Cryopump Adsorbent Coating Strategy for Extended Regeneration Cycles
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Solution Overview
Problem
Cryopumps experience reduced effectiveness over time due to saturation of adsorbent coated surfaces with gas molecules, leading to shorter operation times between regeneration cycles.
Innovation Solution
Implementing a cryopump design where only a subset of the cryopanel surfaces are coated with adsorbent material, allowing non-type III gases to condense on uncoated surfaces before reaching the adsorbent, thereby protecting the adsorbent surfaces and extending their effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If all surfaces of cryopanels are coated with adsorbent material, then pumping speed and time between regenerations are increased, but the adsorbent surfaces become saturated with non-type III gases (such as photoresist) reducing their effectiveness
Solution Approach 1:
The patent applies local quality by coating only specific portions of the cryopanel surfaces with adsorbent material rather than uniformly coating all surfaces. The coated portions are strategically positioned to capture type III gases, while uncoated portions allow non-type III gases to condense without saturating the adsorbent. This selective coating approach maintains high pumping speed for hydrogen while preventing contamination of the adsorbent surface with photoresist and other non-type III gases.
2Productivity
If adsorbent coated surfaces are exposed to all gas molecules entering the pump, then all gases are captured, but the adsorbent becomes saturated faster reducing operation time between regenerations
Solution Approach 1:
The patent segments the cryopanel surfaces into distinct functional zones: coated regions dedicated to type III gas capture and uncoated regions for non-type III gas condensation. This segmentation ensures that non-type III gases such as photoresist are condensed on uncoated surfaces and do not reach the adsorbent material, thereby preventing saturation and extending the operational duration between regeneration cycles while maintaining effective gas capture capability.
3Productivity
If adsorbent material is used to capture type III gases, then hydrogen pumping is enhanced, but non-type III gases also adsorb on these surfaces reducing their lifetime
Solution Approach 1:
The patent introduces uncoated cryopanel surfaces as intermediary zones that intercept and condense non-type III gases before they can reach the adsorbent material. These intermediary uncoated surfaces act as protective barriers, allowing the adsorbent-coated surfaces to focus exclusively on capturing type III gases like hydrogen, thereby extending the adsorbent surface lifetime while maintaining enhanced hydrogen pumping speed.
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 increases the lifetime between regeneration cycles by ensuring that adsorbent surfaces primarily capture type III gases, while reducing the degradation of pumping speed over time.
Implementation Method 1
when gases pass through the inlet into the pump vessel, at least some of the type I gases such as water vapour are condensed on the frontal array
Implementation Method 2
Type II gases, such as nitrogen, condense on the second stage array
Implementation Method 3
type III gases, such as hydrogen, helium and neon which have appreciable vapour pressures at 4K are adsorbed by an adsorbent such as activated carbon, zeolite or a molecular sieve that coats the second stage cryopanels
Data Source
Figure 1~2
Figure 3~4
AI summary
A cryopump with a pump inlet; a two stage refrigerator; a first stage array arranged thermally coupled to a first stage of the two stage refrigerator; and a cryopanel structure coupled to a second stage of the two stage refrigerator. Surfaces of the cryopanel structure have portions that are coated portion with an adsorbent material and other portions that are not coated with the adsorbent material.