Hi All,
In the superconducting magnet manual from Oxford, it mentions to let in dry
nitrogen in and pump out the magnets at least a few times when pumping down
the magnet before cooling down to energize the magnet.
It probably doesn't matter either way for a transfer line, unless you are in
a hurry. Just remember that the vacuum pressure reading with helium gas
in the transfer line is several times higher.
When I pump down my 68" liquid Helium transfer after letting in dry air, it
goes down rapidly to 10E-5 in less than half an hour. I let it pump overnight
anyway. There are a lot of narrow spaces to evacuate.
Best of Luck
Yong-Wah Kim,
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Received on Fri Aug 08 2025 - 13:05:46 MST