Cryopump Shield Cavity Segmentation for Uniform Condensing Layer Growth

Solution Overview

Problem

Cryopumps face limitations in gas capacity due to uneven growth of condensing layers on cryopanels, leading to increased pressure and reduced vacuum pumping efficiency when the condensing layer contacts the radiation shield or first cryopanel.

Innovation Solution

The design includes a cryopump with a radiation shield and multiple cryopanels arranged in a non-contact state, featuring a top cryopanel that partitions the shield cavity into upper and lower portions, and strategically positioned slits to equalize the growth speed of condensing layers, optimizing the internal space usage by adjusting the relative positions and sizes of cryopanel openings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If multiple cryopanels are arranged in the shield cavity to increase gas capacity, then the gas capacity limit is improved, but the condensing layer growth becomes uneven causing contact with the radiation shield and pressure increase

Engineering Contradiction:

Improvegas capacityVSAvoidvacuum pumping efficiency

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The shield cavity is segmented into multiple regions by strategically positioning cryopanels at different locations. The top cryopanel partitions the cavity into upper and lower portions, while additional cryopanels are positioned at intermediate heights. This segmentation allows uniform distribution of gas flow paths and condensing layer growth across all cryopanels, preventing any single panel from becoming overloaded and contacting the radiation shield.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different cryopanels are positioned at different locations within the shield cavity to create localized condensing regions. The top cryopanel is positioned near the inlet to capture incoming gas, while lower cryopanels are positioned at intermediate heights to capture gas that flows downward. This local quality approach ensures that each cryopanel operates within its optimal condensing capacity, maintaining uniform growth rates across all panels.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If the condensing layer grows uniformly on all cryopanels, then the gas capacity limit is maximized, but the structural design becomes more complex

Engineering Contradiction:

Improvegas capacityVSAvoidstructural design

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The shield cavity is segmented into multiple regions by strategically positioning cryopanels at different locations. The top cryopanel partitions the cavity into upper and lower portions, while additional cryopanels are positioned at intermediate heights. This segmentation allows uniform distribution of gas flow paths and condensing layer growth across all cryopanels, preventing any single panel from becoming overloaded and contacting the radiation shield.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Cryopanels are arranged in multiple vertical levels within the shield cavity rather than a single plane. The top cryopanel is positioned at a higher vertical level, while lower cryopanels are positioned at intermediate heights. This three-dimensional arrangement creates multiple gas flow paths and ensures uniform condensing layer growth across all panels, maximizing gas capacity without requiring complex lateral positioning mechanisms.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 enhances the gas capacity limit of the cryopump by ensuring uniform condensing layer growth, maximizing the use of internal space and preventing pressure increases, thus improving the vacuum pumping efficiency.

Implementation Method 1

a radiation shield that includes a shield main opening at the cryopump inlet, that defines a shield cavity continuing from the shield main opening in an axial direction, that is thermally connected to the high-temperature cooling stage

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

a refrigerator that includes a high-temperature cooling stage and a low-temperature cooling stage housed in the cryopump housing; a plurality of cryopanels that are each thermally connected to the low-temperature cooling stage

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 3

A cryopump is a vacuum pump trapping gases on a cryogenically-cooled cryopanel by means of condensation or adsorption

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 4

a radiation shield that includes a shield main opening at the cryopump inlet, that defines a shield cavity continuing from the shield main opening in an axial direction, that is thermally connected to the high-temperature cooling stage, that receives the low-temperature cooling stage in the shield cavity

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS9926920B2Cryopump

Publication Date: 2018.03.27 SUMITOMO HEAVY IND LTD

AI summary

A cryopump includes a top cryopanel that partitions a shield cavity into a shield cavity upper portion and a shield cavity lower portion. A radiation shield includes a shield main slit that communicates a shield outside gap into the shield cavity lower portion. The radiation shield may include a shield auxiliary slit that is formed at a different position from that of the shield main slit in an axial direction of the cryopump and that communicates the shield outside gap into the shield cavity lower portion. The shield auxiliary slit may be formed between the top cryopanel and the shield main slit in the axial direction.