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Monochromated X-Ray Source with XR5 Electron Gun
This is the active anode surface and must face towards the gun cathode.
The anode mini-flange is marked with an "A" adjacent to the bolt hole in line with
this flat.
Make sure that the "A" is facing towards the gun source.
Figure 5-4: XR5 Anode Orientation
13.
Replace all the removed items in reverse order to the removal sequence.
14.
Place the PTFE HT shield tube over the anode and loosely refit the PTFE collar
and retaining flange before fitting the cooling/HT conduit
15.
Make sure the cooling pipe connectors are driven fully on to the anode-cap-
pipes.
16.
Clamp the retaining collar and screw on the PTFE HT shield.
17.
Refit the HT protection cover, remembering to twist home and tighten the clamp
screws. This operates a microswitch which is part of the safety interlocks for the
X-Ray power supply.
18.
Pump down and bake the system before use.
5.5
Replacing Filaments/Cathodes
The emitter should normally give long lifetime, well in excess of 1000 hours, provided
that it is operated in good vacuum conditions and within the recommended
voltage/power limits.
If the emitter condition requires its replacement, the vacuum system will have to be
fully shut down and vented to dry nitrogen.
As a further precaution disconnect the mains supply from the T352/NT X-Ray power
supply.
Refer to the Figure 5-5: XR5 Lens and Emitter Assemblies.
1.
Remove the M8 x 16 hex head bolt clamping the XR5 earth strap.
2.
Unplug the leads from the XR5.
3.
Do not unbolt the 70mm/FC38 11-pin feedthrough flange. This is unnecessary
except when replacing the feedthrough.
4.
Remove all the M8 x 35 hex head bolts except for 3 at well-spaced positions to
retain the main 114mm/FC64 flange.
5.
Unscrew the last 3 bolts in sequence 1-turn at a time. This is to symmetrically
release the loading from the spring-loaded emitter cup.
6.
After about 3mm retraction the spring-loading is released and the flange can be
fully removed.
Stand the flange on a clean work surface with the emitter facing up.
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Monochromator and XR5 (HA600054)
Monochromated X-Ray Source with XR5 Electron Gun
Figure 5-5: XR5 Lens and Emitter Assemblies
Refer to Figure 5-6: XR5 Emitter Flange Assembly.
7.
Note the electrical connections: 1 Focus; 2 filament; 1 cathode; 1 double pin
interlock and 1 ground.
8.
Note the pre-set height of the emitter cup assembly from the vacuum flange
surface.
9.
Loosen the 3 spring loaded screws in sequence, a few turns at a time, until fully
removed.
10.
Using tweezers, disconnect the (2) filament and (1) cathode lead from the pin
base.
11.
Place the emitter cup assembly on the work surface with the leads facing up.
Figure 5-6: XR5 Emitter Flange Assembly
Monochromator and XR5 (HA600054)
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Issue 5
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