From sth at info-igor.org Wed Sep 11 10:58:25 2019
From: sth at info-igor.org (Scott Hannahs)
Date: Wed, 11 Sep 2019 13:58:25 -0400


Subject: Helium!
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The purifier flows gas, the liquefier still puts out 4.2K helium (ambient pressure) and so the gm/sec is a useful number for cooling capacity. There isn?t much difference for superfluid though it is just a bit denser. With superfluid helium you get counter flow, so there can be no actual mass flow but entropy can be moved by exactly counteracting flows of the superfluid and normal components. This give superfluid helium the ability to conduct entropy very easily and be an amazing heat conductor.

But we store a lot of helium in gas form, and in liquid so picking one set of units for quantity of stored helium was very useful.

Now lets discuss the advantages/disadvantages of various pressure units, bar, pa, torr, psi, inches of hg, inches of H2O, etc. That will make anyone?s head spin. Our plant run by ex navy operators is all in PSI, magnet designs and monitoring is al in bar along with the cryogenics.

-Scott

> On Sep 11, 2019, at 1:26 PM, Minoofar, Payam N <Payam.Minoofar at Teledyne.com> wrote:
>
> Liquid calculations are a lot easier and more accurate, too. Even though helium behaves most closely like an ideal gas, money considerations require the horribly complicated equations with umpteen virial coefficients.
>
> How does superfluidity factor in flow calculations?
>
> As far as I am concerned, this is the only valid non-scientific use of helium:
> https://www.youtube.com/watch?v=Fww0OPfyOfg
>
> -- Payam
> x4514