5 First Operating Steps | 5.4 Acquiring an Image ZEISS
25. On the Aperture Align window, click on Auto Aperture Align after changing parameters
such as EHT, I Probe, WD.
5.4.8 Switching on the Gun and EHT | Tungsten Filament
When you switch on the gun and the EHT, the gun starts emitting electrons.
Info
If you operate the microscope with a tungsten filament, then the EHT and the gun are always
switched on or switched off together. You cannot separately switch on or off the EHT or the
gun.
Info
Tungsten filaments have only a limited lifetime of 100–300 operating hours. If you operate the
microscope with a tungsten filament, then do the following:
4 If the microscope is not in operation, then always switch off the EHT and gun to preserve
the filament.
4 Enable Auto Saturation at shutdown.
Prerequisite
ü
The chamber and the gun head have been evacuated.
Procedure
1. In the SEM Controls panel, select the Vacuum tab.
2. Check that Vac Status = Ready is displayed.
3. In the SEM Controls panel, select the Gun tab.
4. Double-click the Fil I Target readout.
à The Fil I Target window is displayed.
5. In the input field, enter the required filament current in mA and click OK.
INFO: Depending on the exact type of tungsten filament, you may start with the following
values for the filament current:
For standard tungsten filaments (Agar A054), use 2500mA.
For longlife tungsten filaments (Agar A054L), use 3200mA.
6. In the SEM Controls panel, select the Gun tab.
7. Double-click the EHT Target readout.
à The EHT Target window is displayed.
8. In the input field, enter the required acceleration voltage in kV and click OK.
9. In the right part of the Status Bar, click
.
à The pop-up menu for vacuum, gun and EHT activation is displayed.
10. Click Beam On.
à The gun is switched on and the EHT runs up to the set voltage.
à In the right part of the Status Bar, the vacuum, gun and EHT status buttons merge to
.
72 Instruction Manual ZEISS EVO | en-US | Rev. 10 | 354706-0780-006
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