MKS 937B Operation Manual
39
6.5.4 Setup a Cold Cathode Sensor
Please refer the Figure 6-10 for setting a Cold Cathode sensor.
1. Gas Type (GT)
To move the cursor to the Gas Type box, press
Enter
, then use the or keys to select
the correct gas type for the sensor. Three gas types (N
2
, Ar and He) can be selected. Default
setting for Gas Type is N
2
.
2. User Input Calibration Gas Correction Factor (U Cal)
This allows the user to enter different correction factors for cold cathode sensors. This
function is useful, when the calibration gas used is not one of these listed above (N
2
, Ar or
He). The valid range is 0.1 to 50, and the default setting is 1.0.
Setup CC Gauge A1
GT
Control SP
Prot SP
N2
5.0E-03
B1AUTO 1.0E-03 1.2E-03
U Cal 1.0E+00
Relay
Relay 02
Relay 01
Enable Dir/Ch SET SP
BELOW
Hyst
SET 1.0E-06 9.0E-07
BELOWCLEAR 3.0E-05 3.3E-05
Relay 04
Relay 03 BELOWENABLE 2.0E-08 1.8E-09
BELOWCLEAR 5.0E-07 5.5E-07
AO Delay 3
Fast Relay SP 1.0E-05
Figure 6-10 Cold cathode setup information as displayed on 937B LCD screen.
3. AO Delay
The Analog Out Delay function prevents the activation of the cold cathode sensor's setpoint
relays and maintains their outputs in the OFF state until the delay has expired. The range is
from 3 to 300 seconds and the default value is 3 seconds. When the AO delay is active,
WAIT will be displayed on the front panel rather than a pressure reading.
4. Fast Relay SP
To meet the requirement for fast control of vacuum system (such as to close a valve rapidly
to protect an UHV system), a special cold cathode control module with a fast relay control is
available. The response time is typically less than 15 msec, and the control setpoint for this
fast relay is set via the Fast Relay SP described here. The hysteresis is approximately 15%
of the setpoint value, that is, the relay will be re-energized when the system pressure is 15%
below the setpoint. The default setpoint value is 1x10
-5
torr.
5. Protect SP
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