Stanford Research Systems RGA100, Operating Manual And Programming Reference

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2-2 What is an RGA?
SRS Residual Gas Analyzer
What is an RGA?
Complete characterization of a vacuum environment requires the detection of all the
component gases present, as well as measurement of the total pressure. The instruments
used for this purpose are called Residual Gas Analyzers or Partial Pressure Analyzers.
A Residual Gas Analyzer (RGA) is mass spectrometer of small physical dimensions
that can be connected directly to a vacuum system and whose function is to analyze the
gases inside the vacuum chamber.
The principle of operation is the same for all RGA instruments: A small fraction of the
gas molecules are ionized (positive ions), and the resulting ions are separated, detected
and measured according to their molecular masses.
RGA’’s are widely used to quickly identify the different molecules present in a residual
gas environment and, when properly calibrated, can be used to determine the
concentrations or absolute partial pressures of the components of a gas mixture.