Photomultiplier Tube Intrinsic Safety via Resilient Optical Coupling

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing gamma detectors face challenges in making photomultiplier apparatus intrinsically safe for use in environments with flammable gases, as the fragile end face of the photomultiplier tube can expose electrical components to hazardous atmospheres, risking explosions, and existing designs struggle to maintain safety when using different scintillation elements or in the absence of a scintillator.

Innovation Solution

The photomultiplier apparatus incorporates resiliently deformable optical coupling means between the window and photomultiplier tube, along with sealing means and a voltage transformer to isolate high voltage components, ensuring the apparatus remains intrinsically safe by preventing exposure to flammable gases and allowing compatibility with various scintillation units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the photomultiplier tube is housed separately to enable coupling with different scintillators, then adaptability is improved, but the risk of electrical component exposure to hazardous atmospheres increases

Engineering Contradiction:
Improvecompatibility with different scintillation elementsVSAvoidexposure to flammable gases
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The photomultiplier tube is nested within a protective housing that contains shock-absorbing material. This nested structure allows the PMT to be physically protected while maintaining the ability to couple with different scintillators through a standardized interface, thus achieving both adaptability and protection against hazardous atmospheres.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

A resiliently deformable optical coupling means acts as an intermediary between the window means and the photomultiplier tube. This intermediary element provides both optical coupling functionality and mechanical protection, sealing the PMT within the housing while allowing light transmission, thereby preventing direct exposure to hazardous gases.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If shock absorbing arrangements are provided within the housing, then protection is improved, but device complexity increases

Engineering Contradiction:
Improveprotection against damageVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sealing means and shock-absorbing arrangements are merged into a single integrated housing structure. The housing simultaneously provides atmospheric sealing, mechanical protection through shock-absorbing material, and structural support, thereby achieving comprehensive protection without proportionally increasing device complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If the end face is made robust to prevent exposure, then intrinsic safety is improved, but optical coupling efficiency deteriorates

Engineering Contradiction:
Improveintrinsic safetyVSAvoidoptical coupling efficiency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The resiliently deformable optical coupling means serves as an intermediary that bridges the robust sealed end face of the PMT and the window means. This intermediary element maintains optical coupling efficiency through its deformable nature while the sealed end face remains protected, thus achieving both intrinsic safety and optical performance.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The optical coupling means is designed with specific material properties (resiliently deformable) that allow it to adapt its physical parameters under different conditions. This enables the system to maintain optimal optical coupling efficiency while the PMT end face remains robust and sealed for intrinsic safety.

Inventive Principle:
Principle #35Parameter changes

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 design achieves intrinsic safety in explosive atmospheres by isolating high voltage components and providing a robust optical coupling that protects the photomultiplier tube, enabling safe operation with different scintillators and maintaining safety even if the scintillator is removed or broken, conforming to international safety standards like EN 60079.

Implementation Method 1

resiliently deformable optical coupling means located between said window means and said photomultiplier means, wherein said resiliently deformable optical coupling means encapsulates an end of the photomultiplier means facing said window means

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 2

a photomultiplier tube for converting visible light from the scintillation element into an electrical output signal

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 3

a scintillation element for converting gamma radiation into visible light

Methodology Applied
Scientific EffectScintillation: Scintillation

Data Source

PatentEP2898348B1Photomultiplier apparatus and radiation detector incorporating such apparatus
Publication Date: 2020.01.01 JOHNSON MATTHEY PLC
  • EP2898348B1 patent drawingFigure 1
  • EP2898348B1 patent drawingFigure 2~3
  • EP2898348B1 patent drawingFigure 4~6

AI summary

A radiation detection apparatus (2) is disclosed. The apparatus comprises a housing (20), a window (26) at least partially transparent to electromagnetic radiation in a first wavelength range and a photomultiplier tube (24) for generating an electrical output signal dependent on the intensity of the electromagnetic radiation. A resiliently deformable optical coupling (28) is located between the window and the photomultiplier tube for allowing at least some electromagnetic radiation passing through the window to enter the photomultiplier tube, and a scintillator element 8 converts gamma radiation into visible light in the first wavelength range entering the photomultiplier tube.