Microwave Window Prestressing Ring Cooling

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Solution Overview

Problem

Existing microwave windows face challenges in achieving high output powers and resistance to thermal stresses while maintaining vacuum integrity and minimizing energy losses due to heating from high power microwave transmission.

Innovation Solution

A microwave window design featuring a dielectric disk with a main metal skirt and a prestressing ring that applies radial compressive stress and includes cooling channels to manage thermal stress and heat dissipation, using materials like stainless steel and graphite to enhance mechanical strength and prevent sintering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If high power microwave transmission is used, then output power increases, but thermal stress and heating losses increase

Engineering Contradiction:
Improveoutput powerVSAvoidthermal stress
Core Design Contradiction:
PowerVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical state of the dielectric material by introducing controlled micro-cracks or voids that alter thermal conductivity and stress distribution, allowing higher power transmission without excessive thermal stress accumulation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite structures combining dielectric materials with metallic reinforcement elements or layered compositions that provide both electrical insulation and thermal stress management capabilities

Inventive Principle:
Principle #40Composite materials

2Loss of energy

If dielectric losses are reduced, then energy efficiency improves, but mechanical strength may be compromised

Engineering Contradiction:
Improvedielectric lossesVSAvoidmechanical strength
Core Design Contradiction:
Loss of energyVSStrength

Solution Approach 1:

The patent applies different material properties to different regions of the window - low-loss dielectric material in the central transmission area and reinforced or dissipated-loss material at the periphery and bonding zones where mechanical strength is critical

Inventive Principle:
Principle #3Local quality

3Strength

If brazing temperature is increased, then bonding strength improves, but thermal shock risk increases

Engineering Contradiction:
Improvebrazing strengthVSAvoidthermal shock resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent performs preliminary stress relief heat treatment on the dielectric component before final brazing, and uses controlled heating rates during brazing to prevent thermal shock while achieving adequate bonding strength

Inventive Principle:
Principle #10Preliminary action

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 design enhances mechanical strength, maintains vacuum integrity, and prevents thermal shock by effectively managing thermal stresses and heat dissipation, allowing for higher output powers and reduced manufacturing costs.

Implementation Method 1

a prestressing ring surrounding in contact the main metal skirt around the periphery of the dielectric disc and exerting at rest, over the entire periphery of the dielectric disc, a radial compressive stress directed towards the center of the dielectric disc, said prestressing ring comprising a set of at least one cooling channel drilled in the longitudinal direction of the preload ring

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

by evacuating the calories due to the microwave losses in the dielectric material, the stresses are thereby minimized

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

exerting at rest, over the entire periphery of the dielectric disc, a radial compressive stress directed towards the center of the dielectric disc

Methodology Applied
Scientific EffectMechanical stress: Mechanical Force

Implementation Method 4

the dielectric disc is brazed over its entire periphery against the inner surface of a metallic cylindrical skirt

Methodology Applied
Scientific EffectBrazing: Brazing

Data Source

PatentEP3166177B1Microwave frequency window
Publication Date: 2021.11.03 THALES SA
  • EP3166177B1 patent drawingFigure 1~2
  • EP3166177B1 patent drawingFigure 3~4

AI summary

microwave window (1) comprising a dielectric disk (2), a main metal skirt (3) brazed all around the periphery of the dielectric disk (2) and a prestressing ring (6) surrounding in contact the main metal skirt (3) around the periphery of the dielectric disk (2) and exerting at rest, on the entire periphery of the dielectric disk (2), a radial compressive stress directed towards the center of the dielectric disk (2), said prestressing ring (6) comprising an assembly of at least one cooling channel (7) in the longitudinal direction of the prestressing ring (6).