SRS Labs QMS 100 Series, Руководство пользователя

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SRS QMS Gas Analyzer
Glossary
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 Nipple . A short section of vacuum pipe terminated with a standard Conflat flange connector at each
end.
CF. Abbreviation for Conflat type flange.
Charge, Q. The electron charge of an ion. Ion charge occurs in multiples of the electron charge, e
-
.
Cleanup time - is a measure of how quickly the response returns to zero when a gas is removed from
the inlet (not necessarily equal to response time).
Delay time - is a measure of the time between when a step change is presented at the inlet and the
response is first seen at the QMS (can be very long without degrading the response time).
Drift. A change in time in the average output signal at constant partial pressure.
ECU. Abbreviation for electronics control unit.
Electron emission current. The electron current from the filament to the grid in milliAmperes.
Electron emission . The release of electrons from the heated filament in the ionizer. The electrons are
accelerated into the anode grid where the ionization of the gas molecules occurs.