Electron Source Manufacturing Method for Uniform Emission
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Solution Overview
Problem
Conventional electron sources, such as the ZrO/W electron source, suffer from non-uniformity in emission current density due to surface damage during machining, leading to fluctuations in electron beam irradiation and reduced operational reliability, especially at high angular intensities.
Innovation Solution
A process involving machining to form a conical and flat electron emitting portion on a single crystal rod, followed by chemical or electrolytic polishing to remove damaged layers, ensuring a uniform emission current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If machining is performed to form a conical and flat electron emitting portion, then the shape and structure of the electron source is defined, but a damaged layer is created on the surface causing non-uniform emission current density
Solution Approach 1:
The patent applies chemical or electrolytic polishing as a preliminary treatment step after machining to remove the damaged layer created during mechanical formation of the conical and flat electron emitting portion. This preliminary removal of surface damage before electron emission operation ensures uniform emission current density across the emitting surface.
Solution Approach 2:
The patent converts the harmful effect of mechanical damage from machining into a beneficial process by using controlled chemical or electrolytic polishing. The damaged layer, which would otherwise cause non-uniform emission, is transformed into a removable surface layer that, when eliminated through polishing, reveals a uniform underlying surface for consistent electron emission.
2Productivity
If high angular intensity operation is performed to increase throughput, then productivity is improved, but arc discharge failure frequency increases due to high field intensity
Solution Approach 1:
The patent implements monitoring and control mechanisms to detect early signs of arc discharge and adjust operating parameters accordingly. By monitoring the electron emission characteristics and field intensity, the system can provide feedback to prevent arc discharge events, allowing sustained high angular intensity operation without excessive failure frequency.
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 process achieves a highly uniform emission current distribution, enhancing the reliability and performance of electron sources for applications like scanning electron microscopes and electron beam lithography machines.
Implementation Method 1
The cathode 1 is Joule heated by the filament 3 and used usually at a temperature of about 1,800 K
Implementation Method 2
from the diffusing source 2, zirconium and oxygen will diffuse and will be continuously supplied to the surface of the cathode 1
Implementation Method 3
removing a damaged layer on the surface of the formed electron emitting portion by chemical polishing or electrolytic polishing
Implementation Method 4
removing a damaged layer on the surface of the formed electron emitting portion by chemical polishing or electrolytic polishing
Data Source
AI summary
An electron source excellent in the uniformity in current emission distribution is provided certainly and at a low cost.A process for producing an electron source having an electron emitting portion at one end of a rod, which comprises a step of forming the electron emitting portion by machining, and a step of removing a damaged layer at the surface of the formed electron emitting portion by chemical polishing or electrolytic polishing.