Could a Shield of Hot Air Block Shockwaves?

Method and system for shockwave attenuation via electromagnetic arc / U.S. Patent Office
Janet Fang 28 Mar 2015, 23:02

Last week, an engineer with Boeing was issued a patent (US 8,981,261) for a “shockwave attenuation” system that seems to work like an invisible shield of super hot air to protect soldiers by dampening shockwaves from explosions.

Brian Tillotson got the idea after noticing the sorts of injuries suffered by soldiers serving in Iraq and Afghanistan. "We were doing a much better job of stopping shrapnel," Tillotson tells Live Science. "But they were coming home with brain injuries." Armored doors and plating on vehicles might stop debris and metal fragments that result from an IED, for example, but the shockwaves that are generated go right through physical barriers, as well as human bodies.

The system intercepts shockwaves with a shield of heated, ionized air, Live Science explains, changing the speed at which the intense waves travel and forcing them to bend around objects. The process resembles the way lenses bend light, Tillotson adds.

The system consists of two major components: a sensor and an arc generator. When the sensor detects a shockwave-producing event, it determines the distance and direction of the shockwave relative to the target being defended—a vehicle carrying soldiers, for example. This communicates with an “arc generator,” which is basically two ends of a circuit connected to a large power source, Live Science explains. With enough current, an electric arc travels between the two ends of the circuit, and its this electric arc that heats and charges the particles of air. 

Certain waves propagate faster in hotter air. So when the shockwave hits the hot-air shield, it speeds up and changes direction slightly—away from the object behind the arc. "With a convex lens you focus the light," Tillotson says. On the other hand, "a concave lens spreads it out." And as it spreads, it becomes weaker and deflected as a result. 
    
Besides arc generators, the air can also be heated with lasers and microwave beams. You can read the full patent description here

Image: U.S. Patent and Trademark Office

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