Cryopump Plate Member Segmentation for Gas Condensation

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Solution Overview

Problem

Cryopumps face inefficiency due to gas vaporization at the interface between cryopanels of different temperatures, limiting the amount of gas condensed and thus the pumping capacity.

Innovation Solution

A cryopump design featuring a first cryopanel with a radiation shield and a plate member across the opening, including a gas passing region with numerous pores and a gas shielding region, where the plate member is thermally connected to the first stage and encloses a second cryopanel cooled to a lower temperature, allowing gases to condense on the second cryopanel while restricting gas flow to enhance condensation efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If gases are allowed to pass freely through the cryopump, then the pumping speed is high, but gases vaporize at the interface between cryopanels and are released into the environment, limiting the amount of gas condensed

Engineering Contradiction:

Improveamount of gas condensedVSAvoidpumping capacity

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The plate member is divided into a gas passing region with pores and a gas shielding region without pores. This segmentation allows different regions to perform different functions: the gas passing region enables gas flow to maintain pumping speed, while the gas shielding region prevents gas vaporization at the interface, thereby resolving the contradiction between pumping capacity and gas condensation amount.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the plate member are given different properties: the gas passing region has porous structure to allow gas flow, while the gas shielding region has solid structure to block gas. This local differentiation of properties enables the system to simultaneously achieve high pumping speed and prevent gas vaporization, resolving the technical contradiction.

Inventive Principle:

Principle #3Local quality

2Reliability

If a solid plate member is used across the main opening, then gas vaporization is prevented, but gas flow is blocked and pumping speed decreases

Engineering Contradiction:

Improvegas condensation efficiencyVSAvoidpumping speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The plate member is segmented into regions with different permeability characteristics. The gas passing region contains pores that allow gas flow while the gas shielding region provides solid barrier. This segmentation enables the system to maintain both high gas condensation efficiency and adequate pumping speed simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The gas passing region utilizes porous structure in the plate member to allow gas flow while maintaining structural integrity. The pores enable gas molecules to pass through to reach the second cryopanel for condensation, preventing the complete blockage of gas flow that would occur with a solid plate, thus maintaining pumping speed while ensuring reliable gas condensation.

Inventive Principle:

Principle #31Porous materials

3Quantity of substance

If the condensing layer grows thick on the cryopanel, then more gas is condensed, but the layer contacts the higher-temperature cryopanel causing vaporization

Engineering Contradiction:

Improvetotal amount of gas condensedVSAvoidcondensing layer stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The gas shielding region acts as an intermediary barrier between the condensing layer on the second cryopanel and the first cryopanel. By blocking gas molecules from reaching the warmer interface region, the gas shielding region prevents vaporization of the condensing layer, allowing the layer to grow thicker and accumulate more condensed gas without stability issues.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 improves the distribution and height of the condensing layer, preventing premature vaporization and maximizing the amount of gas condensed, thereby enhancing the cryopump's pumping performance.

Implementation Method 1

condensing the gases on the second cryopanel

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 2

a second cryopanel opposed to the plate member and cooled to a lower temperature than that of the first cryopanel

Methodology Applied

Scientific EffectTemperature gradient: Temperature Gradient

Implementation Method 3

The plate member includes a gas passing region having a multitude of pores through which gases pass to be condensed on the second cryopanel and a gas shielding region formed at a different position in the main body portion from that of the gas passing region

Methodology Applied

Scientific EffectGas flow restriction:

Data Source

PatentUS10030640B2Cryopump and vacuum pumping method

Publication Date: 2018.07.24 SUMITOMO HEAVY IND LTD

AI summary

A cryopump includes a first cryopanel including a radiation shield and a plate member across a shield opening and a second cryopanel enclosed by the first cryopanel and cooled to a lower temperature than that of the first cryopanel. The plate member includes a plate main portion and a plate peripheral portion adapted to attach the plate main portion to the radiation shield. The plate main portion includes a gas passing region having a multitude of pores through which gases pass to be condensed on the second cryopanel and a gas shielding region formed at a different position in the plate main portion from that of the gas passing region.