5–1
Transpector CPM Operating Manual
Chapter 5
Theory and Application Guide
5.1 Theory of Operation
A Closed Ion Source (CIS) analyzer takes a representative process gas sample
and directs it to the ionization region of a Residual Gas Analyzer (RGA). The
sampling and flow of the gas sample is accomplished by successive reduction of
pressure from the process to the Turbo Molecular Pump through fixed geometry
pump-in channels. Transpector CPM detects levels of impurities in process gases
that are significantly lower—at sub-ppm levels for many components—than those
detected by open-ion source RGA analyzers.
5.2 Sensors
The three main components of the Transpector CPM sensor are:
ion source (ionizer)
quadrupole mass filter
detector/electron multiplier
These components are mounted on an electrical feedthrough flange bolted to the
vacuum manifold. (See Figure 5-1.)
The sensor works only in a high-vacuum environment because the ions, once
created, must not collide with other gas molecules as they move through the
sensor.
Figure 5-1 CPM sensor
Ion Source Mass Filter
Detector / Electron Multiplier
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