FEI Quanta FEG 250, User'S Operation Manual

Page: 21 / 228

System Operation: Vacuum Statuses
3-3
Vacuum Statuses
The vacuum status controls are in the Vacuum module. The Pump
button starts pumping for the operating pressure and the Vent button
starts venting for a sample or detector exchange.
In the Status module at the bottom of any page the actual vacuum
status is represented by the colored icon, which may have three
possible colors with the following meaning:
• Green: PUMPED to the desired vacuum mode
• Orange: TRANSITION between two vacuum modes
(pumping / venting / purging)
• Grey: VENTED for sample or detector exchange
PUMP BUTTON
When the Pump button is clicked and the status is Vented, or when
changing vacuum mode, the target pressure that the system pumps to
depends on the selected vacuum mode. The Pump button is
highlighted in and not accessible.
For the High Vacuum the system achieves the lowest pressure
possible. For the Low Vacuum or ESEM it achieves the pressure
specified in the Vacuum module Chamber Pressure adjuster. The
purge function can be defined in the Preferences… / ESEM dialogue.
When the Pump button is clicked and the status is Transition
(venting), the venting procedure stops and the system immediately
starts to pump to the actually selected vacuum mode.
VENT BUTTON
When the Vent button is clicked and the status is Vacuum , the
confirmation dialogue appears. After confirmation, the system
switches off the detectors voltages, high voltage supplies, vacuum
pumps and uses the appropriate valves to vent the system, with the
use of an air or a gas (the dry Nitrogen typically) brought to the
Nitrogen Inlet . The Nitrogen is recommended to obtain lower
pressure for high resolution imaging in HiVac mode.
The Vent button is highlighted in and not accessible. After a specified
venting time the venting valve closes and the vacuum status
should
indicate Vented . The button is enabled again.
When the Vent button is clicked and the status is Transition
(pumping), the dialogue appears. After confirmation, the pumping
procedure stops and the venting procedure starts.
When the Vent button is clicked and the status is Vented , the
dialogue appears. After confirmation, the venting valves re-open for
the specified venting time and then the valves close.