Hi,
do you possibly have (a lot of) moisture in the air which runs down the side
of the magnet where the nitrogen heat exchangers are? This may get into the
sealing surface at the bottom flange and start some contact corrosion there
(bottom plate is aluminium, outer shell including upper part of bottom flange
is stainless steel). In case of doing low-temperature work - specifically when
using nitrogen gas evaporated from a LN2 dewar - can also lead to water
condensation on the upper magnet flange or even to freezing the flange and
subsequent vacuum loss (quench risk even!).
It can indeed be worthwhile trying to turbo pump the magnet (requires special
vacuum adapter which usually customers don't have but magnet-capable third
parties and of course Bruker do). But if it's corrosion then the effect may
come back and in the end only an inspection/overhaul of the sealing surfaces
and O-rings will help. I can send you pictures how affected sealing surfaces
can look like (aluminium oxide "rust")…
Good luck!
Bert
> Am 06.12.2023 um 21:38 schrieb CHARLES G FRY via groups.io <fry=chem.wisc.edu_at_groups.io>:
>
> Ulli,
>
> Don't mind long emails, but decided to write without reading in detail.
> Sorry if you said smt about the following. I suspect your magnet simply need
> a rebuild with new primary rings. These require the magnet warmed, taken
> apart, cleaned, new oring, and put back together cooled and reenergized.
> Needs to be done every 15-25 yrs.
>
> Odd the Bruker eng didn't discuss this....
>
> Charlie
>
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Received on Wed Dec 06 2023 - 19:33:58 MST