Description
GA10218_002_A7 - 9/2015 - © Oerlikon Leybold
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cal current. When selected another mass than 4, only the corresponding ions can
pass the filter.
For operation the mass spectrometer requires a vacuum level in the range of 1·10
-
4
mbar and lower. This pressure is provided by the turbo molecular pump which in
turn is backed up by a fore vacuum pump.
Besides maintaining the pressure in the mass spectrometer the pump system is
used to evacuate the test parts. It is made sure that the pressure in the mass spec-
trometer is low enough under all circumstances. The valves V1, V2a, V2b, V4a
control the gas flows when measuring. Valves V3 and V5 are used to vent the sys-
tem and the Turbo pump, valve V6 controls the gas ballast function of the fore vac-
uum pump. Valve V7 opens and closes the internal test leak during calibration.
With the pressure in the test part being lower than ambient pressure sprayed
helium (or Hydrogen as forming gas) can penetrate into the part in case of a leak-
age. As soon as the pressure conditions allow it one of the valves to the TMP
opens. Now Helium can penetrate into the mass spectrometer contrary to the
pumping direction of the TMP.
1.1.2 Vacuum Diagram PHOENIX L300i DRY
The PHOENIX L300i DRY has a diaphragm pump as fore vacuum pump, making it
suitable for applications where oil sealed systems can not be used. Furthermore
the PHOENIX L300i DRY contains one more valve, the valve 4b. This valve opens
step by step to regulate the inlet pressure into the turbo pump.
Fig. 3 Vacuum diagram PHOENIX L300i DRY
MS
P
1
V
1
V
2a
V
3
V
2b
P
2
V
V
4 a
4 b
V
6
V
5
V
7
1
2
3
6
5
4
Diaphragm pump
