Curved Hot Cathode for Homogeneous Electron Radiation
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Solution Overview
Problem
Pierce electron guns suffer from non-homogeneous electron radiation due to polycrystalline hot cathodes, requiring sensitive alignment adjustments and being susceptible to particle vapors that reduce radiation quality and limit line lengths.
Innovation Solution
A hot cathode arrangement where electrons are emitted in all radial directions, with a smooth, non-interrupted cathode electrode surface that is either flat or concavely curved, reducing sensitivity to alignment and particle deposition, and allowing for longer line lengths and improved homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wire-shaped hot cathode is used in a Pierce electron gun configuration, then electron radiation can be generated, but the electron radiation becomes non-homogeneous in the longitudinal direction due to polycrystalline structure variations
Solution Approach 1:
The hot cathode is designed with a curved surface (spheroidal or cylindrical geometry) instead of a flat wire shape. This curvature ensures that electrons are emitted radially in all directions, creating a more homogeneous electron radiation distribution in the longitudinal direction and reducing sensitivity to alignment variations.
Solution Approach 2:
The invention changes the geometric parameters of the hot cathode from a linear wire configuration to a curved/spheroidal configuration. This parameter change fundamentally alters the emission pattern from directional to radial, improving homogeneity without requiring precise alignment adjustments.
2Ease of manufacture
If a groove structure is used to hold the hot cathode, then the cathode can be positioned, but particle vapors accumulate on the groove edges forming material accumulations that reduce radiation quality
Solution Approach 1:
The invention removes the groove structure entirely from the cathode electrode design. Instead of holding the cathode in a groove, the cathode is positioned on a smooth, continuous surface, eliminating the groove edges where particle vapors would accumulate and form harmful material accumulations.
Solution Approach 2:
The cathode electrode surface is designed to be smooth and homogeneous without grooves or interruptions. This homogeneous surface prevents localized accumulation of particle vapors and ensures uniform electron emission across the entire cathode surface.
3Reliability
If the hot cathode is tilted at a small angle to achieve uniform intensity distribution, then electron radiation homogeneity improves, but the possible line lengths are limited to about 100 mm
Solution Approach 1:
The curved/spheroidal hot cathode design inherently produces radial electron emission that maintains uniform intensity distribution along the entire length of the cathode, eliminating the need for tilting. This allows line lengths to exceed the 100 mm limitation without compromising intensity uniformity.
4Device complexity
If a wire-shaped hot cathode with rectangular groove is used, then the apparatus structure is simple, but the electron radiation has an elongated line-shaped cross section with non-homogeneous intensity distribution
Solution Approach 1:
The hot cathode is designed with a curved surface (spheroidal or cylindrical geometry) instead of a flat wire shape. This curvature ensures that electrons are emitted radially in all directions, creating a more homogeneous electron radiation distribution in the longitudinal direction and reducing sensitivity to alignment variations.
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
Enhances electron radiation homogeneity and reduces sensitivity to particle vapors, enabling longer line lengths and more efficient electron emission with reduced adjustment time.
Implementation Method 1
a low voltage of, for example, about 10 V, is applied to the hot cathode 1, so that a current flows through the hot cathode 1 that causes the hot cathode 1 to heat up
Implementation Method 2
Between the cathode 2 and the anode electrode 4 a voltage of, for example, up to 50 kV is applied in order to accelerate the electrons emitted from the hot cathode 1
Data Source
AI summary
An apparatus for generating electron radiation comprises a wire-shaped hot cathode that is much more extensive in a longitudinal direction than in a transverse direction. Electron radiation emerges from the hot cathode that, due to the elongated shape of the hot cathode, exhibits an elongated, line-shaped cross section perpendicular to its direction of propagation, where the extension in longitudinal direction of the line is significantly greater than in transverse direction of the line. The apparatus further comprises a cathode electrode and an anode. A voltage for accelerating the electrons emitted from the hot cathode is applied between the cathode electrode and the anode. The hot cathode is arranged to be spaced apart from the cathode electrode such that electrons that are accelerated to the anode are emitted from the hot cathode in each of the transverse directions.