Stanford Research Systems RGA100, Operating Manual And Programming Reference

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8-20 CDEM Refreshment
SRS Residual Gas Analyzer
CDEM Anode
CDEM Clamp
CDEM
CDEM Clip
Faraday Cup Shield
Remove this screw only!
Figure 4 CDEM Replacement
9. Using the clean flat head screwdriver, remove the small screw that fastens the clamp
to the HV rod and rotate the entire multiplier about its axis until the clamp’’s end
points away from the FC Shield.
10. Holding on to the clamp’’s end, pull the multiplier out of the clip.
11. Unpack the new multiplier. Notice that the multiplier has a mounting clamp already
in place so there is no need to keep the old one. Avoid contamination.
12. Install the new multiplier in place reversing the removal steps. Clip it in place, rotate
it about its axis so the clamp fits into the slot in the HV rod, and fasten the clamp
with a small screw.
13. Visually inspect the assembly and do any adjustments that might be necessary. The
CDEM should be standing straight up, centered between its two neighboring rods,
and with its cone facing straight into the FC shield’’s hole. The CDEM anode should
be
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1 mm away from the multiplier’’s exit, and it can easily be pushed up or down
with pliers for correct placement. There should be no electrical contact between the
cone (HV) and any part of the probe. If necessary loosen the clamp’’s screws to do
adjustments.
14. Once satisfied with the alignment, mount the probe back on the vacuum system and
pump it down. Check the correct rotational orientation of the feedtrhu flange (i.e.
same as it was before disassembly) before tightening the flange bolts.
15. Perform the CDEM Preconditioning steps described in this chapter before using the
multiplier for actual measurements.
16. Calibrate the gain of the new electron multiplier before using the device for
quantitative measurements. See instructions in RGA Tuning chapter.