FEI Tecnai F20 S/TEM: cold trap and cryo cycling

Have you ever wondered why your TEM has a cold trap? In this video, I cover the importance of a cold trap in TEM operation, what it does (and doesn't) do, how to safely use it, and why it is necessary to "cryo cycle" your TEM.

[@arjunbarwal1502]

kindly post some videos regarding maintenance and some routine checkups for TEM

[@sud476]

Hi, This is also the same in the JEOL microscope. We call it ACD heat on. The procedure is a bit different in JEOL microscopes compared to FEI microscopes. We do not remove the canister but we insert a heating rod in the canister and switch on the ACD heat button (from the computer screen). The JEOL microscope also takes approximately 6h for the completion of ACD heat. Is the procedure the same on FEI TALOS?

[@shatadruchakravarty167]

Great video! Why do you recommend to not fill the liquid N2 dewar prior to inserting the copper braids in it? We have a tecnai F20 here and I was told to do that instead.

[@NicholasRudawski]

Hi Shatadru: I'm glad you like the video; you could indeed do the approach you mentioned in your comment; I suppose that might be easier than what I showed so then you don't have to lift up your LN2 container as high to fill the dewar.

[@VishalKotha]

What is the suitable duration for the cryocycle? I operate tf30 and at here we do this for 2hrs.

[@NicholasRudawski]

Good question; you would want to run it at least as long as is necessary for the Cu braids to warm up to room temperature and then for the turbo pump to pump out all the stuff that is released into the column. It probably varies from instrument to instrument but most facilities with Tecnais typical run cryo cycles for 6 - 8 h starting at the end of the day so the process is completed by the start of the next day and occur during typical non-use times; 2 h may be sufficient in duration, but I've never tried it; if the cycle isn't run for long enough, too much gets dumped into the IGP when the cycle ends so it's better to err on the side of too long rather than too short.

[@SkynetT800]

Very interesting, so the cold space of air acts like a filter?

[@NicholasRudawski]

It's actually a cold surface inside the column (cooled by the LN2) that acts as the "filter", though I think a more accurate term to describe it would be "getter".

[@SkynetT800]

@@NicholasRudawski I see, so the surrounding columns have to be submerged in liquid nitrogen. Could you use ice cubes?

[@NicholasRudawski]

@@SkynetT800 Ha ha, I've never thought of that, but I don't think it would be as effective; LN2 is many times colder than ice, so the gettering effect would be far better.

[@SkynetT800]

@@NicholasRudawski sorry if the questions are silly. I'm just learning through books and videos.👍

[@NicholasRudawski]

@@SkynetT800 No worries, I'm always happy to answer any questions!

[@gunabossy]

What will happen if ln2 low filling and run Cryo cycle?

[@NicholasRudawski]

Hi gunabossy: you always want to run the cryo cycle with the cold fingers not actively being chilled by LN2; this allows the stuff on the cold fingers to evaporate off and be pumped away by the turbo, which helps to keep the column clean.

[@gunabossy]

@@NicholasRudawski Thanks

[@gunabossy]

@@NicholasRudawski we have Tecnai T12 spirit,

[@KillianTwew]

"Lol doesn't the turbo filter all that stuff out?"

[@NicholasRudawski]

Hi Just Jay: yes, you are correct, but the turbo is (usually automatically) turned off when you open the column valves and operate the microscope; otherwise, the vibrations from the turbo may compromise the image quality. That being said, that would be an interesting experiment to try: just keeping the turbo on the whole time (which is possible) without using the cold trap and seeing how well contamination is handled and how the image stability is affected by the turbo.