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In a railgun the lorentz force causes an object to be propelled

  1. Aug 13, 2006 #1
    In a railgun the lorentz force causes an object to be propelled in a direction because of an electromagnetic force caused by running a current through the "rails". How come you can use aluminium or another such non-magnetic metal as both rails and armature? Surely only a magentic metal would work?
  2. jcsd
  3. Aug 13, 2006 #2

    Andrew Mason

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    You are interested in the ability of the metal to conduct electricity. The magnetic field is due to the current in the rail and projectile/armature. The design does not allow for the use of high permeability core material since there is no core.

  4. Aug 14, 2006 #3


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    First of all, Al is cheap/inexpensive.

    The effect is I x B, and B is induced by the currents in the rails, so a magnetic material is not necessary.

    Al is relatively low density (sg ~2.7) as compared to steel (sg ~ 8.0), so for the same size, the Al would have much less mass, and consequently for a given force, it would accelerate faster.

    I have seen railguns with copper rails which were used to fire steel projectiles - up to several km/s - for a relatively short gun.
  5. Aug 16, 2006 #4
    So, in english, what your saying is it doesnt have to be ferromagnetic to get a magnetic field. Thanks
  6. Aug 20, 2006 #5
    The magnetic field is produced by the current in the aluminum wire and NOT by a magnetic moment in a permanent magnet. Therefore, conductivity of the conductor is what is important, an Al is a very good conductor, and it is cheap.
  7. Oct 7, 2006 #6
    Why can't they use maglev to fire projectiles?

    No contact, no friction!
  8. Jan 29, 2007 #7
    Probably because you would have to have a very long vacuum tube from your device to your target for it to make any significant difference.
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