Thermo Scientific Apreo User's Operation Manual page 68

Low Vacuum
The specimen chamber manual purging procedure (see Chapters 2) can be customized in this section.
Low Vacuum preferences
FIGURE 3-22:
For highly outgassing samples the procedure can take very long time. In this case the Fast Low Vacuum Pumping
Through High Vacuum check box must be cleared; the specimen chamber is then pumped to a pressure slightly
lower then a desired LoVac pressure (see custom settings bellow) and proper purging ensures good water vapor or
gaseous atmosphere in the chamber.
Purge Mode area contains following radio buttons:
• No Purge – the purging is switched off and the chamber pressure goes directly to the set Low Vacuum mode
value. The gas mixture in the chamber slowly changes to the new gas type.
• Automatic – all purging parameters are set automatically, according to the mounted Low Vacuum detector
(Cone).
• Custom – custom settings (see below) are used.
Purge Settings area contains following Custom settings and controls:
• Minimum Pressure
• Maximum Pressure
• Number of cycles
Sets the above three parameters to the desired values for the procedure.
• The Purge button enables starting to purge manually (using the actual Purge Settings) when the system is
already pumped to Low Vacuum; otherwise, the button is disabled. When purging is running, the Purge button
becomes highlighted. Clicking on the highlighted button stops the purging procedure and returns the system to
operation in Low Vacuum.

Note
During the purging procedure, the chamber pressure is not ready for SEM operation (the vacuum status is Pumping).
Therefore, clicking the Purge button automatically switches off the accelerating voltage.
The Purge Settings are not remembered separately for each user. If the Purge settings are important, please check these
Preferences before starting the Low Vacuum operation.
3-42 User Manual
Software control: Preferences dialog
C O N F I D E N T I A L – limited rights
Feb 2018 Revision A