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4.4.2
4 - 27
4.4.2 The Vacuum Level in the Specimen Chamber does not Rise
If the evacuation process does not end in 5 minutes after the evacuation process for the
specimen chamber was started by flipping the EVAC button on the EVAC Panel keeps blinking,
it is an indication of an error, and an error message appears on the PC operation screen. If this
happens, perform the tips provided in the error message, and check the following items:
(1) Is the specimen stage securely inserted into the specimen chamber? The vacuum level
will not rise if the specimen stage is pulled out or there is something caught between the
specimen stage and the contact unit for the specimen chamber. Verify that the Current
Vacuum level displayed in VACUUM MODE on the operation panel declines gradually.
The pump is running normally if the vacuum levels falls to near the set vacuum level in low-
vacuum mode, or to 1 Pa or less in high-vacuum mode.
(2) If the pump is set to the low-vacuum mode, reset it to the high-vacuum mode, and then
press the EVAC button to run the evacuation process.
If you have attached some unit, e.g. objective lens aperture unit, prior to starting
evacuation, then introduce air into the specimen chamber and detach the unit. Clean and
grease up the O-ring of the unit and attach it again. Then restart evacuation.
Check if your specimen has dried. If the specimen is not dry, outgas from the specimen
may cause a longer evacuation time.
(3) If you do not find any failure mentioned above, contact the service engineer.
4.4.3 The Emission Current Fails to Flow Normally
If the emission current fails to flow when an accelerating voltage is applied, the items listed
below should be checked. The emission current, which varies as a function of the accelerating
voltage, gun bias settings, or filament settings, will remain at 50 to 180 µA if the accelerating
voltage is 15 kV, the gun bias is 0, and normal filament settings are in effect.
(1) Make sure that the filament is not blown and that it is installed correctly.
(2) Make sure that the correct filament settings are in effect. Normal filament settings are 70
to 95. This can be confirmed by opening the Optics tab in the Setup menu.
(3) The higher the gun bias value, the lower will be the emission current. Normally, if the
accelerating voltage is 15 kV, the gun bias level will be under 30. This can be confirmed
by opening the Optics tab in the Setup menu.
(4) An accelerating voltage less than 2 kV will reduce the emission current.
See <3.3.2 Setting the Accelerating Voltage and Filament Current>.
See <4.1.1 Filament Exchange>.