Dear all,
Yesterday during Helium refilling a hissing sound came from our 500MHz Magnex magnet installed 13 years ago. It was not loud but could be heard clearly. It lasted for several minutes. The lock signal was ok, shimming was good and the hissing was not related with the lifting gas, anti-vibration legs or VT system.
I searched ammrl mailing archives and found a mail telling the similar story, but the problem was not solved.
http://www.ammrl.org/archives/December-2003/18.html
I checked our helium refilling log and found the boil off rate just fine. After refilling the nmr system is working well. But I am still puzzled by the phenomenon.
Any ideas or experience highly appreciated!
Guangyu
Received on Wed Feb 12 2014 - 20:44:45 MST