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Nuclear Fusion Reactions

  1. Apr 10, 2005 #1

    Astronuc

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    Staff: Mentor

    Some principal nuclear fusion reactions which have been considered are:

    1) D + T -> n + 4He

    2) D + 3He -> H + 4He

    3) D + D -> H + T / 3He + n

    4) T + T -> 4He + 2n

    5) T + 3He -> (various products)

    6) H + 11B -> 3 (4He)

    from G. H. Miley, H. Towner and N. Ivich, U. of Illinois Nucl. Eng. Report COO-2218-17 (1974)

    with the reaction rates in the figure
     

    Attached Files:

  2. jcsd
  3. Apr 10, 2005 #2

    Morbius

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    Astronuc,

    Thank You.

    We see why D-T fusion is the leading contender.

    Boron fusion is at the bottom, and doesn't overtake D-T fusion until
    you get to Megavolt temperatures; that is temperatures at which the
    average kinetic energy of the material is on the same order as the
    nuclear binding energy.

    Dr. Gregory Greenman
    Physicist
     
  4. Apr 11, 2005 #3
    I have seen the first five as being considered canidates for fusion reactors, but I had no clue Boron was a practical material.

    I take that as: fusion occurs because kinetic energy forces the atoms together because it overcomes the repulsion between the nuclei. Is that what you are saying?
     
  5. Apr 11, 2005 #4

    Morbius

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    That's a condition for any of the fusion reaction.

    No I was making a comment pertinent to the curve from Miley, et al;
    posted by Astronuc.

    The graph shows that the D-T reaction has the highest reaction rate of
    any of the reactions being considered, while the Boron reaction has the
    lowest - over most of the temperature range.

    It is only at the extreme high end that the that the Boron reaction
    goes from last place to first place. However, the graph shows that this
    happens at temperatures around 1000 KeV = 1 MeV, and above.

    At temperatures of 1 MeV; the average kinetic energy of the particles
    will be the same order of magnitude as the nuclear binding energy.

    That means that a 1 MeV temperature is EXTREMELY, EXTREMELY HOT -
    even by fusion standards.

    Dr. Gregory Greenman
    Physicist
     
  6. Apr 11, 2005 #5

    Morbius

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    I see that I'm mistake here.

    Upon closer inspection, I see the (T + He3) [curve 5] and ( H + B-11 ) [ curve 6]
    don't cross - they "kiss" but the (H + B-11 ) turns over. It is the (T + He3)
    [curve 5] that ends up taking first place from the D-T reaction - again only
    at extreme temperature.

    Dr. Gregory Greenman
    Physicist
     
  7. Apr 11, 2005 #6
    Interesting:http://nuclearweaponarchive.org/Nwfaq/Nfaq4-3.html

    Some handwaving:http://nuclearweaponarchive.org/Nwfaq/Nfaq4.html

    and some first principles:http://nuclearweaponarchive.org/Nwfaq/Nfaq4-1.html#Nfaq4.1.7

    if one cursors down, there are some graphs showing various reflector materials.
     
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