How high a yield are the fission triggers in fusion (hydrogen) bombs?

Discussion in 'Nuclear, Chemical & Bio Weapons' started by Dayton3, Sep 23, 2017.

  1. Dayton3

    Dayton3 Well-Known Member

    Joined:
    May 3, 2009
    Messages:
    16,745
    Likes Received:
    4,038
    Trophy Points:
    113
    Gender:
    Male
    I have not been able to locate this information.

    To trigger the fusion inside a weapon. That is hydrogen atoms fusing to become helium as happens in the sun and thus releasing huge amounts of energy, you have to have temperatures and pressure similar to that in the sun.

    And the only way you can produce that is by detonating a small fission explosive in close proximately to isotopes of hydrogen. Virtually all of these "fission triggers" are plutonium type "implosion" devices from what I've read. Where the fission explosion is produced by crushing concentric spheres of plutonium together by powerful conventional explosives.

    So, how high a yield in kilotons are these "fission triggers"?
     
  2. tecoyah

    tecoyah Well-Known Member Past Donor

    Joined:
    May 15, 2008
    Messages:
    28,255
    Likes Received:
    9,157
    Trophy Points:
    113
    Gender:
    Male
    There really is no "tonnage" rating for a "Trigger" as the process varies by device.
    "The radiation implosion mechanism exploits the temperature difference between the secondary stage's hot, surrounding radiation channel and its relatively cool interior. This temperature difference is briefly maintained by a massive heat barrier called the "pusher"/"tamper", which also serves as an implosion tamper, increasing and prolonging the compression of the secondary.If made of uranium, enriched uranium or plutonium, it can capture fusion neutrons produced by the fusion reaction and undergo fission itself, increasing the overall explosive yield."
    https://en.wikipedia.org/wiki/Thermonuclear_weapon

    Depending on the type of weapon construction it may be something as small as a stick of dynamite in yield.
     
    Last edited: Sep 23, 2017
  3. Dayton3

    Dayton3 Well-Known Member

    Joined:
    May 3, 2009
    Messages:
    16,745
    Likes Received:
    4,038
    Trophy Points:
    113
    Gender:
    Male
    I didn't know you could even make a fission explosive that small. I thought the smallest fission devices were on the order of 0.05 kilotons which is equivalent to of course 50 tons of TNT.
     
  4. tecoyah

    tecoyah Well-Known Member Past Donor

    Joined:
    May 15, 2008
    Messages:
    28,255
    Likes Received:
    9,157
    Trophy Points:
    113
    Gender:
    Male
    The question seemed to be about the "Trigger" yield so I addressed that. The yield of the actual device is something entirely different.
     
  5. Dayton3

    Dayton3 Well-Known Member

    Joined:
    May 3, 2009
    Messages:
    16,745
    Likes Received:
    4,038
    Trophy Points:
    113
    Gender:
    Male
    I understand. But I though the "fission trigger" was basically a small atomic bomb all on its own and what I've saying is I simply didn't know you could build such a device to have a yield as small as a "stick of dynamite"?
     
  6. tecoyah

    tecoyah Well-Known Member Past Donor

    Joined:
    May 15, 2008
    Messages:
    28,255
    Likes Received:
    9,157
    Trophy Points:
    113
    Gender:
    Male
    You assumed incorrectly.
     
  7. Kash

    Kash Member

    Joined:
    May 19, 2016
    Messages:
    187
    Likes Received:
    19
    Trophy Points:
    18
    Teller-Ulam configuration uses 2-3 kiloton trigger. I am unsure that any other configurations are still alive today.
     
    Dayton3 and Questerr like this.
  8. Dayton3

    Dayton3 Well-Known Member

    Joined:
    May 3, 2009
    Messages:
    16,745
    Likes Received:
    4,038
    Trophy Points:
    113
    Gender:
    Male
    If you can trigger a fusion reaction with a fission reaction as small as a "stick of dynamite" why bother with fission triggers at all?

    Couldn't you just trigger the fusion reaction with extremely powerful conventional explosives? The so called "clean fusion device" that is a bit of the holy grail of nuclear weapons manufactu
     
  9. tecoyah

    tecoyah Well-Known Member Past Donor

    Joined:
    May 15, 2008
    Messages:
    28,255
    Likes Received:
    9,157
    Trophy Points:
    113
    Gender:
    Male
    "There really is no "tonnage" rating for a "Trigger" as the process varies by device.
    "The radiation implosion mechanism exploits the temperature difference between the secondary stage's hot, surrounding radiation channel and its relatively cool interior. This temperature difference is briefly maintained by a massive heat barrier called the "pusher"/"tamper", which also serves as an implosion tamper, increasing and prolonging the compression of the secondary.If made of uranium, enriched uranium or plutonium, it can capture fusion neutrons produced by the fusion reaction and undergo fission itself, increasing the overall explosive yield."
    https://en.wikipedia.org/wiki/Thermonuclear_weapon

    Please read the link this time.
     
