Nanostructure Electron Emitter for X-Ray Tube Cathode
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Solution Overview
Problem
Current x-ray tube technologies rely on hot tungsten filament cathodes for thermionic emission, which are inefficient and prone to poisoning, while carbon nanotube cold cathodes face material and operational challenges, limiting their practical application.
Innovation Solution
An electron emitter using a nanostructure material made of oxides, nitrides, silicides, or tellurides, capable of Schottky emission, which allows for thermally assisted electron emission, reducing poisoning issues and enabling a more compact, portable x-ray device with dual operational modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hot tungsten filament cathodes are used for thermionic emission, then electron emission is achieved, but the system becomes inefficient and prone to poisoning
Solution Approach 1:
The patent changes the material parameters of the cathode from conventional tungsten filament to nanostructured materials (oxides, nitrides, silicides, selenides, or tellurides), fundamentally altering the emission mechanism from pure thermionic emission to a hybrid mode combining field emission and thermionic emission, thereby improving both efficiency and reliability
Solution Approach 2:
The patent employs composite nanostructured coatings on the cathode substrate, combining multiple material properties (oxide, nitride, silicide, selenide, or telluride phases) to achieve superior electron emission characteristics that overcome the limitations of single-material cathodes
2Use of energy by stationary object
If carbon nanotube cold cathodes are used for field emission, then no heating is required, but material and operational challenges limit practical application
Solution Approach 1:
The patent transitions from pure cold field emission to thermally assisted field emission by introducing moderate heating to the nanostructured cathode, changing the operational parameters to achieve stable electron emission without the severe limitations of carbon nanotube cold cathodes
Solution Approach 2:
The patent adopts nanostructured oxide, nitride, silicide, selenide, or telluride coatings that are more robust and longer-lasting than carbon nanotubes, providing a practical alternative that maintains low power consumption while significantly improving operational reliability
3Temperature
If cold cathodes are used, then heating is eliminated, but the cathode can be poisoned by adsorption of electronegative elements requiring cumbersome regeneration
Solution Approach 1:
The patent introduces moderate thermal heating to the nanostructured cathode, changing the temperature parameter from cryogenic/cold operation to moderately elevated temperatures that prevent poisoning through thermal desorption while avoiding the formation of harmful compounds
Solution Approach 2:
The moderate heating of the nanostructured cathode enables self-cleaning by thermally desorbing adsorbed electronegative elements, allowing the cathode to regenerate itself in situ without requiring removal from the housing or cumbersome external processing
4Productivity
If hot filament-based systems are used, then thermionic emission is achieved, but cooling systems and long warm-up periods are required
Solution Approach 1:
The patent changes the emission mechanism from pure thermionic emission requiring high temperatures to thermally assisted field emission that operates at moderate temperatures, fundamentally altering the thermal management requirements and eliminating the need for complex cooling systems
Solution Approach 2:
The patent replaces the mechanical cooling system required by hot filament cathodes with a thermal field-assisted emission mechanism that uses moderate heating to enhance field emission, thereby eliminating the need for active cooling infrastructure and reducing device complexity
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 nanostructure electron emitter provides improved performance and portability by eliminating the need for cooling systems and allowing for regeneration without removing the tube from the housing, offering enhanced electron emission control and versatility in x-ray imaging.
Implementation Method 1
The electron emitter comprises a nanostructure material made of oxides, nitrides, silicides, selenides or tellurides. Such a nanostructure material makes the electron emitter suitable for field emission and more importantly for Schottky emission. The use of a thermally assisted electron emission allows for compensation in the properties of the hot and cold cathodes.
Implementation Method 2
the heating resulting in a moderate temperature rise at the cathode assists the emission of the electrons while at the same time preventing the adsorption of the poisoning gas atoms or molecules on the cathode
Implementation Method 3
such electron emission is induced by a high electric field without heating
Data Source
AI summary
Example embodiments presented herein are directed towards an electron emitter for an x-ray tube. The electron emitter comprises an electrically conductive substrate and a nanostructure material. The nanostructure material is comprised on at least a portion of the electrically conductive substrate. The nanostructure material is made of oxides, nitrides, silicides, selenides or tellurides. Such an electron emitter may be used for hybrid emission, such as Schottky emission or field emission.