10-32 Routine Maintenance
Renewing the filament
To renew the filament:
1. Using a jeweller’s screwdriver, unscrew the single screw securing the
filament to the ion chamber assembly.
2. Remove the filament.
3. Use a jeweller’s screwdriver to transfer the filament contact blocks to
the new filament.
4. Using a pair of wire cutters, cut off the excess lengths of leg close to the
contact blocks.
5. Fit the filament to the ion block.
6. Align the center of the filament wire with the hole in the ion chamber.
See also: Figure titled “Filament wire alignment:” on page 10-30.
7. Fit and tighten the filament securing screw.
8. Reassemble the inner source.
See also: To reassemble the inner source: on page 10-28.
FI/FD inner source maintenance
Storing an emitter
Some types of emitters have a limited lifetime, between three and four months
when stored at atmosphere. The sensitivity of the FI emitter decreases the
longer the emitter is stored. This is normally due to oxidation of the tungsten
wire used.
Caution: The filament is fragile. To avoid damaging it, handle with
care.
Caution: After fitting a new filament, start applying a low
emission/trap current to the filament and slowly ramp it until
you reach operational values.
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