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4.1 Maintenance of Electron Optical Column
4 - 4
(7) If the area around the center of the anode hole is dirty, the screwed-in anode should be
removed. As described in (6) above, clean the area around the hole on the anode plate,
and then install the cleaned anode.
Fig. 4.1-7 Cleaning the Anode
(8) Attach the Wehnelt to the cartridge filament.
Fig. 4.1-8 Wehnelt (left) and Cartridge Filament (right)
NOTICE: The Wehnelt is fitted as shown in the figure below with spacers be attached
individually. Ultimately, verification should be made by using emission current.
The rule of thumb is an emission current level of 90 to 110 µA (Auto Gun Bias ON) or
130 to 150 µA (Auto Gun Bias OFF) at an accelerating voltage of 30.
Fig. 4.1-9 Details of Assembling the Cartridge Filament
Cartridge filament
P/N 51E-0240
Adjust using
s
p
acer
,
1 to 2
Wehnelt
P/N 50E-0524
Discard
Reuse
Blown