TOF Mass Analyser Assembly for Thermal Expansion Compensation
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Solution Overview
Problem
Existing time-of-flight mass analyzers face challenges in thermal compensation and stress/friction due to thermal expansion, particularly in multi-reflection systems, which affect mass-to-charge ratio measurements and require inefficient bake-out processes.
Innovation Solution
A vacuum chamber assembly with supports that allow relative movement between electrodes and the chamber, coupled thermally for efficient heating/cooling during bake-out, and a thermal compensation scheme using connectors to maintain flight path stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the vacuum chamber and analyser are firmly fixed together for good thermal coupling during bake-out, then heating/cooling efficiency is improved, but stress on analyser components increases due to thermal expansion/contraction
Solution Approach 1:
The analyser is divided into modular components (electrode assemblies, detector, ion source) that can be independently supported. Each module is connected to the vacuum chamber through separate support structures, allowing differential thermal expansion without transmitting stress across the entire system.
Solution Approach 2:
Different parts of the analyser system have different thermal coupling characteristics. Critical components requiring stable dimensions (electrodes defining flight path) are thermally isolated or compensated, while non-critical components are firmly coupled for efficient heat transfer during bake-out.
2Stability of the object's composition
If a spacer is used to reduce distance between ion source and detector during thermal expansion, then flight path stability is improved, but friction between spacer and detector increases
Solution Approach 1:
A low-friction intermediary material (such as Teflon or ceramic coating) is introduced between the spacer and detector surfaces. This intermediary maintains the mechanical coupling needed for flight path stability while minimizing friction and wear during thermal expansion cycles.
Solution Approach 2:
The coefficient of friction between contacting surfaces is changed by selecting materials with inherently low friction properties. The spacer material is specifically chosen to have low friction against the detector, allowing smooth relative movement during thermal expansion while maintaining position stability.
3Measurement precision
If multi-reflection time-of-flight mass analyser with longer flight path is used, then mass-to-charge ratio measurement precision is improved, but vacuum conditions require stricter control
Solution Approach 1:
The vacuum chamber undergoes extended bake-out treatment before operation to thoroughly outgas all surfaces. This preliminary action removes contaminants and moisture from the chamber walls and internal components, establishing and maintaining the ultra-high vacuum conditions required for long flight path analysis.
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
Reduces stress and friction on components, maintains flight path stability, and enhances bake-out efficiency by allowing thermal expansion without compromising analysis accuracy.
Implementation Method 1
the inner surface of the vacuum chamber and the first electrode are thermally coupled... the first support permits relative movement between at least a portion of the inner surface of the vacuum chamber and the first electrode
Implementation Method 2
the inner surface of the vacuum chamber and the first electrode are thermally coupled... efficient heating/cooling requires good thermal coupling between the analyser and the vacuum chamber
Data Source
AI summary
The present invention relates to an assembly comprising a vacuum chamber and a time-of-flight mass spectrometer wherein the time-of-flight mass spectrometer is contained within the vacuum chamber. The time-of-flight mass spectrometer comprising a first electrode and a second electrode, the second electrode being spaced apart from the first electrode at a distance defining a portion of an ion-flight path therebetween. The assembly further comprising a first support for supporting the first electrode, the first support arranged between an inner surface of the vacuum chamber and the first electrode. The first support is configured to permit relative movement between at least a portion of the inner surface of the vacuum chamber and the first electrode. The inner surface of the vacuum chamber and the first electrode are thermally coupled. The present invention also relates to a multi-reflection time-of-flight mass analyser. The present invention also relates to an apparatus for out-gassing to remove contaminants from surfaces within a vacuum chamber by heating and subsequently cooling the surfaces.