Vacuum
System
PlasmaQuant MS Series
100
The electrical connection is provided through a screened 8-way RJ45 connector.
The Penning vacuum gauge supplies a logarithmic representation of the vacuum
pressure via a voltage signal that ranges from 1.66 V to 10 V at Pin 3 with reference to
Pin 5, which is signal ground.
The penning vacuum gauge generates the internal supply voltages required for
operation of the integrated PENNING measurement system. When the gas discharge
in the PENNING measurement system is ignited, the operating voltage is raised to 2.8
kV. After successful ignition, this voltage then drops to 1.6 kV, thereby increasing the
useful service life of the PENNING measurement system.
A status output indicates the two possible conditions of the PENNING measurement
system:
Not ignited (including high-tension OFF)
Ignited (and pressure > 3x10
-9
mbar). An LED indicates this status.
Operation of the penning vacuum gauge in the pressure range above 10
-2
mbar will
cause accumulation of contaminants and will reduce the service life.
For this reason, the high voltage is only switched on when the pressure has dropped to
the 10
-2
to 10
-3
mbar range.
7.2.7
Thermovac Transmitter (GMain)
Measurement principle
Thermal conductance
according to Pirani
Measurement range
(air, O
2
, CO, N
2
)
5 x 10
-4
… 1000 mbar
Accuracy (N
2
)
1 x 10
-3
… 100 mbar
5 x 10
-4
… 1 x 10
-3
100 … 1000 mbar
Resolution
Repeatability
1 x 10
-3
… 100 mbar
± 15 % of reading
± 50 % of reading
± 50 % of reading
1 % of reading
2 % of reading
Output signal
(measurement signal)
Voltage range
Measurement range
Voltage vs. pressure
Error signal
0 … +10.3 VDC
+1.9 … +10.0 VDC
Logarithmic 1.286 V/decade
0 … +0.5 V
(filament rupture)
Output impedance
Minimum loaded impedance
Response time
2 x 4.7 Ω
10 kΩ, short
-circuit proof
80 ms
Transmitter identification
27.0 kΩ,
referenced to
supply common
Adjustment
One tactile switch for ATM
and HV adjustment
Technical Data