Cold Cathode Electron Gun Crimped Carbon Fiber for Mesoscopic EBM
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Solution Overview
Problem
Existing electron guns and electron beam additive manufacturing technologies struggle to produce metal microcomponents with complex shapes at mesoscopic scales due to inadequate current extraction capacity, current density, and beam quality, which are essential for efficient metal melting and manufacturing.
Innovation Solution
A quasi-macroscopic cold cathode field emission electron gun is developed, utilizing a quasi-macroscopic carbon fiber filament with a hemispherical end and a conductive capillary tube, fixed through a crimping process, ensuring reliable electrical connection and high emission current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tungsten filament hot cathode or LaB6 cathode is used in existing EBM electron gun, then the electron beam can be generated for macro mechanical parts manufacturing, but the focal spot size is too large (140-250 μm) to enable mesoscopic scale component manufacturing
Solution Approach 1:
The patent changes the fundamental parameters of the electron source by transitioning from hot cathode (tungsten filament, LaB6) to cold cathode field emission. This parameter change enables the focal spot size to be reduced to mesoscopic scale (1-10 μm) while maintaining sufficient current extraction capacity through the field emission mechanism, which does not rely on thermal emission and can achieve high current density at much smaller emission areas.
2Volume of moving object
If electron beam diameter is enlarged to mesoscopic scale range to manufacture metal microcomponents, then the manufacturing scale is appropriate, but the power density decreases significantly and cannot meet manufacturing demand
Solution Approach 1:
The patent applies local quality by creating a highly concentrated electron beam with mesoscopic diameter (1-10 μm) that delivers extremely high power density (10^6-10^8 W/cm²) at the focal point. The cold cathode field emission source generates a narrow, intense electron beam that maintains high power density despite the mesoscopic scale, enabling efficient melting and manufacturing of metal microcomponents.
3Manufacturing precision
If existing EBM technology is used for metal microcomponent manufacturing, then macro mechanical parts can be produced, but the equipment and processes are not suitable for mesoscopic scale manufacturing
Solution Approach 1:
The patent extracts the electron emission function from the complex hot cathode structure (filament, heater, support) and implements it through a simpler cold cathode field emission tip. This extraction simplifies the electron gun structure by eliminating the need for filament heating mechanisms while achieving the required electron emission, thereby reducing device complexity for mesoscopic scale manufacturing.
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 electron gun achieves high-performance focused electron beams with sufficient current and coherence, enabling efficient additive manufacturing of complex metal microcomponents, overcoming the limitations of existing technologies.
Implementation Method 1
quasi-macroscopic cold cathode field emission electron gun
Implementation Method 2
the other end of the conductive capillary tube is connected to the electron gun base
Data Source
AI summary
A quasi-macroscopic cold field emission electron gun and a manufacturing method thereof are provided, which includes a filament device and an electron gun base, wherein the filament device includes a cold cathode filament and a conductive capillary tube, the cold cathode filament passes through one end of the conductive capillary tube and is crimped through a pressing groove device, the other end of the conductive capillary tube is connected to the electron gun base, and the end of the cold cathode filament is the electron emission end. Through the coaxial nesting and pressing deformation of quasi-macroscopic carbon fiber and metal tube and using of the non welding electrical connection method, this technology avoids the problem that it is not easy to form a reliable electrical connection during the welding process due to the poor wettability between carbon fiber and metal.