ian
New Member
Posts: 3
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Post by ian on Feb 10, 2023 18:57:36 GMT -5
Hi,
We were using the model SHI-4-2, and we noticed that the vibrations were conducted to the sample holder and the optical table.
Is that the normal case which the pump of the system vibrates the table, or we probably missed something? Does anyone have the same issue?
Thanks.
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Post by Lake Shore Sam G on Feb 21, 2023 13:50:34 GMT -5
Hello Ian,
Thank you for submitting your question, I apologize for the delayed reply.
The model SHI-4-2 is not a vibration isolated cryostat and I would expect that the vibrations caused by the coldhead and coming from the compressor through the helium flexlines would cause serious issues.
Is this something new? Has the cryostat been moved so that it is now on your optical bench?
Also, having the serial number of your cryostat might help.
~sam
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ian
New Member
Posts: 3
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Post by ian on Feb 22, 2023 12:25:34 GMT -5
Hi Sam,
Thanks for your reply.
The serial number is 154238. It is our first time trying this model, so we do not have any reference that this vibration is new or not.
I guess it is inevitable to deal with it. Do you have any suggestions for us to mitigate the vibration?
Thanks again for your kind reply.
Ian
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Post by Lake Shore Sam G on Feb 22, 2023 14:33:07 GMT -5
Hello Ian,
You can reduce the vibrations, but you won't reduce them to "low" levels.
Expected vibration at the sample on an SHI-4-2 is several microns peak-to-peak laterally and a few tens of microns along the axis of the cryostat.
You're probably seeing significantly worse than this if you aren't doing anything at all to mitigate the incoming vibration on top of the vibration created right at the cryostat by the coldhead.
The easiest two things to do are to connect your turbo pump to the cryostat using a pumping line vibration isolator (a large, weighted pumping line interrupt) and doing the same for the flexlines by either sand bagging them (I like 3 bags - 1 on the floor, two on top of the trapped lines, the lines should have at least one 90° arch or bend in them between the bags and the coldhead so they aren't under tension), or I have seen weighted "stands" that clamp the flexlines similar to the pump isolator.
If you do that, the vibrations at the sample holder will be as expected, but if you have other vibration sensitive components on your optical bench, the whole bench will still be moving because of the coldhead.
~sam
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