I have two questions to bounce off you:
1. About a month ago, we started experiencing significant oscillations
in the He boiloff on one of our Oxford 500MHz magnets. The
flow meter oscillates with a 4-5s rate from 4 to 12 cc/h. We
have added 100 ft of tygon in front of the flow meter, and
also put a ballast valve (not sure of the type, but was
installed last year on a new AC we got from Bruker); neither
have changed the situation significantly. The problem shows
up in 2D spectra with ~60 Hz T1 noise, and we initially looked
for grounding problems before noticing the boiloff fluctuations.
We've confirmed the boiloff is giving the T1 noise by venting the
He dewar and watching the noise come back. Any suggestions
about what the problem might be and how to alleviate it would
be greatly appreciated.
2. I have another Oxford 500MHz magnet that we need to move down
a hallway to another room (same floor, no steps). We have a
faculty member that is adamantly opposed to moving the magnet,
however, for fear of it getting damaged during the move (it's
ten years old). My request is the following: please let me
know if you know of a magnet that was irreparably damaged
during a move due to just moving it (i.e., not due to '
inappropriate handling of energization leads during bringing
the field down, or similar).
Thanks much in advance for the help,
Charlie Fry
Director-Magnetic Resonance Facility
Department of Chemistry
University of Wisconsin-Madison
fry@chem.wisc.edu
(608)262-3182