  10. Dayton3

    Dayton3 Well-Known Member

    Joined:
    May 3, 2009
    Messages:
    16,745
    Likes Received:
    4,038
    Trophy Points:
    113
    Gender:
    Male
    I've read it and I'm familiar with the material.

    Kash's comments about the 2-3 kiloton yield for a Teller-Ulam device is more on point with what I wanted to know though.
     
  11. tecoyah

    tecoyah Well-Known Member Past Donor

    Joined:
    May 15, 2008
    Messages:
    28,255
    Likes Received:
    9,157
    Trophy Points:
    113
    Gender:
    Male
    My mistake then
     
    Dayton3 likes this.
  12. Toggle Almendro

    Toggle Almendro Well-Known Member

    Joined:
    May 17, 2016
    Messages:
    1,281
    Likes Received:
    137
    Trophy Points:
    63
    The unboosted yield of a modern miniaturized primary is three tenths of one kiloton. This is the lowest option on some B61 bombs.

    I suspect that adding enough tritium-deuterium gas would boost the yield of any modern miniaturized primary to ten kilotons, simply because achieving a critical mass of plutonium usually requires that much fissile material.

    I suspect that the primaries used in modern miniaturized warheads cut the design close enough that they couldn't be boosted much over ten kilotons. The entire nature of the design requires the bare minimum amount of fissile material in order to function safely.

    If a secondary was small enough that it did not require the full ten kilotons to compress, a primary probably wouldn't be boosted all the way to ten kilotons, unless there was a tactical role planned for the weapon and they desired a "primary only" set of lower yield options.

    For example, the W80 has a five kiloton "primary only" option. Some B61 bombs have "primary only" options ranging up to ten kilotons.
     
  13. jay runner

    jay runner Well-Known Member

    Joined:
    Oct 5, 2017
    Messages:
    13,247
    Likes Received:
    7,607
    Trophy Points:
    113
    Gender:
    Male
    I don't know much about nukes.

    I came to the probable conclusion that all the talk about suitcase-sized nukes around Y2K time was bravo sierra.

    What say you'all who know something of the technical aspects of nukes?

    If such a thing exists I think we are all dead in the short run.
     
  14. Dayton3

    Dayton3 Well-Known Member

    Joined:
    May 3, 2009
    Messages:
    16,745
    Likes Received:
    4,038
    Trophy Points:
    113
    Gender:
    Male
    IIRC, the demolition nuclear device in the U.S. arsenal that actually "looks" like a suitcase weighs well over 300 lbs.

    Not exactly Samsonite.
     
    jay runner likes this.
  15. jay runner

    jay runner Well-Known Member

    Joined:
    Oct 5, 2017
    Messages:
    13,247
    Likes Received:
    7,607
    Trophy Points:
    113
    Gender:
    Male
    Glad to hear that. Nobody could carry that into a stadium with their strong arm and not be noticed.
     
  16. Toggle Almendro

    Toggle Almendro Well-Known Member

    Joined:
    May 17, 2016
    Messages:
    1,281
    Likes Received:
    137
    Trophy Points:
    63
    What sort of suitcase? A steamer trunk? A buisinessman's briefcase?

    And who would be making the device? The US government? Or some guy in his garage?

    A ten kiloton primary for an American thermonuclear warhead could fit in a steamer trunk. The US actually made some portable demolition nukes with similar dimensions back in the Cold War.

    The US government could probably build a ten kiloton device that would fit in a businessman's briefcase if it wanted to do so. So far as I know, they haven't ever wanted to do anything like that. They did build some nukes that fit inside artillery shells.

    Some guy in his garage who got ahold of reactor-grade plutonium could probably make a truck bomb that could produce a fizzle.

    A fizzle isn't a nuclear explosion, but it isn't nothing either. It would greatly exceed the power of the largest conventional bombs. A fizzle on the street next to the Sears Tower would collapse it instantly.

    Some guy in his garage could also probably use reactor-grade plutonium to make a steamer-trunk-sized bomb that wouldn't produce a significant explosion, but would send out an extremely lethal pulse of radiation that would kill a lot of people if it went off in a crowded area.
     
  17. Dayton3

    Dayton3 Well-Known Member

    Joined:
    May 3, 2009
    Messages:
    16,745
    Likes Received:
    4,038
    Trophy Points:
    113
    Gender:
    Male
    The Soviet equivalent is reportedly about the size and shape of an apartment mini refrigerator
     
  18. Questerr

    Questerr Banned

    Joined:
    Feb 6, 2007
    Messages:
    63,175
    Likes Received:
    4,961
    Trophy Points:
    113
    They don’t even look like suitcase. More like very big duffel bags or rucksacks.
     
  19. Questerr

    Questerr Banned

    Joined:
    Feb 6, 2007
    Messages:
    63,175
    Likes Received:
    4,961
    Trophy Points:
    113
    To answer the OP’s question: between sub-kiloton and low kiloton (<10KT) yield depending on how big the fusion device yield is supposed to be.
     
    Last edited: Oct 31, 2018

Share This Page