Cryopump Radiation Shield Thermal Load Reduction
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Solution Overview
Problem
Cryopumps face challenges in improving pumping speed while minimizing the thermal load on low-temperature cryopanels, particularly when dealing with non-condensable gases, as the miniaturization of high-temperature cryopanels increases heat input and affects the efficiency of gas exhaustion.
Innovation Solution
The design incorporates a radiation shield thermally coupled to the high-temperature cooling stage, which extends axially from the cryopump intake port, and a top cryopanel accommodation compartment to reduce direct heat and gas incidence on the low-temperature cryopanel, enhancing the pumping speed while minimizing thermal load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the high-temperature cryopanel is miniaturized to improve pumping speed of non-condensable gases, then the pumping speed increases, but the thermal load on the low-temperature cryopanel increases
Solution Approach 1:
The cryopanel is divided into two distinct temperature zones: a high-temperature cryopanel section (first cooling temperature) and a low-temperature cryopanel section (second cooling temperature). This segmentation allows the high-temperature section to handle non-condensable gases while the low-temperature section handles condensable gases, resolving the thermal load issue while maintaining pumping speed.
Solution Approach 2:
The high-temperature cryopanel section acts as an intermediary between the gas intake and the low-temperature cryopanel section. It pre-cools and partially condenses gases before they reach the low-temperature section, reducing the thermal load on the low-temperature cryopanel while maintaining efficient pumping of non-condensable gases.
2Productivity
If the high-temperature cryopanel is miniaturized to increase pumping speed, then gas exhaustion efficiency improves, but heat input to the low-temperature cryopanel increases
Solution Approach 1:
The cryopanel is segmented into high-temperature and low-temperature sections, allowing efficient handling of non-condensable gases at higher temperatures while protecting the low-temperature section from excessive heat input. This maintains gas exhaustion efficiency without compromising energy management.
Solution Approach 2:
Different sections of the cryopanel have different thermal properties and cooling temperatures optimized for their specific functions. The high-temperature section is optimized for non-condensable gas pumping, while the low-temperature section is optimized for condensable gas condensation, reducing unnecessary heat transfer.
3Productivity
If the high-temperature cryopanel is miniaturized, then the pumping speed of non-condensable gases increases, but the thermal management becomes more difficult
Solution Approach 1:
The cryocooler system is segmented into multiple cooling stages (first cooling stage and second cooling stage) that correspond to the high-temperature and low-temperature cryopanel sections. This segmentation simplifies thermal management by providing dedicated cooling zones rather than requiring complex active thermal control of a single miniaturized panel.
Solution Approach 2:
The high-temperature cryopanel section automatically manages thermal loads through its higher operating temperature, which naturally reduces heat input to downstream components. This self-regulating thermal management eliminates the need for additional active cooling control mechanisms.
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 effectively increases the pumping speed of non-condensable gases while reducing the thermal load on the low-temperature cryopanel, achieving a balanced improvement in both pumping efficiency and thermal management.
Implementation Method 1
a radiation shield which is thermally coupled to the high-temperature cooling stage and axially extends in a tubular shape from a cryopump intake port
Implementation Method 2
A cryopump is a vacuum pump which condenses and adsorbs gas molecules on a cryopanel cooled to a cryogenic temperature to capture and exhaust the gas molecules
Implementation Method 3
The non-condensable gas can be exhausted by being adsorbed to an adsorption region cooled to a cryogenic temperature
Implementation Method 4
a cryocooler which includes a high-temperature cooling stage and a low-temperature cooling stage
Data Source
AI summary
A cryopump includes a cryocooler which includes a high-temperature cooling stage and a low-temperature cooling stage, a radiation shield which is thermally coupled to the high-temperature cooling stage and axially extends in a tubular shape from a cryopump intake port, a low-temperature cryopanel section which is thermally coupled to the low-temperature cooling stage, is surrounded by the radiation shield, and includes axially arranged cryopanels including a top cryopanel disposed closest to the cryopump intake port, and a top cryopanel accommodation cryopanel which is thermally coupled to the high-temperature cooling stage and is disposed in the cryopump intake port to form a top cryopanel accommodation compartment.