5 OPERATION
EM210F-1
5-47
5.6 USE OF THE ANTICONTAMINATION DEVICE
Use of the anticontamination device reduces specimen contamination caused by electron
beam irradiation. Therefore, this device is useful in that valuable specimens can be
preserved after the completion of microscopy. Also, specimens can be observed at high
resolving power and at high magnification.
5.6.1 Filling the Refrigerant Tank
1.
Make sure that the column pressure is lower than 0.1 Pa (10
—3
Torr) and that
the yellow lamp on the connector box does not light when the check button
on the box is depressed
?
The state of the column vacuum is shown on the “Valve Status” screen (
F
Sect. 4.4.6g).
?
If the refrigerant tank is cooled with liquid nitrogen when the gauge reading is
more than 0.1 Pa (that is, when the column pressure is not sufficiently low), the
residual moisture in the column air will condense into water and settle on the
trap. This will cause oxidation of the trap and charging with electrons, resulting
in an increase of objective lens astigmatism and fluctuation of the electron
beam.
?
If the yellow lamp on the connector box lights up when the check button is
depressed, stop the instrument operation and contact the JEOL service repre-
sentative.
2.
Protect the viewing window glass with the covers provided.
CAUTION
Do not proceed to the next step without covering the window.
Proceeding to the next step with uncovered window may crack the
window glass due to liquid nitrogen splashing, causing serious
damage to the microscope column interior.
3.
Insert the funnel into the tank.
4.
Fill the tank with liquid nitrogen and wait for 15 minutes.
CAUTION
• The room should be well ventilated while filling the refrigerant
tank with liquid nitrogen in order to avoid any oxygen shortage.
• Always wear goggles and anti-frostbite gloves while filing the
refrigerant tank with liquid nitrogen and discharging the tank,
since the liquid nitrogen may gush from the tank and splash on
the operator during filling and discharging.
• Use a steady step when filling the tank with liquid nitrogen and
discharging the tank to avoid accidents.
5.
Replenish the tank once again.
