Notices
Results 1 to 6 of 6

Thread: Some questions about Fusion

  1. #1 Some questions about Fusion 
    New Member
    Join Date
    Feb 2009
    Posts
    4
    I've been reading about fusion lately and I had some questions.

    What happens to the helium atoms in the grand scheme of things? Shouldn't they continue to fuse until they reach the heavy atom state where fusion is no longer possible?

    Other than the released neutron, other nucleons are released as a result of the fusion yes? What are they?

    What can be done to interrupt a self-sustained chain reaction? And how does a reaction 'run out of fuel?'

    Is the heating of the plasma itself the ignition for the reaction? Are the atoms always in motion then?


    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Masters Degree organic god's Avatar
    Join Date
    Feb 2008
    Location
    London
    Posts
    567
    yes if you look at stars the elements continue to fuse until..i think it's iron is fused at which point it stops.

    in nucleur reactors they use neutron acceptors. i think its somekind of boron to absorb neutrons which controls the chain reaction.


    everything is mathematical.
    Reply With Quote  
     

  4. #3  
    New Member
    Join Date
    Feb 2009
    Posts
    4
    Interesting, so then the released nucleons end up clashing together themselves to fuse smaller atoms which keep the reaction going?
    Reply With Quote  
     

  5. #4 Re: Some questions about Fusion 
    Moderator Moderator Janus's Avatar
    Join Date
    Jun 2007
    Posts
    2,232
    Quote Originally Posted by Sheep Extreme
    I've been reading about fusion lately and I had some questions.

    What happens to the helium atoms in the grand scheme of things? Shouldn't they continue to fuse until they reach the heavy atom state where fusion is no longer possible?
    It is harder to fuse helium than hydrogen, and it becomes successively harder as the nuclei get heavier.

    For example, in our Sun the primary fusion is hydrogen fusion. The pressure and temp is not enough to support large scale helium fusion. It isn't until the hydrogen at the core is used up that the core collapses enough to create the pressures needed for Helium burning.

    How much further this process continues depends on the mass of the star. Small red dwarfs won't even reach helium burning, once the Hydrogen is used up, they quit fusing, as they aren't massive enough to produce the pressure needed to fuse Helium. Stars the size of or Sun will get as far as having a carbon core before fusion dies out.

    Only stars much more massive than our Sun will ever reach the point where they fuse up to Iron. (and if the Iron core grows large enough, it will collapse under it own weight. The upper layers will rush in to fill the void and upon collision at the center ignite into a giant fusion explosion called a supernova.)
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


    Edit/Delete Message
    Reply With Quote  
     

  6. #5  
    New Member
    Join Date
    Feb 2009
    Posts
    4
    I see. So as the heavier elements are created, they are dragged in by gravity and compose the core? (Thinking of a star here)
    Reply With Quote  
     

  7. #6  
    Forum Freshman
    Join Date
    Jan 2009
    Posts
    35
    or rather,
    >the higher energies present in the core
    (due to the pressure of the outer material, caused by gravity)

    >allow the fusing of heavier elements

    as the energy output of the core drops (due to the decline in fuel and lack of energy to fuse energy because of this lack of fuel)
    the star contracts, heightening the energy in the core and allowing a heavier element to be fused.
    This is how layers of heavy elements occur in stars.
    I had a simple dream: a dream to kill all humans, and this is how you repay me?
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •