Model 979 Series Helium Mass Spectrometer Leak Detector
DRAFT 9/15/03
3-5
3.1.2.1 Changing Manual Tuning Parameters
To change a manual tuning parameter:
1. Touch the box for the desired parameter.
When you touch the box containing the desired variable, a highlighted indicator
appears to the right of the numbers.
2. Touch the
UP
or
DN
arrow to change the parameter value.
NOTE
Do not touch the ESC box before touching the OK box. This
causes the selected parameter to revert to its previously stored
value.
3. Touch the
OK
box to accept the changes and to store the new parameter value in the
leak detector memory.
4. Touch
DONE
to exit the screen and return to the previous menu screen.
3.1.2.2 Repeller
The REPELLER (Voltage) box displays the current Repeller Voltage value of the Ion Source in
the spectrometer tube and allows for manual adjustment of this parameter. The repeller volt-
age parameter is used to tune the leak detector, maximizing the leak detector output for a
peak helium signal. The repeller voltage parameter is adjusted before the leak detector is
calibrated to helium. This parameter is
not
adjusted automatically during the Calibration
routine.
Typical Repeller Voltage values range from 320 VDC to 360 VDC.
3.1.2.3 Emission Current
The EMISSION adjustment box displays the value of the existing Emission current of the Ion
Source in the spectrometer tube and allows for the adjustment of this parameter. The emis-
sion current parameter is used to tune the leak detector, maximizing the leak detector out-
put for a peak helium signal. The emission current parameter is adjusted before the leak
detector is calibrated to helium. This parameter is not adjusted automatically during the Cal-
ibration routine.
Typical Emission current values range from .7 mA to 1.4 mA.
NOTE
To obtain a maximum Helium peak signal, adjust emission
current during a manual tune.
Summary of Contents for 979 Series
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