Hitachi S-4800 manual Use of Anti-Contamination Trap

3.1.4Use of Anti-Contamination Trap

For image observation at high magnifications or low accelerating voltages, the use of the Anti- contamination trap is recommended to prevent specimen contamination by hydrocarbon build-up. The traps need to be filled with liquid nitrogen.

Injection funnel

The Anti-contamination trap is a plate above the specimen that adsorbs gas around the specimen. The capacity of the liquid nitrogen dewar is about 0.9 liters and is usable for about 5 hours at an ambient temperature of 24°C. For initial filling, about 1.3 liters of liquid nitrogen is required.

B980022

Dewar vessel

CAUTION

Before using liquid nitrogen, be sure to put on leather gloves and eye guard glasses. If liquid nitrogen splashes on your skin, you may suffer frostbite. In addition, the room should be ventilated to prevent oxygen depletion.

CAUTION

Never introduce air into the specimen chamber while the anti-contamination trap is filled with liquid nitrogen. The anti-contamination trap will frost up and the vacuum will deteriorate. Before introducing air into the specimen chamber, wait for a few hours after the liquid nitrogen dewer has completely emptied. The air introduction valve does not have a protection link with the cold trap.

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