I'd like to know what should be done after a magnet has quenched, while
waiting for the engineer to come over. Our 400 MHz Magnex quenched last
Friday, and the engineers from JEOL (Japan or Singapore) are fully booked
until two weeks from now.
Since all the liquid helium has already evaporated (and so has the liquid
nitrogen), I was told to make sure that the cryogen ports do not suck air
and become blocked with ice. The one-way valves have always been in place
and work fine. Noting that the boiloff rates are zero, I have the outlets
vented inside the lab now, where I'm keeping the air dry with
airconditioning and a dehumidifier.
The magnet bore has iced up, but the ice is loose on the surface and not
packed tight inside it. The vacuum was good before the quench, and the
drop-off plate is still in place.
How do I check if a vacuum is forming inside the helium can? Anything
else I might have missed?
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Edward T. Chainani Nuclear Magnetic Resonance Laboratory Manager
National Chemistry Instrumentation Center (NCIC)
Ateneo de Manila University phone: (632) 426-6001 loc. 5629
Loyola Heights, Quezon City e-mail: etch_at_ginto.chem.admu.edu.ph
Philippines FAX: (632) 426-1323
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Received on Tue Feb 19 2002 - 08:40:12 MST