MKS Stabil-Ion 370 Series, Инструкция по эксплуатации, Страница: 65 / 122

4 Preparing the Stabil-Ion System for Operation
4-7
Series 370 Stabil-Ion Instruction Manual - 370119
4.3.3 Control Menu Variables
4.3.3.1 Pressure Range
The
H
range is preferred for applications involving pressure measurement above 1x10
-4
Torr. The
emission current and cathode power are reduced and the upper pressure limit and overpressure IG
shut down setpoint are extended. The
H
range provides increased cathode life when the IG is
operated at higher pressures.
The
L
range is preferred for applications involving pressure measurement below approximately
1x10
-7
Torr. It provides the fastest response to pressures below 1x10
-7
Torr and allows measurement
to the x-ray limit of the Stabil-Ion Gauge.
Whether
H
or
L
is preferred between 10
-4
and 10
-7
Torr depends on whether the expected pressures
will be above 10
-4
Torr or below 10
-7
Torr.
The Stabil-Ion Gauge will provide the best stability and lifetime if the pressure range selector switch
is set as shown in Table 4-3.
For example, if pressures in your application will range from 1 x 10
-2
to say 5 x 10
-8
Torr, leave the
range switch on
H
. If much of the time the system pressure will be below approximately 1 x 10
-4
Torr, set the pressure range setting to
L
. We suggest you do not change the range switch frequently
because there is a significant stabilization time to obtain steady state conditions.
NOTE: When the cathode is first turned on, or has been exposed to atmospheric pressure, it is
normal for a relatively large burst of gas to be released momentarily. Using the
H
range will help
prevent a nuisance shutdown from this burst.
To change the pressure range:
(The factory default setting for this function is HIGH. )
1. Press the
▼
arrow key until you see the control menu in the display.
2. Press the SELECT key to see the pressure range display.
3. Press the SELECT key again so that LOW , or HIGH is flashing.
4. Press the
▲
or
▼
keys to choose the desired range.
Table 4-3
Optimum Pressure Range Settings for N
2
Range Setting
Pressure Extreme
(Torr) Emission
Overpressure Setpoint
(Torr)
H
- High Range above 10
-4
0.1 mA 2 x 10
-2
(100%)
L
- Low Range below 10
-7
4 mA 8 x 10
-4
(100%)
Control
Menu
IG1 HIGH
PRESS. RNG
IG1 LOW
PRESS. RNG
or
IG1 LOW
PRESS. RNG
IG1 HIGH
PRESS. RNG