Hi Junfeng,
this is not completely unexpected. I assume you have a wide-bore shim system
and a standard bore insert. The shim flush gas is injected into the space
between the room temperature bore tube of the magnet and the shimsystem. In
this case these are the WB shims. The SB shim insert is surrounded by the air
in the gap between WB and SB this is not exchanged by the shim flush gas.
What type of liquids high resolution probe are you using? Does it have body
flush gas? It might help a bit to connect this and make sure gas is flowing
when doin low temperature work.
You can also lower the low temperature limit for the shims. Standard is indeed 5 C.
You need the service login for the BSMS webpage and then you can see the setting
in SHIM -> Shim Configuration. I would set it to -10C and check how low the
temperature goes. Then maybe to -20 if the other setting was not low enough.
Bert's warning about freezing the flange is not as critical with a SB insert as
the cold parts are further away from the flange. Doing low temp with the WB
system could be an issue.
Best regards
Clemens
On 5/23/2026 4:55 AM, 向俊锋 via groups.io wrote:
Dear Colleagues
Recently, we have faced one problem which come from the temperature control
in two shim system of Bruker NMR spectrometer. We have a wide-bore 500 MHz
magnetic for microimaging as well as high resolution liquid NMR. To realize
these two functions, two shim coils have been provided: one for microimaging
and another for high resolution. When the NMR spectrometer was setup, the
Bruker engineer try to use the shim coil of microimaging for everything,
everything looks fine thereafter. But years later, high resolution could not
be achieved because of some unknown reason. We have to switch to the shim
coil of high resolution. An unexpected problem occurred during the
low-temperature measurement. When the sample temperature has dropped to -60 oC
or below, a warning message appear that "the shim coil temperature is too low（lower
than 5 oC），then the experiment is stopped by the topspin. We
have checked the setup for gas supply in the webpage, nothing wrong was found.
Shim coil gas is normal and we can hear the gas sound. We have consulted with
local Bruker engineer for help. They said this problem may be due to no gas
flow for the new shim coil and they could not provide a good solution. I
wonder whether anybody have similar experience which could let the flush gas
work both for the two shim coil.
Best wishes
Junfeng Xiang
ICCAS, Beijing China
--
==========================
==========================
====================
Clemens Anklin Ph.D. Vice President
Bruker BioSpin NMR Applications & Training
15 Fortune Drive NEW Phone: 978-313-5NMR(5667)
Billerica MA 01821 bluesky: _at_canklin.bsky.social
web: http://www.bruker.com
e-mail: clemens.anklin_at_bruker.com
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==========================
====================
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Received on Tue May 26 2026 - 05:51:16 MST