Curved Cathode Electron Gun Flat Beam Focusing
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Solution Overview
Problem
Conventional electron guns face challenges in achieving a fine focus with high current density and efficient beam guidance due to the mutual repulsion of electrons, which requires complex magnetic lenses and stringent electron-optical quality, increasing manufacturing and maintenance costs.
Innovation Solution
An electron gun with a curved cathode emission surface and a radially accelerating device that generates a flat electron beam with a large width-to-thickness ratio, allowing for electrostatic focusing and reduced space charge forces, enabling simpler construction and improved beam guidance without magnetic lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electron guns use magnetic lenses to focus high current density beams, then focusing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the magnetic lens component from the electron gun system. By using a curved cathode geometry to provide inherent beam focusing through geometric convergence, the complex magnetic lens system becomes unnecessary, thereby reducing device complexity while maintaining focusing capability
Solution Approach 2:
The curved cathode surface serves a dual function: emitting electrons and providing geometric focusing. The cathode's curved geometry causes electron trajectories to converge naturally toward the target region, making the system self-focusing without requiring external magnetic lens components
2Manufacturing precision
If conventional electron guns use stringent electron-optical quality requirements, then beam focusing is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the geometric parameters of the cathode, specifically using a curved surface with optimized radius of curvature. This geometric parameter change enables the cathode to provide inherent focusing capability, reducing the stringency of electron-optical quality requirements and lowering manufacturing costs
3Quantity of substance
If electron beams of high current density are used, then beam intensity is improved, but minimum focus size increases due to mutual electron repulsion
Solution Approach 1:
The curved cathode geometry applies preliminary focusing action to the electron beam at the source. By shaping the cathode surface to create convergent trajectories, the beam is pre-focused before acceleration, counteracting the space charge repulsion effects that would otherwise limit focus size at high current densities
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 achieves a fine focal line with high current density and reduced space charge effects, simplifying the electron gun design, reducing costs, and enabling efficient generation of high-intensity radiation, such as x-ray light.
Implementation Method 1
a cathode for emitting free electrons
Implementation Method 2
an accelerating device for radially accelerating the electrons in the direction of a target region on the central axis
Implementation Method 3
the curved emission surface and the radial acceleration, which cause the emitted electrons already in the electron gun to converge toward the target region
Implementation Method 4
it is possible to focus purely electrostatically
Data Source
AI summary
The invention relates to an electron gun for generating a flat electron beam, comprising a cathode with an emission surface which is curved about a central axis and which is designed to emit electrons. The electron gun further comprises an accelerating device for accelerating the electrons in a radial direction towards a target region on the central axis. Furthermore, the emission surface has a width in the azimuth direction and a height oriented perpendicularly to the width, said width being at least ten times greater than the height.