MKS Instruments UK Ltd
V2000-C/E Hardware Manual – SP102005.102 March 2013
29
Inlet operation
The Vision 2000C/E system has a special, closed ion-source.
The optimum operating pressure of this source is 1x10
-3
to 3x10
-3
mbar (to 2x10
-3
torr). As the ion source
pressure increases above the optimum, the peak heights become significantly non-linear - that is, they do not
rise as much as the pressure.
Monitoring processes at pressures higher than 5x10
-3
mbar requires inlet pressure reduction. The 3-valve inlet
and high-flow 4-valve inlets accomplish this with a single stage of pressure reduction through the V2 path. This
method is suitable for inlet pressures up to about 10 torr.
In select “fast-response” configurations, additional pumping is provided through V4 to O4. Orifice O4 is a VCR
gasket orifice at the UniBloc™ fitting that connects to the side-port of the turbopump. Its size depends upon the
factory configuration (typically between 0.007” and 0.031”).
Do NOT disassemble this connection unless you have the proper replacement in-hand!
For higher inlet pressures, a two-stage approach must be used, with additional pumping between the two
sequential orifice stages, O2-1 and O2-2.
The inlet pressures that can be sampled properly are determined by this configuration and the size of the
orifices. Again, differential pumping is obtained through V4 and O4. Again, orifice O4 is a VCR gasket orifice at
the UniBloc™ fitting that connects to the side-port of the turbopump. Its size depends upon the factory
configuration.
Do NOT disassemble this connection unless you have the proper replacement in-hand!
The state of the inlet manifold is process chamber pressure dependent. This table summarizes the various
conditions that it can take. The RVC2 interlocks prevent opening a sampling valve (V1 or V2) when the inlet
pressure exceeds the factory set-
point (except when overridden by turning Off the “Interlocks” with the key at the
RVC). The set-points are typically about 10-50% above the maximum intended inlet pressure for a given sample
valve.
System shut down procedure
It is important to follow the procedure outlined below to shut down and switch off the Vision 2000C/E system.
1.
Switch off the RGA filament and wait for 15 minutes for the filament to cool down.
2.
Switch off the turbo pump from the RVC2 Window within Process Eye Professional, or by pressing the
PUMPS switch on the RVC2.
3.
Switch off the RVC2.
4.
Allow the turbopump to come to a complete stop
