Varian sentorr Instruction Manual page 21

Operation
TC2 Setpt (All models with TC or Convectorrs with Set Point option)
The TC2 set point can be set to energize when TC2 reads less than the TC2 Setpt threshold setting.
It will de-energize when the TC2 pressure goes above the TC2 Setpt hysteresis setting (refer to Para.
3-3, Set Point Hysteresis). The TC2 Setpt pressure wll be displayed in the TC2 readout.
Add'l Setpt (All Models with Set Point option)
The additional set point can be assigned to any of the gauges. When this parameter is selected, all
three pressure displays will flash. Press the "Enter" key to assign the Add'l Setpt to the ion gauge,
using the standard parameter programming method. If no value is set in the ion gauge display (man-
tissa = 0.0), the "Enter" key can be pressed again to assign the Add'l Setpt to TC1, or likewise to TC2.
Auto-On (BA2, BA2c, CC2, and CC2c Models)
The Auto-On function assigns TC1 as the turn-on source for the ion gauge. Press "Option Select" until
the Auto-On Setpt annunciator is flashing. The Auto-On setting will be displayed in the TC1 readout.
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The turn-on pressure can be set from 1.3 x 10 Pa to 6.6 x 10 Pa (1.0 x 10 Torr to 5.0 x 10 Torr)
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and additionally between 1.3 Pa to 6.6 Pa (1.0 x 10 Torr to 5.0 x 10 Torr), using the standard para-
meter programming method.
The ion gauge will turn on when TC1 reaches the programmed pressure. When the TC1 pressure rises
10 percent above the programmed Auto-On pressure, the ion gauge will turn off.
The Auto-On feature can be temporarily overridden by pressing the "Emis" key to turn the ion gauge
off. It will go back into effect after the TC1 pressure rises above the programmed Auto-On pressure.
GasCorr (All Models)
The gas correction factor adjusts the ion gauge pressure calculation depending on the system gas.
The gas correction value will be displayed in the IG readout. The default setting is 1.0, for N (air). The
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setting can range from 0.1 to 9.9.
Refer to Appendix A for the Table of Gas Correction Factors.
Emis mA (All Models)
The emission current setting controls the hot filament gauge emission current. The programmed value
will flash in the IG display. Use the standard parameter programming method to select a value from 0.1
mA to 9.9 mA. The default setting is 4 mA for standard gauges and 0.1 mA for broad-range Bayard-
Alpert gauges (Varian models 564 and 580).
If the emission current is set less than or equal to 1.0 mA, it remains constant over all pressures. If the
emission current setting is greater than 1.0 mA, it will be automatically reduced to one-tenth of the set-
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ting at pressures greater than 6.6 x 10 Pa (5 x 10 Torr). This feature extends filament life.
Ion Sens (All Models)
The ion gauge sensitivity compensates for the different gauge geometries. The current setting will flash
in the IG display. Refer to Page 1-2 for the default sensitivity settings.
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