Thermionic Emitter Cooling via Intermediary Heat Transfer
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Solution Overview
Problem
Conventional thermionic emission devices in x-ray tubes experience undesirable radiation exposure during dose-modulated x-ray recordings due to delayed termination of electron emission, which is caused by the time it takes for the emitter to cool down, leading to prolonged radiation exposure and imaging times.
Innovation Solution
A thermionic emission device with a heat emitter that can be switched between different heating potentials, allowing it to emit electrons directly to the main emitter during normal operation and preventing post-heating, thereby accelerating the cooling of the main emitter by emitting electrons towards the heat emitter during dose modulation, reducing radiation exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the heating current is interrupted to reduce radiation exposure, then the radiation dose to the patient is reduced, but the emitter cools down with a time delay causing prolonged electron emission and radiation exposure
Solution Approach 1:
A heat emitter is introduced as an intermediary component between the heating current source and the main emitter. This heat emitter can be independently controlled to transfer thermal energy to the main emitter, allowing the heating current to be interrupted while maintaining emitter temperature through the intermediary heat transfer mechanism.
Solution Approach 2:
The heating function is segmented into two independent components: the main emitter and the heat emitter. This segmentation allows independent control of each component, enabling the heating current to be switched off while the heat emitter continues to maintain the main emitter's temperature, thus reducing radiation exposure without prolonged cooling delays.
2Object-affected harmful factors
If a structured emission surface is used to reduce electron emission, then radiation exposure is reduced, but the device complexity increases
Solution Approach 1:
The heat emitter acts as an intermediary that enables independent thermal control of the main emitter. This allows the main emitter to maintain a simpler unstructured geometry while achieving dose modulation through independent heating control, avoiding the complexity of structured emission surfaces.
Solution Approach 2:
Instead of changing the geometric structure of the emission surface, the invention changes the thermal parameter control by introducing independent heating control through the heat emitter. This allows modulation of electron emission through temperature parameter control rather than structural modification.
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 solution significantly reduces radiation exposure and shortens imaging recording times by accelerating the cooling of the main emitter, improving dose modulation and reducing radiation exposure to the patient.
Implementation Method 1
a heat emitter (2) with a heat emission surface (21), which emits electrons and thus heats the main emitter (1) disposed therebelow
Implementation Method 2
an indirectly heatable main emitter (1) with a main emission surface (11), from which electrons are emitted
Data Source
AI summary
A thermionic emission device includes an indirectly heatable main emitter with a main emission surface and a connectible heat emitter with a heat emission surface. The heat emission surface is disposed at a predefinable distance from the main emission surface. In the operating state, the main emitter is at a constant main potential and the heat emitter can be switched between at least two heating potentials which differ from one another and which differ from the main potential. Through the use of the thermionic emission device, the radiation load for a patient is reduced in the case of dose-modulated x-ray recordings.