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Railgun Plasma Plume

  1. Feb 5, 2012 #1

    I've seen a video of the US navy test firing a rail gun and in the video there is a plasma plume that follows the projectile. I am unsure of what exactly is causing the plasma plume... specifically:

    • Is it the electrical energy passing through the rails that ignites the air and causes the plasma?
    • Is it leftover magnetic charge on the projectile that ignites the air as it moves and causes the plasma plume?
    • I'm guessing it is not merely due to the velocity of the projectile but is mach 7 enough to cause just the friction of the projectile against the atmosphere to cause a plasma plume?

    And also, for how long would one expect there to be a plasma plume following the projectile?
  2. jcsd
  3. Feb 5, 2012 #2


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    1] How do you know it's a plasma plume?
    2] If you could link to a video, we could see what you are talking about.
  4. Feb 5, 2012 #3
  5. Feb 5, 2012 #4


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    Damned thing won't play for me. :grumpy:
    My first thought would be that it's remnants of the "shot cup". With non-magnetic projectiles, a railgun vapourizes a sample of something that is then accelerated and pushes the payload ahead of it. Perhaps the power used in this case is sufficient to turn the material into a plasma rather than just a gas? I don't know a lot about the subject, though.

    edit: Sorry... I generalized. In some cases, an actual open-ended container is used for a non-reactive warhead, something like a saboted bullet in a firearm. What I was talking about is a bridge wire (which I think is copper) that the launching current passes through and detonates before magnetizing the rails.
    Last edited: Feb 5, 2012
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