Atomic bomb, nuclear bomb, hydrogen bomb

Discussion in 'Physics & Math' started by Saint, Jan 10, 2012.

  1. Saint Valued Senior Member

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    Atomic bomb, nuclear bomb, hydrogen bomb,
    are they the same?
    Or different?
     
  2. adoucette Caca Occurs Valued Senior Member

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  3. michael_taylor Registered Senior Member

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    Atomic means the same as nuclear (for bombs). Hydrogen bombs are one type of nuclear bomb.

    The difference between hydrogen bombs and 'normal' atomic bombs is that the 'normal' ones use only fission, whereas the hydrogen bombs use a fission bomb to ignite fusion.
     
  4. billvon Valued Senior Member

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    A fission bomb relies on nuclear fission of heavy elements to produce energy. Uranium and plutonium are common fissile materials. These are often called A-bombs, atomic bombs or nuclear bombs.

    A fusion bomb relies on the fusion of lighter elements to produce energy. Deuterium and tritium (isotopes of hydrogen) are common materials. These are often called H-bombs, hydrogen bombs or thermonuclear bombs.

    Note - all modern fusion bombs use fission bomb primary initiators to reach the temperatures and pressures required for fusion. So every fusion bomb out there has a little fission bomb inside it to start things off.
     
  5. leopold i miss my coco. Valued Senior Member

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    17,009
    atomic bomb and nuclear bomb are interchangeable and denote either fusion or fission types of bombs.
    hydrogen bombs are atomic bombs of the fusion variety.
    the earliest hydrogen bombs employed both fission and fusion.
    they employed fission to compact the hydrogen enough to undergo fusion.

    to recap:
    fusion and fission are 2 types of atomic or nuclear bomb.
     
  6. origin Howdy Valued Senior Member

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    As I recall all fusion bombs require a fission detonation to put the hydrogen under sufficient pressure and heat to get the fusion to initiate.
     
  7. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    The terms "atomic bomb" and, especially, "hydrogen bomb" are both pop terms without precise technical meaning. They're just layman's ways of saying "nuclear weapons."

    The technical term for a "hydrogen bomb" is "thermonuclear weapon," and refers to nuclear weapons that include at least one separate fusion stage. Notably, the fusion stages in such bombs are not actually used to produce output energy, but rather to create free, energetic neutrons that will drive further fission reactions. The actual output energy comes overwhelmingly from fission reactions, and this is why nobody in the know calls them "hydrogen bombs." Likewise, essentially all modern single-stage nuclear weapons uses fusion boosting in the fission primary to improve yield. There really is no firm technical distinction between fission bombs and fusion bombs - all modern nuclear weapons use various combinations of both fission and fusion, and all of them derive most of their output energy from fission reactions.
     
    Last edited: Jan 10, 2012
  8. Saint Valued Senior Member

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    Fusion or fission bomb is more powerful?
     
  9. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    There is no distinction. All modern bomb designs employ both fission and fusion, and derive most of their power from fission reactions.
     
  10. billvon Valued Senior Member

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    Fusion bomb. The largest fission bomb ever built was .5 megatons, and is near the limit of what you can design a fission bomb to produce. The largest fusion bomb ever built was 50 megatons, and the same design could go to 100 megatons with minor changes.
     
  11. AlphaNumeric Fully ionized Moderator

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    Fission reactions act as the detonator for the more powerful fusion devices. Don't you check before you post?
     
  12. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    No, that is not really correct. A two-stage thermonuclear weapon works by setting off a primary stage, which then sets of the secondary stage. Both the primary and secondary stages use both fission and fusion, and most of the energy in each stage comes from fission reactions. In the primary, a fusion-boosted fission reaction is used (this involves filling the hollow core of the fissible pit with deuterium and tritium, which then fuses when the pit is imploded, releasing lots of energetic neutrons and so improving the yield of the pit fission). The secondary uses three distinct nuclear reactions: first is a fission of the internal sparkplug, followed by fusion of the DT fuel, and finally fission of the DU pusher (the majority of the energy for the entire 2-stage bomb comes from the final pusher fission).

    So, there are 2 distinct fusion reactions and 3 distinct fission reactions in a modern thermonuclear bomb design, and the bulk of the yield comes from the final fission reaction. If we're going for a reductive description, it would be that a fission primary sets off a fusion reaction which then sets off a really big fission reaction using depleted uranium.

