Electron Exit Window Foil Sandwich Structure for Corrosion Resistance

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Solution Overview

Problem

Existing electron exit window foils in high-performance electron beam devices face issues with oxidation and corrosion, leading to reduced lifetime and operational stability, especially when exposed to corrosive substances like H2O2, and existing solutions either compromise physical strength or are unsuitable for thin foils with local curvatures.

Innovation Solution

A sandwich structure electron exit window foil comprising a thin Ti film sandwiched between a thermally conductive layer and a flexible protective layer, with the protective layer facing the corrosive environment, and an adhesive coating to prevent material reaction and enhance adhesion, allowing for tailored mechanical and physical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thin Ti foil is used for the electron exit window, then electron permeability is improved, but the foil becomes susceptible to oxidation and corrosion, reducing lifetime and operational stability

Engineering Contradiction:
Improveoperational stabilityVSAvoidoxidation and corrosion
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies composite materials by creating a multi-layer structure consisting of a Ti foil core combined with protective outer layers. The Ti foil maintains electron permeability while the additional layers provide oxidation and corrosion resistance, resolving the contradiction between thin foil performance and environmental stability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent introduces an intermediary protective layer between the Ti foil and the corrosive environment. This intermediate layer acts as a barrier that prevents direct contact between the Ti and corrosive substances like H2O2, thereby protecting the foil while maintaining its functional properties.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If the temperature is increased to improve sterilization performance, then productivity is improved, but the Ti foil oxidizes faster, reducing lifetime

Engineering Contradiction:
Improvesterilization rateVSAvoidfoil lifetime
Core Design Contradiction:
ProductivityVSDuration of action of stationary object

Solution Approach 1:

The protective outer layers serve as an intermediary barrier that shields the Ti foil from direct oxidation at elevated temperatures. This allows the system to operate at higher temperatures for improved sterilization productivity while the protective layers absorb the oxidative stress, preserving the foil's lifetime.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The composite structure combines materials with complementary properties: the Ti foil provides electron permeability and structural integrity, while the outer protective layers provide high-temperature oxidation resistance. This composite approach enables high-productivity operation without compromising foil lifetime.

Inventive Principle:
Principle #40Composite materials

3Reliability

If a protective layer is added to prevent corrosion, then reliability is improved, but the foil structure becomes more complex and may crack in flexible areas

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidfoil structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs flexible thin film protective layers that can bend and flex without cracking. These thin film structures maintain corrosion protection while adapting to the flexible requirements of the exit window, avoiding the complexity and brittleness issues associated with thicker rigid protective layers.

Inventive Principle:
Principle #30Flexible shells and thin films

4Reliability

If a thick protective layer is used to ensure corrosion protection, then reliability is improved, but electron permeability is reduced

Engineering Contradiction:
Improvecorrosion protectionVSAvoidelectron transmission
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent uses thin film protective layers that provide adequate corrosion protection without being thick enough to significantly block electron transmission. These thin films balance the competing requirements of reliability and electron permeability by providing just sufficient protection while maintaining high electron flux.

Inventive Principle:
Principle #30Flexible shells and thin films

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 significantly reduces heat load and corrosion, extending the operating lifetime of electron beam generators, making them more cost-effective and suitable for high-performance applications in corrosive environments.

Implementation Method 1

a first layer of a material having a higher thermal conductivity than Ti

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a flexible second layer of a material being able to protect said film from said corrosive environment

Methodology Applied
Scientific EffectCorrosion resistance:

Implementation Method 3

an adhesive coating to prevent material reaction and enhance adhesion

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2647027B1An electron exit window foil
Publication Date: 2018.12.26 TETRA LAVAL HOLDINGS & FINANCE SA
  • EP2647027B1 patent drawingFigure 1~2
  • EP2647027B1 patent drawingFigure 3a~3d
  • EP2647027B1 patent drawingFigure 3e~3f

AI summary

An electron exit window foil for use with a high performance electron beam generator operating in a corrosive environment is provided. The electron exit window foil comprises a sandwich structure having a film (202) of Ti, a first layer (204) of a material having a higher thermal conductivity than Ti, and a flexible second layer (206) of a material being able to protect said film (202) from said corrosive environment, wherein the second layer (206) is facing the corrosive environment.