Results 1 to 15 of 15

Thread: Can iron be fused?

  1. #1
    Join Date
    Oct 2008
    Posts
    246

    Can iron be fused?

    As I understand it, the supernovae journey involves a range of elements fusing under extreme heat and pressure, each releasing energy when they do, but the later-stage fusion reactions that lead to iron are not exothermic (do not release energy). So once a star is producing iron by fusion it's not producing additional outward radiation pressure to maintain a giant star's structure, so that star implodes and kablooey you get a supernova.

    My question is, if you could create some kind of hypothetical mechanism that kept on progressing the pressure and the temperature, would iron fuse with itself and/or other surrounding elements? What predominant element would be the next step in this process? Can fusion proceed all the way through the periodic table? Thanks, Steve

  2. #2
    Join Date
    Jun 2005
    Posts
    14,434
    Quote Originally Posted by Cheap Astronomy View Post
    As I understand it, the supernovae journey involves a range of elements fusing under extreme heat and pressure, each releasing energy when they do, but the later-stage fusion reactions that lead to iron are not exothermic (do not release energy). So once a star is producing iron by fusion it's not producing additional outward radiation pressure to maintain a giant star's structure, so that star implodes and kablooey you get a supernova.

    My question is, if you could create some kind of hypothetical mechanism that kept on progressing the pressure and the temperature, would iron fuse with itself and/or other surrounding elements? What predominant element would be the next step in this process? Can fusion proceed all the way through the periodic table? Thanks, Steve
    Yes, I'm sure that you can fuse iron with other nuclei, if you use an accelerator. But nobody uses it in reality, because there isn't a need. To explain, most of the artificial fusion being done in accelerators is to create undiscovered elements, so superheavy elements. If you wanted to make the next undiscovered element (119) using iron, you would have to collide iron (26) with Americium (95), which is an unstable element. For example, when the place I work created nihonium (113), they collided zinc (30), which is heavier than iron, with bismuth (83). And fusion can produce all the elements in the periodic table, by definition, since the heaviest elements on the table were created by fusion. There is a question of how far it can proceed, though. Nobody is sure how far the periodic table can go, but people think it may be around 145.
    As above, so below

  3. #3
    Join Date
    Mar 2004
    Posts
    19,233
    My understanding (warning, this is at the bare edge of my knowledge on the subject) is that iron could be fused with itself, but of course it would be an endothermic process, and the temperatures and pressure requirements get absolutely incredible, so moves out of realistic territory (at least for mass process, not a modest number of events in a collider). Instead, to move up to higher elements, the natural processes of growing nuclei are more complex. There is the r-process, or rapid neutron capture process, the s-process, or slow neutron capture process, and the p-process which is partly (but not wholly) about proton capture. There are differences in stellar environments needed for the processes. Rather than trying to fumble a more detailed explanation here, I’d suggest looking them up.
    Last edited by Van Rijn; 2020-Sep-11 at 10:00 AM.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  4. #4
    Join Date
    Jan 2010
    Location
    Wisconsin USA
    Posts
    3,288
    Adding to this. Can certain isotopes of iron being fused with deuterium for an exothermic fusion?
    The moment an instant lasted forever, we were destined for the leading edge of eternity.

  5. #5
    Join Date
    Jul 2005
    Location
    Massachusetts, USA
    Posts
    22,123
    The endothermic issue is an important reason that Iron is the end of the line in stars. Another issue when you start fusing Iron and heavier elements is that the more stable isotopes are increasingly neutron rich. In the lab super-heavy elements have been created, but they are isotopes with too few neutrons to be the most long-lived of those elements, simply because there is no way to get enough neutrons into the fusing process.
    Can fusion proceed all the way through the periodic table?
    Not the process that keeps stars shining, in the star there is a process of spalation which creates a small amount of heavier elements, and during the supernova there is something referred to as "rapid-process" which creates heavier elements. Note that during the supernova, a little bit of endothermic process is supported in nature.
    All that being said, these days, we thing the bulk of the very heavy elements are produced when two neutron stars spiral into each other and spray out chunks that can't hold themselves together as "neutronium" and quickly decay into neutron rich material that nuclear forces can hold together, and then decay by some process to create protons out of the excess neutrons in individual nuclei.
    Forming opinions as we speak

  6. #6
    Join Date
    Feb 2009
    Posts
    2,275
    Note that the most stable isotope, even at zero/negligible electron chemical potential, is not Fe-56. It is Ni-62.

    How are the Fe/Ni ratios in stars?

  7. #7
    Join Date
    Feb 2005
    Posts
    11,950
    The fact that iron is tough to fuse might allow it to be a useful fuel containing rod for future fusion star drives perhaps?
    A sacrificial rod for autophage rockets when bombarded?

  8. #8
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    38,007
    Quote Originally Posted by publiusr View Post
    The fact that iron is tough to fuse might allow it to be a useful fuel containing rod for future fusion star drives perhaps?
    A sacrificial rod for autophage rockets when bombarded?
    IIRC iron suffers neutron embrittlement.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  9. #9
    Join Date
    Feb 2005
    Posts
    11,950
    That would not be a problem if it is sacrificial—part of the fuel to be used up. If anything, that makes it easier to serve as a dissolving capsule of sorts. It holds an easier fuel to fuse, and is also spent/consumed, losing its field of a magnet...
    Last edited by publiusr; 2020-Sep-14 at 09:41 AM.

  10. #10
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    38,007
    Quote Originally Posted by publiusr View Post
    That would not be a problem if it is sacrificial—part of the fuel to be used up. If anything, that makes it easier to serve as a dissolving capsule of sorts. It holds an easier fuel to fuse, and is also spent/consumed, losing its field of a magnet...
    That sounds to me, more like the properties of how a chemical rocket works than nuclear fusion.

    We haven't even mastered the simplest form of fusion thruster, and we're already talking about using a method that Mother Nature has trouble with!
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  11. #11
    Join Date
    Sep 2020
    Posts
    1
    Quote Originally Posted by Noclevername View Post
    That sounds to me, more like the properties of how a chemical rocket works than nuclear fusion.

    We haven't even mastered the simplest form of fusion thruster, and we're already talking about using a method that Mother Nature has trouble with!
    Really? How about the current industry methods overseas?

  12. #12
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    38,007
    Quote Originally Posted by Nattan View Post
    Really? How about the current industry methods overseas?
    Are industries overseas using fusion rocket propulsion?
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  13. #13
    Join Date
    Jul 2005
    Location
    Massachusetts, USA
    Posts
    22,123
    The Original Post was about fusing Iron in stars. We got off track when publiusr speculated on a use for Iron as containment, and Noclevername replied. I have no idea what Nattan is talking about, but I'm asking that we try to get this back to the OP's topic, and if that has been answered, we can just leave this thread alone. If you'd like to discuss uses for Iron as relates to nuclear rockets, please start a new thread in an appropriate section. Thanks in advance.
    Forming opinions as we speak

  14. #14
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    38,007
    OK.
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

  15. #15
    Join Date
    Sep 2020
    Posts
    26
    And if we assume that in conditions of abnormally high temperature and gravity, the elements merge? Purely theoretically, is it possible for chemical elements over No. 145 to appear in the table? If we assume that somewhere far away in the Universe such processes are taking place that we do not even know about and do not assume. After all, we rely on the regularities available to our knowledge and in our assumptions we start from the known quantities.

Posting Permissions

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