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Energy shields

  1. Oct 8, 2014 #1
    So being a Star Wars buff I can't help but wonder if it would be possible to make a similar type of energy shield as per what are mentioned in the vast collection of Star Wars books out there, any thoughts anybody?
     
  2. jcsd
  3. Oct 9, 2014 #2
    A magnetic field will deflect ions, and can also confine a plasma. In principle, one could set up a plasma shell around a spaceship. How effective it would be at shielding is questionable. If the plasma is dense enough (so that the plasma frequency is higher than the laser frequency), it can reflect lasers. It could probably destroy incoming rockets, if the shell were big and dense enough. Slugs might be harder to stop, but in principle, they could be vaporized and plasmafied if the shield has enough power. Neutron beams can probably penetrate pretty easily.

    It seems likely that weapons development will stay a few steps in front of shields..
     
  4. Oct 9, 2014 #3

    Drakkith

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    I can't say that energy shields are impossible, but I can say that the concept is so far beyond out technical capability that we don't even know how to theoretically make them. Even Khashishi's idea is essentially speculation since there is no known way to confine a plasma using a magnetic field in this manner.
     
  5. Oct 9, 2014 #4

    Matterwave

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    I think it would be more accurate to say that we don't know how to create the magnetic fields required that could do the job. We contain plasma all the time inside tokamaks and in our fusion experiments. The problem is, we need a ring of physical super-magnets to create the fields necessary, and even then, there's still a lot of drift and such that are problematic. But confining plasma using magnetic fields is a quite well studied subject in plasma physics.
     
  6. Oct 9, 2014 #5

    Drakkith

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    That's pretty much exactly what I was saying. ;)
     
  7. Oct 9, 2014 #6

    Matterwave

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    Sure, I was just trying to make things a little clearer, because I think an uninformed person might read from your post that plasmas can't be confined by magnetic fields. I'm not saying that's what you said, I'm just trying to make the point more explicit is all. :)
     
  8. Oct 10, 2014 #7
    On the scale of science fiction, I'd say it's very plausible. We'll probably solve all the issues of magnetic confinement before we get to the starship stage. Assuming starships run on fusion power, there will be some energy to power magnetic coils. But weapons will be so powerful that this type of shield might not be useful.
     
  9. Oct 10, 2014 #8

    Drakkith

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    I have my doubts. The main issue is that current confinement methods rely on magnets that are external to the contained plasma. Energy shields are typically portrayed as being on the outside of a ship, so you'd have to find a way to confine the plasma using magnets that are inside the volume enclosed by the plasma. I don't really expect this to be a possibility since this leads to a magnetic field that would push the plasma away from the ship, not contain it. I'm not saying it's an impossibility to develop shields, but you simply aren't going to do it using traditional magnetic confinement methods.
     
  10. Oct 10, 2014 #9
    What if they have an external net of magnets, like an anti torpedo net? (Of course if they hit the net a part of the shield will fail)
     
  11. Oct 10, 2014 #10

    Drakkith

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    Then you're containing the plasma within the net of magnets, but you aren't creating a shield, just a big cloud of confined plasma with a ship in the middle. Without some kind of crazy breakthrough in physics, you simply can't create energy/plasma shields.
     
  12. Oct 10, 2014 #11
    Not necessarily a breakthrough, but a way to store over time and instantly release large quantities of energy. Like some sort of super-capacitors.
     
  13. Oct 10, 2014 #12

    DHF

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    As stated Earlier, Weapon's development will likely outpace defense. For example in said scenario with a ship using a plasma shield. Wouldn't said ship still be very vulnerable to an enemy firing fusion warhead and detonating it a few feet from the shield? wouldn't the blast wave penetrate the shield?
     
  14. Oct 10, 2014 #13
    Building an external magnetic field is not a problem at all. A simple dipole field will confine plasma to some extent. The Earth has an external magnetic field which shields us from cosmic rays. There are actually some fusion experiments set up this way (Levitated Dipole Experiment), although work has stalled.
     
  15. Oct 10, 2014 #14
    IMHO the best defence against kinetics (nukes, hypervelocity stuff) is point range defence, they can penetrate any shielding, probably one rather want an anti beam weapon shield, above reflective armor.
    (As far as i know even in SW, W40k, kinetics are quite able to take out almost anything. The point is that your attack craft have to get them close.)
     
  16. Oct 10, 2014 #15

    Matterwave

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    Although we might contain plasmas only using external magnets, the Earth contains some plasma in its Van Allen belt, and the Earth's dynamo is well inside its core baby. http://en.wikipedia.org/wiki/Van_Allen_radiation_belt

    So I wouldn't say it's all THAT far fetched that we could design something similar to do something with magnetic fields.
     
  17. Oct 11, 2014 #16

    Drakkith

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    But that doesn't help if there's no way to contain the plasma.

    Neither of these are confining the plasma in any way like you would need to in order to make a "plasma shield" on the outside of ship.
     
  18. Oct 11, 2014 #17

    Matterwave

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    Why do you say this? One, the magnetic field itself protects our Earth from harmful solar winds, and two, a diffuse plasma is trapped inside the Van-Allan belt. Of course this is not the same as a plasma shield, but it gives credence to the idea that magnetic fields in a dipole configuration can be used to contain plasmas. One MIGHT not necessarily require a solenoidal/toroidal magnetic field.

    Of course we are talking about science fiction, so I don't think anyone is saying a "plasma shield" is possible right now with our technology. In fact I think in my earlier post I stated clearly that we don't know how to make such a configuration possible.
     
  19. Oct 11, 2014 #18

    Drakkith

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    I don't see how you're coming to this conclusion. I don't see anything that suggests that plasma can be contained using an internal configuration of magnets. In fact, knowing a little about how magnetic confinement works, I see nothing but the very opposite, that it isn't possible. The protection the magnetic field of the Earth provides is due to the fact that charged particles are forced away from the increasing magnetic field, not towards.
     
  20. Oct 11, 2014 #19

    Matterwave

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    The charged particles come from the Sun, and they are trapped within the Van-Allen belts, oscillating between the North and South poles. When the charged particles move to the poles you get the Auroras. They are trapped along the magnetic field lines just as a charged particle inside a tokamak is trapped in a torus, along the field lines. The charged particles spiral long the field lines in partial cyclotronic motion. Certainly there is drift of these particles, and they don't stay trapped perfectly. We also can't trap particles in tokamaks perfectly either. In both cases, particle drift is a big problem. In a tokamak, a poorly contained plasma means having to change your heat shielding.

    There's no inherent difference in the principle that charged particles spiral along magnetic field lines (cyclotron motion) between a solenoidal/toroidal field produced by external magnets, and a dipole field produced by an internal dynamo.
     
  21. Oct 11, 2014 #20

    Drakkith

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    I'm sorry I'm not seeing any connection between particles spiraling around field lines and being able to contain a plasma. In the tokamaks case, the magnets our on the outside and it's still extremely difficult...
     
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