4 ms·

"fusion-enhanced fission stage" The primary is fusion boosted fission, the core ("spark-plug") of the secondary is also fusion boosted fission surrounded by dr

"fusion-enhanced fission stage" The primary is fusion boosted fission, the core ("spark-plug") of the secondary is also fusion boosted fission surrounded by dry fusion fuel (lithium deuteride) and then a fissionable tamper. My understanding is that X rays from the primary compress the entire secondary package - which ignites the spark-plug and then the fusion fuel is caught between the incoming tamper and the exploding spark-plug at its core and ignited. So there does appear to be a real "fusion" stage - with a lot of other steps involving fission and fusion. https://en.wikipedia.org/wiki/Thermonuclear_weapon https://en.wikipedia.org/wiki/Thermonuclear_weapon

denton-scratch 4y ago
The cited article says: "Fast fission of the tamper and radiation case is the main contribution to the total yield and is the dominant process that produces radioactive fission product fallout." The way I read that, even in a large H-bomb, little of the yield is the direct result of fusion reactions. Rather, the neutrons produced by the fusion reaction dramatically increase the efficiency of the fission reactions, which on their own would not produce enough neutrons to fission more than a small part of the fissile material before the device disintegrates.
- arethuza 4y ago
  There is still a considerable about directly from fusion e.g. in the Tsar Bomba the fusion stage produced about 47Mt of the 50Mt total (it had two smaller H-bombs as primaries for the fusion stage). The full design was 100+ Mt so about 50% from the final fission stage seems a rule of thumb, which is also mentioned in this article about "neutron bombs": https://en.wikipedia.org/wiki/Neutron_bomb https://en.wikipedia.org/wiki/Neutron_bomb Neutron bombs don't have fissile tampers on the secondary exposing the neutrons from fusion directly rather than using them to fission the tamper.

denton-scratch 4y ago

The cited article says: "Fast fission of the tamper and radiation case is the main contribution to the total yield and is the dominant process that produces radioactive fission product fallout." The way I read that, even in a large H-bomb, little of the yield is the direct result of fusion reactions. Rather, the neutrons produced by the fusion reaction dramatically increase the efficiency of the fission reactions, which on their own would not produce enough neutrons to fission more than a small part of the fissile material before the device disintegrates.

arethuza 4y ago
There is still a considerable about directly from fusion e.g. in the Tsar Bomba the fusion stage produced about 47Mt of the 50Mt total (it had two smaller H-bombs as primaries for the fusion stage). The full design was 100+ Mt so about 50% from the final fission stage seems a rule of thumb, which is also mentioned in this article about "neutron bombs": https://en.wikipedia.org/wiki/Neutron_bomb https://en.wikipedia.org/wiki/Neutron_bomb Neutron bombs don't have fissile tampers on the secondary exposing the neutrons from fusion directly rather than using them to fission the tamper.