    Meanwhile, I suspect very much that you did not, yourself, actually check your knowledge, but are simply repeating popular misconceptions. You'll find that everything I said is corroborated by the relevant Wikipedia page, which happens to include explicit sections on popular misconceptions about how thermonuclear bombs work (bolds mine):

    Two-stage thermonuclear weapons are essentially a chain of fission-boosted fusion weapons (not to be confused with the previously mentioned fusion-boosted fission weapons), usually with only two stages in the chain. The second stage, called the "secondary," is imploded by x-ray energy from the first stage, called the "primary." This radiation implosion is much more effective than the high-explosive implosion of the primary. Consequently, the secondary can be many times more powerful than the primary, without being bigger. The secondary can be designed to maximize fusion energy release, but in most designs fusion is employed only to drive or enhance fission, as it is in the primary.

    [...]

    For the secondary to be imploded by the hot, radiation-induced plasma surrounding it, it must remain cool for the first microsecond, i.e., it must be encased in a massive radiation (heat) shield. The shield's massiveness allows it to double as a tamper, adding momentum and duration to the implosion. No material is better suited for both of these jobs than ordinary, cheap uranium-238, which also happens to undergo fission when struck by the neutrons produced by D-T fusion. This casing, called the pusher, thus has three jobs: to keep the secondary cool, to hold it, inertially, in a highly compressed state, and, finally, to serve as the chief energy source for the entire bomb. The consumable pusher makes the bomb more a uranium fission bomb than a hydrogen fusion bomb. It is noteworthy that insiders never used the term hydrogen bomb.

    Finally, the heat for fusion ignition comes not from the primary but from a second fission bomb called the spark plug, embedded in the heart of the secondary. The implosion of the secondary implodes this spark plug, detonating it and igniting fusion in the material around it, but the spark plug then continues to fission in the neutron-rich environment until it is fully consumed, adding significantly to the yield.​

    Also note my earlier qualifer: "modern designs." As indicated above, it is indeed possible to design thermonuclear weapons for maximum fusion yield. But this is not done in any modern, deployed designs. The main reason to do that would be to cut down on radioactive by-products (since the fusion reactions are producing helium mostly) and so make a "clean bomb." But, fusion fuel is expensive and you get way, way, way more yield per dollar by including a DU pusher and fissing that. Plus you still have to set off a fission bomb in the primary regardless, so the resulting system is never going to be all that "clean."
     
    Last edited: Jan 11, 2012
  13. Saint Valued Senior Member

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    The stockpiles of USA nuclear weapons, mainly are what kind of bombs?
     
  14. michael_taylor Registered Senior Member

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    Well I didn't know that.

    It's difficult to know precisely, as the exact details are secret, but most seem to agree the Teller-Ulam design is the main one.
     
  15. leopold i miss my coco. Valued Senior Member

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    i would like to see your source for this.

    according to "dark sun" a thermonucluer bomb, specifically the mike device, is exploded by an intitial conventional (tnt etc.) detonation which drive the fissionable material together.
    there is no mention of both fusion and fission employed in this initial, or primary, expolsion.
     
  16. NietzscheHimself Banned

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    1952 designs aren't exactly modern. He cited his main source. Your main source of information is http://en.m.wikipedia.org/wiki/Ivy_Mike. Which blatantly states,

    "Due to its physical size and fusion fuel type (cryogenic liquid deuterium), the Mike device was not suitable for use as a thermonuclear weapon; it was intended as an extremely conservative experiment to validate the concepts used for multi-megaton detonations."

    And "The device was the first full test of the Teller-Ulam design, a staged fusion bomb, and was the first successful test of a hydrogen bomb."

    Meaning it is the precursor to modern designs as we mostly have Teller-Ulam designs in our arsenal. Since hydrogen fuseing makes a bigger bang than TNT detonating... Modern designs are a little smaller.

    Which is pretty cool considering the only natural occurrences of these types occur in stars and supernovas billions of times larger than our silly bombs.
     
  17. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    Two-stage thermonuclear designs, of the type described above. Supposedly this is also the case for Russia, China, France and the UK. The less-advanced nuclear powers (Israel, Pakistan, India, North Korea) are thought to use older fission designs (possibly with DT boosting in some cases).
     
  18. leopold i miss my coco. Valued Senior Member

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    it is?

    richard rhodes writes a good book, you should read it.
     
  19. quadraphonics Bloodthirsty Barbarian Valued Senior Member

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    If you've got a specific citation showing that designs of the "Mike" type are in use today - or were ever deployed at all, for that matter - then we're all ears. AFAIK, that was simply an early experimental design, and all deployed thermonuclear weapons use the designs detailed in my posts and links above.
     
  20. leopold i miss my coco. Valued Senior Member

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    yes, mike was one of the first US thermonuclear devices.

    i'm not privy to military secrets so i have no clue as to the rest of your post.
     

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