Stanford Research Systems RGA100, Operating Manual And Programming Reference

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Glossary of Terms
SRS Residual Gas Analyzer
1
Glossary of Terms
The following is a listing of some of the most important terms used throughout the SRS
RGA Operations Manual. For a more complete listing of terms relevant to partial
pressure analyzers in general, refer to:
““A Dictionary of Vacuum Terms used in Vacuum Science and Technology, Surface
Science, Thin Film Technology and Vacuum Metalurgy””, edited by M. S. Kaminsky and
J. M. Lafferty, published by the American Vacuum Society, 1979.
A. Basford et. al., J. Vac. Sci. Technol. A 11(3) (1993) A22-40: ““Recommended Practice
for the Calibration of Mass Spectrometers for Partial Pressure Analysis. Update to AVS
Standard 2.3””.
Anode Grid (Ionizer Component) : Positively biased grid cage of the ionizer within
which the ionization of the gas molecules takes place. Note : In the SRS RGA, the voltage
bias of the anode grid, in Volts, sets the ion energy (in eV) for the spectrometer.
Atomic mass unit (abbreviation: amu). A unit of mass equal to one twelfth the mass of
a neutral carbon atom having six protons and six neutrons (
12
C); equivalent to
1.660566
.
10
-27
kg.
Background signal, H
0
. Output signal, measured with respect to baseline, which is
obtained before the introduction of any gas in the chamber.
Base pressure (also Background pressure). Total pressure before introduction of any
gases into a vacuum system. Usually, the base pressure is the lowest pressure that is
typically achieved in the vacuum chamber.
Baseline. The output signal from the RGA when no ions are arriving at the detector.
CDEM. Abbreviation for the type of electron multipliers known as: Continuous Dynode
Electron Multiplier.
CF. Abbreviation for Conflat type flange.
CF Nipple . A short section of vacuum pipe terminated with a standard Conflat flange
connector at each end.
Charge, Q. The electron charge of an ion. Ion charge occurs in multiples of the electron
charge, e
-
.
Drift. A change in time in the avearge output signal at constant partial pressure.
ECU. Abbreviation for electronics control unit.