C 30
Detector autocalibration
4/5
Alcatel - High Vacuum Technology - ASM 180 TD/TD+ - ASM 181 TD+ User’s Manual
Edition 03 - May 97
Throughout the autocalibration cycle, the "autocal" key red
indicator light flashes.
• Residual check.
• Autocalibration circuit roughing.
• Connection with the analyzer cell.
The Helium signal measurement is displayed.
• Comparison of the measured signal with the calibrated
leak value
after waiting a few seconds for the signal to
stabilize.
If the difference is less than 10 %,
the autocalibration is stopped and validated.
If the difference is greater than 10 %,
the autocalibration is continued.
• Helium peak detection.
The
automatic control system varies the
acceleration voltage in the
analyzer cell (see
A 30
).
This varies the path of the Helium
ions until the maximum Helium
signal is obtained. The Helium
signal display oscillates during this
stage.
• Sensitivity adjustment.
The filament current in the analyzer
cell (see
A 30
) is automatically
adjusted so that the detector
displays a correct leak value
(internal calibrated leak value
corrected as a function of
temperature).
Stages 6 and 7 can be performed
several times if necessary, until the correct display is obtained.
Autocalibration
procedure
4