Cold Field Emission Electron Source Stability in Lower Vacuum
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Solution Overview
Problem
Cold field emission electron sources (CFE) face instability and burnout issues due to high vacuum requirements and sensitivity to ion bombardment, limiting their application scope and emission current stability.
Innovation Solution
An electron source operating method that forms emission sites by reacting metal atoms on the tip with gas molecules under an electric field, allowing stable operation in lower vacuum environments with increased field emission current, using controlled operating parameters such as bias, temperature, and pressure, and incorporating heat treatment to maintain emission site stability and cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CFE operates in high vacuum environment (10^-9 to 10^-8 Pa), then stability is improved, but device complexity and ease of operation deteriorate due to severe vacuum requirements and limited application scope
Solution Approach 1:
The patent changes the operating pressure parameter from ultra-high vacuum (10^-9 to 10^-8 Pa) to lower vacuum (10^-3 to 10^-1 Pa), enabling the electron source to operate in more practical and widely applicable environments while maintaining stability through the formation of stable emission sites
Solution Approach 2:
The patent uses readily available gas molecules (such as hydrogen) that can be introduced into the vacuum chamber to form stable emission sites, replacing the need for maintaining extreme vacuum conditions, thus simplifying the system requirements and expanding application scope
2Productivity
If CFE operates at larger emission currents, then productivity is improved, but reliability deteriorates due to increased burnout risk from ion bombardment
Solution Approach 1:
The patent converts the harmful effect of gas molecules (which cause ion bombardment and burnout) into a beneficial effect by using these same gas molecules to form stable emission sites. The gas molecules that would normally be considered contaminants are instead utilized to create hydrogen-metal compounds with low work functions, enabling stable high-current operation
Solution Approach 2:
The patent introduces gas molecules as an intermediary substance that mediates between the metal surface and the vacuum environment. These gas molecules form compound layers on the metal surface that serve as stable emission sites, protecting the underlying metal from direct ion bombardment while enabling controlled electron emission at higher currents
3Ease of manufacture
If emission sites are formed by gas molecules or dissociative particles on the surface, then ease of manufacture is improved, but reliability deteriorates due to over-current burnout from aggregation of dissociative substances
Solution Approach 1:
The patent creates composite emission sites by forming compounds between metal atoms and gas molecules (such as hydrogen-metal compounds). These composite structures combine the advantages of both components: the metal provides structural stability and the gas molecule contributes to low work function, resulting in emission sites that are both easy to form and resistant to burnout
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
Enables long-term stable operation of CFE in lower vacuum environments with higher field emission currents, reducing burnout risks and extending service life by forming stable emission sites and maintaining surface cleanliness through controlled parameter management.
Implementation Method 1
If a cathode is made of metal and made into a very fine tip, and applied with a voltage of thousands of volts in a vacuum, electrons in the metal can be emitted from the cold metal cathode. This method of emitting electrons is called field emission and belongs to cold cathode emission.
Implementation Method 2
the emission site being a reaction product formed by metal atoms of a surface of the tip and gas molecules under an electric field
Implementation Method 3
performing a heat treatment, thereby removing adsorbed gas molecules
Data Source
AI summary
The present disclosure provides an electron source operating method, the electron source including at least one emission site fixed on a tip, the emission site being a reaction product formed by metal atoms of a surface of the tip and gas molecules under an electric field, and the operating method comprises emitting electrons by controlling operating parameters of the electron source.