Diffusion Block for Evacuated Instrument Sealing
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Solution Overview
Problem
Inertial sensors and similar instruments operating in evacuated environments face performance degradation and reduced lifetime due to gas diffusion through materials like helium, which can penetrate even when the instrument is environmentally sealed.
Innovation Solution
A diffusion block made of non-diffusive materials, such as ceramic, is coupled to the instrument housing to create an evacuated cavity between the barrier and the diffusion block, featuring through-electrodes that extend through the block and are electrically coupled to instrument electrodes, thereby reducing gas diffusion into the instrument chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If environmental sealing is used to protect against gas diffusion, then most gases are blocked, but helium and other noble gases can still diffuse through materials like glass feedthroughs and penetrations
Solution Approach 1:
The sealing system is divided into multiple segments: the barrier provides primary sealing against most gases, while the diffusion block with non-diffusive material provides specialized protection against helium and noble gases. This segmented approach allows each component to address specific gas diffusion challenges.
Solution Approach 2:
The system uses composite sealing architecture combining barrier materials (effective against most gases) with non-diffusive materials (effective against helium and noble gases). The diffusion block is formed from non-diffusive material and coupled to the instrument housing to create a composite sealing system that addresses the limitations of single-material sealing.
2Ease of operation
If a barrier with electrodes is used to seal the evacuated chamber, then electrical coupling is maintained, but gas diffusion can still occur through the barrier material
Solution Approach 1:
The diffusion block acts as an intermediary component between the barrier and the instrument housing. It provides an additional sealing layer that specifically addresses gas diffusion through the barrier material, while the through-electrodes maintain electrical coupling. The diffusion block with non-diffusive material mediates between the electrical requirements and the vacuum seal integrity requirements.
3Ease of manufacture
If materials with high gas permeability are used for the barrier, then electrode penetration is easier, but gas diffusion into the evacuated volume increases
Solution Approach 1:
The sealing function is segmented between the barrier (which accommodates electrode penetration) and the diffusion block (which provides gas diffusion protection). This allows the barrier to be manufactured with electrode penetration capabilities while the diffusion block addresses the gas diffusion issue that results from using permeable barrier 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
This configuration significantly mitigates gas diffusion into the evacuated chamber, ensuring the instrument operates more accurately and has a longer lifespan by isolating the interior from atmospheric gases.
Implementation Method 1
atmospheric gasses that diffuse into the evacuated volume of the instrument can result in a compromised performance of the instrument
Implementation Method 2
evacuating the chamber and sealing the evacuated chamber with a barrier
Data Source
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AI summary
Instrument system (400), such as a gyroscope, includes instrument components (408) at least partially disposed in an evacuated chamber (410) within an instrument housing (406). The system also includes a barrier (412) that is configured to seal the evacuated chamber (410). The barrier (412) includes a plurality of instrument electrodes (414) that are electrically coupled to the instrument components (408) and extending through the barrier (412). The system further includes a diffusion block (416) formed of a non-diffusive material and coupled to the instrument housing (406) to seal an evacuated cavity (418) within the instrument housing (406) between the barrier (412) and the diffusion block (416).