Differentially Pumped UHV Chamber Bakeout Without Gate Valves
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Solution Overview
Problem
Existing in-situ and ex-situ bakeout methods for differentially pumped vacuum chambers are lengthy, require high thermal power, cause thermal stress, necessitate removal and realignment of electronic components, and rely on expensive and space-consuming gate valves, limiting the efficiency and feasibility of vacuum system maintenance.
Innovation Solution
A system and method for ex-situ bakeout involving a removably disposed UHV chamber, connected via a differential aperture, with a bakeout chamber and heating element, using a mechanical hoist for transfer, and a bypass valve for gas management, allowing for efficient water vapor desorption and backfilling without gate valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If in-situ bakeout is performed on the vacuum chamber, then water vapor can be desorbed from chamber walls, but the process is lengthy and requires high thermal power causing thermal stress
Solution Approach 1:
The vacuum system is divided into two separable chambers: a process chamber that maintains vacuum and a bakeout chamber that receives the UHV chamber for heating. This segmentation allows the bakeout process to occur outside the main vacuum system, reducing the thermal mass that needs to be heated and enabling faster bakeout times without compromising the vacuum chamber's integrity.
Solution Approach 2:
The UHV chamber is extracted from the main vacuum system and placed into a dedicated bakeout chamber. This extraction allows the bakeout process to be performed on a smaller, isolated chamber with reduced thermal mass, significantly decreasing the time and thermal power required while maintaining effective water vapor desorption.
2Reliability
If in-situ bakeout is performed, then vacuum chamber can be cleaned, but electronic components must be removed and realigned
Solution Approach 1:
The system is segmented into a process chamber containing electronic components and a separate bakeout chamber. The UHV chamber acts as an interface that can be selectively attached to either chamber. This allows electronic components to remain in the process chamber while the UHV chamber is baked out separately, eliminating the need to remove and realign sensitive electronic components.
3Device complexity
If ex-situ bakeout is performed without gate valves, then system complexity and cost are reduced, but vacuum integrity during transfer must be maintained
Solution Approach 1:
A bypass valve serves as an intermediary mechanism that allows the UHV chamber to be isolated from the process chamber during transfer to the bakeout chamber. This single bypass valve simplifies the valve system compared to traditional gate valve configurations while maintaining vacuum integrity through the differential aperture's low conductance properties.
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
Facilitates rapid and efficient vacuum chamber cleaning, reducing downtime and complexity, while maintaining vacuum integrity and avoiding thermal stress, without the need for expensive gate valves, thus enhancing the operational efficiency of vacuum systems.
Implementation Method 1
heating the vacuum chamber to allow water vapor to desorb from the vacuum chamber walls
Implementation Method 2
A differentially pumped vacuum system consists of at least two vacuum chambers connected by a differential aperture. By activating a vacuum pump connected to one of the chambers, the low conductance of the differential aperture allows for a pressure differential to be held between the two vacuum chambers.
Implementation Method 3
The differential aperture holds off a pressure differential between the vacuum chambers on either side of the differential aperture
Data Source
AI summary
The system includes a high vacuum chamber, a bakeout chamber, and an ultra-high vacuum (UHV) chamber that is configured to be removably disposed on the high vacuum chamber and the bakeout chamber. The system further includes a heating element configured to heat the UHV chamber and desorb water vapor from the UHV chamber with the UHV chamber disposed on the bakeout chamber, and a gas source configured to supply a backfill gas to the UHV chamber disposed on the bakeout chamber. The system further includes a bakeout vacuum pump configured to extract the water vapor from the UHV chamber with the UHV chamber disposed on the bakeout chamber, and a high vacuum pump configured to extract the backfill gas from the UHV chamber with the UHV chamber disposed on the high vacuum chamber.