Over the past few millennia, we humans have been steadily perfecting more and more violent ways of hurting each other. At the same time, we've been almost as steadily perfecting more and more reliable ways of protecting ourselves.
We’re at the point where physical barrier technologies are capable of stopping most projectile weapons, so predictably, weapons that rely on shockwaves (that can pass through physical barriers) are becoming more prevalent. In response to this, Boeing has filed a patent on a system that can mitigate or prevent damage from an incoming shockwave, using electromagnetic arc generators. Here’s how it works.
When Boeing’s system detects a nearby explosion (a “shockwave producing event”), sensors calculate when the shockwave will arrive at the protected region (a vehicle, in this example) and from what direction. The system’s objective is to create an “intermediate medium” between the shockwave and the protected region that the shockwave will have to pass through. This medium is just a region of air with different temperature, density, or composition, that can attenuate the shockwave, reflecting and absorbing energy as it passes through.
The general concept is to use an electromagnetic arc to create this intermediate medium in mid-air on very short notice by using a stupendous amount of energy to heat the air into a plasma. Boeing has suggested several different ways in which an arc generator might be designed:
- Converging laser or microwave beams to generate a spherical region of plasma
- Lasers that induce plasma channels in the air, providing a path for an electric discharge to create a plasma
- Explosively launched metal pellets that leave conductive trails as they fly through the air, providing a path for an electric discharge to create a plasma
- Sacrifical conductors like wires or metal strips connected to the vehicle that can be vaporized to rapidly heat and ionize the air
- Magnetic induction fields with rigid channels of magnetic flux that can harvest current from energy absorbed from the passing shockwave to recharge the arc generator (!)
It’s tempting to call this a shield or a force field, but words like that are guaranteed to generate a completely incorrect mental picture what Boeing’s system does. The best way to think of this is as an active countermeasure that targets and mitigates specific incoming threats. To get a sense of how it might work in practice, here’s an old video of an active protection system called Iron Curtain that DARPA designed to shoot down RPGs at close range:
Replace the RPG with a shockwave and the countermeasures with arc generators, and you’d probably end up with something like what Boeing has in mind.
Boeing’s patent filing doesn't go into any detail about how well this system works. And it’s just a patent application: it doesn’t mean that Boeing is now, or will ever, build something like this. All it means is that the company thinks enough of the idea to try and protect it, so until we see a prototype, it’s best to remain skeptical.