Multilayer X-Ray Window Structure for Gastight Low-Absorption Foils
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Solution Overview
Problem
Current technologies face challenges in manufacturing thin, gastight, and mechanically strong radiation windows for X-ray measurement apparatuses, as existing materials like beryllium are toxic and limited in thickness, while alternatives like boron carbide suffer from mechanical weakness due to thickness constraints.
Innovation Solution
A multilayer radiation window is manufactured using a method that includes a gas diffusion stop layer of silicon nitride, combined layers with light attenuation and strengthening layers of aluminium, carbon-filled polymer, boron carbide, or diamond-like carbon, and an optional attachment layer of pyrolytic carbon, which are deposited and etched to create a thin, gastight, and mechanically robust foil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If beryllium foil thickness is reduced to minimize X-ray absorption, then radiation transmission is improved, but gastightness deteriorates due to grain boundaries causing gas leaks
Solution Approach 1:
The patent uses a composite structure consisting of a thin beryllium foil layer (for X-ray transmission) combined with a polymer coating layer (for gastightness). The polymer layer compensates for the gas permeability issue of thin beryllium foils while maintaining the low X-ray absorption property of the beryllium layer.
2Strength
If boron carbide layer thickness is increased to improve mechanical strength, then strength is improved, but crystal size increases causing the layer to become fragile
Solution Approach 1:
The patent optimizes the boron carbide layer thickness to a specific range (0.5-2 micrometers) where the material provides sufficient mechanical strength without developing excessive crystal sizes that would cause fragility. This precise parameter control resolves the contradiction between strength and fragility.
3Loss of energy
If beryllium foil is made thinner to reduce absorption, then radiation transmission is improved, but manufacturing capability deteriorates as rolling technology cannot produce foils thinner than 8 micrometres
Solution Approach 1:
The patent combines a thin beryllium foil (manufactured at the limit of current rolling technology) with a polymer coating layer. This composite approach enables the use of extremely thin beryllium for minimal absorption while the polymer layer provides the necessary structural support and gastightness that thin foils lack.
4Loss of energy
If beryllium is used for its low absorption and flexural rigidity, then radiation transmission and mechanical properties are improved, but toxicity increases requiring additional safety requirements
Solution Approach 1:
The patent uses a composite structure where a thin beryllium foil layer (optimized for low X-ray absorption) is combined with a polymer coating layer. This reduces the total amount of toxic beryllium material while maintaining the desired radiation transmission properties, and the polymer layer provides an additional protective barrier.
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 solution enables the production of thin, gastight, and mechanically strong radiation windows with minimal unwanted absorption, using non-toxic and environmentally sustainable materials, effectively addressing the limitations of existing technologies.
Implementation Method 1
producing a gas diffusion stop layer made of silicon nitride on a polished surface of a carrier
Implementation Method 2
A thin film deposition technique is used to produce a boron carbide layer on an opposite side of said etch stop layer than said carrier
Implementation Method 3
The middle area of carrier is etched away, leaving an additional support structure
Data Source
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AI summary
The invention relates to a method for manufacturing a multilayer radiation window for an X-ray measurement apparatus. The method comprises: producing a gas diffusion stop layer (102) made of silicon nitride on a polished surface of a carrier (101); producing at least one combined layer (103) on an opposite side of said gas diffusion stop layer (102) than said carrier (101); attaching the combined structure comprising said carrier (101), said gas diffusion stop layer (102), said at least one combined layer (103) to a region around an opening (106) in a support structure (107) with the at least one combined layer (103) facing said support structure (107); and etching away said carrier (101). The at least one combined layer (103) comprises: a light attenuation layer (104) made of aluminium, and a strengthening layer (105). The invention relates also a radiation window manufactured with the method.