Voltage Pulse Perturbation for Electron Space Charge Stabilization

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Solution Overview

Problem

Ion self-oscillation phenomena in electron ionization sources lead to degraded performance in mass spectrometry, characterized by poor peak area reproducibility and inconsistent ion ratios, particularly under high electron emission currents and strong magnetic fields, which existing solutions fail to adequately address without compromising sensitivity.

Innovation Solution

Applying a voltage pulse to the ionization chamber to perturb the electron space charge, stabilizing ion motions and inhibiting self-oscillation, while maintaining sensitivity by optimizing pulse width, height, and frequency based on operating parameters such as electron emission current and pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high electron emission currents and strong magnetic fields are used to maximize sensitivity, then ion production efficiency is improved, but ion self-oscillation occurs leading to poor peak area reproducibility and inconsistent ion ratios

Engineering Contradiction:

Improveion production efficiencyVSAvoidpeak area reproducibility

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies periodic voltage pulses to the electron beam or ion extraction system to disrupt the formation of ion self-oscillations. By introducing periodic perturbations at optimized frequencies and durations, the system prevents the buildup of space charge instabilities that cause poor reproducibility, while maintaining high electron emission currents for sensitive detection

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent modifies operating parameters including electron beam voltage, extraction voltage, and magnetic field strength to optimize the balance between ion production and stability. By dynamically adjusting these parameters and identifying optimal operating points, the system achieves high sensitivity without suffering from ion self-oscillation effects

Inventive Principle:

Principle #35Parameter changes

2Productivity

If high electron emission currents are used to maximize sensitivity, then ionization efficiency is improved, but space charge-driven ion instabilities occur

Engineering Contradiction:

Improveionization efficiencyVSAvoidion beam stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

Periodic voltage pulses are applied to the electron beam or extraction system to prevent space charge accumulation and stabilize ion beam composition. The pulsed action disrupts the formation of instabilities while allowing high current operation for efficient ionization

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system monitors ion beam stability and adjusts electron beam parameters in real-time to maintain stable ion composition. Feedback control prevents space charge-driven instabilities by correcting deviations from optimal operating conditions

Inventive Principle:

Principle #23Feedback

3Productivity

If strong magnetic fields are used to maximize sensitivity, then ion extraction efficiency is improved, but ion self-oscillation phenomena increase

Engineering Contradiction:

Improveion extraction efficiencyVSAvoidion ratio consistency

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Periodic voltage pulses are applied during ion extraction to counteract the destabilizing effects of strong magnetic fields. The pulsed action prevents ion self-oscillations while maintaining efficient extraction through optimized pulse timing and amplitude

Inventive Principle:

Principle #19Periodic 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

The technique effectively inhibits ion self-oscillation, improving sensitivity, linearity, and signal-to-noise ratio, ensuring consistent ion ratios and peak area reproducibility without altering the mass spectra generated.

Implementation Method 1

Applying a voltage pulse to the ionization chamber to perturb the electron space charge, stabilizing ion motions and inhibiting self-oscillation

Methodology Applied

Scientific EffectElectron space charge: Electrostatics

Implementation Method 2

an electron beam is directed into a chamber to produce ions from sample material in the chamber

Methodology Applied

Scientific EffectElectron impact ionization: Photoionisation

Data Source

PatentEP1875486B1Method for controlling space charge-driven ion instabilities in electron impact ion sources

Publication Date: 2017.03.15 BRUKER DALTONICS INC

AI summary

In a method for inhibiting space charge-related effects in an ion source, an electron beam is directed into a chamber to produce ions from sample material in the chamber. A voltage pulse is applied to the chamber to perturb an electron space charge present in the chamber. The ion source may be an electron impact ionization (EI) apparatus. The ion source may operated in conjunction with a mass spectrometry system.