Planar Cryopanel Structure with Offset Slats for Gas Separation
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Solution Overview
Problem
Cryopumps face reduced gas capture efficiency over time due to saturation of capturing surfaces and interference from type I gases, which affects the pumping performance and requires frequent regeneration, and there is a challenge in balancing conductance and thermal radiation shielding.
Innovation Solution
A two-stage cryopump design featuring a planar second stage cryopanel array with flat panels and a first stage array of longitudinally offset slats, where some panels are not coated with adsorbent material to protect the adsorbent-coated surfaces from non-type III gases, allowing type III gases like hydrogen to be captured effectively while maintaining pumping speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cryopanel structure is coated with adsorbent material to capture type III gases, then pumping speed for type III gases is improved, but the adsorbent surfaces become saturated and require frequent regeneration
Solution Approach 1:
The cryopanel structure is divided into two functional zones: a first stage array of slats that captures type I gases, and a second stage array of flat panels coated with adsorbent material for capturing type III gases. This segmentation allows each zone to specialize in different gas types, preventing saturation of the adsorbent surfaces by type I gases and extending their operational lifetime.
Solution Approach 2:
The first stage array of slats acts as an intermediary barrier between the pump inlet and the second stage adsorbent-coated panels. It captures and removes type I gases before they reach the adsorbent surfaces, protecting the adsorbent material from saturation and extending its operational lifetime while maintaining high pumping speed for type III gases.
2Temperature
If the first stage array is positioned to shield the second stage cryopanels from thermal radiation, then thermal load on cryopanels is reduced, but conductance of gas into the pump is reduced
Solution Approach 1:
The first stage array uses slats with specific geometric properties (angle, spacing, and orientation) that provide localized shielding. The slats are angled to block thermal radiation from reaching the second stage panels while maintaining open pathways for gas molecules to pass through, thus providing directional protection that distinguishes between thermal radiation and gas flow.
Solution Approach 2:
The array is segmented into multiple slats arranged in a specific pattern, where each slat contributes to both thermal shielding and gas conductance. The segmentation allows optimization of individual slat properties to achieve the dual function of blocking thermal radiation while maintaining adequate gas flow channels.
3Adaptability or versatility
If the cryopanel structure uses a circular configuration to match the vacuum chamber outlet, then symmetry and matching are improved, but manufacturing and assembly complexity increases
Solution Approach 1:
The invention deliberately adopts an asymmetric planar configuration with rectangular panels and slats instead of a conventional circular arrangement. This asymmetric design simplifies manufacturing and assembly while maintaining effective functionality through the strategic arrangement of panels and slats in a rectangular footprint.
Solution Approach 2:
The design transitions from a circular two-dimensional configuration to a rectangular two-dimensional configuration, changing the geometric dimensionality approach. This dimensional change allows for simpler manufacturing processes and easier assembly while achieving the same functional objectives through optimized panel and slat arrangement.
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 design enhances the lifetime of adsorbent-coated surfaces, maintains stable pumping speed, and reduces the frequency of regeneration cycles by shielding adsorbent surfaces from contaminants like photoresist, ensuring effective capture of type III gases while preventing degradation.
Implementation Method 1
Type I gases that reach the cryopanels condense on them blocking type III gases from being cryoadsorbed
Implementation Method 2
a second stage at a lower temperature for capturing type II gases such as Nitrogen and in some embodiments for cryoadsorbing type III gases such as hydrogen
Implementation Method 3
provides radiation shielding to the lower temperature array and shields it from type I gases such as water vapour
Data Source
AI summary
A cryopump comprising: a pump inlet, a two stage refrigerator; a first stage array thermally coupled to a first stage of said two stage refrigerator; and a cryopanel structure coupled to a second stage of said two stage refrigerator is disclosed. The cryopanel structure comprises at least three flat panels. The first stage array is mounted between the pump inlet and the cryopanel structure, and comprises a plurality of slats, the plurality of slats each being mounted such that a side of each of the plurality of slats closest to the cryopanel structure is substantially aligned and offset longitudinally with respect to a corresponding one of said at least three flat panels.