Liquid Metal Electron Emitter for Long-Life High-Luminance Guns
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Solution Overview
Problem
Existing electron guns face challenges in achieving high luminance, stable heater temperature, and extended lifetime, particularly with LaB6 electron guns, which experience rapid surface consumption and shape changes at high temperatures, leading to shortened lifetimes and non-uniform electron beam distribution.
Innovation Solution
An electron gun design utilizing a hydrogenated liquid metal emitter, where the liquid metal is stored in a hollow cover tube container and heated to maintain a stable surface tension and electric field balance, emitting electrons from a surface balanced by gravity, surface tension, and electric field, thereby maintaining a consistent emission surface and extending the device's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a LaB6 crystal is used as the electron emission material and heated to high temperature to achieve high luminance, then the luminance increases to 10^6, but the crystal surface is consumed and the shape changes, shortening the lifetime
Solution Approach 1:
The invention changes the physical state of the electron emission material from solid to liquid. By using a liquid metal alloy (e.g., Li-K-Ca-Na) instead of solid LaB6 crystal, the material can be heated to high temperatures (operating temperature range) without the surface consumption and shape changes that occur in solid materials. The liquid state allows the material to maintain a stable emission surface through surface tension while enabling continuous operation for extended periods (lifetime improvement).
Solution Approach 2:
The invention uses a composite liquid metal alloy comprising multiple elements (Li, K, Ca, Na, and/or In) rather than a single material. This composite approach allows optimization of both luminance and lifetime by combining materials with complementary properties: some elements contribute to high electron emission capability while others provide stability at operating temperatures and resist evaporation, thereby simultaneously achieving high luminance and extended lifetime.
2Loss of substance
If a cover is formed to prevent evaporation from the side surface of the LaB6 crystal, then evaporation is prevented, but the upper surface is greatly consumed and retracted, deteriorating electron beam uniformity
Solution Approach 1:
The invention changes the physical state from solid to liquid, fundamentally altering how the material responds to evaporation and heating. In liquid state, the material can flow and self-level, maintaining a stable upper surface through the balance of surface tension and gravity. This eliminates the retreat and shape deformation problems observed in covered solid LaB6 crystals, preserving electron beam uniformity while preventing side surface evaporation.
Solution Approach 2:
The invention utilizes surface tension (a fluid property) to maintain the stability of the liquid metal alloy surface. The liquid material's surface tension acts as a self-regulating mechanism that prevents surface deformation and maintains a stable emission area, analogous to how fluid pressure systems maintain equilibrium. This fluid-based approach naturally prevents both side surface evaporation and upper surface retreat, maintaining electron beam uniformity.
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 achieves high luminance, stable heater temperature, and significantly extends the electron gun's lifetime, allowing for continuous operation for one year or more without the need for replacement, while maintaining uniform electron beam distribution.
Implementation Method 1
an electron gun device configured to emit an electron beam by being heated to a high temperature in vacuum
Implementation Method 2
the hydrogenated liquid metal is exposed from the cover tube container to form a liquid surface on which gravity, an electric field, and a surface tension of the liquid surface are balanced
Implementation Method 3
a surface of a material that emits the electron beam is a liquid hydrogenated metal dissolved during a high-temperature operation
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
An electron gun device according to the present invention emits an electron beam by means of heating to a high temperature in a vacuum. According to the present invention, the surface of a material (108, 125), which emits an electron beam, is a hydrogenated metal that is melted and in a liquid state during a high-temperature operation; the liquid hydrogenated metal is contained in a hollow cover tube container (102, 124), which is in a solid state during the high-temperature operation, in the form of a hydrogenated liquid metal or in the form of a liquid metal before hydrogenation, and heated together with the cover tube container (102, 124) to a high temperature; subsequently, the hydrogenated liquid metal is exposed from the cover tube container (102, 124) and forms a liquid surface where gravity, the electric field and the surface tension of the liquid surface are balanced; and an electron beam is emitted from the exposed surface of the hydrogenated liquid metal.