristics cancel out remanent effects while maintaining strong shielding performance.
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 enhances the overall shielding factor while minimizing material usage and effectively reducing residual magnetic fields within the shielded space, meeting more demanding technical specifications.
Implementation Method 1
The permeability of the individual shells is adjusted in relation to the position of the shell in the shielded room such that the outer shell has a higher maximum permeability than the inner shell, and the inner shell has a higher initial permeability than the outer shell
Implementation Method 2
one or more shells made of a highly electrically conductive material can be present to achieve an additional shielding effect at higher frequencies
Implementation Method 3
An example of this is the use of an additional shell made of aluminium
Data Source
AI summary
A multi-shelled shielded room is provided that has an outer shell with a first soft magnetic alloy having an initial permeability μi1 and a maximum permeability μmax1 and an inner shell with a second soft magnetic alloy having an initial permeability μi2 and a maximum permeability μmax2. The outer shell encases the inner shell and μmax1>μmax2 and μi2>μi1.