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Monochromated X-Ray Source with XR5 Electron Gun
Refer to Figure 5-7: XR5 Emitter Cup Assembly.
Use kit number PRT0001/UG, which comprises of :
1 off Filament/Cathode Assembly.
1 off Spacer
3 off Clamps - (not required on this assembly)
3 off Special Screws - (not required on this assembly)
1 off Retaining Star Washer
12.
Using a jewellers small screwdriver or similar tool, carefully free the tangs of the
star-washer, in circumferential sequence, from the retaining lip inside the emitter
cup. The washer can be reused, if the tangs are straightened out first, but a new
washer is supplied with the emitter components.
13.
Lift out the filament/cathode ceramic-button assembly.
14.
Discard any shim-ring(s) fitted between the cathode-button and the emitter cup.
15.
Carefully fit the Filament/Cathode Assembly with the shim supplied in the kit into
the emitter cup, making sure that the cathode connection-peg is placed
diametrically opposite (away from) the large slot in the emitter-cup-flange.
16.
Gently press the star-washer into place, making sure that all of the tangs are
trapped beneath the retaining lip of the cup.
17.
Make sure that the cathode peg and mating slot in the filament-button, and the
mating slot in the star washer, are orientated symmetrically with respect to each
other, to maximise break-down gaps between cathode and filament and both to
ground.
18.
Refit the cup assembly to the main flange, and before setting the cup-to-flange
height, connect the filament and cathode leads to the pin-base. Check that all
sockets are fully mated to the pin-base and on the correct pins.
19.
Screw in the spring-loaded screws until the correct height is set.
20.
Ensure the Focus spring-connection is located on its retaining ceramic "top-hat".
21.
Refit the flange assembly to the gun body initially with 3 or 4 bolts tightened
gradually in sequence until metal-to-metal contact is made between flanges.
Use a new FC64 copper gasket and make sure that the flange is offered to the
gun in the correct orientation. The main flange is labelled "TOP" on its
circumference adjacent to the focus connection. This should be in the top
vertical position when refitted to the gun on the system.
22.
Check the pin base for filament and interlock continuity and all other pins for
electrical isolation.
23.
Fully tighten the flange with all bolts fitted.
24.
Pump down and bake the system before use.
Discard Shims and
replace with Shim
Star Washer
supplied with kit
Individual Filament and Cathode
Assemblies replaced with a single
Filament/Cathode Assembly
Figure 5-7: XR5 Emitter Cup Assembly
Issue 5
25
Centralise
Filament/Cathode Assembly
button slot with slot in Star
Washer
View of Star Washer
and Filament
Cathode Button
Monochromator and XR5 (HA600054)
Monochromated X-Ray Source with XR5 Electron Gun
The LENS assembly will need to be removed to cure either:
1. Anode scouring
2. Excessive HT "ticks" and breakdown
Item 1. can be achieved without special jigs, whereas item 2 requires expertise and
special jigs: see Ceramics Replacement
Refer to Figure 5-5: XR5 Lens and Emitter Assemblies.
First follow the instructions for Anode Replacement since the Lens assembly cannot
be removed until the anode is removed. Any attempt to remove the lens assembly first
will cause damage!
Secondly, follow the initial steps for removal of the Emitter assembly, to expose the
lens assembly.
Figure 5-8: XR5 Lens Assembly
Refer to Figure 5-8: XR5 Lens Assembly.
Figure 5-8: XR5 Lens AssemblyThe lens assembly is fitted into the main vacuum
housing of the XR5, through the 114mm/FC70 source mounting flange.
To assist in handling the lens assembly (weight ~1 Kg), 3-off M4 screws can be fitted
in the 3 tapped holes in the lens-support flange. Do not attempt to screw these in fully
until the clamping screws have been loosened (next step).
1.
Unscrew the 6-off M2 x 8 cheese-head screws that clamp the lens assembly
into the vacuum housing.
2.
Carefully withdraw the lens assembly.
Do not attempt to loosen any other screws before reading the section "Ceramics
Replacement".
Monochromator and XR5 (HA600054)
26
Issue 5
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