FEI Quanta FEG 250, Руководство пользователя

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System Operation: Vacuum Modes
3-6
Purging
During this procedure the specimen chamber is automatically pumped
down to a lower pressure to remove the old gas, then it is flooded with
the new one (selected in the Vacuum / Mode module) to a higher
pressure. This takes place several times, until the old gas is removed
and the chamber is mostly filled with the new gas.
This is applied when the system is:
• pumping to the LoVac / ESEM mode from the vented status.
• in the LoVac / ESEM mode and the gas type is changed.
• in the LoVac / ESEM mode and the Purge button is pressed.
There may be certain applications (e.g., working with a sensitive
sample) where the operator needs to change the purging parameters.
They can be set up, started and terminated in the
Preferences…
dialogue / Low Vacuum tab (see Chapter 4).
Note:
This procedure can take several minutes, according to Preferences
setting. Wait until Vacuum status indicates
Vacuum , because
detectors do not start operation till desired pressure is reached.