Select Page

Plasma Diagnostics by Mass and Energy Analysis (EQP Mass Spectrometer)

Plasma diagnostics require precise measurement of ion energy, species composition, and time-dependent behaviour. Mass and energy analysers, such as the EQP mass spectrometer, provide a powerful solution by combining quadrupole mass spectrometry with electrostatic energy analysis.

This enables simultaneous measurement of ion energy distributions (IEDs) and mass spectra, allowing detailed investigation of plasma processes in research and industrial applications.

What is Plasma Diagnostics by Mass Spectrometry?

Plasma diagnostics using mass spectrometry involves analysing ions, radicals, and neutral species to understand plasma behaviour.

Unlike conventional mass spectrometry, advanced plasma diagnostic systems measure both:

  • mass-to-charge ratio (m/z)
  • ion energy distributions (IEDs)

This dual capability is essential for studying:

  • plasma potential
  • ion acceleration
  • plasma-surface interactions
  • reaction mechanisms in plasma systems

What is a Mass and Energy Analyser?

A mass and energy analyser combines:

  • a quadrupole mass filter for mass analysis
  • an electrostatic energy analyser for ion energy measurement

The EQP system integrates both technologies into a single instrument, enabling energy-resolved mass spectrometry for plasma diagnostics.

This approach provides significantly more insight than conventional mass spectrometry alone.

Key Advantages of Mass and Energy Analysis for Plasma Diagnostics

Simultaneous Mass and Energy Measurement

Measure ion composition and energy distributions in a single experiment.

Detection of Ions, Radicals, and Neutrals

Analyse:

  • positive and negative ions
  • neutral species
  • reactive radicals

High Sensitivity and Dynamic Range

Pulse-counting detection enables analysis of trace species with a dynamic range greater than 10¹⁰.

Time-Resolved Plasma Analysis

Fast acquisition and gating (down to microseconds) allow investigation of:

  • transient plasma events
  • afterglow behaviour
  • dynamic processes

Flexible Measurement Modes

Supports both direct plasma ion analysis and neutral species detection.

How Mass and Energy Analysis Works in Plasma Systems

Mass and energy analysis involves several key stages:

  1. Sampling from the Plasma
    A configurable sampling orifice extracts species directly from the plasma.
  2. Ion Formation (for Neutrals)
    Neutral species are ionised using electron impact ionisation.
  3. Ion Transfer and Focusing
    Ion optics guide ions into the analyser.
  4. Energy Analysis
    A sector field analyser measures ion energy with high resolution.
  5. Mass Analysis
    A quadrupole mass filter separates ions by mass-to-charge ratio.
  6. Detection
    A high-sensitivity detector records ion signals for analysis.

As shown in the instrument diagram, this process enables detailed characterisation of plasma species and their energy distributions.

Measurement Modes for Plasma Diagnostics

Plasma Ion Mode (PI Mode)

Direct measurement of ions generated within the plasma, providing insight into ion energy and plasma behaviour.

Electron Impact Mode (EI Mode)

Neutral species and radicals are ionised within the instrument, enabling detection of species not directly charged in the plasma.

This dual-mode capability allows comprehensive plasma analysis.

Ion Energy Distribution (IED) Analysis

Ion energy distributions are critical for understanding plasma behaviour.

Using mass and energy analysis, researchers can:

  • determine plasma potential
  • analyse ion acceleration mechanisms
  • study plasma sheath interactions
  • identify collision processes

As illustrated in the example spectra on the poster, energy “tailing” indicates collisions and energy loss within the plasma.

Applications of Plasma Diagnostics Mass Spectrometry

Mass and energy analysers are widely used in plasma science and engineering.

Plasma Process Monitoring

Real-time measurement of ion energy and species composition in plasma reactors.

Semiconductor Manufacturing

Optimisation of plasma conditions during etching and thin film deposition.

Plasma Physics Research

Study of ion dynamics, plasma potential, and sheath behaviour.

Surface Engineering

Analysis of plasma-surface interactions and ion bombardment effects.

Transient and Afterglow Studies

Investigation of short-lived plasma phenomena using fast acquisition and gated detection.

Why Energy-Resolved Mass Spectrometry is Important

Traditional mass spectrometry measures only mass-to-charge ratio. However, plasma behaviour is strongly influenced by ion energy.

Energy-resolved mass spectrometry enables:

  • improved understanding of plasma processes
  • enhanced process control
  • optimisation of plasma-based manufacturing
  • deeper insight into reaction mechanisms

This makes mass and energy analysers essential tools for advanced plasma diagnostics.

Related Techniques

Researchers working in plasma diagnostics may also use:

Download the EQP Technical Poster

For detailed system diagrams, configuration, and example spectra:

EQP Mass and Energy Analyser Poster (PDF)

Sam Bort Biography

Sam is an Applications Specialist at Hiden Analytical, with a BSc (Hons) in Chemistry from the University of Manchester and a background in analytical instrumentation and plasma diagnostics. His work focuses primarily on mass spectrometry and Langmuir probe systems, supporting customers in measuring and characterising plasma processes. Since joining Hiden in 2008, Sam has worked closely with customers across research and industry, providing installation, training, and technical support for new and existing users. By following the latest work carried out with Hiden instruments, he helps identify emerging application areas and ensures customer insight continues to inform the development and support of Hiden’s plasma diagnostic technologies.