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Gamma Ray Laser, possible? Superior Weapon?

  1. Nov 9, 2012 #1
    Hello there. I am wondering if anyone can shed some light on this topic. I am searching all over the Internet to find reliable sources on the possibility of gamma ray lasers. I know that it requires an atom that can be "pumped" without spontaneously emitting its energy so it can be triggered by stimulated emission to provide photons to lase.
    Also I can't seem to find reliable solid physics on the factors associated with the melting and vaporisation depth of lasers. This is required to make my own decision about the gamma ray laser being a superior weapon as it will allow me to calculate what materials it can burn through and timings etc.

    If anyone could offer any help that would be fantastic!
     
  2. jcsd
  3. Nov 9, 2012 #2

    Drakkith

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    I don't think there is any way to make a gamma-ray laser at this time. Gamma rays are extremely high energy, typically thousands to millions of electron-volts per photon, compared with 1.5-3 electron-volts per photon for visible light. By the time you get to gamma-ray energy levels, you no longer have atoms in a gaseous or solid state, but in a plasma or near-plasma state.

    Also, have you considered that gamma-rays can simply pass right through many materials without even doing damage to them? For example, your gamma-ray laser may pass right through your target and only have a few photons even hit the target. This would make it a very bad weapon.
     
  4. Nov 9, 2012 #3

    K^2

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    Actually, that's what makes it a great weapon. Sure, only a small energy gets deposited, so it won't do any physical damage. But it will fry any electronics or persons it passes through, provided beam has enough power, and there is no way to stop it.

    But, of course, that's also what makes it so difficult to make an actual laser. You need each photon to pass through a great length of lasing medium. That's typically achieved with mirrors. Know mirrors that work in gamma ranges? Me neither. Your other alternative is to have a very, very long lasing medium. That's possible, in principle, but now you need to pump that entire medium all at once.

    There are sufficiently meta-stable states in nuclei to allow population inversion you need for lasing, but they don't live long. So you need to pump a very, very long rod of some material with hard gamma radiation all at once. Pretty much the only way to do this is to detonate a whole bunch of nuclear weapons along the length.

    There have been some research done on this by US and Soviets during cold war. It wasn't a total failure, but a practical weapon was never produced by either side.

    US has also done research on trying to pump the lasing medium with nuclear reactions along the length. That could have yielded a weapon. To the best of my knowledge, these experiments have failed.
     
  5. Nov 10, 2012 #4

    sophiecentaur

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    Did you consider how difficult it could be to make the mirrors for each end of the laser? :biggrin:
     
  6. Nov 10, 2012 #5

    mfb

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    There are X-ray lasers which use synchrotron radiation of electrons. I think the same concept could be used to generate higher photon energies, but I doubt that this would make a big difference.
    They need big particle accelerators, so I doubt that they can be used as (mobile) weapon.
     
  7. Nov 10, 2012 #6

    K^2

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    Military looked into use of undulators for production of high power x-ray beams. Requirement of a cyclotron to feed one of these, however, made the whole thing impractical.
     
  8. Nov 10, 2012 #7

    sophiecentaur

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    Lasers are not very efficient (electrically powered lasers, that is) so a useful military laser needs to use a chemical energy source. The plane mounted one in the US was a chemical laser.
    I think the same problem would exist for other, higher frequency weapons.
     
  9. Nov 10, 2012 #8

    ZapperZ

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    The high-intense x-ray laser using accelerators are generated from FELs. There are already production of gamma rays using such a facility, but, this does not produce a "laser".

    http://www.fel.duke.edu/papers/gamma_ray_production_1997.pdf

    (Pssst! This is another area of application in Accelerator Physics!)

    Zz.
     
  10. Nov 10, 2012 #9

    K^2

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    Or you can simply have a power source that's several orders of magnitude better than chemical. Like nuclear, for example. They have built nuclear reactors that can be flown on an airplane. So that's not really a problem.
     
  11. Nov 10, 2012 #10

    sophiecentaur

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    If you have enough power to spare then, yes, why not? There are some details, though . . .
    What about screening for the crew? You'd have the reactor at the end of the wings perhaps. What about crash risk? It's an interesting engineering problem. Do you have a reference?
     
  12. Nov 10, 2012 #11

    K^2

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    Pretty much the reasons I've heard for not using them. But a few experiments were done by both US and the Soviets. Most notable is the Crusader.
     
  13. Nov 10, 2012 #12
    Whom do you wish to kill with this hypothetical weapon, and why?
     
  14. Nov 11, 2012 #13
    "Whom do you wish to kill with this hypothetical weapon, and why?"

    Now that would be telling! I would like to see a decent system in place to destroy nuclear missiles in the boost phase though, haha.

    Does anyone have any idea/reference of how powerful a gamma ray laser beam would be? What would be the destructive power?

    Would it burn a whole through a person? How fast would it burn through steel? I know basics found on a laser drilling website using latent heats of the different states but I can't find any decent physics to quote.

    Very interesting comment about the mirror problem. But the same applies. What properties would the mirror need to be protected against the beam?

    Also the range of the beam... Several factors effect this in current lasers. I know the Airborune Laser Testbed is being scrapped due to its inefficient range meaning that a Boeing 747 would have to be airborne behind enemy lines to be effective.

    (reference for laser cutting rates http://alumni.media.mit.edu/~yarin/laser/physics.html)
     
    Last edited: Nov 11, 2012
  15. Nov 11, 2012 #14

    Drakkith

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    I don't think you could burn a hole through anything with a gamma-ray laser. I would expect only a small portion of the energy would even be deposited into the target, and even then it would be spread out along the beam path through the target. Gamma-rays are simply too penetrating.
     
  16. Nov 11, 2012 #15
    Interesting. So in terms of being a "Superior weapon", do you think it would have any uses?
    Baring in mind the full range of wavelengths in the gamma ray region.
     
  17. Nov 11, 2012 #16

    Drakkith

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    Gamma-rays striking the inner workings of the electronics of something could cause errors in the computations I believe.
     
  18. Nov 11, 2012 #17
    Do you know the physics behind this? Or any reference material? That sounds interesting, but not something I am having ease searching for...
    Forgive me if you find material on this after one search term in google, but I sure can't.

    Also, thank you for your input. Greatly appreciated.
     
  19. Nov 11, 2012 #18

    Drakkith

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  20. Nov 11, 2012 #19
    There's no advantage in using gamma rays to burn things, a 1kW visible/IR laser would be far more effective than a gamma ray laser of the same power for burning things.
    The only uses I see are damaging radiation sensitive equipment as stated and giving people radiation induced illness..

    I wonder though, is there any theoretical limit on the energies of a FEL? Could it produce a beam of the order of 100MeV?
     
  21. Nov 11, 2012 #20
    Could pair production limit these high energy beams? Radiation induced illness would surely be deemed illegal as it has no combat effectiveness and huge ethical problems.
    What would you use the 100MeV beam for? Maybe something fusion or imaging based?
     
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