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Optical (laser/maser) cooling of fusion products.

  1. Jun 28, 2009 #1
    Fusion raction produces high energy neutrons which cause activation of the walls of the reactor. Why can't their energy be collected by, for example, a microwave beam?
     
  2. jcsd
  3. Jul 3, 2009 #2

    Astronuc

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    Because neutrons do not respond to electromagnetic radiation at such low energies.
     
  4. Jul 6, 2009 #3

    mheslep

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    Astronuc, just curious: neutrons can respond to EM radiation at high enough energy because of ... the neutron's spin? What else is there?
     
  5. Jul 6, 2009 #4

    Redbelly98

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    There is the neutron's magnetic moment, as well as the charges of the individual quarks. Not sure which Astronuc had in mind though.
     
  6. Jul 6, 2009 #5

    mheslep

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    Which results from its spin?
     
  7. Jul 7, 2009 #6

    Redbelly98

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    As I understand it, it results from the spin and the fact that there is charge within the neutron's structure. If somebody else can confirm my thinking here, it would be appreciated.
     
  8. Jul 7, 2009 #7

    Astronuc

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    It's the internal structure (quarks), magnetic moment and spin - pretty much as expressed by Redbelly.

    I was prepared to say that neutrons don't interact with photons, but I've seen some articles on neutron-photon interactions. However, I don't believe there is much in the literature on photon interaction with free-neutrons, or neutrons as condensed matter. I caught one article on optically cooling neutrons, but I can't seem to locate the article.

    I was also pondering electro-weak interactions.

    I expect that photons have to be of very high energy - high (100's) MeV range - to have an appreciable effect on a neutron. The gamma photons we get from typical radio-nuclides or nuclear reactions have energies on the order of high keV up to <10 MeV.

    There was a discussion elsewhere in the forums about photons scattering of protons, as opposed to electrons or positrons, and I expect the cross-section for photon-neutron scattering to less than that of protons.
     
  9. Jul 27, 2009 #8
    Maybe, it's possible to boost the energy of photons by heating them with other gamma beams.
    Are there frequency converters for such wavelengths?
     
  10. Jul 27, 2009 #9

    Vanadium 50

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    And now your gammas are activating the walls.
     
  11. Jul 27, 2009 #10

    Redbelly98

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    Photon interaction can occur in nonlinear materials, but those methods and other frequency conversion methods are quite inefficient. You will use up much more energy in the conversion process than you would ever get from the neutrons that are to be captured, so it would be a pointless way of harnessing the neutron's energy.
     
  12. Aug 5, 2009 #11

    Substitute photons with protons or hydrogen atoms held in the shell around the reaction chamber?
     
  13. Sep 3, 2009 #12
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    Fusion raction produces high energy neutrons which cause activation of the walls of the reactor.
     
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