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ZEISS
6 Operation | 6.3 Modifying Gun Parameters
Analytic Gun mode
In Analytic gun mode, the Schottky emitter runs at default temperature but the extraction voltage
is increased in comparison to the Normal gun mode. This leads to a higher probe current. Overall,
the probe current in Analytic gun mode is about twice the probe current in Normal gun mode.
The Analytic gun mode is especially useful for applications which require high intensities (e.g.
WDX).
Info
After switching the gun mode, you can immediately work with the selected gun mode. For ap-
plications, which require a high probe current stability, wait 24 hours until a stability of 0.2 %/
h is reached. It is recommended not to change the gun mode during quantitative specimen
analysis.
1. From the Menu Bar, select Tools > User Preferences.
à
The User Preferences dialog is displayed.
2. Select User > Expert Gun Mode.
3. Click in the Value field and select Yes.
4. Close the User Preferences dialog.
5. In the Panel Configuration Bar, double-click Crossbeam SEM Control.
6. In the Crossbeam SEM Control panel, select the Control tab.
7. In the Beam section, click one of the following buttons:
To switch to Imaging gun mode, click Imaging.
To switch to Normal gun mode, click Normal.
To switch to Analytic gun mode, click Analytic.
INFO:
For maximum probe current, also check the alignment of the gun.
INFO:
If you use the Analytic gun mode, then the lifetime of the emitter is reduced.
6.3.2 Measuring the Probe Current
Measuring the probe current using the Faraday cup ensures that the current displayed in the soft-
ware equals the incident probe current. The Faraday cup consists of a strongly absorbing material
with a cavity covered by a small aperture. If the beam is focused in this cavity, no secondary elec-
trons and no backscattered electrons leave the Faraday cup.
Parts and Tools
Designation
Part no.
Faraday cup
348342-8055-000
1. Load the Faraday cup into the specimen chamber.
2. Evacuate the specimen chamber.
3. Switch on the gun.
4. Switch on the EHT.
5. From the
Panel Configuration Bar
, select
Specimen Current Monitor
.
à
The
Specimen Current Monitor
window is displayed.
6. Activate the
Stage Bias
checkbox.
à
This activates the touch alarm that helps to avoid collisions of the stage.
7. Move the stage to the position of the Faraday cup.
8. Acquire an image of the Faraday cup.
9. Activate the
Spot
checkbox.
à
Green crosshairs are displayed on the image. The crosshairs indicate the position of the
beam spot.
10. Grab the crosshairs and move them into the hole of the Faraday cup.
à
The probe current is measured continuously.
à
The measured probe current is displayed in the
Specimen I
readout.
Instruction Manual ZEISS Crossbeam 350 | en-US | Rev. 3 | 349500-8111-000
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