Mass Spectrometers for Residual Gas Analysis
Quadrupole mass spectrometers are the classic measuring instrument for evaluating residual gas composition in a vacuum system.
The ion currents supplied by the mass spectrometer for the mass-to-charge ratio of the gas components provide meaningful information about a vacuum system in the multiple phases of operation, whether for determining the tightness and the absence of contamination after setup or for its characterization when operating a vacuum process.
The pressure range which can be achieved in the vacuum system based on the design of the vacuum chamber and pumping system determines the selection of the mass spectrometer with respect to the detector. A Faraday detector is frequently sufficient in high vacuum, while a secondary electron multiplier is necessary in ultra-high vacuum to detect the very low gas densities.
Another key criterion is the mass range to be detected. In the traditional vacuum system, atmospheric gases such as nitrogen, oxygen, argon, water vapor, and, generally, contamination with light hydrocarbons are the main focus. In order to detect these gases, a quadrupole mass spectrometer for the range between 1 and 100 atomic mass units (u) is ideal, as this demonstrates excellent mass separation in this range. If heavier gases and their components must also be detected, such as long-chain hydrocarbons, Pfeiffer Vacuum also offers mass filters for this purpose for 1 to 200 u or 1 to 300 u.
An open ion source is the best choice for most tasks in residual gas analysis, as they combine a robust design with high detection sensitivity. Tasks for which gas jets or gas streams must be analyzed can be advantageously mastered with a closed or a cross-beam ion source. For the ultra-high vacuum range, a grid ion source with an extremely low outgassing rate is also available. Thanks to the precise configurability of Pfeiffer Vacuum quadrupole mass spectrometers due to the large number of components to choose from, the spectrometers can be optimally selected for all measurement tasks. Our product and application specialists with many years of experience are happy to advise you on the configuration of the appropriate residual gas analyser.
Brochure Quadrupole Mass Spectrometer PrismaPro – Download Here
Residual gas analysis for high-vacuum applications
Quadrupole mass spectrometers with Faraday detectors are the preferred devices for qualitative analysis of the gas composition in a high-vacuum chamber.
Compared with vacuum gauges, quadrupole mass spectrometers offer a much greater wealth of information about the vacuum. A Faraday detector is often sufficient to obtain information about leaks, the release of water vapor or contamination with hydrocarbons under high vacuum. For this purpose, Pfeiffer Vacuum offers a range of quadrupole mass spectrometers with a variety of mass ranges and filament materials.
Residual gas analysis for ultra-high vacuum applications
Quadrupole mass spectrometers with a secondary electron multiplier offer maximum detection sensitivity in the qualitative analysis of gas composition in an ultra-high vacuum chamber.
For residual gas analysis under high vacuum, extremely small amounts of gas must be detected. A secondary electron multiplier in the Pfeiffer Vacuum residual gas analyzers therefore guarantees a high amplification of the small ion currents supplied by the quadrupole mass filters. All materials used are carefully selected for use in UHV and can withstand high bake-out temperatures.
Several ion sources are available for different applications, including a grid ion source with an extremely low outgassing rate.