Ulvac EGO-40M Instruction Manual page 15

MULTI-HEARTH ELECTRON BEAM SOURCE ～EGO-４０M～
3) Installation of multiple EB guns
Magnetic interference will occur if two or more EB guns are installed in proximity to each other.
Magnetic interference will increase the beam size or deform the beam. In an extreme case, the beam
cannot be deflected and may deflect out of the crucible. To prevent this, provide a space of more
than 84 mm between the sides of EB guns when the filament is mounted in the same direction.
Even if these actions are taken, the beam spot may be deformed slightly or the beam may not be
deflected over the entire surface of the crucible.
NOTE
When filaments are mounted in the same direction, distance between crucibles is 250 mm. In
case of mounting filaments in the opposite direction, the same distance is also need. Considering
the focusing of beam of EGO series, it is advisable to mount filaments in same direction.
4) High voltage feedthrough
In installing a high voltage feedthrough, avoid a location that provides easy access to operator's
hand. Cover the electrode on the atmosphere side with a rigid metal cover.
DANGER
An electrode cover must be a sealed one that does not allow access of fingers, sticks or the like.
5) Filament cable
Use a single or multi-core copper cable having a cross section of 10 mm
solderless terminal removed of plating for a cable terminal and crimp it with a crimping machine.
Filament cables are energized with a high voltage of 10 kVDC in maximum; so lay cables at least 15
mm away from the ground potential portion.
Make wiring arrangement so that the distance between the filament terminal of the EB Gun and that
the terminals of the high voltage feedthrough is as short as possible and the gun shield (mentioned in
the latter part of this manual) can be easily set.
6) Gun shield (See Fig. 3.2.)
Cover the filament cables with a SUS304 stainless steel cover (0.4 to 1.0 mm). Figure 3.2 shows
an example for the gun shield. Since the filament cables are energized with a high voltage of 10
kVDC in maximum, keep a spacing of 15 mm or more between the gun shield and the cable.
Also consider the exhaust conductance so that the vacuum level inside the shield is not
deteriorated due to gas emitted from evaporant.
If the gun shield is not provided, gas particles ionized with the electron beam will sputter the filament
cables and the cables will wear in a short time. It is also likely that an insulation layer will be formed
on the surface of the filament cable and this may cause abnormal discharge. The ionized particles
will also enter the electron beam path and strike against a part of the emitter assembly, causing local
wear.
7) Cooling water piping (See Fig. 3.3.)
Use copper pipes more than 8 mm in diameter for the cooling water piping inside the vacuum
chamber.
Use nylon tube and pressure-proof rubber hose more than 1/2 inch in diameter for the water
feeding and draining lines outside the chamber.
Provide a pressure switch on the water supply side and a flow switch on the water drain side. Also
installation of a valve at the water supply and drain ports for maintenance of the EB gun is
8
３．PREPARATION
2
or more. Use a