A pure fusion weapon (PFB) is a (hypothetical) concept that does
not need a fissile trigger to ignite fusion. Of all the gruesome
scenarios in the current International situation, it is the
scariest. And possibly the truth is somewhere "in between" the
PFB and the Mark ll "Port Chicago" design, which does not require
a high enrichment trigger).
Despite billons of dollars spent during the ColdWar to develop a
pure fusion weapon, no measurable success was ever reported by the
Pentagon. At least that is the official story. In 1998, the DoE
(notice this is NOT the DoD) released a partly declassified doc
stating that even if they had made a substantial investment in the
past to develop a PFB (an admission that they had tried) "the U.S.
does not have and is not developing a pure fusion weapon and no
credible design for a pure fusion weapon resulted from the DoE
investment". This is true, but limited to DoE investment in the
USA.
The power density needed to ignite a fusion reaction (on DT in a
non-plasma) are attainable only with the aid of a fission
explosion, OR with an apparatus which first creates a warm
plasma - but not with conventional explosives alone. However, a
large expendable apparatus such as a Z-pinch, or solenoid, or
array of exploding wires could be conceivably combined with
secondary explosives to implode the pre-plasma, creating a small
neutron-rich explosion and create the illusion of a PFB - by Korea
for its own political ends... i.e. blackmail. A pure fusion, or
this kind of 'bastard' weapon, would only subvert the "intent" of
the Comprehensive Test Ban Treaty but probably not the treaty
itself - so we are in a double-weak bargaining position.
It has been claimed by some experts that it is possible for N.
Korea to have built this kind of crude, hybrid weapon, using only
unclassified 20 year-old technology. The weapon design which is
described below (Jones and von Hippel, Science and Global
security, 1998) and might have a total yield below what Korea or
observers have claimed. From the point of view of explosive
damage, such a weapon would have no clear advantages over lots of
conventional explosives, EXCEPT for the massive neutron flux,
which could deliver a lethal dose of radiation to humans - plus by
using a boron-based tamper (or fuel grade U on the high end) the
damage could be raised to a much higher level - tens of kiloton
range but still not be a usable offensive weapon due to bulk and
complexity.
http://www.princeton.edu/~globsec/publications/pdf/7_2Jones.pdf
That is - no clear advantages unless **blackmail** is now to be
considered to be an offensive weapon...
...as it certainly could be in the sense of a N. Korean "War on
Domestic Poverty"...
Jones
