Sep  8 14:38:35 2000
To: jdotson@belmont.astro.nwu.edu
Subject: questions

Jessie:

You have to heat the charcoal to 30 K to get the He-3 off of it.

The other question I found to be rather challenging.  But after
a half-hour of studying the books on your desk, this is what I
have come up with:

All gasses that are not too near their 'critical points' or
'triple points' - behave pretty much like ideal gasses, so
the specific heat is calculable.  For example, according to
your book by Keeler, the specific heat (constant volume) of
He-4 at temps of 10-50 K and pressures that vary
from 1 atm to several orders of magnitude greater is
almost constant and equal to what theory predicts for
all monatomic gases:  3 J/g

So I think that He-3 would be the same.

To calculate heat load on pumped pot you also need latent heat
of He-3 which is 8 J/g.

Presumably, we want to have a strong thermal link to 4K somewhere
along the bellows that runs between the charcoal pump and the
pumped pot.  This way the pumped pot will have to cool the
He-3 gas from 4 K down to liquid, and not from 20 K down
to liquid.

Hope this info helps.  I'm going to get back to the final
touches on Sgr B2 now.  Erik has the
a/d reading using his basic program.

cheers,
Giles