Transmission Target Structure With Carbon Interlayer for Crack Suppression

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Solution Overview

Problem

Radiation generating apparatuses with transmission type targets suffer from microcracks in the target layer due to thermal stress and linear expansion coefficient mismatch between the target layer and diamond substrate, leading to unstable anode potential and fluctuations in radiation output.

Innovation Solution

Incorporating a carbon-containing region with sp2 bonds between the target layer and diamond substrate to act as a stress-relieving and conductive intermediate layer, reducing thermal stress and enhancing adhesion, thereby stabilizing the anode potential and suppressing microcrack formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a transmission type target with diamond substrate is used to improve heat release and radiation transmission, then radiation generation efficiency is improved, but microcracks occur in the target layer due to thermal stress and linear expansion coefficient mismatch

Engineering Contradiction:
Improveradiation generation efficiencyVSAvoidtarget layer integrity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

A carbon-containing layer is introduced as an intermediate layer between the target layer and diamond substrate. This intermediate layer acts as a mediator that reduces thermal stress and compensates for linear expansion coefficient mismatch, preventing microcrack formation while maintaining the high heat release and radiation transmission properties of the diamond substrate

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The target structure is designed as a composite material system consisting of multiple layers: target layer, carbon-containing layer, and diamond substrate. Each layer contributes specific properties - the diamond substrate provides high heat conductivity and radiation transmission, while the carbon-containing layer provides stress relief and adhesion, achieving overall system reliability

Inventive Principle:
Principle #40Composite materials

2Temperature

If diamond substrate is used to support the target layer, then heat conductivity and radiation transmission are improved, but adhesion between target layer and substrate deteriorates due to low wettability to molten metal

Engineering Contradiction:
Improveheat conductivityVSAvoidadhesion strength
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The carbon-containing layer serves as an intermediary between the target layer and diamond substrate, improving adhesion by providing better wettability to molten metal while the diamond substrate maintains its superior heat conductivity and radiation transmission properties

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively stabilizes the anode potential and suppresses radiation output fluctuations, ensuring a reliable and durable transmission type target with reduced microcrack occurrence, even under prolonged operation.

Implementation Method 1

linear expansion coefficient mismatch occurs between diamond and solid metal. Thus, diamond has low affinity to a target metal. Ensuring the adhesion between a target layer and a diamond substrate has been the issue that needs to be addressed

Methodology Applied
Scientific EffectThermal stress: Thermal Expansion

Implementation Method 2

Incorporating a carbon-containing region with sp2 bonds between the target layer and diamond substrate to act as a stress-relieving and conductive intermediate layer

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

Diamond has not only high heat-resistance and high heat conductivity but also a high radiation transmitting property

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentEP4006949B1Transmission type target, radiation generating tube including the same, radiation generating apparatus, and radiography system
Publication Date: 2024.10.02 CANON KK
  • EP4006949B1 patent drawingFigure 1A~1B
  • EP4006949B1 patent drawingFigure 2A~2D
  • EP4006949B1 patent drawingFigure 3A~3C

AI summary

A radiation emitting target (9), a radiation generating apparatus (101), and a radiography system (60) are provided in which adhesion between a target layer and a diamond substrate is improved and stable radiation emitting properties are exhibited. A transmission type target (9) includes a target layer (42), a carbon-containing region (45, 47) including sp2 bonds, and a diamond substrate (41, 46) that supports the target layer. The carbon-containing region is positioned between the target layer and the diamond substrate.