Passive Electron Optics in Compact X-Ray Tubes for Stable Focal Spots
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Solution Overview
Problem
Existing X-ray tubes are not compact enough for mobile applications and require high power consumption, with focal spots that drift over time and voltage, affecting stability and efficiency.
Innovation Solution
The X-ray tube design incorporates an electron emitter in a focusing recess with an opening that widens in the acceleration direction, utilizing passive electron optics to shape the electric field for stable electron beam focusing, eliminating the need for additional power consumption, and features a compact geometry to maintain focal spot stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the X-ray tube is made compact for mobile applications, then portability and mobility are improved, but maintaining stable electron beam focusing and high voltage sustainability becomes more difficult
Solution Approach 1:
The electron optics component is designed with a specific local geometry featuring an opening that widens in the acceleration direction of electrons. This localized geometric feature creates a passive focusing effect on the electron beam without requiring additional active components, thereby maintaining focal spot stability in a compact tube design
Solution Approach 2:
The electron optics structure utilizes the existing electric field between cathode and anode to achieve passive electron beam focusing. The opening geometry of the electron optics automatically shapes the electron trajectories without requiring external power supplies or active control mechanisms, enabling the compact tube to maintain reliable focusing on its own
2Use of energy by moving object
If passive electron optics is used to reduce power consumption, then energy efficiency is improved, but the ability to actively control and stabilize the electron beam is reduced
Solution Approach 1:
The electron optics structure utilizes the existing electric field between cathode and anode to achieve passive electron beam focusing. The opening geometry of the electron optics automatically shapes the electron trajectories without requiring external power supplies or active control mechanisms, enabling the compact tube to maintain reliable focusing on its own
Solution Approach 2:
The design changes the geometric parameters of the electron optics opening, specifically making it widen in the acceleration direction. This parameter change creates a passive focusing effect that substitutes for active electronic control, achieving beam stabilization through geometric field shaping rather than active feedback control
3Reliability
If the opening of electron optics widens in the acceleration direction, then passive focusing of electrons is improved, but the complexity of the electron optics structure increases
Solution Approach 1:
The electron optics is integrated directly into the cathode structure, merging the electron emission function with the electron focusing function. The opening in the electron optics is formed as part of the cathode assembly, eliminating the need for separate focusing components and reducing overall structural complexity while maintaining effective passive focusing
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 design achieves stable electron beam focusing and efficient X-ray emission with a focal spot deviation of less than 1 mm from the central axis, independent of voltage and current, while maintaining a compact size and low power consumption.
Implementation Method 1
The electron emitter comprises, for example, a hot cathode or thermionic cathode
Implementation Method 2
an element configured to generate free electrons by means of field emission as well as hot electron emission
Implementation Method 3
Free electrons that are generated at the cathode are accelerated towards the anode by an electric field emerging from the applied high voltage
Implementation Method 4
the electron optics is configured to shape a beam of free electrons between the cathode and the anode... the electrical field established between the cathode and the anode due to the high voltage can be influenced by the electron optics
Implementation Method 5
electromagnetic radiation, in particular X-rays, may be emitted as bremsstrahlung and characteristic X-ray emission lines of the anode material
Implementation Method 6
characteristic X-ray emission lines of the anode material
Data Source
AI summary
In an embodiment a X-ray tube includes an anode, a cathode, an electron emitter for generating free electrons, and an electron optics. The electron emitter is arranged in an emitter recess of the cathode. The electron optics is arranged at the recess and includes an opening such that the electron emitter is accessible in the opening. The opening widens in an acceleration direction of the free electrons.