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Linear Induction Coilgun with superconducting projectile

  1. May 9, 2016 #1
    If you have:
    A Linear Induction Coilgun, basically like a series of Induction Furnaces, using copper coils with high AC current at a high frequency.
    Where the projectile travelling inside those coils has a shorted superconducting coil around the outside of it, embedded in the ceramic projectile casing.

    A) Will the projectiles superconducting wire get hot?
    I would assume not since there is no resistance.
    B) Will metallic components or distilled water inside the projectile (within the superconducting coil) get currents induced in them or get hot?
    I would assume not since the superconducting coil is shielding them like a Faraday cage.

    See attached image.

    Attached Files:

  2. jcsd
  3. May 9, 2016 #2

    Paul Colby

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    Assuming this is a made up idealized problem and we're not trying to find new and wonderful ways of hurting each other, the super conductor should expel any applied field, no field no heat. If it is a real question then the superconductor would rapidly quench in the applied field. The resulting fireball would expand rapidly so be sure to duck.
  4. May 9, 2016 #3


    Staff: Mentor

    The OP does not say if the gun is in air or in a vacuum. If air, the superconductor needs very good insulation to avoid warming by the friction heated air.
  5. May 9, 2016 #4
    Sorry it is in a vacuum.
    Pre-cooled and transit through the barrel is less than a second.
  6. May 16, 2016 #5
    No answers?
    Put more simply:

    If you induce eddy currents in a superconductor using a strong magnetic field, does the superconductor heat up at all?
    Last edited: May 16, 2016
  7. May 16, 2016 #6
    Or can you not really induce eddy currents due to the Meissner effect??

    It would be a Niobium-titanium superconductor by the way, so that is Type II.
    Last edited: May 16, 2016
  8. May 16, 2016 #7

    Paul Colby

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    Gold Member

    Sorry, I didn't realize this was a test. The reply I gave is still correct.
  9. May 16, 2016 #8


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    The surface of a superconductor is a perfect reflector of magnetic fields. A current will flow on the surface of the superconductor that generates the exactly equal and opposite magnetic field needed to cancel the incident field. So you cannot use a magnetic field to induce a current inside a superconductor, only a current on the surface.
    There will be physical forces between the magnet conductor and superconductor resulting from the magnetic field. If movement occurs then electrical energy will be converted to kinetic or potential energy, but not to heat in the superconductor.
    Since no energy enters the superconductor it will not be heated. If a superconductor was heated it would become a resistor and the scenario would change instantly.
  10. May 16, 2016 #9
    Got it, thanks guys.
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