I've heard that we are developing plasma launchers capable of firing unstable plasma toroids for now (at least from what I heard). Admitting that the said projectile would be stable, would it be viable to make underwater anti-ship mines? The device would launch the projectile upwards and the projectile would hit the ship. The questions are :

  • Wouldn't the plasma cool down too fast to be effective?
  • Wouldn't water slow down the plasma too much?
  • Would the Archimedes' principle accelerate the plasma or at least counter the water's resistance?
  • Would the plasma's energy be sufficient to damage a ship?
  • Would it be easily counter-able by any material or countermeasures?
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    • $\begingroup$ There was a question where someone said that plasma weapons were impossible. And we already have highly effective sea mines and depth charges, if all else fails get a nuke and shoot it underwater. Btw plasma is at least a few thousand degree Celsius, it might just boil a small lake so at least it won't cool down too fast. A theory of mine is that plasma would explode out underwater due to it's heat causing its electrons to expand out fast. $\endgroup$
      – Skye
      Sep 8, 2016 at 13:18
    • $\begingroup$ I would also add that some underwater weapons are arguably far more interesting than "Mere" plasma - howabout a missile that creates its own airpocket? The latest breed of high-tech torpedoes do exactly that! $\endgroup$
      – Miller86
      Sep 8, 2016 at 13:22
    • $\begingroup$ @Sky - Plasma weapons are not impossible, just not feasible (at least right now). They have been demonstrated. The problem is that they shoot a very small amount of material. The last-known projectile size I could find was 1-2mg (though that was from '93). Definitely not enough to boil a lake. $\endgroup$
      – GrinningX
      Sep 8, 2016 at 13:23
    • $\begingroup$ @GrinningX OP didn't specify the amount of plasma. I would assume that a effective plasma mine would have that much power. $\endgroup$
      – Skye
      Sep 8, 2016 at 13:24
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      $\begingroup$ @MichaelKarnerfors This question is asking about the development/feasibility/functionality of a device, which is on-topic. Just because a device may, at some point, exist in the real world doesn't make it off-topic here. $\endgroup$
      – Frostfyre
      Sep 8, 2016 at 13:52

    1 Answer 1


    They Would Not Be Particularly Effective

    This took some research, but I think I found a link that gives at least a bit of an answer. Note though that most of the actual work on the topic is classified, so it's entirely possibly that feasibility has changed.

    This link discusses the actual explosive yield that plasma toroid weapons were forecasted to carry by the year 2000 - an amount equal to about 5 pounds of TNT under lab conditions. Being fired at a great distance (presumably) and underwater, the yield should certainly be less than that (if not 0).

    At that point I think it's safe to say there are better real-world alternatives, considering that WWII-era sea mines had 80+kg (176lbs) of explosives in them. And obviously today we can make even better explosives than we could 70 years ago.

    In addition, the size, cost, and complexity of the plasma launchers makes them totally unfit for an underwater application.

    • $\begingroup$ Admitting we would have the technology to make plasma launchers small and powerful enough, would it be viable? Of course there are better weapons, but would this system be practical? $\endgroup$
      – Hawker65
      Nov 9, 2016 at 15:40

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