Stanford Research Systems RGA100, Operating Manual And Programming Reference

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Ionizer Replacement 8-9
SRS Residual Gas Analyzer
Probe Assembly
Feedthru Flange
Ionizer
Vacuum Chamber
Vacuum Port
RGA Cover Nipple
Figure 1 Probe Removal for Ionizer Replacement
6. Carry the probe to a clean, dust free area immediately. Avoid contamination using
handling procedures compatible with high vacuum requirements.
7. Hold the probe in a upright position and do a thorough visual inspection of the unit.
Check for loose, damaged, misaligned and contaminated components.
8. Using the clean, flat-head screwdriver remove the screw that connects the repeller to
the longest filament rod and pull out the cage exposing the filament and the anode
grid. Be careful not to damage the delicate filament if you plan to use it again!
9. Remove the filament following the steps and precautions described in the ““Filament
Replacement”” section of this chapter.
10. Next, pull out the anode grid after removing the two screws that fasten its bottom
plate to the alignment rods. The two rods do not need to be replaced and should not
be moved during this procedure!
11. Finally, remove the two screws that hold the focus plate against the top alumina
spacer and pull out the plate. The short alignment rod will also need to be removed
during this step, but it does not need to be replaced (Save it!).
12. Use the new parts from the ““Ionizer Replacement Kit”” to replace the ionizer
components. The new components are clean and vacuum compatible. Avoid
contamination! Replace all components at once! Discard the old ones!
13. Use two fresh screws from the ionizer replacement kit to mount the new focus plate
on the alumina spacer. Make sure the short alignment rod is put back in place and the
screws are tight.
14. Install the new anode grid. Use the new screws to fasten its bottom plate to the
alignment rods. Caution: The anode cage is fairly strong but it should still be
handled very carefully since its correct alignment is essential for optimum
performance of the RGA.
15. Once the anode grid is secured in place, replace the filament following the steps
described in the ““Filament Replacement”” section of this chapter. It is highly
recommended that a new filament be used for this step since damage to the
delicate thoria coating is unavoidable during removal.