Dual-Region Electron Impact Ion Source for Wide Pressure Ranges

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Solution Overview

Problem

Current ion sources for mass spectrometers either operate effectively at low pressures, offering high sensitivity but limited to low pressure ranges, or at high pressures with closed ion sources, which have low sensitivity and require separate pumping systems, leading to inefficiencies and dead time during pressure changes.

Innovation Solution

A wide-range electron impact ion source with multiple filaments positioned in both the process volume and differentially pumped areas, allowing operation in both low and high pressure conditions by controlling filament currents and using specific geometries for electron injection and ion extraction to maintain high sensitivity across pressure ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If open ion sources are used, then sensitivity is improved, but maximum pressure is limited to about 1E-3 mbar

Engineering Contradiction:

ImprovesensitivityVSAvoidmaximum pressure

Core Design Contradiction:

Measurement precisionVSStress or pressure

Solution Approach 1:

The ion source is divided into two separate ionization regions: an open ion source region for low pressure operation with high sensitivity, and a closed ion source region for high pressure operation. This segmentation allows each region to be optimized for its specific pressure range without compromise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between open and closed ion source configurations based on operating pressure conditions. The ability to change the ion source mode (open or closed) in response to pressure changes allows the system to maintain optimal sensitivity across a wide pressure range from 1E-6 to 1E-1 mbar.

Inventive Principle:

Principle #15Dynamics

2Stress or pressure

If closed ion sources are used, then pressure range is extended, but sensitivity deteriorates

Engineering Contradiction:

Improvepressure rangeVSAvoidsensitivity

Core Design Contradiction:

Stress or pressureVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dual ion source design provides universal operation across both low and high pressure ranges. The system can function as an open ion source for high sensitivity applications and as a closed ion source for high pressure applications, making it universally applicable to diverse process conditions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If two separate mass spectrometer systems are installed, then pressure range coverage is improved, but device complexity and dead time increase

Engineering Contradiction:

Improvepressure range coverageVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Two ion source configurations (open and closed) are merged into a single mass spectrometer system. The system integrates both ionization regions within one instrument, allowing seamless operation across the full pressure range without requiring separate spectrometer systems or complex switching mechanisms.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single mass spectrometer system achieves universal operation across both low and high pressure ranges by incorporating dual ion source capabilities. This eliminates the need for multiple separate systems while maintaining full pressure range coverage.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Adaptability or versatility

If valves are used for pressure reduction, then pressure adaptability is improved, but vacuum conductance is limited

Engineering Contradiction:

Improvepressure adaptabilityVSAvoidvacuum conductance

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The system dynamically switches between open and closed ion source modes based on pressure conditions, eliminating the need for valves to adapt pressure ranges. This dynamic configuration change provides pressure adaptability without the conductance limitations imposed by valve components.

Inventive Principle:

Principle #15Dynamics

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

Enables improved detection limits at low pressures and efficient operation across a wide pressure range, reducing dead time and maintaining high sensitivity by optimizing electron flux and ionization volume, as demonstrated by comparison with closed ion sources.

Implementation Method 1

one or more filaments positioned in the process volume or process chamber with a high yield of electrons reaching the ionization volume

Methodology Applied

Scientific EffectThermionic emission: Thermionic Emission

Implementation Method 2

electron impact ion source capable of operating in high and low pressures

Methodology Applied

Scientific EffectElectron impact ionization: Ionisation

Data Source

PatentUS12106953B2Wide range electron impact ion source for a mass spectrometer

Publication Date: 2024.10.01 INFICON INC

AI summary

A wide-range ion source for a mass spectrometer comprises a first portion and a second portion that is positioned downstream of the first portion. The first portion includes an anode and a first filament that is positioned proximate the anode and secured in place relative to the anode. The first filament is exposed to a pressure of a process chamber. A first electron repeller has at least a partially circular shape. The second portion includes a tubular anode, a second filament surrounding the tubular anode, an extraction lens defining an opening and a focus lens to conduct ions into a volume.