【讨论】一台核磁的使用寿命是多久？

超导磁体, From Weixing Zhang
1982
200 MHz Oxford [hw.ac.uk] The LHe boil-off has not changed since it was installed.
1983
300 MHz Oxford [sri.org] (original seal) Helium and Nitrogen boil-off is identical as the original specs.
360 MHz Oxford [uic.edu] resealed when updated in 2001. works great, no change in N2 or He boiloff
1984
500 MHz Oxford [berkeley.edu] installed 1984, at field since 1985 hold time and He boil-off rates have not measurably changed.
1985
500 MHz Oxford [chem.ucla.edu] dewar refurbished 1993 due to relocation, no problem before the refurbishment. no increase in boil-off
360 MHz Oxford [wisc.edu] obtained used in 85, rebuilt 1999; same as installed
500 MHz Oxford [wisc.edu] rebuilt 1999; same as installed
400 MHz Oxford [columbia.edu] all boil off rates are normal.
400 MHz Bruker [ucalgary.ca] Original seal, moved cold in 1990
300 MHz Oxford [ineos.com] Reenergized for different reasons in 1995, 1996, and 2000; seals replaced on one of those occasions. Has high LN2 boiloff due to internal adjustments (not seal-related) but LHe boiloff is still in spec.
300 MHz Spectrospin [lubrizol.com] very similar He, N2 boil off as when installed.
500 MHz Oxford [ohio-state.edu] refurbished (due to a move) in 1998.
500 MHz Bruker [unsw.edu.au] refurbished in 2006 due to relocation, working well before and after relocation.
1986
500 MHz Oxford [chem.ucla.edu] dewar refurbished 1993, due to relocation, no problem before the refurbishment. no increase in boil-off
500 MHz Oxford [mbi.ucla.edu] refurbished 1993. The hold time/volume hasn't changed.
400 MHz Oxford [ineos.com] Original seal, Boiloff has not changed.
1987
400 MHz Oxford [berkeley.edu] hold time and He boil-off rates have not measurably changed.
500 MHz Oxford [uic.edu] resealed 1997, no change in N2 and He boiloff.
300 MHz Oxford [siu.edu] Since installation in 1987, cryogen consumption has not changed.
500 MHz Oxford [siu.edu] Since installation in 1987, cryogen consumption has not changed.
200 MHz Bruker [ut.ee] no remarkable cryogens consumption change
360 MHz Oxford [binghamton.edu] boiloff is normal
600 MHz Oxford dual can [colostate.edu] still up
300 MHz Oxford [colostate.edu] went soft in 2009
300 MHz [iastate.edu] still has the same boil off rate.
250 MHz Bruker [ohio-state.edu] refurbished in 1998.
1988
300 MHz Oxford (chem.ucla.edu) no increase in boil-off
500 MHz Oxford [wisc.edu] ca. as installed (maybe slightly higher boiloff over last year)
500 MHz Oxford [uoregon.edu] boiloff remains about the same as when new
300 MHz Oxford [selcia.com] He boil-off rate did increase slightly about 5 years ago
1989
400 MHz Bruker [berkeley.edu] hold time and He boil-off rates have not measurably changed.
250 MHz Oxford [unm.edu] (moved and seals changed 1998) boiloffs are close to original
500 MHz Bruker [ucalgary.ca] Original seal, has never been recharged in the past 20 years.
500 MHz Oxford [hawaii.edu] He and LN boil off rates have not changed in twenty years.
400 MHz Oxford [nmsu.edu] boil off rates for nitrogen (180) and helium (2-4) are normal.
360 MHz Oxford [uvic.ca] hold time and boil off rate do not seem to have changed.
1990
400 MHz, oxford [averydennison.com] boiloff same as usual with no big changes over the years
400 MHz Oxford [UTMB) no significant change on cryogen boil off
1991
250 MHz Oxford [unm.edu] boiloffs are close to original
2x 600 MHz Oxford [bms.com] no change in boil off rates
500 MHz Oxford [ineos.com] Original seal, boiloff has not changed.
2x 300 MHz Bruker [unsw.edu.au] moved cold in 2006, working fine.
1992
300 MHz Bruker [berkeley.edu] hold time and He boil-off rates have not measurably changed.
270 MHz Oxford [memphis.edu] LN2 20% remaing after one week (vs. 35% in 1992). LHe 30% remaining after 3 months (vs 35% in 1992)
400 MHz Bruker [South Africa] Helium consumption is still at 3% per week as it was in 1992.
600 MHz [spcorp.com]
500 MHz Oxford [unmc.edu] still stable at field
400 MHz Oxford [rz.uni-leipzig.de]
1993
500 MHz Bruker [chem.ucla.edu] no increase in boil-off
2x 300 MHz Oxford [wisc.edu] same as installed
500 MHz Bruker [mbi.ucla.edu] hold time/volume hasn't changed since it was installed. It was a demo magnet for a year or to before installation in 1993.
1994
400 MHz Bruker [chem.ucla.edu] no increase in boil-off
300 MHz Bruker [unm.edu] boiloffs are close to original
300 MHz Bruker [poczta.fm] Boiloff is the same in 15 years.
500 MHz Bruker [columbia.edu] All boil off rates are normal.
1995
600 MHz Oxford [UTMB) no significant change on cryogen boil off
750 MHz Oxford [UTMB) no significant change on cryogen boil off.
400 MHz Bruker [uconn.edu] No change in boiloff in the last 8 years.
300 MHz Oxford [uoregon.edu] boiloff remains about the same as when new
600 MHz Oxford [unsw.edu.au] refurbished in 2007 due to relocation, working well before and after relocation.
1996
600 MHz Magnex [mbi.ucla.edu] hold time/volume hasn't changed since installation.
2x 300 MHz Bruker [columbia.edu] All boil off rates are normal.
600 MHz Oxford [uoregon.edu] boiloff remains about the same as when new
1997
600 MHz Oxford [bms.com] no change in boil off rates
600 MHz Oxford [stjude.org] boiloff is about the same
600 MHz Bruker [macbeth.ls.huji.ac.il] Helium boil-off is 40% more, N2 is about the same
1998
500 MHz Bruker [unm.edu] boiloffs are close to original
600 MHz Oxford [stjude.org] boiloff is about the same
2000
600 MHz Oxford [wisc.edu] same as installed
200 MHz Oxford [unsw.edu.au] moved cold in 2006, working fine.
谱仪电气部分寿命低于磁体。