Hello everybody.
I just started working with a SEM (JEOL JSM 6010 LA) which ventilates without injection of Nitrogen. So apparently the chamber goes from 10E-6 torr to atmospheric pressure by injecting (room) air.
Is this scenario familiar to anybody? Isn't there any potential inner damage in the SEM for venting with air?
Thanks for commenting.
Usually SEM should be ventilated with Nitrogen to avoid contamination in chamber. Although it is highly advised to do so, it is not mandatory.
In our lab we have a FEI Inspect F50, and during a year it was ventilated with atmospheric air, without causing any damage to the microscope. If you choose to ventilate the microscope with atmospheric air, two points should be observed:
- An air filter should be fitted in air entrance to avoid dust particles in the venting system, and in the chamber
- The room humidity should be below 60% (in any case actually).
Hope it helps.
yes, the main problem is the condensation of moisture, which will lead to prolonged pumping-down times...
Cleanroom of the SEM contains little electric wires and thin electric connections. Exposure to air could oxidize these wires and connections, disrupting quality of images or measurements.
Venting with nitrogen is always preferable. But venting with air may not damage your SEM. Although it may prolong the pumpdown time.
If your microscope has an exchange chamber, using N2 is save to avoid contamination and humidity as said before. If you vent the entire microscope chamber to put your sample inside, you let flow room air inside anyway when you open the door. Using N2 in such case is not significant. Our SEM has exchange chamber and I had disconnected the N2 venting system of this exchange chamber because each time we open it N2 go out and room air go in. Consumption of N2 is less now. I'm not agree with Jean-Raoul concerning oxydation of wires or connection.
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