Stanford Research Systems RGA100, Operating Manual And Programming Reference

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Head Calibration and Security 5-22
SRS Residual Gas Analyzer
Head Calibration and Security
Note:
For detailed information and command description of the RGA program please refer to the RGA
On-Line Help files provided with the program disks. The RGA help system includes current and
detailed description of all the features, procedures and commands available in the program.
Tuning the RGA Sensitivity
WARNING!
The sensitivity tuning procedure should be performed by qualified personnel only.
A mistuned RGA Head could give erroneous readings until it is retuned properly.
Please refer to the RGA Tuning Chapter for more information about tuning and
calibration.
While performing the tuning procedure the total pressure in the vacuum chamber
should be around 10E-6 Torr.
In order to set the sensitivity factors of the RGA Head you must have a reference
pressure gauge installed on your vacuum system. There are two sensitivity factors, one
for total pressure and one for partial pressure. Both factors are stored in non-volatile
memory in the RGA Head.
To tune the sensitivity factors do the following:
Make sure you are connected to the head.
1. Select the Sensitivity Tuning command from the Head menu.
2. Select which sensitivity factor you would like to adjust from the Measurement Mode
section (Partial or Total).
3. If you selected Partial Pressure then enter the mass whose pressure you will be
measuring in the Mass Selection edit box.
4. Enter the pressure indicated by your pressure gauge in the Reference Pressure
Reading.
5. Press the Measure button.
6. Press Accept to start using the new factor(s) or Undo to revert back to the old one(s).
Adjusting the CEM Gain
The CEM gain may be set to any desired value between 10 and 1,000,000.
The RGA program will automatically search the required high voltage for such a gain if
the Adjust button is pressed.
All data acquired while the CEM is ON gets divided by the gain automatically before it
is displayed.