Composite Vacuum Vessel for MRI Eddy Current Reduction
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Solution Overview
Problem
Existing MRI vacuum vessels, whether metallic or non-metallic, face challenges such as gas permeability, moisture issues, and eddy current-induced field distortions, which compromise the vacuum operation and imaging quality.
Innovation Solution
A composite sealed vessel is developed, comprising a non-metallic inner and outer containment pieces with metallic flanges and linings, forming a leak-tight pressure boundary to minimize eddy current losses and maintain vacuum integrity, using materials like fiberglass and thin metallic sheets to reduce AC field interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If non-metallic vacuum vessels are used, then eddy current losses are reduced, but gas permeability and moisture issues occur
Solution Approach 1:
The invention uses a composite structure combining non-metallic vacuum vessel material (to reduce eddy currents) with a metallic foil vapor barrier layer (to prevent gas permeability). The non-metallic material forms the main vessel body while the metallic foil is applied as a thin coating or liner to provide the necessary vapor barrier properties, thus achieving both reduced eddy current losses and maintained vacuum integrity.
2Reliability
If thin metallic foils are used over non-metallic vacuum composite structures, then vapor barrier is provided, but sealing at flange joints fails
Solution Approach 1:
The invention employs a thin metallic foil that is sufficiently flexible to conform to the flange joint surfaces and maintain sealing under vacuum conditions. The foil is applied in a manner that allows it to bridge minor surface irregularities at the flange interfaces, ensuring continuous sealing while maintaining the vapor barrier function.
Solution Approach 2:
The invention optimizes the thickness and material properties of the metallic foil to achieve the right balance between providing adequate vapor barrier protection and maintaining flexibility for proper sealing at flange joints. By carefully controlling the foil parameters (thickness, composition, flexibility), both vapor barrier and sealing requirements are satisfied.
3Strength
If metal vacuum vessels are used, then structural strength is sufficient, but eddy currents and field distortions occur
Solution Approach 1:
The invention creates a composite vacuum vessel system where the primary structural component is non-metallic material that does not generate eddy currents, while a thin metallic foil layer is added specifically for vapor barrier protection. This composite approach allows the bulk structure to remain non-metallic (avoiding eddy currents) while still providing necessary vacuum sealing through the metallic layer.
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 reduces eddy current losses and maintains a reliable vacuum, minimizing field distortions and ensuring efficient operation of MRI systems by creating a strong, impermeable, and sealed vacuum environment.
Implementation Method 1
maintaining a vacuum pressure within the cavity
Implementation Method 2
the external lining comprises thin metallic sheets welded over the inner containment piece and the two flanges
Data Source
AI summary
A composite sealed vessel is provided. The vessel includes a non-metallic, generally cylindrical inner containment piece, a non-metallic, generally cylindrical outer containment piece disposed around the inner containment piece. A pair of non-metallic flanges are disposed at ends of the inner and outer containment pieces to form a closed structure defining a cavity therein. The vessel also includes a metallic external lining disposed over the closed structure to form a leak-tight pressure boundary.