Pure fusion weapon

A pure fusion weapon is a hypothetical hydrogen bomb design that does not need a fission "primary" explosive to ignite the fusion of deuterium and tritium, two heavy isotopes of hydrogen (see thermonuclear weapon for more information about fission-fusion weapons). Such a weapon would require no fissile material and would therefore be much easier to build in secret than existing weapons. The necessity of separating high-quality fissile material requires a substantial industrial investment, and blocking the sale and transfer of the needed machinery has been the primary mechanism to control nuclear proliferation to date.

All current thermonuclear weapons use a fission bomb as a first stage to create the high temperatures and pressures necessary to start a fusion reaction between deuterium and tritium in a second stage. For many years, nuclear weapon designers have researched whether it is possible to create high enough temperatures and pressures inside a confined space to ignite a fusion reaction, without using fission. Pure fusion weapons offer the possibility of generating very small nuclear yields and the advantage of reduced collateral damage stemming from fallout because these weapons would not create the highly radioactive byproducts associated with fission-type weapons. These weapons would be lethal not only because of their explosive force, which could be large compared to bombs based on chemical explosives, but also because of the neutrons they generate.

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