Stanford Research Systems RGA100, Руководство по эксплуатации и программированию

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CDEM Replacement 8-19
SRS Residual Gas Analyzer
5. Without disconnecting the cover nipple from the vacuum port, remove the six bolts
from the feedthru flange at the end of the probe and slide the entire probe assembly
out of the vacuum system (Note the rotational orientation of the Feedthru Flange
before removing the probe assembly from the vacuum system so that the probe can
be reassembled in the exact same way at the end of the replacement procedure. Mark
the side of the flanges with a permanent marker if necessary.) The ionizer, the filter,
and the detector are now fully exposed and easily accessible.
Probe Assembly
Feedthru Flange
CDEM
Vacuum Chamber
Vacuum Port
RGA Cover Nipple
Figure 3 Probe Removal for CDEM Replacement
6. Carry the probe to a clean, dust free area immediately. Avoid contamination using
handling procedures compatible with high vacuum/clean room requirements.
7. Hold the probe in a secure upright position and do a thorough visual inspection of the
unit. Check for loose, damaged, misaligned and severely contaminated components.
Carefully inspect the ionizer and, if any problems are detected, perform a filament
and/or ionizer replacement following the procedures described earlier in this chapter.
Inspect the CDEM for signs of arcing and contamination. A blue tinge is an
indication of an electrical arc while brown indicates contamination. A ““burned”” black
color may indicate both arcing and contamination have occurred. If excessive
contamination is evident take the necessary steps to identify and reduce
contamination sources in the vacuum system.
8. CDEM Removal:
Note the position of all parts and their orientation before disassembly!
The CDEM consists of a straight, four-channel tube made out of glass, with a cone of
the same material attached to the front end. It is held upright, next to the FC, and
away from the axis of the analyzer, by a
clamp and a clip . The clamp wraps around
the multiplier tube, and is connected to a neighboring rod. It assures proper alignment
of the cone and provides the electrical connection to the High Voltage power supply.
A hole on the side of the FC Shield allows space for mounting the cone very close to
the FC top. The
clip is spot welded to the side of the FC shield and holds the lower
end of the multiplier’’s tube at ground. Chrome electrical coatings, deposited at both
ends of the multiplier provide the necessary electrical contacts. A plate (
CDEM
Anode ) mounted at the exit of the CDEM collects the secondary electrons. The
whole assembly is self aligning.