From: houle@nmt.edu (Paul Houle)
Newsgroups: sci.physics.fusion
Subject: Re: The H-Bomb secret is out
Date: 3 Oct 92 20:58:18 GMT
Organization: New Mexico Tech

>Actually, the Soviet effort should have been of about the same duration. 
>They were fully informed of the original Teller designs via Klaus Fuchs, 
>so they were thinking about the same issues at about the same time.  It 
>can be argued that it took about 5 years to prove the first guess was 
>wrong and then, if one is sufficiently creative, invent a workable 
>concept shortly thereafter.  

	I just recently borrowed a copy of the recently published ~Los
Alamos Primer~ from the library,  and the author claims that Hans Bethe
pointed out a problem with Teller's idea of the "classical super" around
1942-1943.  The essential idea of the classical super is to use an
atomic bomb to start a detonation wave that is hot enough and strong
enough to cause fusion and propagate through an entire charge of D fuel.
Bethe pointed out that it wouldn't work because too much energy would be
lost by the shock through radiation.

	I was talking to a friend the other day who wrote a paper about
the history of the hydrogen bomb and he brought out a few interesting
points.  One of them is that the hydrogen bomb is based on a linear
instead of spherical implosion.  This does explain the fact that fusion
weapons tend to be long and relatively thin.  The other is that a
"neutron channel" is placed in the middle of the Li-D charge,  which is
a rod of plutonium:  the general design involves having a fission device
at one end surrounded by a shell designed to reflect x-rays from the
explosion in such a way to cause a linear implosion.  The end of the
fusion charge that faces the bomb is made of U238 or some other heavy
material to prevent the direct x-rays from disrupting the implosion.  The
x-rays start the implosion process,  and neutrons are multiplied in the
neutron channel,  which causes the breeding of T from the Li.

	This guy also told me that the particular greenhouse test involving
tritium boosting (the purpose of the greenhouse series was to test advanced
fission weapon cocepts) actually did not work as well as planned,  which
seemed to provide data which invalidated at least one of the designs being
worked on at the time.

>It will be most interesting, someday, to compare the classified histories 
>of the Soviet and American programs and see if there were any similarities 
>in how the solution was found.  Did Sakharov hit on the right idea the 
>first time, perhaps before seeing the first Teller concept, or did he 
>go through the same steps from the obvious to the subtle?  

	From what I read in Sahkarov's autobiography,  he developed something
called "the third idea" which led to the possibility of fusion weapons of
arbitrary size.  I think that this is analagous to the Teller-Ulam discovery.
Before the device based on the "the third idea" was tested,  a smaller device
was fired which incorporated a fusion component.  I seem to think that from
the info in the book I was able to estimate the yield of that one to be
something like ~200 kt;  which would be consistent with a heavily tritium-
boosted weapon.

	A neat story from this book was when Sahkarov and a friend heard about
an American nuclear test and there was a snowfall around the time that the
material from it was likely to be drifting overhead,  so they got into a car
and drove into the country and filled a cardboard box with snow and drove
back and delivered it to laboratory.  It seems that the lab technician lost
the meltwater and it was never analyzed.

>J. A. Carr                                    |  "The New Frontier of which I  
>jac@gw.scri.fsu.edu                           |  speak is not a set of promises
>Florida State University  B-186               |  -- it is a set of challenges."
>Supercomputer Computations Research Institute |   John F. Kennedy (15 July 60)


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