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Ionization by magnetization

  1. May 17, 2010 #1
    I'm interested in the question of what strength magnetic field you need to fully or partially ionize a neutral atom. I'm fairly sure this is possible but I'm not very familiar with quantum physics, atomic physics, solid state physics, and so on. I'm familiar with the "classical analog" calculations of things like the diamagnetic effect, but I have no idea how to proceed using a more accurate QM style analysis. Thanks in advance--
  2. jcsd
  3. May 17, 2010 #2


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    Can't be done for any realistic field.
    The spin magnetic moment of an electron (Bohr magneton) μB is ~ 5.8E-5 eV/T, the orbital magnetic moment is roughly on the same order (l*μB).

    The ionization energy for hydrogen (for instance) is -13.6 eV. So the required field strength to impart the energy required for ionization,
    would be on the order of hundreds of thousands of Teslas. Whereas the strongest superconducting magnets in the world are on the order of tens of Teslas.

    They can't even cause electronic transitions. Which is why it's quite safe to stick your head in an MRI machine.
  4. May 19, 2010 #3
    OK, gotcha. To summarize, I think you are saying that once the spin magnetic moment or orbital magnetic moment of the electron reaches the ionization energy, that is when (in principle) the electron would escape. Could you possibly comment on how the spin energy or orbital energy would cause an ionization/kickout event? In other words, how does the energy transfer from spin/orbital to ballistic?

    Incidentally, I've been looking into literature on the subject, and I think on neutron stars the fields can reach 10^12 Gauss or 10^8 Tesla, so this energy limit could possibly be reached in exotic circumstances. But aside from that, I think the ordinary elastic/inelastic collisions in a plasma, in conjunction with high magnetic field energized states, could lead to this kind ionization. Although to be fair that's not just the magnetic field anymore.
  5. May 19, 2010 #4


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    Magnetars might get as high as 10^14 gauss. Then real weird things can happen. Read this ref for an authoritative account: http://arxiv.org/abs/astro-ph/0002442

    As to ionization, think of the electron and the proton as two small magnets.
    Remember that they can be either parallel or anti-parallel.
    Then imagine the hydrogen atom approaching a third great big magnet, the magnetar.
    If the magnetic gradient pulls the electron away from the proton
    more strongly than the electric charges hold them together, ionization can occur.
    Oversimplified, but not too far wrong, I think.
    Jim Graber
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