Lithium Evaporation Pump with Replenishable Getter Surfaces
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Solution Overview
Problem
Conventional getter pumps face challenges due to expensive and difficult-to-fabricate materials, rapid saturation of the getter surface, and high operational temperatures, which limit their efficiency and maintenance requirements.
Innovation Solution
The evaporation pump system uses a lithium-containing getter source that is heated to form getter vapor, which is deposited onto a target surface to form a getter layer. This system operates at lower temperatures (<1100K) and is designed to efficiently absorb hydrogen and other gases with low maintenance and vibration-free operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional NEG or EG getter materials are used, then gas absorption capability is achieved, but manufacturing cost and fabrication difficulty increase significantly
Solution Approach 1:
The patent employs a disposable lithium-containing getter source that is evaporated and deposited as a thin film on the pump wall. This getter layer is consumed over time as it absorbs gases, and the entire source can be replaced without complex processing, avoiding the high costs and safety hazards associated with conventional NEG alloy fabrication
Solution Approach 2:
The patent changes the physical state of the getter material from bulk solid (conventional NEG/EG) to vapor phase through controlled evaporation. This parameter change enables simple deposition as a thin film on the pump wall, dramatically simplifying manufacturing while maintaining effective gas absorption through the vapor-deposited lithium layer
2Reliability
If conventional getter pumps operate continuously, then vacuum maintenance is achieved, but getter surface saturation occurs rapidly reducing efficiency
Solution Approach 1:
The patent pre-deposits a lithium-containing getter layer on the pump wall before operation. This preliminary action creates an active getter surface that immediately begins absorbing gases when the pump is activated, eliminating the delay associated with conventional getters that must first be activated or heated to become effective
Solution Approach 2:
The patent creates a dynamic getter system where the lithium-containing layer can be replenished by periodic evaporation of additional lithium source material. This dynamic replenishment maintains the getter surface activity over extended operation periods, preventing the efficiency loss that occurs when conventional getters become saturated
3Reliability
If EG pump filament is heated to high temperatures for titanium sublimation, then getter deposition is achieved, but operational temperature and energy consumption increase
Solution Approach 1:
The patent changes the deposition temperature from the extremely high temperatures (1600K+) required for titanium sublimation in EG pumps to a much lower range (400-800K) suitable for lithium evaporation. This parameter change reduces thermal stress on pump components and lowers energy consumption while achieving effective getter layer deposition
Solution Approach 2:
The patent uses a disposable lithium source that can be evaporated at lower temperatures compared to titanium filaments. The lithium source is consumed during evaporation and can be replaced without the need for high-temperature filament heating, reducing both operational temperature and energy requirements
4Ease of operation
If NEG pump getter is heated for reactivation, then chemisorption product removal is achieved, but operational complexity and maintenance requirements increase
Solution Approach 1:
The patent employs a self-replenishing getter system where additional lithium source material is periodically evaporated onto the pump wall to refresh the getter layer. This self-service approach eliminates the need for complex thermal reactivation systems, as the getter is continuously replenished rather than requiring periodic high-temperature processing cycles
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 system achieves efficient gas absorption, low maintenance requirements, and compact, lightweight design, while maintaining high vacuum or ultra-high vacuum conditions with reduced operational costs.
Implementation Method 1
heating a getter source to form a getter vapour
Implementation Method 2
the getter vapour is deposited onto a target surface to form a getter layer
Implementation Method 3
molecules or atoms chemically bond with the getter, thus requiring considerably larger temperatures to release back them back into the volume
Implementation Method 4
hydrogen and other molecules (e.g., hydrocarbons) dissociate at the getter surface and diffuse into the getter bulk in solid solution
Implementation Method 5
hydrogen and other molecules (e.g., hydrocarbons) dissociate at the getter surface and diffuse into the getter bulk in solid solution
Data Source
AI summary
A method of operating an evaporation pump system in a chamber at partial vacuum is provided. The method includes heating a getter source to form a getter vapour; depositing the getter vapour onto a first target surface arranged within the chamber to form a getter layer; and providing a replenished target surface within the chamber, and onto which the getter vapour can be deposited, by at least partially removing, from the first target surface, the getter layer and any chemisorbed, and/or physisorbed products present within the getter layer, said step being carried out within the chamber; and/or arranging a second target surface within the chamber, wherein, the getter source comprises lithium.