Magnex and Spectrospin also have magnets which use no cryogens, as well do
the Japanese, but they all use helium gas. They also make magnets utilizing
high-temp. superconductors, but not in the coil. IIRC, the known high-temp.
superconductors are ceramic, and therefore not ductile to be wound into a
coil. The industry has overcome that obstacle before, but ....? Perhaps if
they mould the ceramic into a cylinder, then cut it into a coil (I want a
piece of that patent!).
I know of imaging magnets that have an 'aftermarket' coldfinger sealed
inside the turret to recondense some of the boiloff. This works quite well,
but one caution should anyone try it: Beware of the boiloff relief valve!
The internal pressure is reduced so much that the turret mechanicals and
boiloff relief valve become very critical in preventing air diffusion into
the LHe space. One must test the turret for leaks, and isolate the relief
valve output from the air (place the end of the tube so the boiloff bubbles
through oil.)
As far as the shortage goes, I've heard speculation that the known, ongoing
'perfect storm' of helium plant maintenance was compounded by the increased
demand presented by the shooting war in Israel. Gee, I wonder what they use
to cool the guided missile sensors? We have seen a couple of shorted
dewars, but no consistent shortage here. I expect things will be OK as long
as there aren't many demands to energise new magnets over the winter (and we
achieve World Peace, of course).
If the suppies run low and get rationed, you should hope no one asks "Why do
most NMR structures seem to be 'verified' by X-ray Crystallography?" I
would expect medical diagnostic and military uses to take priority over much
research.
Cheers,
Jerry Hirschinger, NMR Instrumentation Specialist
Purdue Interdepartmental NMR Facility
560 Oval Dr. West Lafayette, IN 47907-2084
Office: Wetherill 365A
Phone / Fax: (765) 494-5288 / 494-0239
Cellular: (765) 427-3034
> -----Original Message-----
> From: Christopher Singleton [mailto:cas40_at_bu.edu]
> Sent: Thursday, November 16, 2006 9:53 AM
> To: ammrl_at_ammrl.org
> Subject: AMMRL: Re: He shortage....Alternative 'magnetic' resources...
>
>
> I remembered Oxford having some kind of helium recycling magnet:
>
> http://www.oxinst.com/wps/wcm/connect/Oxford+Instruments/Products/
> Low+Temp+&+Magnetic+Sample+Environment/MCV+Magnets/MCV+Magnets
>
> This may be where we're heading if helium supplies remain low. Of
> course, it sounds like it would be a lot more convenient also.
>
>
> Chris
>
> Rajan Paranji wrote:
>
> > Hello
> > Although I should be focusing my energy on the immediate things,
> > having visited the link provided by Jeff and some other links that I
> > googled related to He shortage, I could not help my train of thoughts
> > getting distracted by this issue and feeling a little depressed.
> > What happens to all the NMR and MRI systems when we near the day
> > when He is going to run out, as obtained from the conventional means
> > now ? I read one article, about 5 years old, that rumoured that the
> > Russians are planning to mine the moon for He gas, by 2020 and there
> > seems to be exist this (mis)/information that the supplies may last
> > only upto 2015. I heard my friend Bill come up with "scooping" the
> > He from solar winds in the outer atmosphere of mother earth and
> > transporting it down.
> >
> > I was musing to myself, what are the potential ways the spectrometers
> > could be saved ?
> >
> > * He recovery systems is an immediate possibility
> > * As I am writing this, got a call from Jason Jacob of Wyeth, who
> > mentioned about compressed He magnet systems that essentially recycle
> > the He boil off to keep the system going without the need for frequent
> > refills. Jason mentioned something like an year to 2 years fill cycle
> > on these. (I am feeling better already ) :)
> > * High Tc supercon magnets.
> > * Permanent super magnets and micro sample volumes ?
> > * Field cycling techniques ?
> >
> > What can you come up with (however outlandish or out'planet'ish) ?
> >
> > Cheers
> >
> > Rajan
> > --
> >
> > *_______________________________
> > Rajan K Paranji, Ph.D.
> > *NMR Facility Manager
> >
> > Department of Chemistry
> > Room 65, Bagley Hall
> >
> > University of Washington
> > *Seattle**, WA 98195*
> >
> > *ph: 206 685 2581
> > fax: 206 685 8665
> > email: paranji_at_chem.washington.edu
> > ___________________________________*
> >
>
Received on Fri Nov 17 2006 - 11:24:25 MST