Cryopump Lateral Gap Design for Condensation Capacity
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Solution Overview
Problem
Cryopumps fail to efficiently condense gases due to vaporization at the interface between cryopanels of different temperatures, limiting their gas-handling capacity.
Innovation Solution
A cryopump design featuring a two-stage refrigerator with a first cryopanel acting as a radiation shield and a second cryopanel enclosed by the first, where the second cryopanel is thermally connected to a lower temperature stage, and the shape and arrangement of the cryopanels prevent initial contact between the condensing layer and the radiation shield, allowing for increased gas condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional cryopump design with two cryopanels of different temperatures is used, then the structure is simple and easy to manufacture, but the condensing layer contacts the higher-temperature cryopanel causing vaporization and limiting the maximum gas condensation capacity
Solution Approach 1:
The radiation shield is divided into a shield portion and an attaching pedestal that are spatially separated, creating a segmented structure. This segmentation allows the condensing layer to extend uniformly toward the shield portion without premature contact with the pedestal, thereby increasing the gas condensation capacity while maintaining structural simplicity
Solution Approach 2:
The patent introduces a lateral dimension by positioning the attaching pedestal laterally to the second cryopanel rather than directly above or below it. This lateral arrangement creates a three-dimensional gap structure that prevents condensing layer contact with the pedestal, effectively utilizing spatial dimensions to solve the vaporization problem
2Productivity
If the condensing layer grows on the lower-temperature cryopanel, then gas condensation occurs efficiently, but the condensing layer eventually contacts the higher-temperature cryopanel causing vaporization and releasing gases
Solution Approach 1:
The attaching pedestal acts as an intermediary element that spatially separates the higher-temperature cryopanel from the condensing layer. By positioning the pedestal laterally and creating a lateral gap, it serves as a mediator that prevents direct contact between the condensing layer and the cryopanel, thereby maintaining gas retention stability without compromising condensation efficiency
Solution Approach 2:
The lateral gap and gap part are designed in advance to provide a buffer space between the condensing layer and the attaching pedestal. This pre-established spatial buffer prevents premature contact and vaporization, ensuring reliable gas retention throughout the operation of the cryopump
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 design enhances the maximum amount of gas condensed within the cryopump by preventing premature vaporization and ensuring uniform condensation distribution, thereby improving the cryopump's efficiency and capacity.
Implementation Method 1
a refrigerator (16) including a first stage (22) and a second stage (24) cooled to a lower temperature than that of the first stage (22)
Implementation Method 2
Gases condense on a lower-temperature cryopanel
Implementation Method 3
a first cryopanel including a radiation shield having a main opening and an inlet cryopanel disposed at the main opening
Data Source
AI summary
A cryopump includes a cryopump including: a refrigerator; a first cryopanel including a radiation shield; and a second cryopanel enclosed by the first cryopanel and cooled to a lower temperature than that of the first cryopanel. The radiation shield includes an attaching pedestal located lateral to the second cryopanel for attachment of the refrigerator to the radiation shield, and a shield portion adjacent to the attaching pedestal and enclosing the second cryopanel. A lateral gap is formed between the second cryopanel and the attaching pedestal. A gap part continuing into the lateral gap is formed between the second cryopanel and the shield portion. The second cryopanel is shaped and/or located such that the lateral gap is comparable in width to the gap part.