Multi-Material Planar Filament for Directed Electron Emission
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Solution Overview
Problem
Existing x-ray tubes face challenges in achieving a small and controlled electron spot, maintaining low filament temperature, reducing power consumption, and improving ergonomics, which affect the reliability and efficiency of x-ray imaging and diffraction spectroscopy.
Innovation Solution
The design of x-ray tubes with an elongated filament made of multiple materials, featuring a top-side and bottom-side with different work functions, and a core material, which suppresses electron emission in undesirable directions, allowing for a smaller and more focused electron spot, reduced filament temperature, and lower power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional filament design is used, then electron emission is achieved, but the electron spot size is large and difficult to control
Solution Approach 1:
The filament is designed with non-uniform thickness, having a first thickness at the first end and a second thickness at the second end. This local variation in geometry creates corresponding local variations in electron emission characteristics, allowing different regions of the filament to produce electrons with different transverse velocities, thereby enabling precise control over the electron spot size and shape on the target.
Solution Approach 2:
The patent changes the geometric parameter of the filament (thickness) along its length to control electron emission properties. By varying the thickness parameter, the invention achieves control over the transverse velocity distribution of emitted electrons, which directly affects the electron spot characteristics on the target without requiring additional control mechanisms.
2Power
If high voltage is applied to achieve sufficient electron emission, then electron beam intensity is adequate, but filament temperature increases and power consumption rises
Solution Approach 1:
The filament's non-uniform thickness creates regions with different emission efficiencies. The varying geometry allows the filament to achieve adequate electron beam intensity through optimized local emission characteristics rather than requiring uniformly high temperature across the entire filament, thereby reducing overall power consumption.
Solution Approach 2:
The filament comprises multiple materials with different work functions arranged in a specific configuration. This composite structure enables different segments of the filament to contribute differently to electron emission, optimizing the overall electron beam intensity while allowing operation at lower temperatures and reduced power consumption compared to single-material filaments.
3Duration of action of stationary object
If filament temperature is reduced to extend lifespan, then reliability improves, but electron emission efficiency decreases
Solution Approach 1:
The filament is constructed from multiple materials with different work functions, allowing it to maintain effective electron emission at lower temperatures. The combination of materials with complementary properties enables the filament to achieve adequate emission efficiency without requiring high operating temperatures, thereby extending filament lifespan and improving reliability.
Solution Approach 2:
By changing the geometric parameters (thickness variation) and material composition along the filament length, the invention optimizes electron emission efficiency at reduced temperatures. This allows the filament to maintain sufficient electron beam production while operating in a lower temperature regime that extends its operational life.
4Power
If conventional battery size is used to power portable x-ray device, then sufficient power is available, but device weight increases and ergonomics deteriorate
Solution Approach 1:
The optimized filament design with varied thickness and composite materials improves electron emission efficiency per unit power consumed. This increased efficiency allows the x-ray tube to generate sufficient electron beams for imaging with lower power input, enabling the use of smaller, lighter batteries in portable devices while maintaining adequate power availability.
Solution Approach 2:
The non-uniform filament structure optimizes power utilization by creating regions with different emission characteristics. This local optimization of electron production efficiency reduces the total power required to achieve the necessary electron beam intensity, thereby allowing smaller battery capacity and reduced device weight for portable applications.
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
This design enhances the precision and efficiency of x-ray imaging, increases the lifespan of the x-ray tube, reduces environmental impact by lowering power consumption and waste, and improves operator ergonomics through reduced battery size and weight.
Implementation Method 1
A large voltage between a cathode and an anode of the x-ray tube, and sometimes a heated filament, can cause electrons to emit from the cathode to the anode.
Implementation Method 2
The target material can generate x-rays in response to impinging electrons from the cathode.
Data Source
AI summary
A planar filament 11f can include multiple materials to increase electron emission in desired directions and to suppress electron emission in undesired directions. The filament 11f can include a core-material CM between a top-material TM and a bottom-material BM. The top-material TM can have a lowest work function WFt; the bottom-material BM can have a highest work function WFb; and the core-material CM can have an intermediate work function WFc (WFt<WFc<WFb). A width Wt of the filament 11f at a top-side 31t can be greater than its width Wb at a bottom-side 31b (Wt>Wb). This shape makes it easier to coat the edges 31e with the bottom-material BM, because the edges 31e tilt toward and partially face the sputter target. This shape also helps direct more electrons to a center of the target 14, and reduce electron emission in undesired directions.