10-42 Routine Maintenance
4. Test the polarity of the second magnet by ensuring it is attracted to the
outer end of the first magnet in the ion block. Turn the magnet round
(end-to end) if required.
5. Repeat steps 1 through step 3 to fit the second magnet to the ion block,
ensuring that the polarity is as determined in step 4.
FI/FD outer source maintenance
A dirty outer source can cause loss of sensitivity, poor stability, or it can even
affect the instrument resolution of the GCT Premier. As the beam goes
through the source it passes through collimating slits, which are only 0.5 mm
wide. These slits are the first to get dirty with ion burn.
If current leakage occurs, then is it recommended that you perform the
following maintenance procedures:
• Change the emitter. See Changing an emitter on page 10-33.
• Clean the extraction rods. See Cleaning the extraction rods on
page 10-42.
• Clean the focus plates in the outer source. See Cleaning the source
ceramic and focus plates on page 10-45.
Cleaning the extraction rods
Sometimes it is sufficient to clean the extraction rod in the ion source to
improve sensitivity. The rod assembly has been designed to allow easy
removal, without the need to strip away all the ion source parts.
Caution: When fitting the second magnet to the ion block, ensure
that the polarity is the same as the first magnet. The overall
orientation of the magnets in the ion block is not relevant.
rub screw
agnet
tainless steel cap
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