D397-01-880 Issue E
Page 32
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Operation
Figure 23 - Setup screen IGC
IGC has a built-in error monitoring capability. Refer to table below.
Restrike
When the Ion gauge is first switched on it is possible that the demanded emission is not
achieved. When the IGC is reading pressure normally it is possible for emission to fail e.g. due
to a pressure surge. Normally (with the default Restrike setting of off) either of these
occurrences will lead to an emission error. The TIC will then turn off the emission demand.
If the Restrike option is ‘ON’ after an emission error time out period the TIC will turn off
emission demand and then immediately turn it back on for a second time. The emission error
state is then only entered after a 2nd emission time out period.
‘Scroll’ to ‘Restrike’ and press ‘Select’. ‘Scroll’ to change option and press ‘Select’ for change
to occur.
Fil 1 Const
Gauge sensitivity is a unique figure for each filament which is primarily the result of gauge
geometry. In an ‘off the shelf’ gauge head, a value will be quoted in the document
accompanying the gauge (same for both filaments). A gauge head received from a calibration
laboratory will come with a precise sensitivity value for each filament. This sensitivity figure
needs to be entered into the TIC. Scroll to Fil 1 Const and press select. Amend the sensitivity
value. See
changing numerical values.
Note:
Gauge sensitivity has units /mbar or /Torr or /pascal, the value is pressure unit
dependent e.g. 6.4/mbar = 8.53/Torr.
Fil 2 Const
As for Fil 1 Const above (but for Filament 2).
Table 26 - Diagnostic messages
Diagnostic Messages
Description
Off
Ion gauge emission is not on.
Filament life will be reduced if the user attempts to turn on the gauge at pressures
above 5 x 10
-3
mbar.
Inhibited
Setpoint output from gauge connected to IGC auxiliary port is bad or IGC mains is off.
Initialising
Emission cannot be established instantly after gauge is turned on as the filament
power must be slowly ramped. This process can take a maximum of 22 seconds. The
‘initialising’ message means this start-up timer is in progress. If emission is not
established before the end of the 22 second period an error message will be
generated. N.B. Also see section on restrike.
Table 25 - Setup options IGC (continued)
Menu Option
Description
gea/d39701/f23
/d39721/f22
/d39701/f22
