SRS Labs QMS 100 Series, Руководство пользователя

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Overview of the RGA B-3
Technical Reference
Overview of the RGA
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.
The quadrupole probe is a mass spectrometer sensor consisting of an ion source, a quadrupole mass
filter, a Faraday cup and an optional electron multiplier. Ions are created from the residual gas of a
vacuum system by electron impact ionization. Ions of a particular mass-to-charge ratio have stable
trajectories through the mass filter, depending on the DC and RF voltages applied to the quadrupole
rods. The selected ions are collected in a Faraday cup or multiplied in an electron multiplier.
The ECU box (3” x 4” x9”) contains all the electronics necessary to operate the RGA. It connects
directly to the probe’s feedthru flange, and also to a host computer. Its regulated power supplies set the
ionizer voltages, the filament’s electron emission current, the high voltage across the electron multiplier
and the RF/DC levels on the quadrupole filter. A logarithmic transconductance amplifier converts ion
currents into voltages that are read by an A/D converter. A microprocessor and control firmware direct
the operations of the spectrometer, the data acquisition, and the communications through the RS232
serial link.
The electronics operate from a single 24 +/-2 V DC power supply. The peak current requirement is
about 2A.