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From fission bomb to fusion

  1. Apr 10, 2009 #1
    How big is the step from a fission bomb to a fusion bomb?Do you simply put H next to some fission bombs?
     
  2. jcsd
  3. Apr 10, 2009 #2

    Astronuc

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    More or less, one puts some form of hydrogen, e.g. DT, or LiD in a configuration where it was undergo fusion. The fission trigger simply provides the energy used to compress and heat the DT or LiD. At DT can be placed in a fissile device to boost its yield.

    The devil is in the details.
     
  4. Apr 10, 2009 #3

    Morbius

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    Datafree,

    NOT simple AT ALL!!! It's more difficult than just putting H next to a fission bomb.

    As Astronuc points out; the devil is in the details and it took years to figure out how make
    a workable hydrogen bomb even though it was conjectured to be possible back during the
    Manhattan Project.

    If you are interested - read Richard Rhodes book "Dark Sun: The Making of the Hydrogen Bomb"

    Dr. Gregory Greenman
    Physicist
     
  5. Apr 11, 2009 #4
    Thank you.I thought the fission bomb had only to create the heat and pressure of the sun
     
  6. Apr 13, 2009 #5

    Morbius

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    Datafree,

    Just having heat and pressure may not give you what you want. It's like saying all you need to fly
    is to run down the runway real fast and you will lift off. NOPE - you have to have a wing that can
    make use of that velocity and turn it into lift.

    Likewise, with a thermonuclear bomb - you have to have a configuration that can make use of the
    heat and pressure. Just having heat and pressure is NOT sufficient.

    Dr. Gregory Greenman
    Physicist
     
  7. Apr 15, 2009 #6
    Kip Thorne in BLACK HOLES AND TIME WARPS has an historical discussion of the development of fission and fusion bombs...
    He explains the first Soviet "hydrogen" bomb was really a souped up fission bomb....but they came acroos LiD before the US....and he also discusses how the two atomic (fission) bombs dropped on Japan were of two different material designs...U235 first then plutonium for the second....
     
  8. Apr 17, 2009 #7
    Yes, it's really just as simple as that. :smile: No one who actually knows anything about this stuff can or should comment.
     
  9. Apr 17, 2009 #8

    Morbius

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    Jeff,

    You CAN tell them what the Department of Energy has released.

    In fact, you can find the Dept of Energy statement saying EXACTLY what I've
    stated in Richard Rhodes' book!!!

    Dr. Gregory Greenman
    Physicist
     
  10. Apr 18, 2009 #9
    Greg, did you have your posts formally ADC'd?

     
  11. Apr 20, 2009 #10

    Morbius

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    Jeff,

    I AM an ADC!!

    Like I said - you can ALWAYS refer to official statements by DOE.

    Dr. Gregory Greenman
     
  12. Apr 20, 2009 #11
    My concern is your reference to a book for more information, which could be construed to imply some kind of official blessing. I have no idea what is in the book, I've never read it, but as you must know it could potentially skirt the line.
     
  13. Apr 21, 2009 #12

    vanesch

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    No, not really. The book is out there, you can find it in every good library, you can order it on amazon and all that. I really think it doesn't contain any undisclosed material. I've read it, and it contains far more detailled information than what Greg said here - and one can also imagine that it is still far from containing useful design information to quickly make a bomb. It is an interesting story of physics too. To summarise the argument: the "naive" idea that the fission bomb materially (hydrodynamically) compresses and heats the hydrogen was the wrong way, and led people astray for a while. The actual idea that worked was to use *radiative pressure*. This sounds crazy at first, as radiative pressure seems to be quite elusive as compared to hydrodynamical pressure - for matter in normal circumstances. But it turns out that in the thermodynamical states one is interested in, radiative pressure is far stronger than hydrodynamical pressure, and moreover can be much better concentrated.
    This is explained in much more detail in Rhodes' book.
     
  14. Apr 21, 2009 #13
    Heat, pressure and duration.
     
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