Varian 4000 GC, Hardware Operation Manual

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Samples are first injected into the GC either manually or by way of an
autosampler. The sample is vaporized and the gas goes though a column in the
GC oven. After separation in the column, the sample enters the mass
spectrometer through a heated transfer line. The MS analyzer consists of three
parts: the source, ion trap, and detector. The samples flow from the transfer line
into either an external source, where the sample is ionized, or directly into the ion
trap for ionization. Once ionized, the ions are stored in the ion trap where they
are systematically ejected for analysis. After ion ejection, the detector (consisting
of a conversion dynode and electron multiplier) senses the ions.
The vacuum manifold maintains the necessary vacuum conditions for proper
analyzer operation. A turbomolecular pump and foreline pump create the
necessary vacuum in the manifold. Various pneumatics components feed
required gases into the vacuum manifold. An ion gauge and thermocouple gauge
measure the vacuum levels in the manifold and foreline respectively.
Physically the vacuum manifold is mounted on top of an RF coil assembly. RF
generation and ion detection electronics components are placed around the
RF coil assembly. Some source and trap related electronics components reside
in an enclosure mounted to the vacuum manifold top flange. A system controller
and power board are contained in an enclosure formed by a central bulkhead
and outer cover.
WARNING:
SHOCK HAZARD
HIGH VOLTAGES INSIDE. No user serviceable parts under screw-attached
covers. Contact your local Varian, Inc. service representative for instrument
repair and service.
Thermocouple
Vacuum Gauge
Electronics Compartment
Electronic Flow
Control
Service Switch
Manifold Electronics
Enclosure
Foreline Line
4000 Mass Spectrometer Getter
Turbomolecular
Pump
Ion
Amplifier
Transfer
Li
Vacuum Manifold
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