I stand corrected. Mod parent up. Mod me down if you like.
With each of the embodiments discussed, the system 10 is deployed to attenuate the energy of an advancing shockwave 24 form an explosion 22 by creating a second fluid medium 30 that differs from the first fluid medium 26, which may be ambient air, positioned so that it interacts with the shockwave. As shown in FIG. 10, as the shockwave contacts the interface 90 between the first fluid medium 26 and the second fluid medium 30, the difference in refractive index reflects a fraction of the incoming energy toward the explosion 22, as indicated by arrows A. This partial reflection occurs a second time as the shockwave passes through the second fluid medium 30 and contacts the interface 92 between the second medium and the ambient 26 as it exits the second medium. All gradients or discontinuities in the medium provide a reflection point for the incoming shockwave 24. For example, if the second medium 30 is non-uniform, reflection will occur at each of many places within the medium.
As shown in FIG. 11, shockwaves 24 obey Fermat's theory of least time and therefore an effective refractive index for the shockwave can be defined that is inversely proportional to the shock speed. The properties or composition of the second medium 30 are chosen such that the effective refractive index of the second medium 30 differs from the first medium 26 in at least one of temperature, molecular weight and composition. As the shockwave passes into or out of the second medium 30, the difference in effective refractive index refracts the wave, as shown by lines B, diverting it and defocusing it away from the protected asset 18. In the disclosed embodiments, the second medium 30 is created such that the shockwave travels faster in the second medium 30 than in the first medium 26, so the refractive index of the second medium is less than that of the first medium. Further, the second medium is created to have a convex shape and therefore acts as a divergent lens, so that the energy of the shockwave 24 spreads out, as shown by lines C, so its intensity drops as it approaches the protected asset 18.
In addition, the second medium 30 may absorb some shock energy as the shock travels through it. Factors contributing to the absorption of energy include energy retained in the molecules of the second medium itself (e.g., enhanced rotational energy, excited molecular bonds, excited electrons, molecular decomposition, and ionization) and shock energy converted to electromagnetic energy through blackbody emission from hot particles or photon emission from de-exciting various excited states.
A further mechanism for attenuating the energy density of the shockwave 24 is momentum exchange. If the second medium 30 is moving relative to the first medium 26, then it will exchange momentum with the shockwave 24. The result is a combination of reflection, slowing, and redirection of the shockwave. Any or all of the foregoing mechanisms may operate in a given embodiment. The composition, temperature, speed and location of the second medium 30 may be chosen or created to create any one or all of the aforementioned mechanisms.
So, it's not necessarily lasers that generate the plasma, and the protection comes mainly from the plasma having a different refractive index than the air through which the shock wave has propagated.
My comment that this serves as a "counter-wave" is in the patent but only as a "it might also do this" thing, not as the main thing.
Countering a shock wave with a generated one would be horribly complex.
I never thought they were trying to cancel out the explosion with another explosion whose sound waves have opposite phase to the first.
I tried to read TFA and figure out what the invention really did. You are right, going to the actual patent text was a better idea. That article did not do a good job of explaining the science.