Thermo Finnigan LTQ - Page 79

Functional Description
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___________________________________________________________________ MS Detector
_______________________ Finnigan LTQ Hardware Manual _____________________
2-25
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Vacuum Manifold
The vacuum manifold encloses the ion source interface, ion guides, mass
analyzer, and ion detection system assemblies. The vacuum manifold is a
thick-walled, aluminum chamber with a removable top cover plate, machined
flanges on the front, sides, and bottom, and various electrical feedthroughs
and gas inlets.
The vacuum manifold is divided into four chambers by three baffles. See
Figure 2-14. The region inside the first chamber, called the capillary/skimmer
region, is evacuated to 1Torr by the rotary-vane pump. The region inside the
second chamber, called the Q00 ion guide region, is evacuated to 50 mTorr
by the third inlet in the molecular drag section of the triple-inlet
turbomolecular vacuum pump. The region inside the third chamber, called the
Q0 ion guide region, is evacuated to 1 mTorr by the interstage port of the
turbomolecular vacuum pump. The region inside the fourth chamber, called
the analyzer region, is evacuated to less than 10
-5
Torr by the high vacuum
port of the turbomolecular pump. The turbomolecular pump in turn discharges
into the rotary-vane pump through the foreline.
Figure 2-13. Functional block diagram of the vacuum system and inlet gasses hardware
VENT
VALVE
TRIPLE-INLET
TURBOMOLECULAR PUMP
FORELINE
AIR
FILTER
ION
GAUGE
ANALYZER
REGION
Q0
ION GUIDE
REGION
Q00
ION GUIDE
REGION
CAPILLARY/
SKIMMER
REGION
(1 TORR)
ATMO-
SPHERIC
PRESSURE
REGION
(760 TORR)
CONVECTRON
GAUGE
SAMPLE TUBE
LC
(OR OTHER
SAMPLE
INPUT
DEVICE)
EXHAUST
AUX GAS
VALVE
SHEATH
GAS VALVE
NITROGEN
GAS PORT
FOREPUMP
SWEEP
GAS VALVE
DAMPING GAS
REGULATOR
RESTRICTOR
HELIUM
GAS PORT
(1 mTORR)
(2x10 TORR)
-5
(50 mTORR)