Head
GA10218_0101 - 5/2002
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9
1.1.4 Definiton of Terms
Autoranging
The range of the preamplifier and the vacuum ranges are selected auto-
matically.
The autoranging feature of the PhoeniXL covers the entire range or leak
rates depending on the selected operating mode. Not only the leak rate
signal, but also the pressure in the test sample (inlet pressure P1) and the
forevacuum pressure (P2) are used for control purposes. Range switching
between the main ranges is performed via valves. Fine range switching
within the main ranges is implemented by switching over the gain factor of
the preamplifier.
Autotune
Mass alignment
This function automatically aligns the mass spectrometer so that a maxi-
mum leak rate is displayed. The control processor changes the voltage
which erates the ions in the selected mass range until a maximum ion cur-
rent is detected by the ion detector. During each calibration the mass ali-
gnment is run automatically.
Auto zero
Determination and automatic adaptation of the internal background.
Through this function, the internal zero level of the instrument is determi-
ned which is then substracted from the current leak rate signal. This fuc-
tion is run during the calibration process or when operating the start
pushbutton, provided the PhoeniXL has been running previously for at
least 20 seconds in the stanby or vent mode.
GROSS
GROSS is a measurement mode which allows high inlet pressure (15 to
0,2 mbar). The smallest detectable leak rate is 1 · 10
-7
mbar l / s.
FINE
FINE is a measurement mode with inlet pressure < 0.2 mbar. The mini-
mum detectable leak rate is
≤
5 · 10
-12
mbar l / s
PRECISION
Precision is a measurement mode for the PhoeniXL
300 dry
only from an
inlet pressure < 0,1 mbar. In this mode the PhoeniXL
300 dry
has the high-
est sensitivity, the minimum detectable leak rate is
≤
3 · 10
-11
mbar l / s.
Foreline pressure
Pressure in the foreline between Turbo pump and rotary vane pump.
Internal helium
background
The existing helium partial pressure in the measurement system. The level
of the internal helium background is measured in the Stand-by mode and
subtracted from the measured signal.
Minimum detectable
leak rate
The smallest leak rate the PhoeniXL is able to detect (
≤
5·10
-12
mbar l / s)
in vacuum mode.
Menu
The menu allows the user to program the PhoeniXL according to his requi-
rements. The menu has a tree architecture.
Measure
Measurement mode
The PhoeniXL measures the leak rate of the test sample.
Default
Status of the PhoeniXL when supplied by the factory.
