Electron Source Fixed Emission Sites via Metal-Gas Reaction
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Solution Overview
Problem
Cold field emission electron sources suffer from poor stability, vulnerability to ion bombardment, and limited operational lifespan, especially at higher emission currents, requiring ultra-high vacuum conditions which restricts their application scope.
Innovation Solution
An electron source with fixed emission sites formed by the reaction of metal atoms on the tip surface with hydrogen-containing gas molecules, creating a stable reaction product that enhances stability and reduces susceptibility to gas interference, allowing operation at lower vacuum levels and increased emission currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If cold field emission electron source is used to achieve high brightness, then brightness is improved, but stability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameter of the emission surface by forming a reaction product between metal atoms and gas molecules. This parameter change reduces the work function and stabilizes the emission sites, allowing the source to maintain high brightness while operating stably at poorer vacuum levels
Solution Approach 2:
The emission site is formed as a composite structure consisting of metal atoms reacted with gas molecules (e.g., hydrogen). This composite material has different properties than the pure metal surface, providing both low work function for high brightness and chemical stability for improved reliability
2Quantity of substance
If cold field emission electron source operates at higher emission currents, then field emission current is improved, but stability deteriorates due to ion bombardment
Solution Approach 1:
The patent converts the harmful effect of gas molecules (which cause instability through dissociative emission sites) into a beneficial reaction product formed on the metal surface. This reaction product creates stable emission sites that can withstand higher emission currents without the detrimental effects of ion bombardment
3Illumination intensity
If cold field emission electron source is used to achieve atomic-scale emission, then brightness is improved, but operational lifespan deteriorates
Solution Approach 1:
The patent changes the chemical state of the emission surface atoms from pure metal to reaction product (e.g., metal hydride). This parameter change creates emission sites with lower work function for higher brightness while the chemical bond provides structural stability that extends operational lifespan
4Ease of operation
If cold field emission electron source operates at poor vacuum degree, then ease of operation is improved, but emission stability deteriorates
Solution Approach 1:
The patent converts the previously harmful gas molecules present at poor vacuum levels into beneficial reaction products on the metal surface. These reaction products form stable emission sites that are insensitive to vacuum fluctuations, allowing stable operation at poorer vacuum degrees
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 solution provides a stable and high-field emission current electron source capable of operating in poor vacuum conditions, with improved stability and extended operational lifespan, while maintaining a low work function and atomic-scale emission capability.
Implementation Method 1
the emission sites comprises a reaction product of metal atoms on a surface of the tip with gas molecules
Implementation Method 2
If a cathode is made of metal and made into a very fine tip and it is applied by a voltage of thousands of volts in a vacuum, then the electrons in the metal may be emitted from the cathode cold metal. This method of emitting electrons is called as field emission
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5C
AI summary
The present disclosure provides an electron source, including one or more tips, wherein at least one of the tips comprises one or more fixed emission sites, wherein at least one of the tips includes one or more fixed emission sites, wherein the emission sites includes a reaction product of metal atoms on a surface of the tip with gas molecules.