Stanford Research Systems RGA100, Operating Manual And Programming Reference

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Programming the RGA Head 6-15
SRS Residual Gas Analyzer
memory. However, all offset correction factors are cleared after a recalibration (CL) of
the electrometer is performed, and when the unit is turned off.
Please consult the RGA Command Set section for details on the CA command.
Detector Programming example
The following list of commands starts by checking the RGA head to make sure there is a
multiplier installed: A CDEM is present if a 1<LF><CR> response is sent back to the
computer. After the test (and assuming the CDEM option was detected), a voltage of
-1400V is set across the multiplier, and the noise floor setting is programmed for
minimum averaging and maximum scan rate. The detector is now fully configured for
CDEM measurements with -1400 V of CDEM bias voltage.
MO? Multiplier Option Query.
Check query response: 1<LF><CR> confirms CDEM option.
HV1400
High Voltage CDEM = 1400V. Echoes the STATUS Byte.
NF7 Noise Floor = 7.
Notes :
Append a CA command at the end of this list to readjust the zero of the ion detector
measurements under the present detector settings. The correction factor will then be used
by all measurements (i.e. single mass and total pressure) under this same detector settings
to correct against zero drifts. Use the HV0 command to go back to FC detection mode.
Important: Total Pressure measurements are disallowed when the CDEM is activated
(TP_Flag is cleared as soon as the CDEM is biased). Please see the TP command for
details.
Detector Programming Tips
x
Use the ElecMult LED to visually inspect the status of the CDEM during
programming.
x
Use the HV? command to query the type of detector that is currently active. The
CDEM is active if a non-zero response is returned to the computer.
x
Check the value of STATUS as returned after the HV command execution: Bit 3
provides immediate information about the success of the command.
x
The HV command checks for the presence of a CDEM option in the RGA Head
before execution starts and an error is reported if no CDEM is available. (Please see
EM query command for details.)
x
It is possible to activate the CDEM if the filament is not emitting electrons, but the
CDEM will be deactivated by any overpressure that shuts-down the filament.
x
The correct operation of the electrometer can be tested using the Error Reporting
command ED?.