Graded Absorption Plasma Lamp Windows Thermal Stress
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Solution Overview
Problem
Laser-sustained plasma lamps experience mechanical failure due to strong thermal gradients caused by non-uniform heating from broadband radiation, which can lead to stress and cracking of windows and other optical components.
Innovation Solution
Incorporating graded absorption layers or bulk doping on transparent portions of the plasma lamp to control heating by varying the absorption profile, matching the intensity profile of the broadband radiation and reducing thermal gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional plasma lamps with uniform glass or crystalline containment structures are used, then the device is simple in structure and easy to manufacture, but strong thermal gradients cause stress and mechanical failure of windows and optical components
Solution Approach 1:
The patent applies local quality by implementing graded absorption coatings on specific portions of the plasma lamp containment structure, particularly on windows and optical components. These coatings have spatially varying absorption coefficients that are tailored to match the local intensity distribution of broadband radiation from the plasma, thereby distributing thermal loads more uniformly across the structure and preventing stress concentration that leads to mechanical failure.
Solution Approach 2:
The patent changes the optical absorption parameter of the containment structure by introducing graded absorption coatings with spatially varying properties. The absorption coefficient varies continuously or in steps across different regions of the window or optical component, transforming the uniform absorption characteristic into a graded one that compensates for non-uniform radiation intensity and resulting thermal gradients.
2Reliability
If graded absorption layers are added to control heating, then thermal gradient control improves and mechanical failure is prevented, but device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The patent applies segmentation by dividing the graded absorption coating into discrete layers or zones with different absorption coefficients. Rather than requiring a continuously varying absorption profile, the containment structure is coated with multiple distinct layers, each having a specific absorption property. This segmented approach simplifies the manufacturing process while still achieving the fundamental goal of distributing thermal loads more uniformly across the optical components.
3Device complexity
If uniform absorption materials are used in plasma lamps, then the device is simple to construct, but non-uniform heating from broadband radiation causes strong thermal gradients and stress
Solution Approach 1:
The patent applies local quality by implementing graded absorption coatings on specific portions of the plasma lamp containment structure, particularly on windows and optical components. These coatings have spatially varying absorption coefficients that are tailored to match the local intensity distribution of broadband radiation from the plasma, thereby distributing thermal loads more uniformly across the structure and preventing stress concentration that leads to mechanical failure.
Solution Approach 2:
The patent converts the harmful effect of broadband radiation-induced thermal gradients into a beneficial outcome by using graded absorption coatings. The coatings are specifically designed to absorb radiation more strongly in regions where the radiation intensity is highest, thereby converting the non-uniform radiation field into a more uniform temperature distribution. The harmful thermal stress is transformed into a controlled thermal profile that protects the optical components.
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 implementation of graded absorption layers or bulk doping in plasma lamps helps achieve uniform temperature distribution, reducing stress and preventing mechanical failure by managing thermal gradients effectively.
Implementation Method 1
The one or more transmissive structures have a graded absorption profile so as to control heating of the one or more transmissive structures caused by the broadband radiation emitted by the plasma
Implementation Method 2
the plasma emits broadband radiation
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A laser-sustained plasma lamp includes a gas containment structure configured to contain a volume of gas. The gas containment structure is configured to receive pump illumination from a pump laser for generating a plasma within the volume of gas. The gas containment structure includes one or more transmissive structures being at least partially transparent to the pump illumination from the pump laser and at least a portion of the broadband radiation emitted by the plasma. The one or more transmissive structures have a graded absorption profile so as to control heating of the one or more transmissive structures caused by the broadband radiation emitted by the plasma.