Stanford Research Systems RGA100, Operating Manual And Programming Reference

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8-18 CDEM Refreshment
SRS Residual Gas Analyzer
CDEM Replacement
There is no need to send the RGA unit back to the factory for this service. The
replacement procedure is very simple and can be completed in a few minutes by qualified
personnel.
Gain degradation limits the lifetime of all electron multipliers. Eventually the gain drops
to unacceptable values and the multiplier needs to be replaced. As a rule of thumb, the
CDEM should be replaced when the required gains can no longer be achieved by
increasing the bias voltage.
Warnings:
The CDEM is very delicate and should be handled with extreme care.
Handling and mounting of the CDEM should only be performed in a clean vacuum
fashion:
Work on a clean dust-free area. Avoid dust, lint and any kind of particulate
matter.
Wear talc-free rubber gloves or finger cots.
Use properly degreased tools.
Avoid excessive shock, such as from dropping onto a hard surface
(Remember that the CDEM is made out of glass).
Use only SRS supplied electron multipliers for replacement.
Equipment
x
Multiplier Replacement kit: consisting of new CDEM with mounting clamp in place
and spare screws and nuts.
x
One standard OFHC copper gasket for 2 3/4”” CF Flange. New and Clean!
x
Precision flat-head screw driver: 2.5 mm head.
x
Needle nose pliers.
x
Latex gloves/powder free.
x
Clean, dust-free work area.
Procedure
1. Read all warnings at the beginning of this chapter before attempting to service the
probe.
2. Set up in advance a clean dust-free working area where to carry out this procedure.
3. Turn off the RGA and disconnect the ECU from the probe.
4. Wait for the probe to cool down for at least 30 minutes after the emission is turned
off. Severe burns can result if the probe is handled too soon .