MKS HPS 903 Series, Operation And Maintenance Manual

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12
Cold Cathode Ionization Vacuum Sensor
1 2 3 4 5 6 7 8 9
Pressure (Torr)
Output Voltage (VDC)
Operating the Series 903 (IMT)
Starting the (IMT)
The (IMT) starts quickly in low vacuum. In the UHV pressure range,
starting may be delayed by several minutes. The SensaVac IgniTorr™
Cold Cathode Starting Device may be used to reduce starting time
(see Accessories, p. 22).
Reading Pressure
To measure nitrogen gas pressure with the (IMT), turn the power on and start
the high voltage. Refer to the graph below, showing pressure as a function of
output voltage for nitrogen. To independently convert voltage to pressure, use
the equation in the next section.
When using the graph, remember that the pressure scale is
logarithmic, and the voltage scale is linear. Equal increments of
distance along the pressure scale do not correspond to equal
pressure changes.
10
-2
10
-3
10
-4
10
-5
10
-6
10
-7
10
-8
10
-9
10
-10