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From: JWJ%MIT-MC@sri-unix.UUCP
Newsgroups: net.physics
Subject: fusion -- deuterium reactions
Message-ID: <12137@sri-arpa.UUCP>
Date: Thu, 29-Sep-83 07:27:00 EDT
Article-I.D.: sri-arpa.12137
Posted: Thu Sep 29 07:27:00 1983
Date-Received: Thu, 6-Oct-83 23:05:23 EDT
Lines: 21

From:  Joseph W. Johnson <JWJ @ MIT-MC>

      Now it should be noted that if pure deuterium is burned,
    the reaction only produces helium nuclei. There are no neutrons
    and hence no neutron induced radioactivity and no neutron
    damage to the materials...

  Unfortunately, this is not quite true. In deuterium-deuterium fusion,
there are two reaction paths, one produces a Helium-3 nucleus and a proton.
The other produces tritium and a neutron. The two branches happen with almost
equal probability. If we consider that the energy yield from either branch is
approximately 4 MeV while the yield from a deuterium-tritium fusion is 17.6 MeV,
its apparent that there will be more neutrons produced (per unit energy) in a
pure deuterium plasma than in the D-T plasma (although the D-D neutrons will be
of lower energy). The bottom line is that any reactor that contains deuterium
will produce neutrons from D-D fusion. There are reactions, such as a proton
fusing with Boron-11, which do not produce neutrons, but confining and igniting
such a plasma would be considerably more difficult than the D-T plasmas which
form the basis for most fusion reactor designs.

Joe Johnson