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From: jtchew@csa3.lbl.gov (JOSEPH T CHEW)
Newsgroups: sci.military
Subject: Re: Question about Nuclear Weapons
Summary: (Con) fusion about fission vs. fusion
Message-ID: <1990Oct29.032600.10035@cbnews.att.com>
Date: 29 Oct 90 03:26:00 GMT
References: <1990Oct23.190943.7623@cbnews.att.com> <1990Oct26.021043.27122@cbnews.att.com>
Sender: military@cbnews.att.com (William B. Thacker)
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
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From: jtchew@csa3.lbl.gov (JOSEPH T CHEW)
In article <1990Oct26.021043.27122@cbnews.att.com>, cr2r+@andrew.cmu.edu 
(Christian M. Restifo) writes...


>Most nuclear weapons, nowadays, are actually two nuclear weapons in one.
>Afission explosion causes the radioactive material to go critical and
>start a fusion reaction.  I don't think any known depth could implode
>the material enough (at the same level of a fission explosion) to
>initiate a fusion reaction.

Hmm.  This seems to confuse three issues.  A fission device is triggered by a
conventional explosion.  Mr. Restifo is probably thinking specifically of
how a plutonium fission device works: conventional explosion compresses a
sphere of fissile material.  The resulting fission chain reaction does not
involve fusion.

A fusion device is triggered by a fission device.  X-rays from the fission
compress the tritium in a small target capsule.  This was, I believe, the
key idea contributed by Dr. Teller:  radiative compression.

An excellent beginner's introduction to fission weapons is John McPhee, "The
Curve of Binding Energy" (Farrar Strauss Giroux, NY, 1976).  The technical
details of fusion weapons are harder to come by.  I learned the above stuff
(a subset of the nonclassified information, simplified for reasons of space)
in the context of inertial-confinement fusion.

--Joe
"Just another personal opinion from the People's Republic of Berkeley"