SRS Labs QMS 100 Series, Руководство пользователя

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3-46 RGA Command Set
SRS QMS Gas Analyzer
The upper mass limit depends on the RGA model number: M_MAX=100 for RGA100, 200 for RGA200
and 300 for the RGA300.
Error Checking:
The command does not accept query or default parameters.
Programming tips:
•
Single mass measurements are commonly performed in sets where several
different masses are monitored sequencially and in a merry-go-round fashion.
For best accuracy of results, it is best to perform the consecutive mass
measurements in a set with the same type of detector and at the same noise
floor (NF) setting. Fixed detector settings eliminate settling time problems in
the electrometer and in the CDEM’s HV power supply.
•
It is good practice to perform an analog scan before triggering a long set of
measurements to assure the correct tuning (i.e. correct peak locations and
widths) of the quadrupole mass filter. Perform a complete Peak Tuning
Procedure as described in the RGA Tuning chapter of this manual if shifts in
the peak locations are observed.
•
The RF/DC voltages are left on at the end of a single mass measurement.
Use the MR0 command at the end of a set of measurements and
before quitting a program to make sure the RF/DC voltages are
turned off.
SAparam, param: 10 - 25, *, ?
Description : Steps per amu of analog scan.
Echo: Query Response.
Set the number of steps excecuted per amu of analog scan. The parameter specifies the number of steps-
per-amu.
During an analog scan the quadrupole mass filter is stepped at fixed mass increments through the mass
range specified by the MI and MF commands. An ion current is measured after each step and transmitted
to the host computer over RS232. SA programs the number of steps excecuted by the RGA per amu of
analog scan. The fixed mass-increment corresponding to each analog scan step is equal to the inverse of
the SA parameter value. Since the RGA is usually operated at unit mass resolution throughout its available
mass range, the parameter value can also be interpreted as the approximate number of ion currents to be
collected for each mass peak in the spectrum.