1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    Gold Member

    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


    User Avatar
    Gold Member

    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
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook