Field-Emission Electron Source Zirconia Diffusion Layer Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Field-emission type electron sources face challenges in achieving stable long-life operation due to zirconia consumption and structural damage caused by temperature changes, leading to a limited operational life of less than 8,000 hours.
Innovation Solution
A field-emission type electron source with a zirconia diffusion and supply source formed within specific thickness and length ranges, optimized for each temperature, where the zirconia is initially oxidized and then heated to promote surface diffusion, reducing consumption and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the volume or weight of zirconia diffusion and supply source is increased to extend the life of the field-emission type electron source, then the operational life is improved, but the diffusion and supply source itself or the tungsten needle is easily subjected to damage due to volume change of zirconia during temperature cycling
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness and length of the zirconia diffusion and supply source to fall within specific predetermined ranges. This optimization allows the zirconia layer to provide sufficient material for extended operational life while maintaining a thickness and length that minimize volume changes during temperature cycling, thereby preventing structural damage to both the zirconia source and the tungsten needle.
2Reliability
If the zirconia diffusion and supply source is made thinner to reduce damage and chips, then the structural integrity is improved, but the operational life is reduced due to faster consumption of zirconia
Solution Approach 1:
The patent resolves this contradiction by optimizing both the thickness and length parameters of the zirconia diffusion and supply source simultaneously. By controlling the thickness to be within a predetermined range (thin enough to reduce damage and chips) while adjusting the length to compensate, the patent achieves both improved structural integrity and extended operational life. The specific dimensional parameters ensure sufficient zirconia material is available for long-term operation without excessive thickness that would cause structural damage.
3Productivity
If the temperature is increased from 1700K to 1800K to improve electron emission, then the electron emission performance is improved, but the zirconia undergoes crystal structure shift from monoclinic to tetragonal causing volume change and structural damage
Solution Approach 1:
The patent addresses this contradiction by optimizing the dimensional parameters of the zirconia diffusion and supply source (thickness and length) to fall within predetermined ranges that are suitable for high-temperature operation. These optimized dimensions allow the zirconia to withstand the crystal structure transition from monoclinic to tetragonal at elevated temperatures (1700K-1800K) without suffering excessive volume change damage, while still enabling improved electron emission performance at these higher temperatures.
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 optimized zirconia structure extends the operational life of the electron source to 8,000 hours or more with minimal damage and few chips or cracks, while reducing the volume of the diffusion and supply source.
Implementation Method 1
The field-emission type electron source supplies zirconium and oxygen onto a tungsten crystal plane (100) by thermal diffusion to form a region with a low work function
Implementation Method 2
by providing a crystal plane (100) at a tip of a tungsten needle and applying a strong electric field, thermoelectrons that surpass a potential barrier and electrons transmitted by the tunnel effect can be extracted
Data Source
AI summary
Increasing the volume or weight of zirconia which is a diffusion and supply source, to extend the life of a field-emission type electron source causes a problem that the diffusion and supply source itself or a tungsten needle is easily subjected to damage. As another problem, although it is considered to form the diffusion and supply source using a thin film to avoid the above-described problem, it is difficult to stably obtain practical life exceeding 8,000 hours. It has been found that practical life exceeding 8,000 hours is stably obtained by providing a field-emission type electron source that has no chips or cracks in a diffusion and supply source and that can extend life with a little bit of an increase in the amount of the diffusion and supply source.