Stanford Research Systems RGA100, Operating Manual And Programming Reference

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3-2 Introduction
SRS Residual Gas Analyzer
Introduction
The SRS RGA is a mass spectrometer consisting of a quadrupole probe , and an
Electronics Control Unit ( ECU ) which mounts directly on the probe’’s flange and
contains all the necessary electronics for operating the instrument.
Electronics Control
Unit (ECU)
Ionizer
Quadrupole Probe
Figure 1 Quadrupole Head Components
The probe is a specially engineered form of quadrupole mass spectrometer sensor. It is
mostly constructed out of type 304 stainless steel and high purity alumina, and mounts
directly onto any standard 2.75" CF port of a vacuum chamber. It analyzes residual gases
ionizing some of the gas molecules (positive ions), separating the resulting ions
according to their respective masses and measuring the ion currents at each mass.
The total probe equipment consists of three parts: the ionizer , the quadrupole filter and
the ion detector . All of these parts reside in the vacuum space where the gas analysis
measurements are made.
Ionizer Ion Filter Ion Detector
Figure 2 Probe Components
A stainless steel tube (RGA Cover Nipple) covers the probe assembly with the exception
of the ionizer. A 2.75”” CF port with at least 1.375”” inside diameter and 2.5”” depth is
needed to provide clearance for the insertion of the ionizer into a vacuum system. This
insertion volume is comparable to that taken by a regular Bayard-Albert ion gauge.
A high vacuum environment (10
-4
Torr or less) is required for operation.