Varian 979 Series, Operation Manual

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Model 979 Series Helium Mass Spectrometer Leak Detector
DRAFT 9/15/03
B-9
The commands listed in Table B-3 are used to cause an immediate change in the spectrom-
eter operating parameters.
These Commands Do Not Change The Non-volatile Operating
Parameters .
The commands listed in Table B-4 are used to cause certain leak detection actions.
Table B-3 Spectrometer Operating Parameters
Command Parameter
PUT-EMISSION A four-digit number of microamps, in the range 0300 to 2000, which sets the
emission current of the ion source.
PUT-EXPONENT A three-character number indicating the exponent of the range of leak in
MANUAL mode. Acceptable values are 0 through
−
10. Unacceptable values are
not stored.
PUT-FOCUS A three-digit number of volts, in the range 150 to 400, which sets the variable
focus voltage of the ion source.
PUT-GAIN A two-digit number with a decimal point after the first digit, in the range 1.0 to
6.0, which sets the position of a variable gain (digi-pot) device used for adjusting
the helium signal to match a calibration standard leak.
PUT-ION A three-digit number of volts, in the range 200 to 350, which sets the ion voltage
of the ion source.
PUT-OFFSET A two-digit number, in the range 00 to 99, which sets the percentage of an offset
variable.
PUT-RANGE A two-character number indicating the exponent of the least sensitive range of
detectable leak. Acceptable values are 0 through –6. Unacceptable values are
not stored.
PUT-REPELLER A three-digit number of volts, in the range 300 to 600, which sets the repeller
voltage of the ion source.
Table B-4 Leak Detection Actions
Command Action
AUTO Initiates auto-ranging mode. Success is indicated by the normal ok response.
CALIBRATE Tunes, then adjusts the gain so that the current helium signal causes the current
leak rate measurement to be the same as was most recently input using
INIT-STDLEAK. Success is indicated by the normal ok response.
DECREMENT Subtracts 1 from the Manual Ranging leak rate exponent (making it more
negative). Success is indicated by the normal ok response. Does nothing in
auto-ranging mode. Does nothing upon reaching the most sensitive range.
DISABLE-RANGESTOP Disables the Rangestop function.
ENABLE-RANGESTOP Enables the Rangestop function.