From: noring@netcom.com (Jon Noring)
Subject: Re: The H-Bomb secret is out
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 
Date: Mon, 12 Oct 1992 19:03:50 GMT

In article houle@nmt.edu (Paul Houle) writes:
>
>	Probably the only isotope separation technology that should scale
>down well is laser isotope separation,  but that is still kinda blue-skyish.
>Yet,  if it could be made to work,  there is no reason why one couldn't
>build a rather small isotope separation system that might even scale to
>basement operation size.  Now,  it might take you forever to make enough
>high-enriched U235 to do anything interesting with it.  If we assume that
>35 kg is "enough",  and that U235 is about %1 by weight,  then we would
>need something like 3.5 metric tons of uranium to get it.  I suppose that
>you could fit all that in a basement,  but it would be hard.  A really
>high-tech laser enrichment system might continuously process metallic
>natural U (most efficient for storage) into UF6,  run one-pass separation
>to ~90% U235,  and then recycle the F at the end of the cycle which
>might barely make this into something you could run at home.  Building
>it in your basement might be harder;  and it all depends on developments
>in technology which are certainly not known to the public...  Although it
>is almost certain that somebody has done classified work on it.

It is true that LIS (Laser Isotope Separation) could be scaled down in size
and still work efficiently.  However, it requires VERY precisely tuned lasers
of high power (even for small sizes), which are (at the present) VERY
expensive.  At this time, I do not see anybody tinkering in their basement
and build a cheap and workable LIS (even a micro-LIS in a test-tube).  And
you're right, there's been a lot of classified work done on it, and, like the
H-bomb, there are many not-so-obvious subtleties in the design of a working
LIS system that even a well-funded program ($100+ million/year) would take
several years to find them all out.  LIS, though simple at first glance, is
not a trivial process to implement.


>	Then again,  laser isotope separation might become very handy
>for other elements.  Diamonds that contain isotopically pure C12 have
>about an order of magnitude better heat conductivity than regular
>diamonds...  And C13 diamonds should be harder.

This is an interesting field.  Another area that I've been involved with is
the isotopic purification of silicon.  Just like diamond, we should find an
improvement in the thermal conductivity of single crystaline silicon when
isotopically pure (there may be other property changes as well.)  We believe
there could be a lot of practical uses for t.c.-enhanced silicon, for
example, in high power devices employing large silicon chips, photovoltaic
cells, etc.

Isotopic purification of mercury using LIS has also been studied since
isotopically pure mercury significantly boosts the efficiency of fluorescent
lights.  I don't recall the particular physics as to why this is so - maybe
one of the net.readers can fill all of us in on the physics involved here.

Jon Noring

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