Vacuum Technology Know How - Triumf

Inlet System
No pressure reduction
SPM ion source
Capillary inlet
Orifice inlet
Metering valve
Pressure-regulated
gas inlet
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At pressures p of less than 10 mbar, pressure is reduced by means of an orifice and with
a mass spectrometer that is differentially pumped by means of a turbomolecular pump
At pressures p of less than 10 - 4 mbar, the mass spectrometer can be installed directly in
the process chamber with an open ion source
Table 4.3: Various gas inlet systems and their attributes
Pressure Range
10 -12 to 10 - 4 mbar
10 - 9 to 10 mbar
700 to 1,100 mbar,
as a function of capillary
length and upstream orifice
0.1 to 10 mbar, as a
function of orifice diameter
0.1 to 1,000 mbar
10 - 3 to 1,000 mbar
4.1.3 Application notes
Product Example
PrismaPlus QMG 220,
HiQuad QMG 700
PrismaPlus SPM 220,
HiQuad SPM 700
OmniStar,
ThermoStar,
GES 020 and GES 010
inlet system
PrismaPlus HPA 220
HPA 220 PrismaPlus,
UDV 040 to 146
metering valves
EVR 016 with RVC 300,
OmniStar with
pressure-regulated inlet
Characteristics
A further pressure range can be
covered with various ion sources
Special ion source for analyzing
sputter processes. This system
analyzes the unfalsified state of the
plant by means of pressure reduction
Differentially pumped inlet system,
low mass discrimination,
not suitable for changing inlet
pressures
Orifices with diameters of 0.01 to
0.5 mm,simple, robust design,
mass discrimination, changing inlet
pressure possible with various orifice
diameters, not suitable for
fast-changing gas compositions
Metering valves are suitable for gas
inlet throughout a very broad
measurement range, differentially
pumped valves also enable analysis
of rapidly changing gas compositions
Differentially pumped inlet system,
comprising a control loop with
regulating valve and pressure
measurement, relatively large dead
volume, long gas changing times
Mass spectrometer analysis is every bit as varied as vacuum applications. The above-described
gas inlet systems with heated capillaries are used for gas analysis in the pressure range of
up to 1 bar. Gas flows can be channeled directly to gas-tight ion sources in order to reduce
the background noise of the vacuum environment. Gas beams are passed through crossbeam
ion sources, with the beam either falling directly into a vacuum pump or condensing in
a cooling trap.
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