I want to thank all of the many folks who responded to my query - so
many that it would be impossible to list them all.
In summary:
- yes, it is very risky to let the magnet quench due to loss of He. Some
have reported being able to bring the magnet back after this, while
others have reported that they were unable to do so.
- a controlled discharge is preferred, but there needs to be a fair
amount of He in the magnet to do a controlled discharge, so that may not
be possible.
- because a magnet quenching from He loss could "go at any time", it
might be a good idea to induce a quench by
accelerating the He loss by allowing the LN2 to drop to zero, or by
breaking the vacuum with N2 gas. This is sort of a "last resort", but
may be necessary.
This is such a great resource, and I again want to thank everyone who
responded.
Tom P.
> On Jun 23, 2022, at 3:39 PM, AMMRL List <ammrlrev_at_webserver2.chem.hawaii.edu> wrote:
>
> Hello All-
> I think this question may have already been asked here, but I don't recall for sure:
>
> A friend at another university (don’t want to say which one)
> has a 300 MHz magnet (Oxford "family style") that is running low on
> helium and they are not able to get any in the short term, as has been
> the case for many of us. They have been advised by the vendor (again,
> don't want to say which one) that it is OK to allow the magnet to quench
> on its own if it runs too low. I have personally never had a magnet quench
> due to helium loss alone and am wondering if this is really OK to allow.
> My concern is that, if there are not enough cryogens around to dissipate
> the energy released, then significant damage could occur. Is that true?
> Or is allowing the magnet to quench on its own OK?
>
> Any advice is greatly appreciated!
>
>
>
> Tom Pratum, Southern Oregon Univ
Received on Sat Jun 25 2022 - 06:36:25 MST