Cold Cathode X-Ray Apparatus in Magnetic Fields
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Medical x-ray apparatuses with hot cathodes experience reduced electron current and impaired focusing when exposed to strong magnetic fields, leading to decreased image quality and shortened cathode lifespan.
Innovation Solution
An x-ray radiation apparatus using a cold cathode with a convex, semi-cylinder electron emitter made of carbon-based materials, aligned collinearly with an external magnetic field, generates a high electron current without risking cathode destruction, maintaining image quality and extending service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a hot cathode is used in an external magnetic field, then the apparatus can generate x-ray radiation, but the electron current is reduced and the focusing of the electron beam is impaired
Solution Approach 1:
The patent changes the fundamental parameter of cathode operation from thermal emission (hot cathode) to field emission (cold cathode). This parameter change allows the electron beam to be generated without thermal effects that are disrupted by magnetic fields, thereby maintaining both high electron current and proper beam focusing in the presence of external magnetic fields
Solution Approach 2:
The patent replaces the thermal-mechanical system of hot cathode heating with an electric field-based emission system. The cold cathode uses strong electric fields to extract electrons directly from the cathode surface via field emission, eliminating the need for thermal heating and the associated focusing problems in magnetic fields
2Quantity of substance
If the heating temperature of the hot cathode is increased to compensate for reduced current density, then the current density increases, but the service life of the cathode is impaired
Solution Approach 1:
The patent fundamentally changes the emission parameter from thermal emission requiring high temperatures to field emission operating at lower temperatures. This parameter change enables maintaining high current density without the need for elevated heating temperatures, thereby preserving cathode service life while achieving the required electron current for x-ray generation
Solution Approach 2:
The patent converts the previously harmful effect of magnetic fields on hot cathode operation into a beneficial configuration by using a cold cathode design where the magnetic field aligns with the electric field. This configuration actually enhances the field emission process and maintains stable operation in magnetic field environments that would otherwise be detrimental
3Duration of action of stationary object
If a cold cathode is used to generate high electron current without heating, then the service life is extended, but the electron current may be insufficient without proper focusing
Solution Approach 1:
The patent optimizes the electric field parameters in the collinear configuration to achieve sufficient field emission current density. By carefully controlling the electric field strength and distribution along the magnetic field lines, the system generates adequate electron current from the cold cathode without thermal heating, maintaining both high current output and extended service life
Solution Approach 2:
The collinear arrangement of electric and magnetic fields creates a configuration where the electron emission and acceleration occur along field lines that are aligned, creating an equipotential pathway for electrons. This alignment ensures efficient electron extraction and transport from the cold cathode to the anode, maintaining high current density without requiring thermal emission
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 apparatus achieves a high electron current and maintains image quality in external magnetic fields without compromising the cathode's service life, ensuring a punctiform x-ray source with reduced beam spot dimensions.
Implementation Method 1
The cathode as an electron emitter comprises a cold cathode which passively supplies free electrons by field emission
Implementation Method 2
the electrons emitted by the cathode are initially accelerated by the applied electric field
Implementation Method 3
The electrons leave the surface of the electron emitter with such a low energy that they follow the field lines of the magnetic field
Implementation Method 4
Overlaid thereon is the so-called bremsstrahlung, which is caused by the pure change in velocity of the electrons as a consequence of the interaction with the anode
Implementation Method 5
The holes in the shells are filled by other electrons, with, inter alia, the characteristic x-ray radiation arising
Data Source
AI summary
An apparatus is provided for generating X-ray radiation in an outer magnetic field, which may be generated by a magnetic field device. The apparatus includes a cathode configured to generate an electron beam and an anode configured to retard the electrons of the electron beam and generate an X-ray beam. The apparatus further includes a device configured to generate an electric field orientated from the anode in the direction of the cathode and substantially collinear to the outer magnetic field, wherein the cathode, as an electron emitter, includes a cold cathode that passively provides free electrons by field emission.